linux-kernel - [PATCH v2 0/7] linkage: better symbol aliasing

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Date:   Tue, 25 Jan 2022 11:31:53 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     linux-kernel@...r.kernel.org
Cc:     acme@...hat.com, ardb@...nel.org, bp@...en8.de, broonie@...nel.org,
        catalin.marinas@....com, dave.hansen@...ux.intel.com,
        jpoimboe@...hat.com, jslaby@...e.cz,
        linux-arm-kernel@...ts.infradead.org, linux@...linux.org.uk,
        mark.rutland@....com, mingo@...hat.com, peterz@...radead.org,
        tglx@...utronix.de, will@...nel.org
Subject: [PATCH v2 0/7] linkage: better symbol aliasing

This series aims to make symbol aliasing simpler and more consistent.
The basic idea is to replace SYM_FUNC_START_ALIAS(alias) and
SYM_FUNC_END_ALIAS(alias) with a new SYM_FUNC_ALIAS(alias, name), so
that e.g.

    SYM_FUNC_START(func)
    SYM_FUNC_START_ALIAS(alias1)
    SYM_FUNC_START_ALIAS(alias2)
        ... asm insns ...
    SYM_FUNC_END(func)
    SYM_FUNC_END_ALIAS(alias1)
    SYM_FUNC_END_ALIAS(alias2)
    EXPORT_SYMBOL(alias1)
    EXPORT_SYMBOL(alias2)

... can become:

    SYM_FUNC_START(name)
        ... asm insns ...
    SYM_FUNC_END(name)

    SYM_FUNC_ALIAS(alias1, func)
    EXPORT_SYMBOL(alias1)

    SYM_FUNC_ALIAS(alias2, func)
    EXPORT_SYMBOL(alias2)

This avoids repetition and hopefully make it easier to ensure
consistency (e.g. so each function has a single canonical name and
associated metadata).

I've build+boot tested arm64 defconfig without issues, and also build
tested arm/i386/x86_64 defconfig without issues. I've pushed the series
to my `linkage/alias-rework` branch on git.kernel.org, atop v5.17-rc1:

  git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git linkage/alias-rework
  https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=linkage/alias-rework

Since RFCv1 [1]:
* Drop arm64 dma alias removal (taken via arm64 for v5.17)
* Rename SYM_FUNC_LOCAL_ALIAS() -> SYM_FUNC_ALIAS_LOCAL()
* Update the tools/ copies of x86 routines
* Add preparatory fix for 32-bit arm
* Rebase to v5.17-rc1

[1] https://lore.kernel.org/r/20211206124715.4101571-1-mark.rutland@arm.com/

Thanks,
Mark.

Mark Rutland (7):
  arm: lib: remove leading whitespace in bitop macro
  linkage: add SYM_{ENTRY,START,END}_AT()
  linkage: add SYM_FUNC_ALIAS{,_LOCAL,_WEAK}()
  arm64: clean up symbol aliasing
  x86: clean up symbol aliasing
  linkage: remove SYM_FUNC_{START,END}_ALIAS()
  tools: update x86 string routines

 Documentation/asm-annotations.rst       | 11 ++--
 arch/arm/lib/bitops.h                   |  8 +--
 arch/arm64/include/asm/linkage.h        | 24 -------
 arch/arm64/kvm/hyp/nvhe/cache.S         |  5 +-
 arch/arm64/lib/clear_page.S             |  5 +-
 arch/arm64/lib/copy_page.S              |  5 +-
 arch/arm64/lib/memchr.S                 |  5 +-
 arch/arm64/lib/memcmp.S                 |  6 +-
 arch/arm64/lib/memcpy.S                 | 21 +++---
 arch/arm64/lib/memset.S                 | 12 ++--
 arch/arm64/lib/strchr.S                 |  6 +-
 arch/arm64/lib/strcmp.S                 |  6 +-
 arch/arm64/lib/strlen.S                 |  6 +-
 arch/arm64/lib/strncmp.S                |  6 +-
 arch/arm64/lib/strnlen.S                |  6 +-
 arch/arm64/lib/strrchr.S                |  5 +-
 arch/arm64/mm/cache.S                   | 35 ++++++----
 arch/x86/boot/compressed/head_32.S      |  3 +-
 arch/x86/boot/compressed/head_64.S      |  3 +-
 arch/x86/crypto/aesni-intel_asm.S       |  4 +-
 arch/x86/lib/memcpy_64.S                | 10 +--
 arch/x86/lib/memmove_64.S               |  4 +-
 arch/x86/lib/memset_64.S                |  6 +-
 include/linux/linkage.h                 | 87 +++++++++++++++----------
 tools/arch/x86/lib/memcpy_64.S          | 10 +--
 tools/arch/x86/lib/memset_64.S          |  6 +-
 tools/perf/util/include/linux/linkage.h | 80 +++++++++++++++--------
 27 files changed, 209 insertions(+), 176 deletions(-)

-- 
2.30.2