Also add a bit of documentation.
Reviewed-by: Borislav Petkov <b...@alien8.de>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: H. Peter Anvin <h...@zytor.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: Ingo Molnar <mi...@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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