Re: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

Re: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Aktemur, Baris]

AMD General

Hi Klaus,

This is a reply to

 https://inbox.sourceware.org/gdb-patches/87zffcn798.fsf@redhat.com/

It seems the patch is not merged to upstream master, yet.  I assume it's
simply an oversight.  Could you take a look?

I have one comment below:

> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index 43eca814e29..eb34aed09e0 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -6138,7 +6138,9 @@ handle_inferior_event (struct execution_control_state *ecs)
>       stack.  */
>    if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
>        && (ecs->ws.sig () == GDB_SIGNAL_ILL
> -       || ecs->ws.sig () == GDB_SIGNAL_SEGV
> +       || (ecs->ws.sig () == GDB_SIGNAL_SEGV
> +           && !gdbarch_imprecise_pagefault_reporting
> +             (current_inferior ()->arch ()))

In a case like AMD GPUs, the inferior contains a mixture of CPU and GPU threads.
The imprecise reporting property would depend on the kind of the thread.  Therefore,
instead of

  current_inferior ()->arch ()

I'd propose

  target_thread_architecture (ecs->event_thread->ptid)

That should still give the same behavior for Intel's case because by default a
process stratum target returns the inferior's arch.

Best,
-Baris

RE: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Gerlicher, Klaus]

Hi Baris,

Thanks a lot for noticing this, indeed it's an oversight.

I'll try the target_thread_architecture (ecs->event_thread->ptid) modificiation.

Thanks
Klaus


> -----Original Message-----
> From: Aktemur, Baris <TankutBaris.Aktemur@amd.com>
> Sent: Wednesday, May 13, 2026 10:20 AM
> To: Gerlicher, Klaus <klaus.gerlicher@intel.com>; gdb-
> patches@sourceware.org
> Cc: aburgess@redhat.com
> Subject: Re: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on
> user breakpoints
> 
> AMD General
> 
> Hi Klaus,
> 
> This is a reply to
> 
>  https://inbox.sourceware.org/gdb-patches/87zffcn798.fsf@redhat.com/
> 
> It seems the patch is not merged to upstream master, yet.  I assume it's
> simply an oversight.  Could you take a look?
> 
> I have one comment below:
> 
> > diff --git a/gdb/infrun.c b/gdb/infrun.c
> > index 43eca814e29..eb34aed09e0 100644
> > --- a/gdb/infrun.c
> > +++ b/gdb/infrun.c
> > @@ -6138,7 +6138,9 @@ handle_inferior_event (struct
> execution_control_state *ecs)
> >       stack.  */
> >    if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
> >        && (ecs->ws.sig () == GDB_SIGNAL_ILL
> > -       || ecs->ws.sig () == GDB_SIGNAL_SEGV
> > +       || (ecs->ws.sig () == GDB_SIGNAL_SEGV
> > +           && !gdbarch_imprecise_pagefault_reporting
> > +             (current_inferior ()->arch ()))
> 
> In a case like AMD GPUs, the inferior contains a mixture of CPU and GPU
> threads.
> The imprecise reporting property would depend on the kind of the thread.
> Therefore,
> instead of
> 
>   current_inferior ()->arch ()
> 
> I'd propose
> 
>   target_thread_architecture (ecs->event_thread->ptid)
> 
> That should still give the same behavior for Intel's case because by default a
> process stratum target returns the inferior's arch.
> 
> Best,
> -Baris
> 

Intel Deutschland GmbH
Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
Tel: +49 89 991 430, www.intel.de
Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
Chairperson of the Supervisory Board: Nicole Lau
Registered Seat: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

RE: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Aktemur, Baris]

AMD General

Hi Klaus,

On Tuesday, May 19, 2026 12:30 PM, Gerlicher, Klaus wrote:
> Hi Baris,
>
> Thanks a lot for noticing this, indeed it's an oversight.
>
> I'll try the target_thread_architecture (ecs->event_thread->ptid) modificiation.

Any update on this?

Regards,
-Baris

> Thanks
> Klaus
>
>
> > -----Original Message-----
> > From: Aktemur, Baris <TankutBaris.Aktemur@amd.com>
> > Sent: Wednesday, May 13, 2026 10:20 AM
> > To: Gerlicher, Klaus <klaus.gerlicher@intel.com>; gdb-
> > patches@sourceware.org
> > Cc: aburgess@redhat.com
> > Subject: Re: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on
> > user breakpoints
> >
> > AMD General
> >
> > Hi Klaus,
> >
> > This is a reply to
> >
> >  https://inbox.sourceware.org/gdb-patches/87zffcn798.fsf@redhat.com/
> >
> > It seems the patch is not merged to upstream master, yet.  I assume it's
> > simply an oversight.  Could you take a look?
> >
> > I have one comment below:
> >
> > > diff --git a/gdb/infrun.c b/gdb/infrun.c
> > > index 43eca814e29..eb34aed09e0 100644
> > > --- a/gdb/infrun.c
> > > +++ b/gdb/infrun.c
> > > @@ -6138,7 +6138,9 @@ handle_inferior_event (struct
> > execution_control_state *ecs)
> > >       stack.  */
> > >    if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
> > >        && (ecs->ws.sig () == GDB_SIGNAL_ILL
> > > -       || ecs->ws.sig () == GDB_SIGNAL_SEGV
> > > +       || (ecs->ws.sig () == GDB_SIGNAL_SEGV
> > > +           && !gdbarch_imprecise_pagefault_reporting
> > > +             (current_inferior ()->arch ()))
> >
> > In a case like AMD GPUs, the inferior contains a mixture of CPU and GPU
> > threads.
> > The imprecise reporting property would depend on the kind of the thread.
> > Therefore,
> > instead of
> >
> >   current_inferior ()->arch ()
> >
> > I'd propose
> >
> >   target_thread_architecture (ecs->event_thread->ptid)
> >
> > That should still give the same behavior for Intel's case because by default a
> > process stratum target returns the inferior's arch.
> >
> > Best,
> > -Baris
> >
>
> Intel Deutschland GmbH
> Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
> Tel: +49 89 991 430, www.intel.de
> Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
> Chairperson of the Supervisory Board: Nicole Lau
> Registered Seat: Munich
> Commercial Register: Amtsgericht Muenchen HRB 186928

