[RFC 0/12] Unify asm/unaligned.h around struct helper

Sat May 8 08:07:45 AEST 2021

From: Arnd Bergmann <arnd at arndb.de>

The get_unaligned()/put_unaligned() helpers are traditionally architecture
specific, with the two main variants being the "access-ok.h" version
that assumes unaligned pointer accesses always work on a particular
architecture, and the "le-struct.h" version that casts the data to a
byte aligned type before dereferencing, for architectures that cannot
always do unaligned accesses in hardware.

Based on the discussion linked below, it appears that the access-ok
version is not realiable on any architecture, but the struct version
probably has no downsides. This series changes the code to use the
same implementation on all architectures, addressing the few exceptions
separately.

I've pushed the patches to the asm-generic git tree for testing.

	Arnd

Link: https://lore.kernel.org/lkml/75d07691-1e4f-741f-9852-38c0b4f520bc@synopsys.com/
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100363
Link: git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git unaligned-rework

Arnd Bergmann (12):
  asm-generic: use asm-generic/unaligned.h for most architectures
  openrisc: always use unaligned-struct header
  sh: remove unaligned access for sh4a
  m68k: select CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
  powerpc: use linux/unaligned/le_struct.h on LE power7
  asm-generic: unaligned: remove byteshift helpers
  asm-generic: unaligned always use struct helpers
  partitions: msdos: fix one-byte get_unaligned()
  apparmor: use get_unaligned() only for multi-byte words
  mwifiex: re-fix for unaligned accesses
  netpoll: avoid put_unaligned() on single character
  asm-generic: simplify asm/unaligned.h

 arch/alpha/include/asm/unaligned.h          |  12 --
 arch/arm/include/asm/unaligned.h            |  27 ---
 arch/ia64/include/asm/unaligned.h           |  12 --
 arch/m68k/Kconfig                           |   1 +
 arch/m68k/include/asm/unaligned.h           |  26 ---
 arch/microblaze/include/asm/unaligned.h     |  27 ---
 arch/mips/crypto/crc32-mips.c               |   2 +-
 arch/openrisc/include/asm/unaligned.h       |  47 -----
 arch/parisc/include/asm/unaligned.h         |   6 +-
 arch/powerpc/include/asm/unaligned.h        |  22 ---
 arch/sh/include/asm/unaligned-sh4a.h        | 199 --------------------
 arch/sh/include/asm/unaligned.h             |  13 --
 arch/sparc/include/asm/unaligned.h          |  11 --
 arch/x86/include/asm/unaligned.h            |  15 --
 arch/xtensa/include/asm/unaligned.h         |  29 ---
 block/partitions/ldm.h                      |   2 +-
 block/partitions/msdos.c                    |   2 +-
 drivers/net/wireless/marvell/mwifiex/pcie.c |  10 +-
 include/asm-generic/unaligned.h             | 149 ++++++++++++---
 include/linux/unaligned/access_ok.h         |  68 -------
 include/linux/unaligned/be_byteshift.h      |  71 -------
 include/linux/unaligned/be_memmove.h        |  37 ----
 include/linux/unaligned/be_struct.h         |  37 ----
 include/linux/unaligned/generic.h           | 115 -----------
 include/linux/unaligned/le_byteshift.h      |  71 -------
 include/linux/unaligned/le_memmove.h        |  37 ----
 include/linux/unaligned/le_struct.h         |  37 ----
 include/linux/unaligned/memmove.h           |  46 -----
 net/core/netpoll.c                          |   4 +-
 security/apparmor/policy_unpack.c           |   2 +-
 30 files changed, 137 insertions(+), 1000 deletions(-)
 delete mode 100644 arch/alpha/include/asm/unaligned.h
 delete mode 100644 arch/arm/include/asm/unaligned.h
 delete mode 100644 arch/ia64/include/asm/unaligned.h
 delete mode 100644 arch/m68k/include/asm/unaligned.h
 delete mode 100644 arch/microblaze/include/asm/unaligned.h
 delete mode 100644 arch/openrisc/include/asm/unaligned.h
 delete mode 100644 arch/powerpc/include/asm/unaligned.h
 delete mode 100644 arch/sh/include/asm/unaligned-sh4a.h
 delete mode 100644 arch/sh/include/asm/unaligned.h
 delete mode 100644 arch/sparc/include/asm/unaligned.h
 delete mode 100644 arch/x86/include/asm/unaligned.h
 delete mode 100644 arch/xtensa/include/asm/unaligned.h
 delete mode 100644 include/linux/unaligned/access_ok.h
 delete mode 100644 include/linux/unaligned/be_byteshift.h
 delete mode 100644 include/linux/unaligned/be_memmove.h
 delete mode 100644 include/linux/unaligned/be_struct.h
 delete mode 100644 include/linux/unaligned/generic.h
 delete mode 100644 include/linux/unaligned/le_byteshift.h
 delete mode 100644 include/linux/unaligned/le_memmove.h
 delete mode 100644 include/linux/unaligned/le_struct.h
 delete mode 100644 include/linux/unaligned/memmove.h

Cc: Amitkumar Karwar <amitkarwar at gmail.com>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>
Cc: Borislav Petkov <bp at alien8.de>
Cc: Eric Dumazet <edumazet at google.com>
Cc: Florian Fainelli <f.fainelli at gmail.com>
Cc: Ganapathi Bhat <ganapathi017 at gmail.com>
Cc: Geert Uytterhoeven <geert at linux-m68k.org>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Ingo Molnar <mingo at redhat.com>
Cc: Jakub Kicinski <kuba at kernel.org>
Cc: James Morris <jmorris at namei.org>
Cc: Jens Axboe <axboe at kernel.dk>
Cc: John Johansen <john.johansen at canonical.com>
Cc: Jonas Bonn <jonas at southpole.se>
Cc: Kalle Valo <kvalo at codeaurora.org>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Paul Mackerras <paulus at samba.org>
Cc: Rich Felker <dalias at libc.org>
Cc: "Richard Russon (FlatCap)" <ldm at flatcap.org>
Cc: Russell King <linux at armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge at hallyn.com>
Cc: Sharvari Harisangam <sharvari.harisangam at nxp.com>
Cc: Stafford Horne <shorne at gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson at saunalahti.fi>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Vladimir Oltean <vladimir.oltean at nxp.com>
Cc: Xinming Hu <huxinming820 at gmail.com>
Cc: Yoshinori Sato <ysato at users.sourceforge.jp>
Cc: x86 at kernel.org
Cc: linux-kernel at vger.kernel.org
Cc: linux-arm-kernel at lists.infradead.org
Cc: linux-m68k at lists.linux-m68k.org
Cc: linux-crypto at vger.kernel.org
Cc: openrisc at lists.librecores.org
Cc: linuxppc-dev at lists.ozlabs.org
Cc: linux-sh at vger.kernel.org
Cc: sparclinux at vger.kernel.org
Cc: linux-ntfs-dev at lists.sourceforge.net
Cc: linux-block at vger.kernel.org
Cc: linux-wireless at vger.kernel.org
Cc: netdev at vger.kernel.org
Cc: linux-arch at vger.kernel.org
Cc: linux-security-module at vger.kernel.org

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2.29.2