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i#3956 arm locks: Use release-acquire atomics (#4254)
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Replaces ldxr..stxr with ldaxr..stlxr in the atomic sequences used to
implement DR's mutexes.  DR's mutexes, and its other atomic
operations, assume release-acquire memory ordering.

Fixes #3956
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@derekbruening
derekbruening authored Apr 17, 2020
1 parent 686229c commit 0f15b50
Showing 1 changed file with 10 additions and 10 deletions.
20 changes: 10 additions & 10 deletions core/arch/arch_exports.h
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Original file line number Diff line number Diff line change
Expand Up @@ -695,9 +695,9 @@ atomic_add_exchange_int64(volatile int64 *var, int64 value)
{ \
type tmp1; \
int tmp2; \
__asm__ __volatile__("1: ldxr %" r "0, [%x2] \n\t" \
__asm__ __volatile__("1: ldaxr %" r "0, [%x2] \n\t" \
" " op " %" r "0, %" r "0, #1 \n\t" \
" stxr %w1, %" r "0, [%x2] \n\t" \
" stlxr %w1, %" r "0, [%x2] \n\t" \
" cbnz %w1, 1b \n\t" \
: "=&r"(tmp1), "=&r"(tmp2) \
: "r"(var)); \
Expand All @@ -716,9 +716,9 @@ DEF_ATOMIC_incdec(ATOMIC_INC_int, int, "w", "add") DEF_ATOMIC_incdec(ATOMIC_INC_
{ \
type tmp1; \
int tmp2; \
__asm__ __volatile__("1: ldxr %" r "0, [%x2] \n\t" \
__asm__ __volatile__("1: ldaxr %" r "0, [%x2] \n\t" \
" add %" r "0, %" r "0, %" r "3 \n\t" \
" stxr %w1, %" r "0, [%x2] \n\t" \
" stlxr %w1, %" r "0, [%x2] \n\t" \
" cbnz %w1, 1b \n\t" \
: "=&r"(tmp1), "=&r"(tmp2) \
: "r"(var), "r"(val)); \
Expand All @@ -734,9 +734,9 @@ DEF_ATOMIC_incdec(ATOMIC_INC_int, int, "w", "add") DEF_ATOMIC_incdec(ATOMIC_INC_
{ \
type ret; \
int tmp; \
__asm__ __volatile__("1: ldxr %" reg "1, [%x2] \n\t" \
__asm__ __volatile__("1: ldaxr %" reg "1, [%x2] \n\t" \
" add %" reg "1, %" reg "1, %" reg "3 \n\t" \
" stxr %w0, %" reg "1, [%x2] \n\t" \
" stlxr %w0, %" reg "1, [%x2] \n\t" \
" cbnz %w0, 1b \n\t" \
: "=&r"(tmp), "=&r"(ret) \
: "r"(var), "r"(val)); \
Expand All @@ -754,10 +754,10 @@ DEF_ATOMIC_incdec(ATOMIC_INC_int, int, "w", "add") DEF_ATOMIC_incdec(ATOMIC_INC_
type tmp1; \
int tmp2; \
bool ret; \
__asm__ __volatile__("1: ldxr %" r "0, [%x3] \n\t" \
__asm__ __volatile__("1: ldaxr %" r "0, [%x3] \n\t" \
" cmp %" r "0, %" r "4 \n\t" \
" b.ne 2f \n\t" \
" stxr %w1, %" r "5, [%x3] \n\t" \
" stlxr %w1, %" r "5, [%x3] \n\t" \
" cbnz %w1, 1b \n\t" \
" cmp %" r "0, %" r "4 \n\t" \
"2: clrex \n\t" \
Expand All @@ -775,8 +775,8 @@ DEF_ATOMIC_incdec(ATOMIC_INC_int, int, "w", "add") DEF_ATOMIC_incdec(ATOMIC_INC_
int newval)
{
int tmp, ret;
__asm__ __volatile__("1: ldxr %w0, [%x2] \n\t"
" stxr %w1, %w3, [%x2] \n\t"
__asm__ __volatile__("1: ldaxr %w0, [%x2] \n\t"
" stlxr %w1, %w3, [%x2] \n\t"
" cbnz %w1, 1b \n\t"
: "=&r"(ret), "=&r"(tmp)
: "r"(var), "r"(newval));
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