[PATCH v4 0/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Klaus Gerlicher]

From: "Gerlicher, Klaus" <klaus.gerlicher@intel.com>

Hi Baris, Andrew, all,

thanks for the feedback and approval.

I incorporated your suggestions and added target_thread_architecture() instead of 
current_inferior()->arch() to obtain the architecture for the imprecise_pagefault_reporting
check.

Changes since V3:
- Use target_thread_architecture() instead of current_inferior()->arch()
  to obtain the architecture for the imprecise_pagefault_reporting check.

Thanks
Klaus

Gerlicher, Klaus (1):
  gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

 gdb/gdbarch-gen.c         | 22 ++++++++++++++++++++++
 gdb/gdbarch-gen.h         |  7 +++++++
 gdb/gdbarch_components.py | 12 ++++++++++++
 gdb/infrun.c              |  4 +++-
 4 files changed, 44 insertions(+), 1 deletion(-)

-- 
2.34.1

Intel Deutschland GmbH

Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
Tel: +49 89 991 430, www.intel.de
Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
Chairperson of the Supervisory Board: Nicole Lau
Registered Seat: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

[PATCH v4 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Klaus Gerlicher]

From: "Gerlicher, Klaus" <klaus.gerlicher@intel.com>

GDB converts signals GDB_SIGNAL_ILL, GDB_SIGNAL_SEGV and GDB_SIGNAL_EMT to
GDB_SIGNAL_TRAP if a breakpoint is inserted at the fault location.  If, due
to imprecise page fault reporting, a breakpoint is at the same address as
the fault address, this signal would always be reported as GDB_SIGNAL_TRAP.

Add a new gdbarch function, imprecise_pagefault_reporting, that allows the
signal conversion from GDB_SIGNAL_SEGV to GDB_SIGNAL_TRAP to be skipped for
an architecture.  The default is false (conversion enabled), preserving
existing behavior.
---
 gdb/gdbarch-gen.c         | 22 ++++++++++++++++++++++
 gdb/gdbarch-gen.h         |  7 +++++++
 gdb/gdbarch_components.py | 12 ++++++++++++
 gdb/infrun.c              |  4 +++-
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/gdb/gdbarch-gen.c b/gdb/gdbarch-gen.c
index f424fa2a86e..d9bb3e7078c 100644
--- a/gdb/gdbarch-gen.c
+++ b/gdb/gdbarch-gen.c
@@ -253,6 +253,7 @@ struct gdbarch
   gdbarch_core_parse_exec_context_ftype *core_parse_exec_context = default_core_parse_exec_context;
   gdbarch_shadow_stack_push_ftype *shadow_stack_push = nullptr;
   gdbarch_get_shadow_stack_pointer_ftype *get_shadow_stack_pointer = default_get_shadow_stack_pointer;
+  gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting = [] () -> bool {return false;};
 };
 
