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author | Andy Lutomirski <luto@kernel.org> | 2015-04-26 23:47:59 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-04-27 00:57:38 (GMT) |
commit | 61f01dd941ba9e06d2bf05994450ecc3d61b6b8b (patch) | |
tree | 3a4a4ef2d5e4d44bb4cb1708f9fc4749e9c9824a /arch/x86/include/asm/cpufeature.h | |
parent | 1190944f4b12203330ac5ed8784f6c181bf26f2d (diff) | |
download | linux-61f01dd941ba9e06d2bf05994450ecc3d61b6b8b.tar.xz |
x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue
AMD CPUs don't reinitialize the SS descriptor on SYSRET, so SYSRET with
SS == 0 results in an invalid usermode state in which SS is apparently
equal to __USER_DS but causes #SS if used.
Work around the issue by setting SS to __KERNEL_DS __switch_to, thus
ensuring that SYSRET never happens with SS set to NULL.
This was exposed by a recent vDSO cleanup.
Fixes: e7d6eefaaa44 x86/vdso32/syscall.S: Do not load __USER32_DS to %ss
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/include/asm/cpufeature.h')
-rw-r--r-- | arch/x86/include/asm/cpufeature.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 7ee9b94..3d6606f 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -265,6 +265,7 @@ #define X86_BUG_11AP X86_BUG(5) /* Bad local APIC aka 11AP */ #define X86_BUG_FXSAVE_LEAK X86_BUG(6) /* FXSAVE leaks FOP/FIP/FOP */ #define X86_BUG_CLFLUSH_MONITOR X86_BUG(7) /* AAI65, CLFLUSH required before MONITOR */ +#define X86_BUG_SYSRET_SS_ATTRS X86_BUG(8) /* SYSRET doesn't fix up SS attrs */ #if defined(__KERNEL__) && !defined(__ASSEMBLY__) |