diff options
| author |   Borislav Petkov <bp@suse.de> | 2016-04-07 17:31:49 -0700 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2016-04-13 10:20:42 +0200 |
| commit | 96e5d28ae7a5250f3deb2434f1895c9daf48b1bd (patch) | |
| tree | 5bd439d3de521744c90937879ba0ee3f032e1142 /arch | |
| parent | x86/cpu: Move X86_BUG_ESPFIX initialization to generic_identify() (diff) | |
| download | linux-dev-96e5d28ae7a5250f3deb2434f1895c9daf48b1bd.tar.xz linux-dev-96e5d28ae7a5250f3deb2434f1895c9daf48b1bd.zip | |
x86/cpu: Add Erratum 88 detection on AMD
Erratum 88 affects old AMD K8s, where a SWAPGS fails to cause an input
dependency on GS. Therefore, we need to MFENCE before it.
But that MFENCE is expensive and unnecessary on the remaining x86 CPUs
out there so patch it out on the CPUs which don't require it.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Andy Lutomirski <luto@kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rudolf Marek <r.marek@assembler.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/aec6b2df1bfc56101d4e9e2e5d5d570bf41663c6.1460075211.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/cpufeatures.h | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 1 |
3 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 858b555e274b..64d2033d1e49 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -783,7 +783,7 @@ ENTRY(native_load_gs_index) SWAPGS gs_change: movl %edi, %gs -2: mfence /* workaround */ +2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE SWAPGS popfq ret diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index 2a052302bc43..7bfb6b70c745 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -295,6 +295,8 @@ #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 */ #define X86_BUG_NULL_SEG X86_BUG(9) /* Nulling a selector preserves the base */ +#define X86_BUG_SWAPGS_FENCE X86_BUG(10) /* SWAPGS without input dep on GS */ + #ifdef CONFIG_X86_32 /* diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 6e47e3a916f1..b7cc9efe08b5 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -632,6 +632,7 @@ static void init_amd_k8(struct cpuinfo_x86 *c) */ msr_set_bit(MSR_K7_HWCR, 6); #endif + set_cpu_bug(c, X86_BUG_SWAPGS_FENCE); } static void init_amd_gh(struct cpuinfo_x86 *c) |