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authorDave Hansen <dave.hansen@linux.intel.com>2014-11-11 14:01:33 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-12-06 15:05:46 -0800
commitc97aaf68301be4943f3f1aa0943d8150165a8f61 (patch)
treec58ec5dcc5fba9b272ea3adec9aae3bfd62678c3
parent69c5d32d83e9f2a7cb4dfd5a5c631470e816bf6a (diff)
downloadlinux-linaro-stable-c97aaf68301be4943f3f1aa0943d8150165a8f61.tar.gz
x86: Require exact match for 'noxsave' command line option
commit 2cd3949f702692cf4c5d05b463f19cd706a92dd3 upstream. 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 Link: http://lkml.kernel.org/r/20141111220133.FE053984@viggo.jf.intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-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 6a7e3e9cffc3..564140155c36 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -144,6 +144,8 @@ 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_AVX);