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authorDave Hansen <dave.hansen@linux.intel.com>2014-11-11 14:01:33 -0800
committerThomas Gleixner <tglx@linutronix.de>2014-11-16 12:13:16 +0100
commit2cd3949f702692cf4c5d05b463f19cd706a92dd3 (patch)
tree43142a52795b60abcb84bcbad1031bdc27eaf53d
parent0cafa3e714fa34af100c575ada31d52caea20957 (diff)
x86: Require exact match for 'noxsave' command line option
We have some very similarly named command-line options: arch/x86/kernel/cpu/common.c:__setup("noxsave", x86_xsave_setup); arch/x86/kernel/cpu/common.c:__setup("noxsaveopt", x86_xsaveopt_setup); arch/x86/kernel/cpu/common.c:__setup("noxsaves", x86_xsaves_setup); __setup() is designed to match options that take arguments, like "foo=bar" where you would have: __setup("foo", x86_foo_func...); The problem is that "noxsave" actually _matches_ "noxsaves" in the same way that "foo" matches "foo=bar". If you boot an old kernel that does not know about "noxsaves" with "noxsaves" on the command line, it will interpret the argument as "noxsave", which is not what you want at all. This makes the "noxsave" handler only return success when it finds an *exact* match. [ tglx: We really need to make __setup() more robust. ] Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dave Hansen <dave@sr71.net> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: x86@kernel.org Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20141111220133.FE053984@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--arch/x86/kernel/cpu/common.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 4b4f78c9ba19..cfa9b5b2c27a 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -146,6 +146,8 @@ EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
static int __init x86_xsave_setup(char *s)
{
+ if (strlen(s))
+ return 0;
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
setup_clear_cpu_cap(X86_FEATURE_XSAVES);