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ACPICA: Save current masks of enabled GPEs after enable register writes
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There is a race condition between acpi_hw_disable_all_gpes() or
acpi_enable_all_wakeup_gpes() and acpi_ev_asynch_enable_gpe() such
that if the latter wins the race, it may mistakenly enable a GPE
disabled by the former.  This may lead to premature system wakeups
during system suspend and potentially to more serious consequences.

The source of the problem is how acpi_hw_low_set_gpe() works when
passed ACPI_GPE_CONDITIONAL_ENABLE as the second argument.  In that
case, the GPE will be enabled if the corresponding bit is set in the
enable_for_run mask of the GPE enable register containing that bit.
However, acpi_hw_disable_all_gpes() and acpi_enable_all_wakeup_gpes()
don't modify the enable_for_run masks of GPE registers when writing
to them.  In consequence, if acpi_ev_asynch_enable_gpe(), which
eventually calls acpi_hw_low_set_gpe() with the second argument
equal to ACPI_GPE_CONDITIONAL_ENABLE, is executed in parallel with
one of these functions, it may reverse changes made by them.

To fix the problem, introduce a new enable_mask field in struct
acpi_gpe_register_info in which to store the current mask of
enabled GPEs and modify acpi_hw_low_set_gpe() to take this
mask into account instead of enable_for_run when its second
argument is equal to ACPI_GPE_CONDITIONAL_ENABLE.  Also modify
the low-level routines called by acpi_hw_disable_all_gpes(),
acpi_enable_all_wakeup_gpes() and acpi_enable_all_runtime_gpes()
to update the enable_mask masks of GPE registers after all
(successful) writes to those registers.

Acked-by: Lv Zheng <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>
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@rafaeljw
rafaeljw committed Dec 1, 2014
1 parent e587459 commit c50f13c
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Showing 4 changed files with 51 additions and 13 deletions.
1 change: 1 addition & 0 deletions drivers/acpi/acpica/aclocal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -454,6 +454,7 @@ struct acpi_gpe_register_info {
u16 base_gpe_number; /* Base GPE number for this register */
u8 enable_for_wake; /* GPEs to keep enabled when sleeping */
u8 enable_for_run; /* GPEs to keep enabled when running */
u8 enable_mask; /* Current mask of enabled GPEs */
};

/*
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6 changes: 3 additions & 3 deletions drivers/acpi/acpica/evgpe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -134,7 +134,7 @@ acpi_status acpi_ev_enable_gpe(struct acpi_gpe_event_info *gpe_event_info)

/* Enable the requested GPE */

status = acpi_hw_low_set_gpe(gpe_event_info, ACPI_GPE_ENABLE);
status = acpi_hw_low_set_gpe(gpe_event_info, ACPI_GPE_ENABLE_SAVE);
return_ACPI_STATUS(status);
}

Expand Down Expand Up @@ -213,7 +213,7 @@ acpi_ev_remove_gpe_reference(struct acpi_gpe_event_info *gpe_event_info)
if (ACPI_SUCCESS(status)) {
status =
acpi_hw_low_set_gpe(gpe_event_info,
ACPI_GPE_DISABLE);
ACPI_GPE_DISABLE_SAVE);
}

if (ACPI_FAILURE(status)) {
Expand Down Expand Up @@ -655,7 +655,7 @@ acpi_status acpi_ev_finish_gpe(struct acpi_gpe_event_info * gpe_event_info)

/*
* Enable this GPE, conditionally. This means that the GPE will
* only be physically enabled if the enable_for_run bit is set
* only be physically enabled if the enable_mask bit is set
* in the event_info.
*/
(void)acpi_hw_low_set_gpe(gpe_event_info, ACPI_GPE_CONDITIONAL_ENABLE);
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53 changes: 43 additions & 10 deletions drivers/acpi/acpica/hwgpe.c
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Original file line number Diff line number Diff line change
Expand Up @@ -115,12 +115,12 @@ acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u32 action)
/* Set or clear just the bit that corresponds to this GPE */

register_bit = acpi_hw_get_gpe_register_bit(gpe_event_info);
switch (action) {
switch (action & ~ACPI_GPE_SAVE_MASK) {
case ACPI_GPE_CONDITIONAL_ENABLE:

/* Only enable if the enable_for_run bit is set */
/* Only enable if the corresponding enable_mask bit is set */

if (!(register_bit & gpe_register_info->enable_for_run)) {
if (!(register_bit & gpe_register_info->enable_mask)) {
return (AE_BAD_PARAMETER);
}

