diff options
| author | Andi Kleen <ak@suse.de> | 2006-10-05 18:47:22 +0200 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2006-10-05 18:47:22 +0200 |
| commit | 0a5ace2ab08d45cd78d7ef0067cdcd5c812ac54f (patch) | |
| tree | a4da5e79010de2391ee92d6a71b2a7217ed68d61 | |
| parent | [PATCH] x86: Terminate the kernel stacks for the unwinder (diff) | |
| download | linux-0a5ace2ab08d45cd78d7ef0067cdcd5c812ac54f.tar.xz linux-0a5ace2ab08d45cd78d7ef0067cdcd5c812ac54f.zip | |
[PATCH] x86-64: Fix FPU corruption
This reverts an earlier patch that was found to cause FPU
state corruption. I think the corruption happens because
unlazy_fpu() can cause FPU exceptions and when it happens
after the current switch some processing would affect
the state in the wrong process.
Thanks to Douglas Crosher and Tom Hughes for testing.
Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
| -rw-r--r-- | arch/x86_64/kernel/process.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index de10cb8a2c97..5e95b257ee26 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -615,6 +615,9 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) prev->gsindex = gsindex; } + /* Must be after DS reload */ + unlazy_fpu(prev_p); + /* * Switch the PDA and FPU contexts. */ @@ -622,10 +625,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) write_pda(oldrsp, next->userrsp); write_pda(pcurrent, next_p); - /* This must be here to ensure both math_state_restore() and - kernel_fpu_begin() work consistently. - And the AMD workaround requires it to be after DS reload. */ - unlazy_fpu(prev_p); write_pda(kernelstack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET); #ifdef CONFIG_CC_STACKPROTECTOR |