x86/fpu: Merge fpu__reset() and fpu__clear()

With recent cleanups and fixes the fpu__reset() and fpu__clear()
functions have become almost identical in functionality: the only
difference is that fpu__reset() assumed that the fpstate
was already active in the eagerfpu case, while fpu__clear()
activated it if it was inactive.

This distinction almost never matters, the only case where such
fpstate activation happens if if the init thread (PID 1) gets exec()-ed
for the first time.

So keep fpu__clear() and change all fpu__reset() uses to
fpu__clear() to simpify the logic.

( In a later patch we'll further simplify fpu__clear() by making
  sure that all contexts it is called on are already active. )

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
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>

1 files changed, 6 insertions, 15 deletions

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 0ccdd8348872..1ba866cce00a 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -116,7 +116,7 @@ void __kernel_fpu_end(void)
 
 	if (fpu->fpregs_active) {
 		if (WARN_ON(copy_fpstate_to_fpregs(fpu)))
-			fpu__reset(fpu);
+			fpu__clear(fpu);
 	} else {
 		__fpregs_deactivate_hw();
 	}
@@ -339,7 +339,7 @@ void fpu__restore(void)
 	kernel_fpu_disable();
 	fpregs_activate(fpu);
 	if (unlikely(copy_fpstate_to_fpregs(fpu))) {
-		fpu__reset(fpu);
+		fpu__clear(fpu);
 		force_sig_info(SIGSEGV, SEND_SIG_PRIV, tsk);
 	} else {
 		tsk->thread.fpu.counter++;
@@ -376,19 +376,10 @@ void fpu__drop(struct fpu *fpu)
 }
 
 /*
- * Reset the FPU state back to init state:
- */
-void fpu__reset(struct fpu *fpu)
-{
-	if (!use_eager_fpu())
-		fpu__drop(fpu);
-	else
-		restore_init_xstate();
-}
-
-/*
- * Called by sys_execve() to clear the FPU fpregs, so that FPU state
- * of the previous binary does not leak over into the exec()ed binary:
+ * Clear the FPU state back to init state.
+ *
+ * Called by sys_execve(), by the signal handler code and by various
+ * error paths.
  */
 void fpu__clear(struct fpu *fpu)
 {