linux-kernel - [tip:x86/fpu] x86/fpu: Always init the state in fpu_

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Message-ID: <tip-88f5260a3bf9bfb276b5b4aac2e81587e425a1d7@git.kernel.org>
Date:   Sat, 13 Apr 2019 13:48:43 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, bp@...e.de, kvm@...r.kernel.org,
        aubrey.li@...el.com, linux-kernel@...r.kernel.org, x86@...nel.org,
        tglx@...utronix.de, mingo@...nel.org, rkrcmar@...hat.com,
        luto@...nel.org, bigeasy@...utronix.de, pbonzini@...hat.com,
        jannh@...gle.com, mingo@...hat.com, Jason@...c4.com,
        nstange@...e.de, riel@...riel.com, dave.hansen@...el.com,
        billm@...bpc.org.au
Subject: [tip:x86/fpu] x86/fpu: Always init the state in fpu__clear()

Commit-ID:  88f5260a3bf9bfb276b5b4aac2e81587e425a1d7
Gitweb:     https://git.kernel.org/tip/88f5260a3bf9bfb276b5b4aac2e81587e425a1d7
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Wed, 3 Apr 2019 18:41:33 +0200
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Tue, 9 Apr 2019 19:28:06 +0200

x86/fpu: Always init the state in fpu__clear()

fpu__clear() only initializes the state if the CPU has FPU support.
This initialisation is also required for FPU-less systems and takes
place in math_emulate(). Since fpu__initialize() only performs the
initialization if ->initialized is zero it does not matter that it
is invoked each time an opcode is emulated. It makes the removal of
->initialized easier if the struct is also initialized in the FPU-less
case at the same time.

Move fpu__initialize() before the FPU feature check so it is also
performed in the FPU-less case too.

 [ bp: Massage a bit. ]

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Dave Hansen <dave.hansen@...el.com>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Aubrey Li <aubrey.li@...el.com>
Cc: Bill Metzenthen <billm@...bpc.org.au>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Jann Horn <jannh@...gle.com>
Cc: "Jason A. Donenfeld" <Jason@...c4.com>
Cc: kvm ML <kvm@...r.kernel.org>
Cc: Nicolai Stange <nstange@...e.de>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Rik van Riel <riel@...riel.com>
Cc: x86-ml <x86@...nel.org>
Link: https://lkml.kernel.org/r/20190403164156.19645-5-bigeasy@linutronix.de
---
 arch/x86/include/asm/fpu/internal.h | 1 -
 arch/x86/kernel/fpu/core.c          | 5 ++---
 arch/x86/math-emu/fpu_entry.c       | 3 ---
 3 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 75a1d5f712ee..70ecb7c032cb 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -24,7 +24,6 @@
 /*
  * High level FPU state handling functions:
  */
-extern void fpu__initialize(struct fpu *fpu);
 extern void fpu__prepare_read(struct fpu *fpu);
 extern void fpu__prepare_write(struct fpu *fpu);
 extern void fpu__save(struct fpu *fpu);
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 1940319268ae..e43296854e37 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -223,7 +223,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
  * Activate the current task's in-memory FPU context,
  * if it has not been used before:
  */
-void fpu__initialize(struct fpu *fpu)
+static void fpu__initialize(struct fpu *fpu)
 {
 	WARN_ON_FPU(fpu != &current->thread.fpu);
 
@@ -236,7 +236,6 @@ void fpu__initialize(struct fpu *fpu)
 		fpu->initialized = 1;
 	}
 }
-EXPORT_SYMBOL_GPL(fpu__initialize);
 
 /*
  * This function must be called before we read a task's fpstate.
@@ -365,8 +364,8 @@ void fpu__clear(struct fpu *fpu)
 	/*
 	 * Make sure fpstate is cleared and initialized.
 	 */
+	fpu__initialize(fpu);
 	if (static_cpu_has(X86_FEATURE_FPU)) {
-		fpu__initialize(fpu);
 		user_fpu_begin();
 		copy_init_fpstate_to_fpregs();
 	}
diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c
index 9e2ba7e667f6..a873da6b46d6 100644
--- a/arch/x86/math-emu/fpu_entry.c
+++ b/arch/x86/math-emu/fpu_entry.c
@@ -113,9 +113,6 @@ void math_emulate(struct math_emu_info *info)
 	unsigned long code_base = 0;
 	unsigned long code_limit = 0;	/* Initialized to stop compiler warnings */
 	struct desc_struct code_descriptor;
-	struct fpu *fpu = &current->thread.fpu;
-
-	fpu__initialize(fpu);
 
 #ifdef RE_ENTRANT_CHECKING
 	if (emulating) {