Messages in this thread | | | Date | Fri, 27 Mar 2015 16:07:43 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 08/17] x86, mpx: boot-time disable |
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On Thu, Mar 26, 2015 at 11:33:43AM -0700, Dave Hansen wrote: > > From: Dave Hansen <dave.hansen@linux.intel.com> > > 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> > --- > > b/Documentation/kernel-parameters.txt | 4 ++++ > b/arch/x86/kernel/cpu/common.c | 16 ++++++++++++++++ > 2 files changed, 20 insertions(+) > > diff -puN arch/x86/kernel/cpu/common.c~x86-mpx-disable-boot-time arch/x86/kernel/cpu/common.c > --- a/arch/x86/kernel/cpu/common.c~x86-mpx-disable-boot-time 2015-03-26 11:27:31.269400935 -0700 > +++ b/arch/x86/kernel/cpu/common.c 2015-03-26 11:27:31.275401206 -0700 > @@ -172,6 +172,22 @@ static int __init x86_xsaves_setup(char > } > __setup("noxsaves", x86_xsaves_setup); > > +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); > + printk("nompx: Intel Memory Protection Extensions (MPX) disabled\n");
WARNING: printk() should include KERN_ facility level #52: FILE: arch/x86/kernel/cpu/common.c:186: + printk("nompx: Intel Memory Protection Extensions (MPX) disabled\n");
checkpatch is sometimes right.
-- Regards/Gruss, Boris.
ECO tip #101: Trim your mails when you reply. --
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