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| author | H. Peter Anvin <hpa@zytor.com> | 2008-09-04 09:04:45 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2008-09-04 09:04:45 -0700 |
| commit | fe47784ba5cbb6b713c013e046859946789b45e4 (patch) | |
| tree | 6384958d55e29be0d2eb8ae78fa437c10636d8d6 /arch/x86/kernel/cpu/common.c | |
| parent | 83b8e28b14d63db928cb39e5c5ed2a548246bd71 (diff) | |
| parent | af2e1f276ff08f17192411ea3b71c13a758dfe12 (diff) | |
Merge branch 'x86/cpu' into x86/xsave
Conflicts:
arch/x86/kernel/cpu/feature_names.c
include/asm-x86/cpufeature.h
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 6c2b9e756db..c63ec65f484 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -13,6 +13,7 @@ #include <asm/mtrr.h> #include <asm/mce.h> #include <asm/pat.h> +#include <asm/asm.h> #ifdef CONFIG_X86_LOCAL_APIC #include <asm/mpspec.h> #include <asm/apic.h> @@ -341,6 +342,35 @@ static void __init early_cpu_detect(void) early_get_cap(c); } +/* + * The NOPL instruction is supposed to exist on all CPUs with + * family >= 6, unfortunately, that's not true in practice because + * of early VIA chips and (more importantly) broken virtualizers that + * are not easy to detect. Hence, probe for it based on first + * principles. + */ +static void __cpuinit detect_nopl(struct cpuinfo_x86 *c) +{ + const u32 nopl_signature = 0x888c53b1; /* Random number */ + u32 has_nopl = nopl_signature; + + clear_cpu_cap(c, X86_FEATURE_NOPL); + if (c->x86 >= 6) { + asm volatile("\n" + "1: .byte 0x0f,0x1f,0xc0\n" /* nopl %eax */ + "2:\n" + " .section .fixup,\"ax\"\n" + "3: xor %0,%0\n" + " jmp 2b\n" + " .previous\n" + _ASM_EXTABLE(1b,3b) + : "+a" (has_nopl)); + + if (has_nopl == nopl_signature) + set_cpu_cap(c, X86_FEATURE_NOPL); + } +} + static void __cpuinit generic_identify(struct cpuinfo_x86 *c) { u32 tfms, xlvl; @@ -395,8 +425,8 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c) } init_scattered_cpuid_features(c); + detect_nopl(c); } - } static void __cpuinit squash_the_stupid_serial_number(struct cpuinfo_x86 *c) |