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| author | Dave Hansen <dave.hansen@linux.intel.com> | 2015-06-07 18:37:02 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2015-06-09 10:24:31 (GMT) |
| commit | 8c3641e957a948f41f0174290096ed7a3b95e703 (patch) | |
| tree | 2db374d86670e0a129e91a3cd669a9f926a0e996 /arch | |
| parent | eb099e5bc5457c42043e57cf0f4ce574669b9697 (diff) | |
| download | linux-8c3641e957a948f41f0174290096ed7a3b95e703.tar.xz | |
x86/mpx: Introduce a boot-time disable flag
MPX has the _potential_ to cause some issues. Say part of your
init system tried to protect one of its components from buffer
overflows with MPX. If there were a false positive, it's
possible that MPX could keep a system from booting.
MPX could also potentially cause performance issues since it is
present in hot paths like the unmap path.
Allow it to be disabled at boot time.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150607183702.2E8B77AB@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 401ccb03..3956858 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -144,6 +144,22 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = { } }; EXPORT_PER_CPU_SYMBOL_GPL(gdt_page); +static int __init x86_mpx_setup(char *s) +{ + /* require an exact match without trailing characters */ + if (strlen(s)) + return 0; + + /* do not emit a message if the feature is not present */ + if (!boot_cpu_has(X86_FEATURE_MPX)) + return 1; + + setup_clear_cpu_cap(X86_FEATURE_MPX); + pr_info("nompx: Intel Memory Protection Extensions (MPX) disabled\n"); + return 1; +} +__setup("nompx", x86_mpx_setup); + #ifdef CONFIG_X86_32 static int cachesize_override = -1; static int disable_x86_serial_nr = 1; |