From 394a15051c33f2b18e72f42283b36a9388fa414b Mon Sep 17 00:00:00 2001 From: Mark Langsdorf Date: Thu, 14 Aug 2008 09:11:26 -0500 Subject: [PATCH] x86: invalidate caches before going into suspend MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Acked-by: Mark Borden Acked-by: Michael Hohmuth Signed-off-by: Ingo Molnar --- arch/x86/kernel/process_32.c | 5 ++--- arch/x86/kernel/process_64.c | 5 ++--- include/asm-x86/processor.h | 23 +++++++++++++++++++++++ 3 files changed, 27 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 53bc653ed5..3b7a1ddcc0 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -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) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 3fb62a7d9a..71553b664e 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -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) diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h index 5f58da401b..4df3e2f6fb 100644 --- a/include/asm-x86/processor.h +++ b/include/asm-x86/processor.h @@ -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); -- 2.39.5