 /* Create a new ``struct gdbarch'' based on information provided by
@@ -513,6 +514,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of core_parse_exec_context, invalid_p == 0.  */
   /* Skip verify of shadow_stack_push, has predicate.  */
   /* Skip verify of get_shadow_stack_pointer, invalid_p == 0.  */
+  /* Skip verify of imprecise_pagefault_reporting, invalid_p == 0.  */
   if (!log.empty ())
     internal_error (_("verify_gdbarch: the following are invalid ...%s"),
 		    log.c_str ());
@@ -1339,6 +1341,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
   gdb_printf (file,
 	      "gdbarch_dump: get_shadow_stack_pointer = <%s>\n",
 	      host_address_to_string (gdbarch->get_shadow_stack_pointer));
+  gdb_printf (file,
+	      "gdbarch_dump: imprecise_pagefault_reporting = <%s>\n",
+	      host_address_to_string (gdbarch->imprecise_pagefault_reporting));
   if (gdbarch->dump_tdep != nullptr)
     gdbarch->dump_tdep (gdbarch, file);
 }
@@ -5286,3 +5291,20 @@ set_gdbarch_get_shadow_stack_pointer (struct gdbarch *gdbarch,
 {
   gdbarch->get_shadow_stack_pointer = get_shadow_stack_pointer;
 }
+
+bool
+gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->imprecise_pagefault_reporting != NULL);
+  if (gdbarch_debug >= 2)
+    gdb_printf (gdb_stdlog, "gdbarch_imprecise_pagefault_reporting called\n");
+  return gdbarch->imprecise_pagefault_reporting ();
+}
+
+void
+set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch,
+					   gdbarch_imprecise_pagefault_reporting_ftype imprecise_pagefault_reporting)
+{
+  gdbarch->imprecise_pagefault_reporting = imprecise_pagefault_reporting;
+}
diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
index 678b308fba5..bb95df25eb6 100644
--- a/gdb/gdbarch-gen.h
+++ b/gdb/gdbarch-gen.h
@@ -1752,3 +1752,10 @@ void set_gdbarch_shadow_stack_push (struct gdbarch *gdbarch, gdbarch_shadow_stac
 using gdbarch_get_shadow_stack_pointer_ftype = std::optional<CORE_ADDR> (struct gdbarch *gdbarch, regcache *regcache, bool &shadow_stack_enabled);
 std::optional<CORE_ADDR> gdbarch_get_shadow_stack_pointer (struct gdbarch *gdbarch, regcache *regcache, bool &shadow_stack_enabled);
 void set_gdbarch_get_shadow_stack_pointer (struct gdbarch *gdbarch, gdbarch_get_shadow_stack_pointer_ftype *get_shadow_stack_pointer);
+
+/* Returns true if architecture has imprecise pagefault reporting.  This is
+   used in conversion of SIGSEGV to SIGTRAP for an architecture. */
+
+typedef bool (gdbarch_imprecise_pagefault_reporting_ftype) ();
+extern bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
+extern void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting);
diff --git a/gdb/gdbarch_components.py b/gdb/gdbarch_components.py
index b9304d3036d..d903446435f 100644
--- a/gdb/gdbarch_components.py
+++ b/gdb/gdbarch_components.py
@@ -2781,3 +2781,15 @@ SHADOW_STACK_ENABLED to false.
     predefault="default_get_shadow_stack_pointer",
     invalid=False,
 )
+
+Function(
+    comment="""
+Returns true if architecture has imprecise pagefault reporting.  This is
+used in conversion of SIGSEGV to SIGTRAP for an architecture.
+""",
+    type="bool",
+    name="imprecise_pagefault_reporting",
+    params=[],
+    predefault="[] () -> bool {return false;}",
+    invalid=False
+)
diff --git a/gdb/infrun.c b/gdb/infrun.c
index c0767e7f764..25ed7e7523f 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -6331,7 +6331,9 @@ handle_inferior_event (struct execution_control_state *ecs)
      stack.  */
   if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
       && (ecs->ws.sig () == GDB_SIGNAL_ILL
-	  || ecs->ws.sig () == GDB_SIGNAL_SEGV
+	  || (ecs->ws.sig () == GDB_SIGNAL_SEGV
+	      && !gdbarch_imprecise_pagefault_reporting
+		  (target_thread_architecture (ecs->event_thread->ptid)))
 	  || ecs->ws.sig () == GDB_SIGNAL_EMT))
     {
       struct regcache *regcache = get_thread_regcache (ecs->event_thread);
-- 
2.34.1

Intel Deutschland GmbH

Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
Tel: +49 89 991 430, www.intel.de
Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
Chairperson of the Supervisory Board: Nicole Lau
Registered Seat: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

RE: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Gerlicher, Klaus]

Hi Baris,

Yes, I posted V4 just now.

