[PATCH 0/1] MR11071: ntdll: Ignore hardware breakpoint traps inside the signal stack.

[Soham Nandy (＠natimerry)]

Ignore hardware-breakpoint traps raised to avoid recursively dispatching a trap through the Unix signal handler when user code installs a hardware breakpoint that is also reached from Wine's signal-handling path.

This is split up from https://gitlab.winehq.org/wine/wine/-/merge_requests/11069 as asked.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11071

[PATCH 1/1] ntdll: Ignore hardware breakpoint traps inside the signal stack.

[Soham Nandy]

From: Soham Nandy <[e-mail]>

Ignore hardware-breakpoint traps raised to avoid recursively
dispatching a trap through the Unix signal handler when user code
installs a hardware breakpoint that is also reached from Wine's
signal-handling path
---
 dlls/ntdll/unix/signal_x86_64.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
index 41293fe5607..c48636ee194 100644
--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -2149,9 +2149,12 @@ static BOOL handle_syscall_trap( struct thread_data *data, ucontext_t *sigcontex
         R10_sig( sigcontext ) = RCX_sig( sigcontext );
         fixup_frame_fpu_state( frame, sigcontext );
     }
-    else if (siginfo->si_code == 4 /* TRAP_HWBKPT */ && is_inside_syscall( data, RSP_sig(sigcontext) ))
+    else if (siginfo->si_code == 4 /* TRAP_HWBKPT */ &&
+             (is_inside_syscall( data, RSP_sig(sigcontext) ) ||
+              is_inside_signal_stack( data, (void *)RSP_sig(sigcontext) )))
     {
-        TRACE_(seh)( "ignoring HWBKPT in syscall rip=%p\n", (void *)RIP_sig(sigcontext) );
+        TRACE_(seh)( "ignoring HWBKPT in syscall/signal stack rip=%p\n",
+                     (void *)RIP_sig(sigcontext) );
         return TRUE;
     }
     else return FALSE;
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/11071

[Elizabeth Figura (＠zfigura)]

For traceability, the application in question sets R/W breakpoints on several locations in the USD, including ProcessorFeatures[PF_RDWRFSGSBASE_AVAILABLE]. The application takes a SEGV and then the SEGV handler trips the breakpoint.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11071#note_142238

[Paul Gofman (＠gofman)]

Paul Gofman (@gofman) commented about dlls/ntdll/unix/signal_x86_64.c:
> R10_sig( sigcontext ) = RCX_sig( sigcontext );
>          fixup_frame_fpu_state( frame, sigcontext );
>      }
> -    else if (siginfo->si_code == 4 /* TRAP_HWBKPT */ && is_inside_syscall( data, RSP_sig(sigcontext) ))
> +    else if (siginfo->si_code == 4 /* TRAP_HWBKPT */ &&
> +             (is_inside_syscall( data, RSP_sig(sigcontext) ) ||
> +              is_inside_signal_stack( data, (void *)RSP_sig(sigcontext) )))
>      {
> -        TRACE_(seh)( "ignoring HWBKPT in syscall rip=%p\n", (void *)RIP_sig(sigcontext) );
> +        TRACE_(seh)( "ignoring HWBKPT in syscall/signal stack rip=%p\n",
> +                     (void *)RIP_sig(sigcontext) );

```suggestion
    else if (siginfo->si_code == 4 /* TRAP_HWBKPT */ && (is_inside_syscall( data, RSP_sig(sigcontext) )
             || is_inside_signal_stack( data, (void *)RSP_sig(sigcontext) )))
    {
        TRACE_(seh)( "ignoring HWBKPT rip=%p\n", (void *)RIP_sig(sigcontext) );
        return TRUE;
    }
```

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11071#note_142240

[Paul Gofman (＠gofman)]

Also it is probably best to do exactly the same in signal_i386.c at once.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11071#note_142241

[Soham Nandy (＠natimerry)]

Oh hey! I guess we spoke on #winehackers yesterday. Should I upload the logs here?

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11071#note_142243

[Soham Nandy (＠natimerry)]

On Thu Jun  4 21:09:00 2026 +0000, Paul Gofman wrote:
> Also it is probably best to do exactly the same in signal_i386.c at once.
> I will rebase and mirror the changes to i386

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/11071#note_142244