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

On Fri, 14 Nov 2025 16:17:06 +0000
Will Deacon [off-list ref] wrote:

On Tue, Nov 04, 2025 at 10:37:35PM +0900, Masami Hiramatsu wrote:

quoted

Gently ping.

There is a bugfix (or strange behavior) on arm64 hw breakpoint but
to fix it cleanly, it should change the perf itself (but I'm not
sure why arm64 changes the behavior only for the default overflow
handlers.) Anyone knows it?

It's because GDB expects to handle the stepping itself when using the
ptrace interface (with a custom overflow handler to deliver SIGTRAP).

Hmm, would you mean GDB for user program?
If so, it expects hw breakpoint is used by:
 - user-space ptrace (for GDB)
 - kernel-space perf (must be default overflow handler)

And not expects to be used by 

 - kernel-space custom overflow handler

This series is to handle the third use case.

Thank you,

-- 
Masami Hiramatsu (Google) [off-list ref]