Expand All @@ -145,6 +145,9 @@ acpi_hw_low_set_gpe(struct acpi_gpe_event_info *gpe_event_info, u32 action)
/* Write the updated enable mask */

status = acpi_hw_write(enable_mask, &gpe_register_info->enable_address);
if (ACPI_SUCCESS(status) && (action & ACPI_GPE_SAVE_MASK)) {
gpe_register_info->enable_mask = enable_mask;
}
return (status);
}

Expand Down Expand Up @@ -260,6 +263,32 @@ acpi_hw_get_gpe_status(struct acpi_gpe_event_info * gpe_event_info,
return (AE_OK);
}

/******************************************************************************
*
* FUNCTION: acpi_hw_gpe_enable_write
*
* PARAMETERS: enable_mask - Bit mask to write to the GPE register
* gpe_register_info - Gpe Register info
*
* RETURN: Status
*
* DESCRIPTION: Write the enable mask byte to the given GPE register.
*
******************************************************************************/

static acpi_status
acpi_hw_gpe_enable_write(u8 enable_mask,
struct acpi_gpe_register_info *gpe_register_info)
{
acpi_status status;

status = acpi_hw_write(enable_mask, &gpe_register_info->enable_address);
if (ACPI_SUCCESS(status)) {
gpe_register_info->enable_mask = enable_mask;
}
return (status);
}

/******************************************************************************
*
* FUNCTION: acpi_hw_disable_gpe_block
Expand Down Expand Up @@ -287,8 +316,8 @@ acpi_hw_disable_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
/* Disable all GPEs in this register */

status =
acpi_hw_write(0x00,
&gpe_block->register_info[i].enable_address);
acpi_hw_gpe_enable_write(0x00,
&gpe_block->register_info[i]);
if (ACPI_FAILURE(status)) {
return (status);
}
Expand Down Expand Up @@ -355,21 +384,23 @@ acpi_hw_enable_runtime_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
{
u32 i;
acpi_status status;
struct acpi_gpe_register_info *gpe_register_info;

/* NOTE: assumes that all GPEs are currently disabled */

/* Examine each GPE Register within the block */

for (i = 0; i < gpe_block->register_count; i++) {
if (!gpe_block->register_info[i].enable_for_run) {
gpe_register_info = &gpe_block->register_info[i];
if (!gpe_register_info->enable_for_run) {
continue;
}

/* Enable all "runtime" GPEs in this register */

status =
acpi_hw_write(gpe_block->register_info[i].enable_for_run,
&gpe_block->register_info[i].enable_address);
acpi_hw_gpe_enable_write(gpe_register_info->enable_for_run,
gpe_register_info);
if (ACPI_FAILURE(status)) {
return (status);
}
Expand Down Expand Up @@ -399,19 +430,21 @@ acpi_hw_enable_wakeup_gpe_block(struct acpi_gpe_xrupt_info *gpe_xrupt_info,
{
u32 i;
acpi_status status;
struct acpi_gpe_register_info *gpe_register_info;

/* Examine each GPE Register within the block */

for (i = 0; i < gpe_block->register_count; i++) {
gpe_register_info = &gpe_block->register_info[i];

/*
* Enable all "wake" GPEs in this register and disable the
* remaining ones.
*/

status =
acpi_hw_write(gpe_block->register_info[i].enable_for_wake,
&gpe_block->register_info[i].enable_address);
acpi_hw_gpe_enable_write(gpe_register_info->enable_for_wake,
gpe_register_info);
if (ACPI_FAILURE(status)) {
return (status);
}
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4 changes: 4 additions & 0 deletions include/acpi/actypes.h
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Original file line number Diff line number Diff line change
Expand Up @@ -736,6 +736,10 @@ typedef u32 acpi_event_status;
#define ACPI_GPE_ENABLE 0
#define ACPI_GPE_DISABLE 1
#define ACPI_GPE_CONDITIONAL_ENABLE 2
#define ACPI_GPE_SAVE_MASK 4

#define ACPI_GPE_ENABLE_SAVE (ACPI_GPE_ENABLE | ACPI_GPE_SAVE_MASK)
#define ACPI_GPE_DISABLE_SAVE (ACPI_GPE_DISABLE | ACPI_GPE_SAVE_MASK)

/*
* GPE info flags - Per GPE
Expand Down

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