Thanks
Klaus

> -----Original Message-----
> From: Aktemur, Baris <TankutBaris.Aktemur@amd.com>
> Sent: Tuesday, July 7, 2026 8:36 AM
> To: Gerlicher, Klaus <klaus.gerlicher@intel.com>; gdb-
> patches@sourceware.org
> Cc: aburgess@redhat.com
> Subject: RE: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on
> user breakpoints
> 
> AMD General
> 
> Hi Klaus,
> 
> On Tuesday, May 19, 2026 12:30 PM, Gerlicher, Klaus wrote:
> > Hi Baris,
> >
> > Thanks a lot for noticing this, indeed it's an oversight.
> >
> > I'll try the target_thread_architecture (ecs->event_thread->ptid)
> modificiation.
> 
> Any update on this?
> 
> Regards,
> -Baris
> 
> > Thanks
> > Klaus
> >
> >
> > > -----Original Message-----
> > > From: Aktemur, Baris <TankutBaris.Aktemur@amd.com>
> > > Sent: Wednesday, May 13, 2026 10:20 AM
> > > To: Gerlicher, Klaus <klaus.gerlicher@intel.com>; gdb-
> > > patches@sourceware.org
> > > Cc: aburgess@redhat.com
> > > Subject: Re: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP
> on
> > > user breakpoints
> > >
> > > AMD General
> > >
> > > Hi Klaus,
> > >
> > > This is a reply to
> > >
> > >  https://inbox.sourceware.org/gdb-patches/87zffcn798.fsf@redhat.com/
> > >
> > > It seems the patch is not merged to upstream master, yet.  I assume it's
> > > simply an oversight.  Could you take a look?
> > >
> > > I have one comment below:
> > >
> > > > diff --git a/gdb/infrun.c b/gdb/infrun.c
> > > > index 43eca814e29..eb34aed09e0 100644
> > > > --- a/gdb/infrun.c
> > > > +++ b/gdb/infrun.c
> > > > @@ -6138,7 +6138,9 @@ handle_inferior_event (struct
> > > execution_control_state *ecs)
> > > >       stack.  */
> > > >    if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
> > > >        && (ecs->ws.sig () == GDB_SIGNAL_ILL
> > > > -       || ecs->ws.sig () == GDB_SIGNAL_SEGV
> > > > +       || (ecs->ws.sig () == GDB_SIGNAL_SEGV
> > > > +           && !gdbarch_imprecise_pagefault_reporting
> > > > +             (current_inferior ()->arch ()))
> > >
> > > In a case like AMD GPUs, the inferior contains a mixture of CPU and GPU
> > > threads.
> > > The imprecise reporting property would depend on the kind of the thread.
> > > Therefore,
> > > instead of
> > >
> > >   current_inferior ()->arch ()
> > >
> > > I'd propose
> > >
> > >   target_thread_architecture (ecs->event_thread->ptid)
> > >
> > > That should still give the same behavior for Intel's case because by default a
> > > process stratum target returns the inferior's arch.
> > >
> > > Best,
> > > -Baris
> > >
> >
> > Intel Deutschland GmbH
> > Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
> > Tel: +49 89 991 430, www.intel.de
> > Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
> > Chairperson of the Supervisory Board: Nicole Lau
> > Registered Seat: Munich
> > Commercial Register: Amtsgericht Muenchen HRB 186928

RE: [PATCH v4 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Aktemur, Baris]

AMD General

Hi Klaus,

On Friday, July 17, 2026 9:45 AM, Klaus Gerlicher wrote:
> GDB converts signals GDB_SIGNAL_ILL, GDB_SIGNAL_SEGV and GDB_SIGNAL_EMT to
> GDB_SIGNAL_TRAP if a breakpoint is inserted at the fault location.  If, due
> to imprecise page fault reporting, a breakpoint is at the same address as
> the fault address, this signal would always be reported as GDB_SIGNAL_TRAP.
>
> Add a new gdbarch function, imprecise_pagefault_reporting, that allows the
> signal conversion from GDB_SIGNAL_SEGV to GDB_SIGNAL_TRAP to be skipped for
> an architecture.  The default is false (conversion enabled), preserving
> existing behavior.

It seems gdbarch.py has been updated since the last time you generated gdbarch files.
Re-generating gives the diff below.  The patch LGTM with that fixed.

Reviewed-By: Tankut Baris Aktemur <TankutBaris.Aktemur@amd.com>

Thank you.
-Baris


diff --git a/gdb/gdbarch-gen.c b/gdb/gdbarch-gen.c
index d9bb3e7078c..0b815296261 100644
--- a/gdb/gdbarch-gen.c
+++ b/gdb/gdbarch-gen.c
@@ -5295,8 +5295,8 @@ set_gdbarch_get_shadow_stack_pointer (struct gdbarch *gdbarch,
 bool
 gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch)
 {
-  gdb_assert (gdbarch != NULL);
-  gdb_assert (gdbarch->imprecise_pagefault_reporting != NULL);
+  gdb_assert (gdbarch != nullptr);
+  gdb_assert (gdbarch->imprecise_pagefault_reporting != nullptr);
   if (gdbarch_debug >= 2)
     gdb_printf (gdb_stdlog, "gdbarch_imprecise_pagefault_reporting called\n");
   return gdbarch->imprecise_pagefault_reporting ();
diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
index bb95df25eb6..a96692c206c 100644
--- a/gdb/gdbarch-gen.h
+++ b/gdb/gdbarch-gen.h
@@ -1756,6 +1756,6 @@ void set_gdbarch_get_shadow_stack_pointer (struct gdbarch *gdbarch, gdbarch_get_
 /* Returns true if architecture has imprecise pagefault reporting.  This is
    used in conversion of SIGSEGV to SIGTRAP for an architecture. */

-typedef bool (gdbarch_imprecise_pagefault_reporting_ftype) ();
-extern bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
-extern void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting);
+using gdbarch_imprecise_pagefault_reporting_ftype = bool ();
+bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
+void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting);

RE: [PATCH v4 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Gerlicher, Klaus]

Thank you, Baris.

 I discovered this too *after* I posted. I'll make sure it's updated once Andrew approves again.

