* + atomic-add-alignment-check-to-instrumented-atomic-operations.patch added to mm-nonmm-unstable branch
@ 2025-12-16 19:50 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2025-12-16 19:50 UTC (permalink / raw)
To: mm-commits, ysato, yonghong.song, will, stefan.kristiansson, song,
shorne, sdf, martin.lau, mark.rutland, kpsingh, jonas, jolsa,
john.fastabend, haoluo, guoren, glaubitz, geert, gary, fthain,
eddyz87, dinguyen, daniel, dalias, boqun.feng, ast, arnd, andrii,
peterz, akpm
The patch titled
Subject: atomic: add alignment check to instrumented atomic operations
has been added to the -mm mm-nonmm-unstable branch. Its filename is
atomic-add-alignment-check-to-instrumented-atomic-operations.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/atomic-add-alignment-check-to-instrumented-atomic-operations.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Peter Zijlstra <peterz@infradead.org>
Subject: atomic: add alignment check to instrumented atomic operations
Date: Tue, 16 Dec 2025 17:31:05 +1100
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.
Link: https://lore.kernel.org/lkml/20250901093600.GF4067720@noisy.programming.kicks-ass.net/
Link: https://lkml.kernel.org/r/0c18fd08ef19497768070783da28086e01d11a00.1765866665.git.fthain@linux-m68k.org
Signed-off-by: Finn Thain <fthain@linux-m68k.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
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: Geert Uytterhoeven <geert@linux-m68k.org>
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>
---
include/linux/instrumented.h | 4 ++++
lib/Kconfig.debug | 10 ++++++++++
2 files changed, 14 insertions(+)
--- a/include/linux/instrumented.h~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/include/linux/instrumented.h
@@ -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>
@@ -67,6 +68,7 @@ static __always_inline void instrument_a
{
kasan_check_read(v, size);
kcsan_check_atomic_read(v, size);
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
}
/**
@@ -81,6 +83,7 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_write(v, size);
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
}
/**
@@ -95,6 +98,7 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_read_write(v, size);
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
}
/**
--- a/lib/Kconfig.debug~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/lib/Kconfig.debug
@@ -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
_
Patches currently in -mm which might be from peterz@infradead.org are
atomic-add-alignment-check-to-instrumented-atomic-operations.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + atomic-add-alignment-check-to-instrumented-atomic-operations.patch added to mm-nonmm-unstable branch
@ 2025-12-27 15:09 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2025-12-27 15:09 UTC (permalink / raw)
To: mm-commits, ysato, yonghong.song, will, tglx, stefan.kristiansson,
song, shorne, sdf, sashal, mingo, martin.lau, mark.rutland,
kpsingh, jonas, jolsa, john.fastabend, hpa, haoluo, guoren,
glaubitz, geert, gary, fthain, eddyz87, dinguyen, dave.hansen,
daniel, dalias, bp, boqun.feng, ast, arnd, ardb, andrii, peterz,
akpm
The patch titled
Subject: atomic: add alignment check to instrumented atomic operations
has been added to the -mm mm-nonmm-unstable branch. Its filename is
atomic-add-alignment-check-to-instrumented-atomic-operations.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/atomic-add-alignment-check-to-instrumented-atomic-operations.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Peter Zijlstra <peterz@infradead.org>
Subject: atomic: add alignment check to instrumented atomic operations
Date: Wed, 31 Dec 2025 19:25:42 +1100
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_BUG_TABLE macro]
Link: https://lkml.kernel.org/r/f8cfe0d121be0849f5175495e73eafeeb85e1ad3.1767169542.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>
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: Geert Uytterhoeven <geert@linux-m68k.org>
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>
---
arch/x86/boot/compressed/Makefile | 1 +
drivers/firmware/efi/libstub/Makefile | 1 +
include/linux/instrumented.h | 10 ++++++++++
lib/Kconfig.debug | 10 ++++++++++
4 files changed, 22 insertions(+)
--- a/arch/x86/boot/compressed/Makefile~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/arch/x86/boot/compressed/Makefile
