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x86/fpu: Add debugging check to fpu_copy()

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Also add a bit of documentation.

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Ingo Molnar 2015-04-23 08:55:34 +02:00
parent e102f30f4e
commit bfd6fc0581
1 changed files with 10 additions and 0 deletions
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10
arch/x86/kernel/fpu/core.c
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@ -203,8 +203,18 @@ void fpstate_free(struct fpu *fpu)
}
EXPORT_SYMBOL_GPL(fpstate_free);
/*
* Copy the current task's FPU state to a new task's FPU context.
*
* In the 'eager' case we just save to the destination context.
*
* In the 'lazy' case we save to the source context, mark the FPU lazy
* via stts() and copy the source context into the destination context.
*/
static void fpu_copy(struct task_struct *dst, struct task_struct *src)
{
WARN_ON(src != current);
if (use_eager_fpu()) {
memset(&dst->thread.fpu.state->xsave, 0, xstate_size);
__save_fpu(dst);