LoongArch: Only send SIGTRAP signal if necessary in do_watch()

In do_watch(), the kernel unconditionally forces a SIGTRAP signal at the
end of the handler via force_sig(SIGTRAP). This is essential for ptrace
operations, but it severely disrupts standard perf_event usage.

Under normal perf usage, it is not necessary to force a SIGTRAP signal
on every hit. Forcing it unnecessarily aborts the target process if no
user-space signal handler is registered, which violates performance
monitoring behaviors and injects context switch overheads.

However, a conditional check using only 'current->ptrace' would block
legitimate user-requested signals when a perf_event is configured with
'attr.sigtrap = 1' for asynchronous user-space tracking.

Fix this by refactoring breakpoint_handler() and watchpoint_handler()
to return a boolean status indicating whether any triggered breakpoint
explicitly requires a signal notification. Update do_watch() to enforce
the SIGTRAP signal only when the process is actively being debugged via
ptrace, or when the underlying perf_event infrastructure specifically
demands it via 'attr.sigtrap'.

Cc: stable@vger.kernel.org
Fixes: 424421a7f34c ("LoongArch: ptrace: Add hardware single step support")
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

0 files changed, 0 insertions, 0 deletions