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

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Message-Id: <1422987390-17878-1-git-send-email-bp@alien8.de>
Date:	Tue,  3 Feb 2015 19:16:18 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	X86 ML <x86@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH v1 00/12] x86, alternatives: Instruction padding and more robust JMPs

From: Borislav Petkov <bp@...e.de>

  [ Changelog is in version-increasing number so that one can follow the
    evolution of the patch set in a more natural way (i.e., latest version
    comes at the end. ]

v0:

this is something which hpa and I talked about recently: the ability for
the alternatives code to add padding to the original instruction in case
the replacement is longer and also to be able to simply write "jmp" and
not care about which JMP exactly the compiler generates and whether the
relative offsets are correct.

So this is a stab at it, it seems to boot in kvm here but it needs more
staring to make sure we're actually generating the proper code at all
times.

Thus the RFC tag, comments/suggestions are welcome.

v1:

This is the first version which passes testing on AMD/Intel, 32/64-bit
boxes I have here. For more info what it does, you can boot with
"debug-alternative" to see some verbose information about what gets
changed into what.

Patches 1 and 2 are cleanups.

Patch 3 is adding the padding at build time and patch 4 simplifies using
JMPs in alternatives without having to do crazy math with labels, as a
user of the alternatives facilities.

Patch 5 optimizes the single-byte NOPs we're adding at build time to
longer NOPs which should go easier through the frontend.

Patches 6-12 then convert most of the alternative callsites to the
generic macros and kill the homegrown fun.

As always, constructive comments/suggestions are welcome.

Borislav Petkov (12):
  x86, copy_user: Remove FIX_ALIGNMENT define
  x86, alternatives: Cleanup DPRINTK macro
  x86, alternatives: Add instruction padding
  x86, alternatives: Make JMPs more robust
  x86, alternatives: Use optimized NOPs for padding
  x86, copy_page_64.S: Use generic ALTERNATIVE macro
  x86, copy_user_64.S: Convert to ALTERNATIVE_2
  x86, SMAP: Use ALTERNATIVE macro
  x86, alternative: Convert X86_INVD_BUG to generic macro
  x86, alternatives: Convert clear_page_64.S
  x86, alternative: Use alternative_2 in rdtsc_barrier
  x86, alternative: Cleanup prefetch primitives

 arch/x86/include/asm/alternative-asm.h |  40 ++++++++
 arch/x86/include/asm/alternative.h     |  58 +++++++-----
 arch/x86/include/asm/apic.h            |   2 +-
 arch/x86/include/asm/barrier.h         |   6 +-
 arch/x86/include/asm/cpufeature.h      |  23 ++---
 arch/x86/include/asm/processor.h       |  16 ++--
 arch/x86/include/asm/smap.h            |  30 ++----
 arch/x86/kernel/alternative.c          | 164 ++++++++++++++++++++++++++++-----
 arch/x86/kernel/cpu/amd.c              |   5 +
 arch/x86/kernel/entry_32.S             |  12 +--
 arch/x86/lib/clear_page_64.S           |  66 ++++++-------
 arch/x86/lib/copy_page_64.S            |  37 +++-----
 arch/x86/lib/copy_user_64.S            |  46 ++-------
 arch/x86/um/asm/barrier.h              |   4 +-
 14 files changed, 305 insertions(+), 204 deletions(-)

-- 
2.2.0.33.gc18b867

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