Thanks
Klaus

> -----Original Message-----
> From: Aktemur, Baris <TankutBaris.Aktemur@amd.com>
> Sent: Friday, July 17, 2026 11:17 AM
> To: Gerlicher, Klaus <klaus.gerlicher@intel.com>; gdb-
> patches@sourceware.org
> Cc: aburgess@redhat.com
> Subject: RE: [PATCH v4 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on
> user breakpoints
> 
> AMD General
> 
> Hi Klaus,
> 
> On Friday, July 17, 2026 9:45 AM, Klaus Gerlicher wrote:
> > GDB converts signals GDB_SIGNAL_ILL, GDB_SIGNAL_SEGV and
> GDB_SIGNAL_EMT to
> > GDB_SIGNAL_TRAP if a breakpoint is inserted at the fault location.  If, due
> > to imprecise page fault reporting, a breakpoint is at the same address as
> > the fault address, this signal would always be reported as
> GDB_SIGNAL_TRAP.
> >
> > Add a new gdbarch function, imprecise_pagefault_reporting, that allows the
> > signal conversion from GDB_SIGNAL_SEGV to GDB_SIGNAL_TRAP to be
> skipped for
> > an architecture.  The default is false (conversion enabled), preserving
> > existing behavior.
> 
> It seems gdbarch.py has been updated since the last time you generated
> gdbarch files.
> Re-generating gives the diff below.  The patch LGTM with that fixed.
> 
> Reviewed-By: Tankut Baris Aktemur <TankutBaris.Aktemur@amd.com>
> 
> Thank you.
> -Baris
> 
> 
> diff --git a/gdb/gdbarch-gen.c b/gdb/gdbarch-gen.c
> index d9bb3e7078c..0b815296261 100644
> --- a/gdb/gdbarch-gen.c
> +++ b/gdb/gdbarch-gen.c
> @@ -5295,8 +5295,8 @@ set_gdbarch_get_shadow_stack_pointer (struct
> gdbarch *gdbarch,
>  bool
>  gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch)
>  {
> -  gdb_assert (gdbarch != NULL);
> -  gdb_assert (gdbarch->imprecise_pagefault_reporting != NULL);
> +  gdb_assert (gdbarch != nullptr);
> +  gdb_assert (gdbarch->imprecise_pagefault_reporting != nullptr);
>    if (gdbarch_debug >= 2)
>      gdb_printf (gdb_stdlog, "gdbarch_imprecise_pagefault_reporting
> called\n");
>    return gdbarch->imprecise_pagefault_reporting ();
> diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
> index bb95df25eb6..a96692c206c 100644
> --- a/gdb/gdbarch-gen.h
> +++ b/gdb/gdbarch-gen.h
> @@ -1756,6 +1756,6 @@ void set_gdbarch_get_shadow_stack_pointer
> (struct gdbarch *gdbarch, gdbarch_get_
>  /* Returns true if architecture has imprecise pagefault reporting.  This is
>     used in conversion of SIGSEGV to SIGTRAP for an architecture. */
> 
> -typedef bool (gdbarch_imprecise_pagefault_reporting_ftype) ();
> -extern bool gdbarch_imprecise_pagefault_reporting (struct gdbarch
> *gdbarch);
> -extern void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch
> *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype
> *imprecise_pagefault_reporting);
> +using gdbarch_imprecise_pagefault_reporting_ftype = bool ();
> +bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
> +void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch,
> gdbarch_imprecise_pagefault_reporting_ftype
> *imprecise_pagefault_reporting);
> 

Intel Deutschland GmbH

Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
Tel: +49 89 991 430, www.intel.de
Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
Chairperson of the Supervisory Board: Nicole Lau
Registered Seat: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928

RE: [PATCH v4 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Aktemur, Baris]

AMD General

Hi Andrew,

Kindly pinging for a re-approval.

