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| author | H. Peter Anvin <hpa@zytor.com> | 2009-11-13 15:28:13 -0800 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2009-11-16 13:44:56 -0800 |
| commit | 8a50e5135af0c243e117e94e27feb8d149c879b4 (patch) | |
| tree | 12779c0a7fca8a43c16054e68a24f0315919576f | |
| parent | 196cf0d67acad70ebb2572da489d5cc7066cdd05 (diff) | |
| download | linux-8a50e5135af0c243e117e94e27feb8d149c879b4.tar.gz linux-8a50e5135af0c243e117e94e27feb8d149c879b4.tar.bz2 linux-8a50e5135af0c243e117e94e27feb8d149c879b4.zip | |
x86-32: Use symbolic constants, safer CPUID when enabling EFER.NX
Use symbolic constants rather than hard-coded values when setting
EFER.NX in head_32.S, and do a more rigorous test for the validity of
the response when probing for the extended CPUID range.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <1258154897-6770-2-git-send-email-hpa@zytor.com>
Acked-by: Kees Cook <kees.cook@canonical.com>
| -rw-r--r-- | arch/x86/kernel/head_32.S | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 050c278481b1..7fd318bac59c 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -18,6 +18,8 @@ #include <asm/asm-offsets.h> #include <asm/setup.h> #include <asm/processor-flags.h> +#include <asm/msr-index.h> +#include <asm/cpufeature.h> #include <asm/percpu.h> /* Physical address */ @@ -297,25 +299,27 @@ ENTRY(startup_32_smp) orl %edx,%eax movl %eax,%cr4 - btl $5, %eax # check if PAE is enabled - jnc 6f + testb $X86_CR4_PAE, %al # check if PAE is enabled + jz 6f /* Check if extended functions are implemented */ movl $0x80000000, %eax cpuid - cmpl $0x80000000, %eax - jbe 6f + /* Value must be in the range 0x80000001 to 0x8000ffff */ + subl $0x80000001, %eax + cmpl $(0x8000ffff-0x80000001), %eax + ja 6f mov $0x80000001, %eax cpuid /* Execute Disable bit supported? */ - btl $20, %edx + btl $(X86_FEATURE_NX & 31), %edx jnc 6f /* Setup EFER (Extended Feature Enable Register) */ - movl $0xc0000080, %ecx + movl $MSR_EFER, %ecx rdmsr - btsl $11, %eax + btsl $_EFER_NX, %eax /* Make changes effective */ wrmsr |