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authorQuentin Casasnovas <quentin.casasnovas@oracle.com>2015-03-05 15:19:22 +0300
committerIngo Molnar <mingo@kernel.org>2015-03-05 20:20:36 +0300
commit06c8173eb92bbfc03a0fe8bb64315857d0badd06 (patch)
tree73ecc10d3017c9ae7a6403fca3afbf3d7ec12997 /arch
parent9ab6eb51ef4ad63cb71533d3a4dfb09ea8f69b4c (diff)
downloadlinux-06c8173eb92bbfc03a0fe8bb64315857d0badd06.tar.xz
x86/fpu/xsaves: Fix improper uses of __ex_table
Commit: f31a9f7c7169 ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area") introduced alternative instructions for XSAVES/XRSTORS and commit: adb9d526e982 ("x86/xsaves: Add xsaves and xrstors support for booting time") added support for the XSAVES/XRSTORS instructions at boot time. Unfortunately both failed to properly protect them against faulting: The 'xstate_fault' macro will use the closest label named '1' backward and that ends up in the .altinstr_replacement section rather than in .text. This means that the kernel will never find in the __ex_table the .text address where this instruction might fault, leading to serious problems if userspace manages to trigger the fault. Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com> Signed-off-by: Jamie Iles <jamie.iles@oracle.com> [ Improved the changelog, fixed some whitespace noise. ] Acked-by: Borislav Petkov <bp@alien8.de> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: <stable@vger.kernel.org> Cc: Allan Xavier <mr.a.xavier@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: adb9d526e982 ("x86/xsaves: Add xsaves and xrstors support for booting time") Fixes: f31a9f7c7169 ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area") Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/include/asm/xsave.h28
1 files changed, 11 insertions, 17 deletions
diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index 5fa9770035dc..c9a6d68b8d62 100644
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -82,18 +82,15 @@ static inline int xsave_state_booting(struct xsave_struct *fx, u64 mask)
if (boot_cpu_has(X86_FEATURE_XSAVES))
asm volatile("1:"XSAVES"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
else
asm volatile("1:"XSAVE"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
-
- asm volatile(xstate_fault
- : "0" (0)
- : "memory");
-
return err;
}
@@ -112,18 +109,15 @@ static inline int xrstor_state_booting(struct xsave_struct *fx, u64 mask)
if (boot_cpu_has(X86_FEATURE_XSAVES))
asm volatile("1:"XRSTORS"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
else
asm volatile("1:"XRSTOR"\n\t"
"2:\n\t"
- : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+ xstate_fault
+ : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");
-
- asm volatile(xstate_fault
- : "0" (0)
- : "memory");
-
return err;
}
@@ -149,9 +143,9 @@ static inline int xsave_state(struct xsave_struct *fx, u64 mask)
*/
alternative_input_2(
"1:"XSAVE,
- "1:"XSAVEOPT,
+ XSAVEOPT,
X86_FEATURE_XSAVEOPT,
- "1:"XSAVES,
+ XSAVES,
X86_FEATURE_XSAVES,
[fx] "D" (fx), "a" (lmask), "d" (hmask) :
"memory");
@@ -178,7 +172,7 @@ static inline int xrstor_state(struct xsave_struct *fx, u64 mask)
*/
alternative_input(
"1: " XRSTOR,
- "1: " XRSTORS,
+ XRSTORS,
X86_FEATURE_XSAVES,
"D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
: "memory");