linux-kernel - Fwd: [PATCH 00/16] treewide: prefer __section from compiler

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Date:   Mon, 12 Aug 2019 14:57:26 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, Joe Perches <joe@...ches.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Yonghong Song <yhs@...com>,
        Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Subject: Fwd: [PATCH 00/16] treewide: prefer __section from compiler_attributes.h

---------- Forwarded message ---------
From: Nick Desaulniers <ndesaulniers@...gle.com>
Date: Mon, Aug 12, 2019 at 2:53 PM
Subject: [PATCH 00/16] treewide: prefer __section from compiler_attributes.h
To: <akpm@...ux-foundation.org>
Cc: <sedat.dilek@...il.com>, <jpoimboe@...hat.com>, <yhs@...com>,
<miguel.ojeda.sandonis@...il.com>,
<clang-built-linux@...glegroups.com>, Nick Desaulniers
<ndesaulniers@...gle.com>, Alexei Starovoitov <ast@...nel.org>, Daniel
Borkmann <daniel@...earbox.net>, Martin KaFai Lau <kafai@...com>, Song
Liu <songliubraving@...com>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>


GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.

This fixes an Oops observed in distro's that use systemd and not
net.core.bpf_jit_enable=1, when their kernels are compiled with Clang.

Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).

This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r

See the discussions in:
https://bugs.llvm.org/show_bug.cgi?id=42950
https://marc.info/?l=linux-netdev&m=156412960619946&w=2

Nick Desaulniers (16):
  s390/boot: fix section name escaping
  arc: prefer __section from compiler_attributes.h
  parisc: prefer __section from compiler_attributes.h
  um: prefer __section from compiler_attributes.h
  sh: prefer __section from compiler_attributes.h
  ia64: prefer __section from compiler_attributes.h
  arm: prefer __section from compiler_attributes.h
  mips: prefer __section from compiler_attributes.h
  sparc: prefer __section from compiler_attributes.h
  powerpc: prefer __section and __printf from compiler_attributes.h
  x86: prefer __section from compiler_attributes.h
  arm64: prefer __section from compiler_attributes.h
  include/asm-generic: prefer __section from compiler_attributes.h
  include/linux: prefer __section from compiler_attributes.h
  include/linux/compiler.h: remove unused KENTRY macro
  compiler_attributes.h: add note about __section

 arch/arc/include/asm/linkage.h        |  8 +++----
 arch/arc/include/asm/mach_desc.h      |  3 +--
 arch/arm/include/asm/cache.h          |  2 +-
 arch/arm/include/asm/mach/arch.h      |  4 ++--
 arch/arm/include/asm/setup.h          |  2 +-
 arch/arm64/include/asm/cache.h        |  2 +-
 arch/arm64/kernel/smp_spin_table.c    |  2 +-
 arch/ia64/include/asm/cache.h         |  2 +-
 arch/mips/include/asm/cache.h         |  2 +-
 arch/parisc/include/asm/cache.h       |  2 +-
 arch/parisc/include/asm/ldcw.h        |  2 +-
 arch/powerpc/boot/main.c              |  3 +--
 arch/powerpc/boot/ps3.c               |  6 ++----
 arch/powerpc/include/asm/cache.h      |  2 +-
 arch/powerpc/kernel/btext.c           |  2 +-
 arch/s390/boot/startup.c              |  2 +-
 arch/sh/include/asm/cache.h           |  2 +-
 arch/sparc/include/asm/cache.h        |  2 +-
 arch/sparc/kernel/btext.c             |  2 +-
 arch/um/kernel/um_arch.c              |  6 +++---
 arch/x86/include/asm/cache.h          |  2 +-
 arch/x86/include/asm/intel-mid.h      |  2 +-
 arch/x86/include/asm/iommu_table.h    |  5 ++---
 arch/x86/include/asm/irqflags.h       |  2 +-
 arch/x86/include/asm/mem_encrypt.h    |  2 +-
 arch/x86/kernel/cpu/cpu.h             |  3 +--
 include/asm-generic/error-injection.h |  2 +-
 include/asm-generic/kprobes.h         |  5 ++---
 include/linux/cache.h                 |  6 +++---
 include/linux/compiler.h              | 31 ++++-----------------------
 include/linux/compiler_attributes.h   | 10 +++++++++
 include/linux/cpu.h                   |  2 +-
 include/linux/export.h                |  2 +-
 include/linux/init_task.h             |  4 ++--
 include/linux/interrupt.h             |  5 ++---
 include/linux/sched/debug.h           |  2 +-
 include/linux/srcutree.h              |  2 +-
 37 files changed, 62 insertions(+), 83 deletions(-)

--
2.23.0.rc1.153.gdeed80330f-goog



-- 
Thanks,
~Nick Desaulniers