On Mon, Sep 01, 2025 at 11:36:00AM +0200, Peter Zijlstra wrote:
Something like the completely untested below should do I suppose.
diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h index 711a1f0d1a73..e39cdfe5a59e 100644 --- a/include/linux/instrumented.h +++ b/include/linux/instrumented.h @@ -67,6 +67,7 @@ static __always_inline void instrument_atomic_read(const volatile void *v, size_ { kasan_check_read(v, size); kcsan_check_atomic_read(v, size);
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & 3));
} /** @@ -81,6 +82,7 @@ static __always_inline void instrument_atomic_write(const volatile void *v, size { kasan_check_write(v, size); kcsan_check_atomic_write(v, size);
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & 3));
} /** @@ -95,6 +97,7 @@ static __always_inline void instrument_atomic_read_write(const volatile void *v, { kasan_check_write(v, size); kcsan_check_atomic_read_write(v, size);
- WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ATOMIC) && ((unsigned long)v & 3));
} /**
Arguably, that should've been something like:
((unsigned long)v & (size-1))
I suppose.
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index dc0e0c6ed075..1c7e30cdfe04 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1363,6 +1363,16 @@ 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 checkto atomic accesses. Useful for architectures that do not have trap onmis-aligned access.This option has potentially significant overhead.menu "Lock Debugging (spinlocks, mutexes, etc...)" config LOCK_DEBUGGING_SUPPORT