From c4d72e2db3a36bf560b506df8a3490f140aeae26 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@kernel.org>
Date: Mon, 27 Apr 2015 07:18:17 +0200
Subject: x86/fpu: Simplify fpstate_init_curr() usage

Now that fpstate_init_curr() is not doing implicit allocations
anymore, almost all uses of it involve a very simple pattern:

	if (!fpu->fpstate_active)
		fpstate_init_curr(fpu);

which is basically activating the FPU fpstate if it was not active
before.

So propagate the check into the function itself, and rename the
function according to its new purpose:

	fpu__activate_curr(fpu);

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: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 1345ab3..de19fc5 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -44,7 +44,7 @@ extern void fpu__init_system_xstate(void);
 extern void fpu__init_cpu_xstate(void);
 extern void fpu__init_system(struct cpuinfo_x86 *c);
 
-extern void fpstate_init_curr(struct fpu *fpu);
+extern void fpu__activate_curr(struct fpu *fpu);
 extern void fpstate_init(struct fpu *fpu);
 extern void fpu__clear(struct task_struct *tsk);
 
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 97b4f9e..74cc322 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -259,19 +259,21 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 }
 
 /*
- * Initialize the current task's in-memory FPU context:
+ * Activate the current task's in-memory FPU context,
+ * if it has not been used before:
  */
-void fpstate_init_curr(struct fpu *fpu)
+void fpu__activate_curr(struct fpu *fpu)
 {
 	WARN_ON_ONCE(fpu != &current->thread.fpu);
-	WARN_ON_ONCE(fpu->fpstate_active);
 
-	fpstate_init(fpu);
+	if (!fpu->fpstate_active) {
+		fpstate_init(fpu);
 
-	/* Safe to do for the current task: */
-	fpu->fpstate_active = 1;
+		/* Safe to do for the current task: */
+		fpu->fpstate_active = 1;
+	}
 }
-EXPORT_SYMBOL_GPL(fpstate_init_curr);
+EXPORT_SYMBOL_GPL(fpu__activate_curr);
 
 /*
  * This function is called before we modify a stopped child's
@@ -325,8 +327,7 @@ void fpu__restore(void)
 	struct task_struct *tsk = current;
 	struct fpu *fpu = &tsk->thread.fpu;
 
-	if (!fpu->fpstate_active)
-		fpstate_init_curr(fpu);
+	fpu__activate_curr(fpu);
 
 	/* Avoid __kernel_fpu_begin() right after fpregs_activate() */
 	kernel_fpu_disable();
@@ -352,7 +353,7 @@ void fpu__clear(struct task_struct *tsk)
 		drop_fpu(fpu);
 	} else {
 		if (!fpu->fpstate_active) {
-			fpstate_init_curr(fpu);
+			fpu__activate_curr(fpu);
 			user_fpu_begin();
 		}
 		restore_init_xstate();
diff --git a/arch/x86/kernel/fpu/xsave.c b/arch/x86/kernel/fpu/xsave.c
index 49d9f3d..f549e2a 100644
--- a/arch/x86/kernel/fpu/xsave.c
+++ b/arch/x86/kernel/fpu/xsave.c
@@ -358,8 +358,7 @@ int __restore_xstate_sig(void __user *buf, void __user *buf_fx, int size)
 	if (!access_ok(VERIFY_READ, buf, size))
 		return -EACCES;
 
-	if (!fpu->fpstate_active)
-		fpstate_init_curr(fpu);
+	fpu__activate_curr(fpu);
 
 	if (!static_cpu_has(X86_FEATURE_FPU))
 		return fpregs_soft_set(current, NULL,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 92a8490..9ff4df7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6601,8 +6601,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	int r;
 	sigset_t sigsaved;
 
-	if (!fpu->fpstate_active)
-		fpstate_init_curr(fpu);
+	fpu__activate_curr(fpu);
 
 	if (vcpu->sigset_active)
 		sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);
diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index 4c6ab79..5b85051 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -149,8 +149,7 @@ void math_emulate(struct math_emu_info *info)
 	struct desc_struct code_descriptor;
 	struct fpu *fpu = &current->thread.fpu;
 
-	if (!fpu->fpstate_active)
-		fpstate_init_curr(fpu);
+	fpu__activate_curr(fpu);
 
 #ifdef RE_ENTRANT_CHECKING
 	if (emulating) {
-- 
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