[PATCH 0/2] tracing/wprobe: Fix to avoid inifinite watchpoint exception on arm64

[Masami Hiramatsu (Google)]

Ingo, Will, Ping?

I also found that Kyle made a change on this area recently.

Thank you,

On Thu, 30 Oct 2025 12:26:55 +0900
"Masami Hiramatsu (Google)" <mhiramat at kernel.org> wrote:

> Hi,
> 
> Here are patches which fixes a wprobe bug reported by Mark Brown on
> arm64[1]. The root cause was that the infinite watchpoint exception on
> the same instruction, because arm64 watchpoint exception happens before
> the memory access has done, it needs to configure a single-step after
> calling overflow handler. It does that only for the default overflow
> handlers, and not for custom overflow handler registered via
> hw_breakpoint interface.
> 
> [1] https://lore.kernel.org/all/aPvwGhMBJqMKcC9D@finisterre.sirena.org.uk/
> 
> To fix this issue, this series introduces default_overflow_compatible
> flag in the perf_event and use it for identifying default overflow
> handlers instead of checking handler functions everytime[1/2], and
> set it in wprobe[2/2].
> 
> Thank you,
> 
> ---
> 
> Masami Hiramatsu (Google) (2):
>       perf: Introduce default_overflow_compatible flag
>       tracing: wprobe: Make wprobe_handler default overflow_handler compatible
> 
> 
>  include/linux/perf_event.h  |    9 ++-------
>  kernel/events/core.c        |    2 ++
>  kernel/trace/trace_wprobe.c |    7 +++++++
>  3 files changed, 11 insertions(+), 7 deletions(-)
> 
> --
> Masami Hiramatsu (Google) <mhiramat at kernel.org>


-- 
Masami Hiramatsu (Google) <mhiramat at kernel.org>