[RFC 0/12] Unify asm/unaligned.h around struct helper
4 messages,
2 authors,
2021-05-10 · open the first message on its own page
From: Arnd Bergmann <arnd@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 <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ganapathi Bhat <redacted>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: James Morris <jmorris@namei.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Kalle Valo <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Rich Felker <dalias@libc.org>
Cc: "Richard Russon (FlatCap)" <ldm@flatcap.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Sharvari Harisangam <redacted>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Thomas Gleixner <redacted>
Cc: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Xinming Hu <redacted>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-crypto@vger.kernel.org
Cc: openrisc@lists.librecores.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-ntfs-dev@lists.sourceforge.net
Cc: linux-block@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
--
2.29.2
From: Arnd Bergmann <arnd@arndb.de>
Using get_unaligned() on a u8 pointer is pointless, and will
result in a compiler warning after a planned cleanup:
In file included from arch/x86/include/generated/asm/unaligned.h:1,
from security/apparmor/policy_unpack.c:16:
security/apparmor/policy_unpack.c: In function 'unpack_u8':
include/asm-generic/unaligned.h:13:15: error: 'packed' attribute ignored for field of type 'u8' {aka 'unsigned char'} [-Werror=attributes]
13 | const struct { type x __packed; } *__pptr = (typeof(__pptr))(ptr); \
| ^
Simply dereference this pointer directly.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
security/apparmor/policy_unpack.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index b8efbda545cb..0acca6f2a93f 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c @@ -304,7 +304,7 @@ static bool unpack_u8(struct aa_ext *e, u8 *data, const char *name)
if ( ! inbounds ( e , sizeof ( u8 )))
goto fail ;
if ( data )
- * data = get_unaligned (( u8 * ) e -> pos ); + * data = * (( u8 * ) e -> pos ); e -> pos += sizeof ( u8 );
return true ;
} --
2.29.2
From: Arnd Bergmann <arnd@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 <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ganapathi Bhat <redacted>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: James Morris <jmorris@namei.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Kalle Valo <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <redacted>
Cc: Rich Felker <dalias@libc.org>
Cc: "Richard Russon (FlatCap)" <ldm@flatcap.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Sharvari Harisangam <redacted>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Thomas Gleixner <redacted>
Cc: Vladimir Oltean <vladimir.oltean@nxp.com>
Cc: Xinming Hu <redacted>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-crypto@vger.kernel.org
Cc: openrisc@lists.librecores.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-ntfs-dev@lists.sourceforge.net
Cc: linux-block@vger.kernel.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
--
2.29.2
On 5/7/21 3:07 PM, Arnd Bergmann wrote: From: Arnd Bergmann <arnd@arndb.de>
Using get_unaligned() on a u8 pointer is pointless, and will
result in a compiler warning after a planned cleanup:
In file included from arch/x86/include/generated/asm/unaligned.h:1,
from security/apparmor/policy_unpack.c:16:
security/apparmor/policy_unpack.c: In function 'unpack_u8':
include/asm-generic/unaligned.h:13:15: error: 'packed' attribute ignored for field of type 'u8' {aka 'unsigned char'} [-Werror=attributes]
13 | const struct { type x __packed; } *__pptr = (typeof(__pptr))(ptr); \
| ^
Simply dereference this pointer directly.
Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: John Johansen <john.johansen@canonical.com>
quoted hunk ---
security/apparmor/policy_unpack.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index b8efbda545cb..0acca6f2a93f 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c @@ -304,7 +304,7 @@ static bool unpack_u8(struct aa_ext *e, u8 *data, const char *name)
if ( ! inbounds ( e , sizeof ( u8 )))
goto fail ;
if ( data )
- * data = get_unaligned (( u8 * ) e -> pos ); + * data = * (( u8 * ) e -> pos ); e -> pos += sizeof ( u8 );
return true ;
}