libbpf: fix array_size.cocci warning #112
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=620666 irrelevant now. Closing PR. |
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The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 16, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 16, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 17, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 17, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 17, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 17, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 18, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 18, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 18, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 18, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 18, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 21, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 22, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 22, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 22, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 23, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 23, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 24, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 29, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 31, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
kernel-patches-bot
pushed a commit
that referenced
this pull request
Mar 31, 2022
The BPF STX/LDX instruction uses offset relative to the FP to address
stack space. Since the BPF_FP locates at the top of the frame, the offset
is usually a negative number. However, arm64 str/ldr immediate instruction
requires that offset be a positive number. Therefore, this patch tries to
convert the offsets.
The method is to find the negative offset furthest from the FP firstly.
Then add it to the FP, calculate a bottom position, called FPB, and then
adjust the offsets in other STR/LDX instructions relative to FPB.
FPB is saved using the callee-saved register x27 of arm64 which is not
used yet.
Before adjusting the offset, the patch checks every instruction to ensure
that the FP does not change in run-time. If the FP may change, no offset
is adjusted.
For example, for the following bpftrace command:
bpftrace -e 'kprobe:do_sys_open { printf("opening: %s\n", str(arg1)); }'
Without this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: mov x25, sp
1c: mov x26, #0x0 // #0
20: bti j
24: sub sp, sp, #0x90
28: add x19, x0, #0x0
2c: mov x0, #0x0 // #0
30: mov x10, #0xffffffffffffff78 // #-136
34: str x0, [x25, x10]
38: mov x10, #0xffffffffffffff80 // #-128
3c: str x0, [x25, x10]
40: mov x10, #0xffffffffffffff88 // #-120
44: str x0, [x25, x10]
48: mov x10, #0xffffffffffffff90 // #-112
4c: str x0, [x25, x10]
50: mov x10, #0xffffffffffffff98 // #-104
54: str x0, [x25, x10]
58: mov x10, #0xffffffffffffffa0 // #-96
5c: str x0, [x25, x10]
60: mov x10, #0xffffffffffffffa8 // #-88
64: str x0, [x25, x10]
68: mov x10, #0xffffffffffffffb0 // #-80
6c: str x0, [x25, x10]
70: mov x10, #0xffffffffffffffb8 // #-72
74: str x0, [x25, x10]
78: mov x10, #0xffffffffffffffc0 // #-64
7c: str x0, [x25, x10]
80: mov x10, #0xffffffffffffffc8 // #-56
84: str x0, [x25, x10]
88: mov x10, #0xffffffffffffffd0 // #-48
8c: str x0, [x25, x10]
90: mov x10, #0xffffffffffffffd8 // #-40
94: str x0, [x25, x10]
98: mov x10, #0xffffffffffffffe0 // #-32
9c: str x0, [x25, x10]
a0: mov x10, #0xffffffffffffffe8 // #-24
a4: str x0, [x25, x10]
a8: mov x10, #0xfffffffffffffff0 // #-16
ac: str x0, [x25, x10]
b0: mov x10, #0xfffffffffffffff8 // #-8
b4: str x0, [x25, x10]
b8: mov x10, #0x8 // #8
bc: ldr x2, [x19, x10]
[...]
With this patch, jited code(fragment):
0: bti c
4: stp x29, x30, [sp, #-16]!
8: mov x29, sp
c: stp x19, x20, [sp, #-16]!
10: stp x21, x22, [sp, #-16]!
14: stp x25, x26, [sp, #-16]!
18: stp x27, x28, [sp, #-16]!
1c: mov x25, sp
20: sub x27, x25, #0x88
24: mov x26, #0x0 // #0
28: bti j
2c: sub sp, sp, #0x90
30: add x19, x0, #0x0
34: mov x0, #0x0 // #0
38: str x0, [x27]
3c: str x0, [x27, #8]
40: str x0, [x27, #16]
44: str x0, [x27, #24]
48: str x0, [x27, #32]
4c: str x0, [x27, #40]
50: str x0, [x27, #48]
54: str x0, [x27, #56]
58: str x0, [x27, #64]
5c: str x0, [x27, #72]
60: str x0, [x27, #80]
64: str x0, [x27, #88]
68: str x0, [x27, #96]
6c: str x0, [x27, #104]
70: str x0, [x27, #112]
74: str x0, [x27, #120]
78: str x0, [x27, #128]
7c: ldr x2, [x19, #8]
[...]
