Commit 80047d84 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Andrew Morton
Browse files

atomic: add alignment check to instrumented atomic operations 

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: default avatarFinn Thain <fthain@linux-m68k.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: default avatarGeert 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent e428b013

include/linux/instrumented.h

+11 −0
Original line number Diff line number Diff line
@@ -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);

}



/**

lib/Kconfig.debug

+10 −0
Original line number Diff line number Diff line
@@ -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