linux-kernel - [PATCH 136/208] x86/fpu: Remove failure return from fpstate_alloc

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Date:	Tue,  5 May 2015 19:50:28 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	linux-kernel@...r.kernel.org
Cc:	Andy Lutomirski <luto@...capital.net>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Oleg Nesterov <oleg@...hat.com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 136/208] x86/fpu: Remove failure return from fpstate_alloc_init()

Remove the failure code and propagate this down to callers.

Note that this function still has an 'init' aspect, which must be
called.

Reviewed-by: Borislav Petkov <bp@...en8.de>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/fpu/internal.h |  2 +-
 arch/x86/kernel/fpu/core.c          | 37 +++++++------------------------------
 arch/x86/kernel/fpu/xsave.c         |  4 ++--
 arch/x86/kvm/x86.c                  |  4 ++--
 arch/x86/math-emu/fpu_entry.c       |  8 ++------
 5 files changed, 14 insertions(+), 41 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 9454f21f0edf..1d0c5cee29eb 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 int fpstate_alloc_init(struct fpu *fpu);
+extern void fpstate_alloc_init(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 7d42a54b5f23..567d789d7736 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -259,26 +259,17 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
 }
 
 /*
- * Allocate the backing store for the current task's FPU registers
- * and initialize the registers themselves as well.
- *
- * Can fail.
+ * Initialize the current task's in-memory FPU context:
  */
-int fpstate_alloc_init(struct fpu *fpu)
+void fpstate_alloc_init(struct fpu *fpu)
 {
-	int ret;
-
-	if (WARN_ON_ONCE(fpu != &current->thread.fpu))
-		return -EINVAL;
-	if (WARN_ON_ONCE(fpu->fpstate_active))
-		return -EINVAL;
+	WARN_ON_ONCE(fpu != &current->thread.fpu);
+	WARN_ON_ONCE(fpu->fpstate_active);
 
 	fpstate_init(fpu);
 
 	/* Safe to do for the current task: */
 	fpu->fpstate_active = 1;
-
-	return 0;
 }
 EXPORT_SYMBOL_GPL(fpstate_alloc_init);
 
@@ -340,20 +331,8 @@ void fpu__restore(void)
 	struct task_struct *tsk = current;
 	struct fpu *fpu = &tsk->thread.fpu;
 
-	if (!fpu->fpstate_active) {
-		local_irq_enable();
-		/*
-		 * does a slab alloc which can sleep
-		 */
-		if (fpstate_alloc_init(fpu)) {
-			/*
-			 * ran out of memory!
-			 */
-			do_group_exit(SIGKILL);
-			return;
-		}
-		local_irq_disable();
-	}
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(fpu);
 
 	/* Avoid __kernel_fpu_begin() right after fpregs_activate() */
 	kernel_fpu_disable();
@@ -379,9 +358,7 @@ void fpu__clear(struct task_struct *tsk)
 		drop_fpu(fpu);
 	} else {
 		 if (!fpu->fpstate_active) {
-			/* kthread execs. TODO: cleanup this horror. */
-			if (WARN_ON(fpstate_alloc_init(fpu)))
-				force_sig(SIGKILL, tsk);
+			fpstate_alloc_init(fpu);
 			user_fpu_begin();
 			restore_init_xstate();
 		}
diff --git a/arch/x86/kernel/fpu/xsave.c b/arch/x86/kernel/fpu/xsave.c
index c7d48eb0a194..dd2cef08a1a4 100644
--- a/arch/x86/kernel/fpu/xsave.c
+++ b/arch/x86/kernel/fpu/xsave.c
@@ -358,8 +358,8 @@ 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_alloc_init(fpu))
-		return -1;
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(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 68529251e897..707f4e27ee91 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6601,8 +6601,8 @@ 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_alloc_init(fpu))
-		return -ENOMEM;
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(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 5e003704ebfa..99ddfc274df3 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -149,12 +149,8 @@ void math_emulate(struct math_emu_info *info)
 	struct desc_struct code_descriptor;
 	struct fpu *fpu = &current->thread.fpu;
 
-	if (!fpu->fpstate_active) {
-		if (fpstate_alloc_init(fpu)) {
-			do_group_exit(SIGKILL);
-			return;
-		}
-	}
+	if (!fpu->fpstate_active)
+		fpstate_alloc_init(fpu);
 
 #ifdef RE_ENTRANT_CHECKING
 	if (emulating) {
-- 
2.1.0

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