Regards,
-Baris

On Friday, July 17, 2026 3:25 PM, Gerlicher, Klaus wrote:
> Thank you, Baris.
>
>  I discovered this too *after* I posted. I'll make sure it's updated once Andrew
> approves again.
>
> Thanks
> Klaus
>
> > -----Original Message-----
> > From: Aktemur, Baris <TankutBaris.Aktemur@amd.com>
> > Sent: Friday, July 17, 2026 11:17 AM
> > To: Gerlicher, Klaus <klaus.gerlicher@intel.com>; gdb-
> > patches@sourceware.org
> > Cc: aburgess@redhat.com
> > Subject: RE: [PATCH v4 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on
> > user breakpoints
> >
> > AMD General
> >
> > Hi Klaus,
> >
> > On Friday, July 17, 2026 9:45 AM, Klaus Gerlicher wrote:
> > > GDB converts signals GDB_SIGNAL_ILL, GDB_SIGNAL_SEGV and
> > GDB_SIGNAL_EMT to
> > > GDB_SIGNAL_TRAP if a breakpoint is inserted at the fault location.  If, due
> > > to imprecise page fault reporting, a breakpoint is at the same address as
> > > the fault address, this signal would always be reported as
> > GDB_SIGNAL_TRAP.
> > >
> > > Add a new gdbarch function, imprecise_pagefault_reporting, that allows the
> > > signal conversion from GDB_SIGNAL_SEGV to GDB_SIGNAL_TRAP to be
> > skipped for
> > > an architecture.  The default is false (conversion enabled), preserving
> > > existing behavior.
> >
> > It seems gdbarch.py has been updated since the last time you generated
> > gdbarch files.
> > Re-generating gives the diff below.  The patch LGTM with that fixed.
> >
> > Reviewed-By: Tankut Baris Aktemur <TankutBaris.Aktemur@amd.com>
> >
> > Thank you.
> > -Baris
> >
> >
> > diff --git a/gdb/gdbarch-gen.c b/gdb/gdbarch-gen.c
> > index d9bb3e7078c..0b815296261 100644
> > --- a/gdb/gdbarch-gen.c
> > +++ b/gdb/gdbarch-gen.c
> > @@ -5295,8 +5295,8 @@ set_gdbarch_get_shadow_stack_pointer (struct
> > gdbarch *gdbarch,
> >  bool
> >  gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch)
> >  {
> > -  gdb_assert (gdbarch != NULL);
> > -  gdb_assert (gdbarch->imprecise_pagefault_reporting != NULL);
> > +  gdb_assert (gdbarch != nullptr);
> > +  gdb_assert (gdbarch->imprecise_pagefault_reporting != nullptr);
> >    if (gdbarch_debug >= 2)
> >      gdb_printf (gdb_stdlog, "gdbarch_imprecise_pagefault_reporting
> > called\n");
> >    return gdbarch->imprecise_pagefault_reporting ();
> > diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
> > index bb95df25eb6..a96692c206c 100644
> > --- a/gdb/gdbarch-gen.h
> > +++ b/gdb/gdbarch-gen.h
> > @@ -1756,6 +1756,6 @@ void set_gdbarch_get_shadow_stack_pointer
> > (struct gdbarch *gdbarch, gdbarch_get_
> >  /* Returns true if architecture has imprecise pagefault reporting.  This is
> >     used in conversion of SIGSEGV to SIGTRAP for an architecture. */
> >
> > -typedef bool (gdbarch_imprecise_pagefault_reporting_ftype) ();
> > -extern bool gdbarch_imprecise_pagefault_reporting (struct gdbarch
> > *gdbarch);
> > -extern void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch
> > *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype
> > *imprecise_pagefault_reporting);
> > +using gdbarch_imprecise_pagefault_reporting_ftype = bool ();
> > +bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
> > +void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch,
> > gdbarch_imprecise_pagefault_reporting_ftype
> > *imprecise_pagefault_reporting);
> >
>
> Intel Deutschland GmbH
>
> Registered Address: Dornacher Strasse 1, 85622 Feldkirchen, Germany
> Tel: +49 89 991 430, www.intel.de
> Managing Directors: Harry Demas, Jeffrey Schneiderman, Yin Chong Sorrell
> Chairperson of the Supervisory Board: Nicole Lau
> Registered Seat: Munich
> Commercial Register: Amtsgericht Muenchen HRB 186928

Re: [PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Andrew Burgess]

Klaus Gerlicher <klaus.gerlicher@intel.com> writes:

> From: "Gerlicher, Klaus" <klaus.gerlicher@intel.com>
>
> GDB converts signals GDB_SIGNAL_ILL, GDB_SIGNAL_SEGV and GDB_SIGNAL_EMT to
> GDB_SIGNAL_SEGV if a breakpoint is inserted at the fault location.  If, due
> to imprecise page fault reporting, a breakpoint is at the same address as
> the fault address, this signal would always be reported as GDB_SIGNAL_TRAP.
>
> Add a new gdbarch function that allows the signal conversion from SIGNAL_SEGV
> to SIGNAL_TRAP to be skipped for an architecture.

LGTM.

