From: Nick Desaulniers <ndesaulniers@google.com>
To: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: kbuild-all@lists.01.org,
clang-built-linux <clang-built-linux@googlegroups.com>,
linux-toolchains@vger.kernel.org,
kernel test robot <lkp@intel.com>,
Arvind Sankar <nivedita@alum.mit.edu>,
Ard Biesheuvel <ardb@kernel.org>,
Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [RFC][PATCH 21/24] x86/entry: Disable stack-protector for IST entry C handlers
Date: Fri, 13 Nov 2020 10:59:26 -0800 [thread overview]
Message-ID: <CAKwvOdnvhyNs1arkVO1=pw9GB9NePKUfQYAY+Q0Ur9Qe9HJ37w@mail.gmail.com> (raw)
In-Reply-To: <202011131552.4kvOb9Id-lkp@intel.com>
On Thu, Nov 12, 2020 at 11:59 PM kernel test robot <lkp@intel.com> wrote:
>
> Hi Alexandre,
>
> [FYI, it's a private test report for your RFC patch.]
> [auto build test WARNING on tip/x86/mm]
> [also build test WARNING on v5.10-rc3]
> [cannot apply to tip/x86/core tip/x86/asm next-20201112]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
>
> url: https://github.com/0day-ci/linux/commits/Alexandre-Chartre/x86-pti-Defer-CR3-switch-to-C-code/20201109-225007
> base: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 1fcd009102ee02e217f2e7635ab65517d785da8e
> config: x86_64-randconfig-a011-20201109 (attached as .config)
> compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 09ec07827b1128504457a93dee80b2ceee1af600)
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # install x86_64 cross compiling tool for clang build
> # apt-get install binutils-x86-64-linux-gnu
> # https://github.com/0day-ci/linux/commit/1095b6a7acb8dc568c474cd3b3d1c8393fb49728
> git remote add linux-review https://github.com/0day-ci/linux
> git fetch --no-tags linux-review Alexandre-Chartre/x86-pti-Defer-CR3-switch-to-C-code/20201109-225007
> git checkout 1095b6a7acb8dc568c474cd3b3d1c8393fb49728
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
>
> All warnings (new ones prefixed by >>):
>
> >> arch/x86/kernel/cpu/mce/core.c:2023:1: warning: unknown attribute 'optimize' ignored [-Wunknown-attributes]
> DEFINE_IDTENTRY_MCE(exc_machine_check)
> ^
> arch/x86/include/asm/idtentry.h:539:30: note: expanded from macro 'DEFINE_IDTENTRY_MCE'
> #define DEFINE_IDTENTRY_MCE DEFINE_IDTENTRY_IST
> ^
> arch/x86/include/asm/idtentry.h:428:2: note: expanded from macro 'DEFINE_IDTENTRY_IST'
> no_stack_protector DEFINE_IDTENTRY_RAW(func)
> ^
> arch/x86/include/asm/idtentry.h:110:18: note: expanded from macro 'no_stack_protector'
> __attribute__ ((optimize("-O2,-fno-stack-protector,-fno-omit-frame-pointer")))
> ^
Hi Alexandre,
The `optimize` attribute is both non-portable across toolchains (hence
this warning) and a little quirky in GCC. It's advised that you do
not use it. If you can describe the issue you're trying to solve with
it, we likely have a better way to fix.
If it's removing a stack protector, -fno-stack-protector for the whole
translation unit is the only portable solution today. (GCC 10 just
gained the no_stack_protector attribute, but the kernel needs to
support older versions of GCC).
> 1 warning generated.
>
> vim +/optimize +2023 arch/x86/kernel/cpu/mce/core.c
>
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 2020
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 2021 #ifdef CONFIG_X86_64
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 2022 /* MCE hit kernel mode */
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 @2023 DEFINE_IDTENTRY_MCE(exc_machine_check)
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 2024 {
> cd840e424f27fc arch/x86/kernel/cpu/mce/core.c Peter Zijlstra 2020-05-29 2025 unsigned long dr7;
> cd840e424f27fc arch/x86/kernel/cpu/mce/core.c Peter Zijlstra 2020-05-29 2026
> cd840e424f27fc arch/x86/kernel/cpu/mce/core.c Peter Zijlstra 2020-05-29 2027 dr7 = local_db_save();
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 2028 exc_machine_check_kernel(regs);
> cd840e424f27fc arch/x86/kernel/cpu/mce/core.c Peter Zijlstra 2020-05-29 2029 local_db_restore(dr7);
> 4c0dcd8350a03c arch/x86/kernel/cpu/mce/core.c Thomas Gleixner 2020-02-25 2030 }
> 9eda8cb3ac2352 arch/x86/kernel/cpu/mcheck/mce.c Andi Kleen 2009-07-09 2031
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>
> --
> You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
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> To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/202011131552.4kvOb9Id-lkp%40intel.com.
--
Thanks,
~Nick Desaulniers
next parent reply other threads:[~2020-11-13 18:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201109144425.270789-22-alexandre.chartre@oracle.com>
[not found] ` <202011131552.4kvOb9Id-lkp@intel.com>
2020-11-13 18:59 ` Nick Desaulniers [this message]
2020-11-13 19:39 ` [RFC][PATCH 21/24] x86/entry: Disable stack-protector for IST entry C handlers Alexandre Chartre
2020-11-13 19:45 ` Nick Desaulniers
2020-11-13 23:47 ` Segher Boessenkool
2020-11-14 0:01 ` Miguel Ojeda
2020-11-14 0:26 ` Segher Boessenkool
2020-11-14 1:58 ` Miguel Ojeda
2020-11-14 10:20 ` Ard Biesheuvel
2020-11-25 19:56 ` Kees Cook
2020-11-25 23:00 ` Segher Boessenkool
2020-11-26 6:40 ` Ard Biesheuvel
2020-11-26 20:22 ` Segher Boessenkool
2020-11-26 21:05 ` Arvind Sankar
2020-11-26 22:00 ` Ard Biesheuvel
2020-11-14 0:11 ` Nick Desaulniers
2020-11-14 0:43 ` Segher Boessenkool
2020-11-14 0:48 ` Nick Desaulniers
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