x86/fpu: Move all the fpu__*() high level methods closer to each other

The fpu__*() methods are closely related, but they are defined
in scattered places within the FPU code.

Concentrate them, and also uninline fpu__save(), fpu__drop()
and fpu__reset() to save about 5K of kernel text on 64-bit kernels:

   text            data    bss     dec        filename
   14113063        2575280 1634304 18322647   vmlinux.before
   14108070        2575280 1634304 18317654   vmlinux.after

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, 38 insertions, 0 deletions

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 14d8e33d9fe0..acca83be23f0 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -349,6 +349,44 @@ void fpu__restore(void)
 EXPORT_SYMBOL_GPL(fpu__restore);
 
 /*
+ * Drops current FPU state: deactivates the fpregs and
+ * the fpstate. NOTE: it still leaves previous contents
+ * in the fpregs in the eager-FPU case.
+ *
+ * This function can be used in cases where we know that
+ * a state-restore is coming: either an explicit one,
+ * or a reschedule.
+ */
+void fpu__drop(struct fpu *fpu)
+{
+	preempt_disable();
+	fpu->counter = 0;
+
+	if (fpu->fpregs_active) {
+		/* Ignore delayed exceptions from user space */
+		asm volatile("1: fwait\n"
+			     "2:\n"
+			     _ASM_EXTABLE(1b, 2b));
+		fpregs_deactivate(fpu);
+	}
+
+	fpu->fpstate_active = 0;
+
+	preempt_enable();
+}
+
+/*
+ * 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:
  */