Approved-By: Andrew Burgess <aburgess@redhat.com>

Thanks,
Andrew


> ---
>  gdb/gdbarch-gen.c         | 22 ++++++++++++++++++++++
>  gdb/gdbarch-gen.h         |  7 +++++++
>  gdb/gdbarch_components.py | 12 ++++++++++++
>  gdb/infrun.c              |  4 +++-
>  4 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/gdb/gdbarch-gen.c b/gdb/gdbarch-gen.c
> index d05c7a3cbdf..255f851ffa3 100644
> --- a/gdb/gdbarch-gen.c
> +++ b/gdb/gdbarch-gen.c
> @@ -260,6 +260,7 @@ struct gdbarch
>    gdbarch_get_pc_address_flags_ftype *get_pc_address_flags = default_get_pc_address_flags;
>    gdbarch_read_core_file_mappings_ftype *read_core_file_mappings = default_read_core_file_mappings;
>    gdbarch_use_target_description_from_corefile_notes_ftype *use_target_description_from_corefile_notes = default_use_target_description_from_corefile_notes;
> +  gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting = [] () -> bool {return false;};
>  };
>  
>  /* Create a new ``struct gdbarch'' based on information provided by
> @@ -531,6 +532,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
>    /* Skip verify of get_pc_address_flags, invalid_p == 0.  */
>    /* Skip verify of read_core_file_mappings, invalid_p == 0.  */
>    /* Skip verify of use_target_description_from_corefile_notes, invalid_p == 0.  */
> +  /* Skip verify of imprecise_pagefault_reporting, invalid_p == 0.  */
>    if (!log.empty ())
>      internal_error (_("verify_gdbarch: the following are invalid ...%s"),
>  		    log.c_str ());
> @@ -1396,6 +1398,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
>    gdb_printf (file,
>  	      "gdbarch_dump: use_target_description_from_corefile_notes = <%s>\n",
>  	      host_address_to_string (gdbarch->use_target_description_from_corefile_notes));
> +  gdb_printf (file,
> +	      "gdbarch_dump: imprecise_pagefault_reporting = <%s>\n",
> +	      host_address_to_string (gdbarch->imprecise_pagefault_reporting));
>    if (gdbarch->dump_tdep != NULL)
>      gdbarch->dump_tdep (gdbarch, file);
>  }
> @@ -5507,3 +5512,20 @@ set_gdbarch_use_target_description_from_corefile_notes (struct gdbarch *gdbarch,
>  {
>    gdbarch->use_target_description_from_corefile_notes = use_target_description_from_corefile_notes;
>  }
> +
> +bool
> +gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch)
> +{
> +  gdb_assert (gdbarch != NULL);
> +  gdb_assert (gdbarch->imprecise_pagefault_reporting != NULL);
> +  if (gdbarch_debug >= 2)
> +    gdb_printf (gdb_stdlog, "gdbarch_imprecise_pagefault_reporting called\n");
> +  return gdbarch->imprecise_pagefault_reporting ();
> +}
> +
> +void
> +set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch,
> +					   gdbarch_imprecise_pagefault_reporting_ftype imprecise_pagefault_reporting)
> +{
> +  gdbarch->imprecise_pagefault_reporting = imprecise_pagefault_reporting;
> +}
> diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
> index 9fda85f860f..e2ca6e59680 100644
> --- a/gdb/gdbarch-gen.h
> +++ b/gdb/gdbarch-gen.h
> @@ -1778,3 +1778,10 @@ extern void set_gdbarch_read_core_file_mappings (struct gdbarch *gdbarch, gdbarc
>  typedef bool (gdbarch_use_target_description_from_corefile_notes_ftype) (struct gdbarch *gdbarch, struct bfd *corefile_bfd);
>  extern bool gdbarch_use_target_description_from_corefile_notes (struct gdbarch *gdbarch, struct bfd *corefile_bfd);
>  extern void set_gdbarch_use_target_description_from_corefile_notes (struct gdbarch *gdbarch, gdbarch_use_target_description_from_corefile_notes_ftype *use_target_description_from_corefile_notes);
> +
> +/* Returns true if architecture has imprecise pagefault reporting.  This is
> +   used in conversion of SIGSEGV to SIGTRAP for an architecture. */
> +
> +typedef bool (gdbarch_imprecise_pagefault_reporting_ftype) ();
> +extern bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
> +extern void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting);
> diff --git a/gdb/gdbarch_components.py b/gdb/gdbarch_components.py
> index cc7c6d8677b..8f518e1052a 100644
> --- a/gdb/gdbarch_components.py
> +++ b/gdb/gdbarch_components.py
> @@ -2815,3 +2815,15 @@ The corefile's bfd is passed through COREFILE_BFD.
>      predefault="default_use_target_description_from_corefile_notes",
>      invalid=False,
>  )
> +
> +Function(
> +    comment="""
> +Returns true if architecture has imprecise pagefault reporting.  This is
> +used in conversion of SIGSEGV to SIGTRAP for an architecture.
> +""",
> +    type="bool",
> +    name="imprecise_pagefault_reporting",
> +    params=[],
> +    predefault="[] () -> bool {return false;}",
> +    invalid=False
> +)
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index 43eca814e29..eb34aed09e0 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -6138,7 +6138,9 @@ handle_inferior_event (struct execution_control_state *ecs)
>       stack.  */
>    if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
>        && (ecs->ws.sig () == GDB_SIGNAL_ILL
> -	  || ecs->ws.sig () == GDB_SIGNAL_SEGV
> +	  || (ecs->ws.sig () == GDB_SIGNAL_SEGV
> +	      && !gdbarch_imprecise_pagefault_reporting
> +	        (current_inferior ()->arch ()))
>  	  || ecs->ws.sig () == GDB_SIGNAL_EMT))
>      {
>        struct regcache *regcache = get_thread_regcache (ecs->event_thread);
> -- 
> 2.34.1
>
> Intel Deutschland GmbH
> Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
> Tel: +49 89 99 8853-0, www.intel.de
> Managing Directors: Sean Fennelly, Jeffrey Schneiderman, Tiffany Doon Silva
> Chairperson of the Supervisory Board: Nicole Lau
> Registered Office: Munich
> Commercial Register: Amtsgericht Muenchen HRB 186928

[PATCH v3 1/1] gdb: avoid conversion of SIGSEGV to SIGTRAP on user breakpoints

[Klaus Gerlicher]

From: "Gerlicher, Klaus" <klaus.gerlicher@intel.com>

GDB converts signals GDB_SIGNAL_ILL, GDB_SIGNAL_SEGV and GDB_SIGNAL_EMT to
GDB_SIGNAL_SEGV if a breakpoint is inserted at the fault location.  If, due
to imprecise page fault reporting, a breakpoint is at the same address as
the fault address, this signal would always be reported as GDB_SIGNAL_TRAP.

