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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Tony Luck <tony.luck@intel.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Peter Ziljstra <peterz@infradead.org>,
	Song Liu <songliubraving@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>
Subject: [patch V3 00/20] x86/fpu: Clean up exception fixups and error handling in sigframe related code
Date: Wed,  8 Sep 2021 15:29:10 +0200 (CEST)	[thread overview]
Message-ID: <20210908130922.118265849@linutronix.de> (raw)

A recent discussion [1] about hardware poisoning unearthed some short
comings in the error handling of the sigframe related FPU code:

  - The error exit for exceptions other than #PF is obfuscated

  - The error code return values of the various functions are pointless
    because all callers just care about success or failure and the error
    codes are never propagated to user space.

  - Some of the buffer clearing happens needlessly inside of page fault
    disabled regions.

  - The MCE aware exception fixup is inconsistent and confusing especially
    in copy_mc_64.c. It uses a fixup function which stores the trap number
    in regs->ax just to overwrite regs->ax at the callsite specific fixup.

The following series cleans this up. The resulting excecutable code is
slightly smaller with that.

It's also available in git:

    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu

Changes vs. V2 [2]:

  - Fix the bogus left over check for #PF which causes boot failures

Thanks,

	tglx

[1] https://lore.kernel.org/r/87r1edgs2w.ffs@tglx
[2] https://lore.kernel.org/20210907200722.067068005@linutronix.de

---
 arch/x86/ia32/ia32_signal.c                |   14 +-
 arch/x86/include/asm/asm.h                 |   49 ++++-----
 arch/x86/include/asm/extable.h             |   44 +++++---
 arch/x86/include/asm/extable_fixup_types.h |   22 ++++
 arch/x86/include/asm/fpu/internal.h        |   84 ++++++++++------
 arch/x86/include/asm/msr.h                 |    4 
 arch/x86/include/asm/segment.h             |    2 
 arch/x86/kernel/cpu/mce/core.c             |   40 ++------
 arch/x86/kernel/cpu/mce/internal.h         |   14 --
 arch/x86/kernel/cpu/mce/severity.c         |   22 ++--
 arch/x86/kernel/fpu/signal.c               |  144 ++++++++++++++---------------
 arch/x86/kernel/signal.c                   |   18 +--
 arch/x86/lib/copy_mc_64.S                  |    8 -
 arch/x86/mm/extable.c                      |  131 ++++++++++----------------
 arch/x86/net/bpf_jit_comp.c                |   11 --
 scripts/sorttable.c                        |    4 
 16 files changed, 301 insertions(+), 310 deletions(-)


             reply	other threads:[~2021-09-08 13:29 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-08 13:29 Thomas Gleixner [this message]
2021-09-08 13:29 ` [patch V3 01/20] x86/extable: Tidy up redundant handler functions Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 02/20] x86/extable: Get rid of redundant macros Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 03/20] x86/mce: Deduplicate exception handling Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 04/20] x86/mce: Get rid of stray semicolons Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 05/20] x86/extable: Rework the exception table mechanics Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 06/20] x86/extable: Provide EX_TYPE_DEFAULT_MCE_SAFE and EX_TYPE_FAULT_MCE_SAFE Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 07/20] x86/copy_mc: Use EX_TYPE_DEFAULT_MCE_SAFE for exception fixups Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 08/20] x86/fpu: Use EX_TYPE_FAULT_MCE_SAFE " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 09/20] x86/extable: Remove EX_TYPE_FAULT from MCE safe fixups Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 10/20] x86/fpu/signal: Clarify exception handling in restore_fpregs_from_user() Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 11/20] x86/fpu: Dont use MCE safe fixups for writing FPU state to user space Thomas Gleixner
2021-09-08 13:29 ` [patch V3 12/20] x86/fpu/signal: Move header zeroing out of xsave_to_user_sigframe() Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 13/20] x86/fpu/signal: Move xstate clearing out of copy_fpregs_to_sigframe() Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 14/20] x86/fpu/signal: Change return type of copy_fpstate_to_sigframe() to boolean Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 15/20] x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-21 10:58   ` [patch V3 15/20] " Anders Roxell
2021-09-21 17:35     ` Nick Desaulniers
2021-09-22 18:23       ` Nick Desaulniers
2021-09-21 20:13     ` Thomas Gleixner
2021-09-22 19:42       ` Anders Roxell
2021-09-08 13:29 ` [patch V3 16/20] x86/signal: Change return type of restore_sigcontext() " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 17/20] x86/fpu/signal: Change return type of fpu__restore_sig() " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 18/20] x86/fpu/signal: Change return type of __fpu_restore_sig() " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 19/20] x86/fpu/signal: Change return code of check_xstate_in_sigframe() " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 13:29 ` [patch V3 20/20] x86/fpu/signal: Change return code of restore_fpregs_from_user() " Thomas Gleixner
2021-09-14 19:19   ` [tip: x86/fpu] " tip-bot2 for Thomas Gleixner
2021-09-08 15:57 ` [patch V3 00/20] x86/fpu: Clean up exception fixups and error handling in sigframe related code Luck, Tony
2021-09-08 17:01   ` Luck, Tony

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