[PATCH 028/208] x86/fpu: Factor out fpu__flush_thread() from flush_thread()

[Ingo Molnar]

flush_thread() open codes a lot of FPU internals - create a separate
function for it in fpu/core.c.

Turns out that this does not hurt performance:

   text    data     bss     dec     hex filename
   11843039        1884440 1130496 14857975         e2b6f7 vmlinux.before
   11843039        1884440 1130496 14857975         e2b6f7 vmlinux.after

and since this is a slowpath clarity comes first anyway.

We can reconsider inlining decisions after the FPU code has been cleaned up.

Reviewed-by: Borislav Petkov <bp@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/i387.h |  1 +
 arch/x86/kernel/fpu/core.c  | 15 +++++++++++++++
 arch/x86/kernel/process.c   | 12 +-----------
 3 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/arch/x86/include/asm/i387.h b/arch/x86/include/asm/i387.h
index 6552a16e0e38..d6fc84440b73 100644
--- a/arch/x86/include/asm/i387.h
+++ b/arch/x86/include/asm/i387.h
@@ -20,6 +20,7 @@ struct user_i387_struct;
 
 extern int fpstate_alloc_init(struct task_struct *curr);
 extern void fpstate_init(struct fpu *fpu);
+extern void fpu__flush_thread(struct task_struct *tsk);
 
 extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
 extern void math_state_restore(void);
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 9211582f5d3f..d31812d973a3 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -227,6 +227,21 @@ static int fpu__unlazy_stopped(struct task_struct *child)
 	return 0;
 }
 
+void fpu__flush_thread(struct task_struct *tsk)
+{
+	if (!use_eager_fpu()) {
+		/* FPU state will be reallocated lazily at the first use. */
+		drop_fpu(tsk);
+		fpstate_free(&tsk->thread.fpu);
+	} else if (!used_math()) {
+		/* kthread execs. TODO: cleanup this horror. */
+		if (WARN_ON(fpstate_alloc_init(tsk)))
+			force_sig(SIGKILL, tsk);
+		user_fpu_begin();
+		restore_init_xstate();
+	}
+}
+
 /*
  * The xstateregs_active() routine is the same as the fpregs_active() routine,
  * as the "regset->n" for the xstate regset will be updated based on the feature
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index a9bff373f7eb..0a4c35c3fb2f 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -146,17 +146,7 @@ void flush_thread(void)
 	flush_ptrace_hw_breakpoint(tsk);
 	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
 
-	if (!use_eager_fpu()) {
-		/* FPU state will be reallocated lazily at the first use. */
-		drop_fpu(tsk);
-		fpstate_free(&tsk->thread.fpu);
-	} else if (!used_math()) {
-		/* kthread execs. TODO: cleanup this horror. */
-		if (WARN_ON(fpstate_alloc_init(tsk)))
-			force_sig(SIGKILL, tsk);
-		user_fpu_begin();
-		restore_init_xstate();
-	}
+	fpu__flush_thread(tsk);
 }
 
 static void hard_disable_TSC(void)
-- 
2.1.0

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