Signed-off-by: Xu Kuohai <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]
kernel-patches-daemon-bpf-rc bot
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Nov 27, 2023
With latest upstream llvm18, the following test cases failed: $ ./test_progs -j #13/2 bpf_cookie/multi_kprobe_link_api:FAIL #13/3 bpf_cookie/multi_kprobe_attach_api:FAIL #13 bpf_cookie:FAIL #77 fentry_fexit:FAIL #78/1 fentry_test/fentry:FAIL #78 fentry_test:FAIL #82/1 fexit_test/fexit:FAIL #82 fexit_test:FAIL #112/1 kprobe_multi_test/skel_api:FAIL #112/2 kprobe_multi_test/link_api_addrs:FAIL ... #112 kprobe_multi_test:FAIL #356/17 test_global_funcs/global_func17:FAIL #356 test_global_funcs:FAIL Further analysis shows llvm upstream patch [1] is responsible for the above failures. For example, for function bpf_fentry_test7() in net/bpf/test_run.c, without [1], the asm code is: 0000000000000400 <bpf_fentry_test7>: 400: f3 0f 1e fa endbr64 404: e8 00 00 00 00 callq 0x409 <bpf_fentry_test7+0x9> 409: 48 89 f8 movq %rdi, %rax 40c: c3 retq 40d: 0f 1f 00 nopl (%rax) and with [1], the asm code is: 0000000000005d20 <bpf_fentry_test7.specialized.1>: 5d20: e8 00 00 00 00 callq 0x5d25 <bpf_fentry_test7.specialized.1+0x5> 5d25: c3 retq and <bpf_fentry_test7.specialized.1> is called instead of <bpf_fentry_test7> and this caused test failures for #13/#77 etc. except #356. For test case #356/17, with [1] (progs/test_global_func17.c)), the main prog looks like: 0000000000000000 <global_func17>: 0: b4 00 00 00 2a 00 00 00 w0 = 0x2a 1: 95 00 00 00 00 00 00 00 exit which passed verification while the test itself expects a verification failure. Let us add 'barrier_var' style asm code in both places to prevent function specialization which caused selftests failure. [1] llvm/llvm-project#72903 Signed-off-by: Yonghong Song <[email protected]>
kernel-patches-daemon-bpf-rc bot
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Nov 27, 2023
With latest upstream llvm18, the following test cases failed: $ ./test_progs -j #13/2 bpf_cookie/multi_kprobe_link_api:FAIL #13/3 bpf_cookie/multi_kprobe_attach_api:FAIL #13 bpf_cookie:FAIL #77 fentry_fexit:FAIL #78/1 fentry_test/fentry:FAIL #78 fentry_test:FAIL #82/1 fexit_test/fexit:FAIL #82 fexit_test:FAIL #112/1 kprobe_multi_test/skel_api:FAIL #112/2 kprobe_multi_test/link_api_addrs:FAIL [...] #112 kprobe_multi_test:FAIL #356/17 test_global_funcs/global_func17:FAIL #356 test_global_funcs:FAIL Further analysis shows llvm upstream patch [1] is responsible for the above failures. For example, for function bpf_fentry_test7() in net/bpf/test_run.c, without [1], the asm code is: 0000000000000400 <bpf_fentry_test7>: 400: f3 0f 1e fa endbr64 404: e8 00 00 00 00 callq 0x409 <bpf_fentry_test7+0x9> 409: 48 89 f8 movq %rdi, %rax 40c: c3 retq 40d: 0f 1f 00 nopl (%rax) ... and with [1], the asm code is: 0000000000005d20 <bpf_fentry_test7.specialized.1>: 5d20: e8 00 00 00 00 callq 0x5d25 <bpf_fentry_test7.specialized.1+0x5> 5d25: c3 retq ... and <bpf_fentry_test7.specialized.1> is called instead of <bpf_fentry_test7> and this caused test failures for #13/#77 etc. except #356. For test case #356/17, with [1] (progs/test_global_func17.c)), the main prog looks like: 0000000000000000 <global_func17>: 0: b4 00 00 00 2a 00 00 00 w0 = 0x2a 1: 95 00 00 00 00 00 00 00 exit ... which passed verification while the test itself expects a verification failure. Let us add 'barrier_var' style asm code in both places to prevent function specialization which caused selftests failure. [1] llvm/llvm-project#72903 Signed-off-by: Yonghong Song <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
kernel-patches-daemon-bpf-rc bot
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Dec 25, 2023
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
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Jan 3, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
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Jan 3, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
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Jan 3, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
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Jan 3, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
pushed a commit
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Jan 3, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
pushed a commit
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Jan 3, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
pushed a commit
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Jan 4, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
kernel-patches-daemon-bpf-rc bot
pushed a commit
that referenced
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Jan 4, 2024
If CONFIG_BPF_JIT_ALWAYS_ON is not set and bpf_jit_enable is 0, there exist 6 failed tests. [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL #107/p inline simple bpf_loop call FAIL #108/p don't inline bpf_loop call, flags non-zero FAIL #109/p don't inline bpf_loop call, callback non-constant FAIL #110/p bpf_loop_inline and a dead func FAIL #111/p bpf_loop_inline stack locations for loop vars FAIL #112/p inline bpf_loop call in a big program FAIL Summary: 505 PASSED, 266 SKIPPED, 6 FAILED The test log shows that callbacks are not allowed in non-JITed programs, interpreter doesn't support them yet, thus these tests should be skipped if jit is disabled, just return -ENOTSUPP instead of -EINVAL for pseudo calls in fixup_call_args(). With this patch: [root@linux bpf]# echo 0 > /proc/sys/net/core/bpf_jit_enable [root@linux bpf]# ./test_verifier | grep FAIL Summary: 505 PASSED, 272 SKIPPED, 0 FAILED Signed-off-by: Tiezhu Yang <[email protected]>
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Pull request for series with
subject: libbpf: fix array_size.cocci warning
version: 1
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=620666