@@ -42,6 +42,7 @@ KBUILD_CFLAGS += -Wno-microsoft-anon-tag
endif
KBUILD_CFLAGS += -Wno-pointer-sign
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
+KBUILD_CFLAGS += -D__DISABLE_BUG_TABLE
KBUILD_CFLAGS += -D__DISABLE_EXPORTS
# Disable relocation relaxation in case the link is not PIE.
KBUILD_CFLAGS += $(call cc-option,-Wa$(comma)-mrelax-relocations=no)
--- a/drivers/firmware/efi/libstub/Makefile~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/drivers/firmware/efi/libstub/Makefile
@@ -42,6 +42,7 @@ KBUILD_CFLAGS := $(subst $(CC_FLAGS_FT
-ffreestanding \
-fno-stack-protector \
$(call cc-option,-fno-addrsig) \
+ -D__DISABLE_BUG_TABLE \
-D__DISABLE_EXPORTS
#
--- a/include/linux/instrumented.h~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/include/linux/instrumented.h
@@ -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>
@@ -67,6 +68,9 @@ static __always_inline void instrument_a
{
kasan_check_read(v, size);
kcsan_check_atomic_read(v, size);
+#ifndef __DISABLE_BUG_TABLE
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+#endif
}
/**
@@ -81,6 +85,9 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_write(v, size);
+#ifndef __DISABLE_BUG_TABLE
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+#endif
}
/**
@@ -95,6 +102,9 @@ static __always_inline void instrument_a
{
kasan_check_write(v, size);
kcsan_check_atomic_read_write(v, size);
+#ifndef __DISABLE_BUG_TABLE
+ WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & (size - 1)));
+#endif
}
/**
--- a/lib/Kconfig.debug~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/lib/Kconfig.debug
@@ -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
_
Patches currently in -mm which might be from peterz@infradead.org are
atomic-add-alignment-check-to-instrumented-atomic-operations.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
* + atomic-add-alignment-check-to-instrumented-atomic-operations.patch added to mm-nonmm-unstable branch
@ 2026-01-13 23:34 Andrew Morton
0 siblings, 0 replies; 3+ messages in thread
From: Andrew Morton @ 2026-01-13 23:34 UTC (permalink / raw)
To: mm-commits, ysato, yonghong.song, will, tglx, stefan.kristiansson,
song, shorne, sdf, sashal, mingo, martin.lau, mark.rutland,
kpsingh, jonas, jolsa, john.fastabend, hpa, haoluo, guoren,
glaubitz, geert, gary, fthain, eddyz87, dinguyen, dave.hansen,
daniel, dalias, bp, boqun.feng, ast, arnd, ardb, andrii, peterz,
akpm
The patch titled
Subject: atomic: add alignment check to instrumented atomic operations
has been added to the -mm mm-nonmm-unstable branch. Its filename is
atomic-add-alignment-check-to-instrumented-atomic-operations.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/atomic-add-alignment-check-to-instrumented-atomic-operations.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days
------------------------------------------------------
From: Peter Zijlstra <peterz@infradead.org>
Subject: atomic: add alignment check to instrumented atomic operations
Date: Tue, 13 Jan 2026 16:22:28 +1100
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>
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: Geert Uytterhoeven <geert@linux-m68k.org>
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>
---
include/linux/instrumented.h | 11 +++++++++++
lib/Kconfig.debug | 10 ++++++++++
2 files changed, 21 insertions(+)
--- a/include/linux/instrumented.h~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/include/linux/instrumented.h
@@ -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_r
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_a
{
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_a
{
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_a
{
kasan_check_write(v, size);
kcsan_check_atomic_read_write(v, size);
+ instrument_atomic_check_alignment(v, size);
}
/**
--- a/lib/Kconfig.debug~atomic-add-alignment-check-to-instrumented-atomic-operations
+++ a/lib/Kconfig.debug
@@ -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
_
Patches currently in -mm which might be from peterz@infradead.org are
atomic-add-alignment-check-to-instrumented-atomic-operations.patch
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-01-13 23:34 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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-- strict thread matches above, loose matches on Subject: below --
2026-01-13 23:34 Andrew Morton
2025-12-16 19:50 Andrew Morton
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