Re: [PATCH v1 00/12] x86, alternatives: Instruction padding and more robust JMPs

From: Borislav Petkov
Date: Tue Feb 24 2015 - 06:05:32 EST


On Wed, Feb 18, 2015 at 10:20:13PM +0100, Ingo Molnar wrote:
> Do you have any stats about how many such (affected) patch
> sites we have in say the 64-bit defconfig kernel?

It is a good thing I have a tool to dump the alternatives patch sites
and what gets replaced by what. Because now I can create such stats just
like that! And hpa was questioning that tool's justification at the time
:-)

Anyway, here are the stats:

x86_64 defconfig:

Alternatives sites total: 2478
Total padding added (in Bytes): 6051

The padding is currently done for:

X86_FEATURE_ALWAYS
X86_FEATURE_ERMS
X86_FEATURE_LFENCE_RDTSC
X86_FEATURE_MFENCE_RDTSC
X86_FEATURE_SMAP

This is with the latest version of the patchset. Of course, on each
machine the alternatives sites actually being patched are a subset of
the total number.

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
--
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/