From 43b287b3f4d8665cd5a4909132259b663cc1c0e3 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@kernel.org>
Date: Mon, 25 May 2015 10:59:31 +0200
Subject: [PATCH] x86/fpu: Add debugging checks to all copy_kernel_to_*()
functions
Copying from in-kernel FPU context buffers to FPU registers are
never supposed to fault.
Add debugging checks to copy_kernel_to_fxregs() and copy_kernel_to_fregs()
to double check this assumption.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Bobby Powers <bobbypowers@gmail.com>
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: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/include/asm/fpu/internal.h | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index e3bd93c849287..eb8fa0f9d2798 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -143,14 +143,22 @@ static inline int copy_fxregs_to_user(struct fxregs_state __user *fx)
static inline int copy_kernel_to_fxregs(struct fxregs_state *fx)
{
- if (config_enabled(CONFIG_X86_32))
- return check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
- else if (config_enabled(CONFIG_AS_FXSAVEQ))
- return check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+ int err;
- /* See comment in copy_fxregs_to_kernel() below. */
- return check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx),
- "m" (*fx));
+ if (config_enabled(CONFIG_X86_32)) {
+ err = check_insn(fxrstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ } else {
+ if (config_enabled(CONFIG_AS_FXSAVEQ)) {
+ err = check_insn(fxrstorq %[fx], "=m" (*fx), [fx] "m" (*fx));
+ } else {
+ /* See comment in copy_fxregs_to_kernel() below. */
+ err = check_insn(rex64/fxrstor (%[fx]), "=m" (*fx), [fx] "R" (fx), "m" (*fx));
+ }
+ }
+ /* Copying from a kernel buffer to FPU registers should never fail: */
+ WARN_ON_FPU(err);
+
+ return err;
}
static inline int copy_user_to_fxregs(struct fxregs_state __user *fx)
@@ -167,7 +175,11 @@ static inline int copy_user_to_fxregs(struct fxregs_state __user *fx)
static inline int copy_kernel_to_fregs(struct fregs_state *fx)
{
- return check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+ int err = check_insn(frstor %[fx], "=m" (*fx), [fx] "m" (*fx));
+
+ WARN_ON_FPU(err);
+
+ return err;
}
static inline int copy_user_to_fregs(struct fregs_state __user *fx)
--
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