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authorMark Langsdorf <mark.langsdorf@amd.com>2008-08-14 09:11:26 -0500
committerIngo Molnar <mingo@elte.hu>2008-08-15 14:04:30 +0200
commit394a15051c33f2b18e72f42283b36a9388fa414b (patch)
tree3e0b4acbd9e940758b184991d78bfe8f3a168050 /include/asm-x86
parentdcc984166870150709f0c645b521a47becd9a047 (diff)
downloadop-kernel-dev-394a15051c33f2b18e72f42283b36a9388fa414b.zip
op-kernel-dev-394a15051c33f2b18e72f42283b36a9388fa414b.tar.gz
x86: invalidate caches before going into suspend
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>
Diffstat (limited to 'include/asm-x86')
-rw-r--r--include/asm-x86/processor.h23
1 files changed, 23 insertions, 0 deletions
diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 5f58da4..4df3e2f 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);
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