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x86: invalidate caches before going into suspend

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When a CPU core is shut down, all of its caches need to be flushed
to prevent stale data from causing errors if the core is resumed.
Current Linux suspend code performs an assignment after the flush,
which can add dirty data back to the cache.  On some AMD platforms,
additional speculative reads have caused crashes on resume because
of this dirty data.

Relocate the cache flush to be the very last thing done before
halting.  Tie into an assembly line so the compile will not
reorder it.  Add some documentation explaining what is going
on and why we're doing this.

Signed-off-by: Mark Langsdorf <mark.langsdorf@amd.com>
Acked-by: Mark Borden <mark.borden@amd.com>
Acked-by: Michael Hohmuth <michael.hohmuth@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Mark Langsdorf 2008-08-14 09:11:26 -05:00 committed by Ingo Molnar
parent dcc9841668
commit 394a15051c
3 changed files with 27 additions and 6 deletions
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5
arch/x86/kernel/process_32.c
View File

@ -95,7 +95,6 @@ static inline void play_dead(void)
{
/* This must be done before dead CPU ack */
cpu_exit_clear();
wbinvd();
mb();
/* Ack it */
__get_cpu_var(cpu_state) = CPU_DEAD;
@ -104,8 +103,8 @@ static inline void play_dead(void)
* With physical CPU hotplug, we should halt the cpu
*/
local_irq_disable();
while (1)
halt();
/* mask all interrupts, flush any and all caches, and halt */
wbinvd_halt();
}
#else
static inline void play_dead(void)

5
arch/x86/kernel/process_64.c
View File

@ -93,14 +93,13 @@ DECLARE_PER_CPU(int, cpu_state);
static inline void play_dead(void)
{
idle_task_exit();
wbinvd();
mb();
/* Ack it */
__get_cpu_var(cpu_state) = CPU_DEAD;
local_irq_disable();
while (1)
halt();
/* mask all interrupts, flush any and all caches, and halt */
wbinvd_halt();
}
#else
static inline void play_dead(void)

23
include/asm-x86/processor.h
View File

@ -728,6 +728,29 @@ extern unsigned long boot_option_idle_override;
extern unsigned long idle_halt;
extern unsigned long idle_nomwait;
/*
* on systems with caches, caches must be flashed as the absolute
* last instruction before going into a suspended halt. Otherwise,
* dirty data can linger in the cache and become stale on resume,
* leading to strange errors.
*
* perform a variety of operations to guarantee that the compiler
* will not reorder instructions. wbinvd itself is serializing
* so the processor will not reorder.
*
* Systems without cache can just go into halt.
*/
static inline void wbinvd_halt(void)
{
mb();
/* check for clflush to determine if wbinvd is legal */
if (cpu_has_clflush)
asm volatile("cli; wbinvd; 1: hlt; jmp 1b" : : : "memory");
else
while (1)
halt();
}
extern void enable_sep_cpu(void);
extern int sysenter_setup(void);