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atomic: add alignment check to instrumented atomic operations

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Add a Kconfig option for debug builds which logs a warning when an
instrumented atomic operation takes place that's misaligned.  Some
platforms don't trap for this.

[fthain@linux-m68k.org: added __DISABLE_EXPORTS conditional and refactored as helper function]
Link: https://lkml.kernel.org/r/51ebf844e006ca0de408f5d3a831e7b39d7fc31c.1768281748.git.fthain@linux-m68k.org
Link: https://lore.kernel.org/lkml/20250901093600.GF4067720@noisy.programming.kicks-ass.net/
Link: https://lore.kernel.org/linux-next/df9fbd22-a648-ada4-fee0-68fe4325ff82@linux-m68k.org/
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Guo Ren <guoren@kernel.org>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Rich Felker <dalias@libc.org>
Cc: Song Liu <song@kernel.org>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Will Deacon <will@kernel.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Peter Zijlstra 2026-01-13 16:22:28 +11:00 committed by Andrew Morton
parent e428b013d9
commit 80047d84ee
2 changed files with 21 additions and 0 deletions
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11
include/linux/instrumented.h
View File

@ -7,6 +7,7 @@
#ifndef _LINUX_INSTRUMENTED_H
#define _LINUX_INSTRUMENTED_H
#include <linux/bug.h>
#include <linux/compiler.h>
#include <linux/kasan-checks.h>
#include <linux/kcsan-checks.h>
@ -55,6 +56,13 @@ static __always_inline void instrument_read_write(const volatile void *v, size_t
kcsan_check_read_write(v, size);
}
static __always_inline void instrument_atomic_check_alignment(const volatile void *v, size_t size)
{
#ifndef __DISABLE_EXPORTS
WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
#endif
}
/**
* instrument_atomic_read - instrument atomic read access
* @v: address of access
@ -67,6 +75,7 @@ static __always_inline void instrument_atomic_read(const volatile void *v, size_
{
kasan_check_read(v, size);
kcsan_check_atomic_read(v, size);
instrument_atomic_check_alignment(v, size);
}
/**
@ -81,6 +90,7 @@ static __always_inline void instrument_atomic_write(const volatile void *v, size
{
kasan_check_write(v, size);
kcsan_check_atomic_write(v, size);
instrument_atomic_check_alignment(v, size);
}
/**
@ -95,6 +105,7 @@ static __always_inline void instrument_atomic_read_write(const volatile void *v,
{
kasan_check_write(v, size);
kcsan_check_atomic_read_write(v, size);
instrument_atomic_check_alignment(v, size);
}
/**

10
lib/Kconfig.debug
View File

@ -1360,6 +1360,16 @@ config DEBUG_PREEMPT
depending on workload as it triggers debugging routines for each
this_cpu operation. It should only be used for debugging purposes.
config DEBUG_ATOMIC
bool "Debug atomic variables"
depends on DEBUG_KERNEL
help
If you say Y here then the kernel will add a runtime alignment check
to atomic accesses. Useful for architectures that do not have trap on
mis-aligned access.
This option has potentially significant overhead.
menu "Lock Debugging (spinlocks, mutexes, etc...)"
config LOCK_DEBUGGING_SUPPORT