| From | Ingo Molnar <> | Subject | [PATCH 043/208] x86/fpu: Add debugging check to fpu_copy() | Date | Tue, 5 May 2015 18:24:23 +0200 |
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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: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> --- arch/x86/kernel/fpu/core.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 3f3c79c75e37..7711539bcda5 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -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); -- 2.1.0
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