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quark_se: power_mgmt: Fixes a cpu context save bug

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The cpu context save function was manipulating stack and
returning to C caller. This can corrupt stack if the calling
function has data saved and it pops before entering deep
sleep. Moved sleep functions into assembly to avoid this.

Jira: ZEP-1345
Change-Id: I8a6d279ec14e42424f764d9ce8cbbef32149fe84
Signed-off-by: Ramesh Thomas <ramesh.thomas@intel.com>
This commit is contained in:
Ramesh Thomas 2016-11-22 21:24:52 -08:00 • committed by Anas Nashif
commit 4a09593714
3 changed files with 48 additions and 71 deletions
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20
arch/x86/soc/intel_quark/quark_se/power.c
View file

@ -30,15 +30,15 @@ uint64_t _pm_save_gdtr;
uint64_t _pm_save_idtr;
uint32_t _pm_save_esp;
extern void _power_soc_sleep(void);
extern void _power_restore_cpu_context(void);
extern void _power_soc_deep_sleep(void);
#if (defined(CONFIG_SYS_POWER_DEEP_SLEEP))
static uint32_t *__x86_restore_info = (uint32_t *)CONFIG_BSP_SHARED_RAM_ADDR;
static void _deep_sleep(enum power_states state)
{
int restore;
__asm__ volatile ("wbinvd");
/*
* Setting resume vector inside the restore_cpu_context
* function since we have nothing to do before cpu context
@ -47,23 +47,21 @@ static void _deep_sleep(enum power_states state)
* can be done before cpu context is restored and control
* transferred to _sys_soc_suspend.
*/
qm_x86_set_resume_vector(_sys_soc_restore_cpu_context,
qm_x86_set_resume_vector(_power_restore_cpu_context,
*__x86_restore_info);
restore = _sys_soc_save_cpu_context();
if (!restore) {
power_soc_set_x86_restore_flag();
switch (state) {
case SYS_POWER_STATE_DEEP_SLEEP_1:
power_soc_sleep();
_power_soc_sleep();
break;
case SYS_POWER_STATE_DEEP_SLEEP:
power_soc_deep_sleep();
_power_soc_deep_sleep();
break;
default:
break;
}
}
}
#endif

54
arch/x86/soc/intel_quark/quark_se/soc_power.S
View file

@ -23,30 +23,24 @@ GDATA(_pm_save_gdtr)
GDATA(_pm_save_idtr)
GDATA(_pm_save_esp)
GTEXT(_sys_soc_save_cpu_context)
GTEXT(_sys_soc_restore_cpu_context)
GTEXT(_sys_soc_resume_from_deep_sleep)
GTEXT(_power_restore_cpu_context)
GTEXT(_power_soc_sleep)
GTEXT(_power_soc_deep_sleep)
SECTION_FUNC(TEXT, _sys_soc_save_cpu_context)
SECTION_FUNC(TEXT, save_cpu_context)
movl %esp, %eax /* save ptr to return address */
pushf /* save flags */
pusha /* save GPRs */
movl %esp, _pm_save_esp /* save stack ptr */
sidtl _pm_save_idtr /* save idtr */
sgdtl _pm_save_gdtr /* save gdtr */
pushl (%eax) /* push return address */
xorl %eax, %eax /* 0 indicates saved context */
ret
SECTION_FUNC(TEXT, _sys_soc_restore_cpu_context)
/*
* Will transfer control to _sys_power_save_cpu_context,
* from where it will return 1 indicating the function
* is exiting after a context switch.
*/
SECTION_FUNC(TEXT, _power_restore_cpu_context)
lgdtl _pm_save_gdtr /* restore gdtr */
lidtl _pm_save_idtr /* restore idtr */
movl _pm_save_esp, %esp /* restore saved stack ptr */
@ -54,18 +48,32 @@ SECTION_FUNC(TEXT, _sys_soc_restore_cpu_context)
popf /* restore saved flags */
/*
* At this point context is restored as it was saved
* in _sys_soc_save_cpu_context. The following ret
* will emulate a return from that function. Move 1
* to eax to emulate a return 1. The caller of
* _sys_soc_save_cpu_context will identify it is
* returning from a context restore based on the
* return value = 1.
* At this point the stack contents will be as follows:
*
* Saved context
* ESP ---> Return address of save_cpu_context
* Return address of _power_soc_sleep/deep_sleep
*
* We just popped the saved context. Next we pop out the address
* of the caller of save_cpu_context.Then the ret would return
* to caller of _power_soc_sleep or _power_soc_deep_sleep.
*
*/
xorl %eax, %eax
incl %eax
addl $4, %esp
ret
SECTION_FUNC(TEXT, _power_soc_sleep)
call save_cpu_context
wbinvd
call power_soc_sleep
/* Does not return */
SECTION_FUNC(TEXT, _power_soc_deep_sleep)
call save_cpu_context
wbinvd
call power_soc_deep_sleep
/* Does not return */
/*
* This is an example function to handle the deep sleep resume notification
* in the absence of bootloader context restore support.
@ -78,8 +86,8 @@ SECTION_FUNC(TEXT, _sys_soc_restore_cpu_context)
*/
SECTION_FUNC(TEXT, _sys_soc_resume_from_deep_sleep)
movl $CONFIG_BSP_SHARED_RAM_ADDR, %eax
cmpl $_sys_soc_restore_cpu_context, (%eax)
je _sys_soc_restore_cpu_context
cmpl $_power_restore_cpu_context, (%eax)
je _power_restore_cpu_context
ret
#endif

29
arch/x86/soc/intel_quark/quark_se/soc_power.h
View file

@ -30,35 +30,6 @@ enum power_states {
SYS_POWER_STATE_MAX
};
/**
* @brief Save CPU context
*
* This function would save the CPU context in the stack. It
* would also save the idtr and gdtr registers. When context is
* restored by _sys_soc_restore_cpu_context(), control will be
* transferred into this function where the context was originally
* saved. The return values would indicate whether it is returning
* after saving context or after a context restore transferred
* control to it.
*
* @retval 0 Indicates it is returning after saving cpu context
* @retval 1 Indicates cpu context restore transferred control to it.
*/
int _sys_soc_save_cpu_context(void);
/**
* @brief Restore CPU context
*
* This function would restore the CPU context that was saved in
* the stack by _sys_soc_save_cpu_context(). It would also restore
* the idtr and gdtr registers.
*
* After context is restored, control will be transferred into
* _sys_soc_save_cpu_context() function where the context was originally
* saved.
*/
FUNC_NORETURN void _sys_soc_restore_cpu_context(void);
/**
* @brief Put processor into low power state
*