Add a new gdbarch function that allows the signal conversion from SIGNAL_SEGV
to SIGNAL_TRAP to be skipped for an architecture.
---
 gdb/gdbarch-gen.c         | 22 ++++++++++++++++++++++
 gdb/gdbarch-gen.h         |  7 +++++++
 gdb/gdbarch_components.py | 12 ++++++++++++
 gdb/infrun.c              |  4 +++-
 4 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/gdb/gdbarch-gen.c b/gdb/gdbarch-gen.c
index d05c7a3cbdf..255f851ffa3 100644
--- a/gdb/gdbarch-gen.c
+++ b/gdb/gdbarch-gen.c
@@ -260,6 +260,7 @@ struct gdbarch
   gdbarch_get_pc_address_flags_ftype *get_pc_address_flags = default_get_pc_address_flags;
   gdbarch_read_core_file_mappings_ftype *read_core_file_mappings = default_read_core_file_mappings;
   gdbarch_use_target_description_from_corefile_notes_ftype *use_target_description_from_corefile_notes = default_use_target_description_from_corefile_notes;
+  gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting = [] () -> bool {return false;};
 };
 
 /* Create a new ``struct gdbarch'' based on information provided by
@@ -531,6 +532,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of get_pc_address_flags, invalid_p == 0.  */
   /* Skip verify of read_core_file_mappings, invalid_p == 0.  */
   /* Skip verify of use_target_description_from_corefile_notes, invalid_p == 0.  */
+  /* Skip verify of imprecise_pagefault_reporting, invalid_p == 0.  */
   if (!log.empty ())
     internal_error (_("verify_gdbarch: the following are invalid ...%s"),
 		    log.c_str ());
@@ -1396,6 +1398,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
   gdb_printf (file,
 	      "gdbarch_dump: use_target_description_from_corefile_notes = <%s>\n",
 	      host_address_to_string (gdbarch->use_target_description_from_corefile_notes));
+  gdb_printf (file,
+	      "gdbarch_dump: imprecise_pagefault_reporting = <%s>\n",
+	      host_address_to_string (gdbarch->imprecise_pagefault_reporting));
   if (gdbarch->dump_tdep != NULL)
     gdbarch->dump_tdep (gdbarch, file);
 }
@@ -5507,3 +5512,20 @@ set_gdbarch_use_target_description_from_corefile_notes (struct gdbarch *gdbarch,
 {
   gdbarch->use_target_description_from_corefile_notes = use_target_description_from_corefile_notes;
 }
+
+bool
+gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->imprecise_pagefault_reporting != NULL);
+  if (gdbarch_debug >= 2)
+    gdb_printf (gdb_stdlog, "gdbarch_imprecise_pagefault_reporting called\n");
+  return gdbarch->imprecise_pagefault_reporting ();
+}
+
+void
+set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch,
+					   gdbarch_imprecise_pagefault_reporting_ftype imprecise_pagefault_reporting)
+{
+  gdbarch->imprecise_pagefault_reporting = imprecise_pagefault_reporting;
+}
diff --git a/gdb/gdbarch-gen.h b/gdb/gdbarch-gen.h
index 9fda85f860f..e2ca6e59680 100644
--- a/gdb/gdbarch-gen.h
+++ b/gdb/gdbarch-gen.h
@@ -1778,3 +1778,10 @@ extern void set_gdbarch_read_core_file_mappings (struct gdbarch *gdbarch, gdbarc
 typedef bool (gdbarch_use_target_description_from_corefile_notes_ftype) (struct gdbarch *gdbarch, struct bfd *corefile_bfd);
 extern bool gdbarch_use_target_description_from_corefile_notes (struct gdbarch *gdbarch, struct bfd *corefile_bfd);
 extern void set_gdbarch_use_target_description_from_corefile_notes (struct gdbarch *gdbarch, gdbarch_use_target_description_from_corefile_notes_ftype *use_target_description_from_corefile_notes);
+
+/* Returns true if architecture has imprecise pagefault reporting.  This is
+   used in conversion of SIGSEGV to SIGTRAP for an architecture. */
+
+typedef bool (gdbarch_imprecise_pagefault_reporting_ftype) ();
+extern bool gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch);
+extern void set_gdbarch_imprecise_pagefault_reporting (struct gdbarch *gdbarch, gdbarch_imprecise_pagefault_reporting_ftype *imprecise_pagefault_reporting);
diff --git a/gdb/gdbarch_components.py b/gdb/gdbarch_components.py
index cc7c6d8677b..8f518e1052a 100644
--- a/gdb/gdbarch_components.py
+++ b/gdb/gdbarch_components.py
@@ -2815,3 +2815,15 @@ The corefile's bfd is passed through COREFILE_BFD.
     predefault="default_use_target_description_from_corefile_notes",
     invalid=False,
 )
+
+Function(
+    comment="""
+Returns true if architecture has imprecise pagefault reporting.  This is
+used in conversion of SIGSEGV to SIGTRAP for an architecture.
+""",
+    type="bool",
+    name="imprecise_pagefault_reporting",
+    params=[],
+    predefault="[] () -> bool {return false;}",
+    invalid=False
+)
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 43eca814e29..eb34aed09e0 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -6138,7 +6138,9 @@ handle_inferior_event (struct execution_control_state *ecs)
      stack.  */
   if (ecs->ws.kind () == TARGET_WAITKIND_STOPPED
       && (ecs->ws.sig () == GDB_SIGNAL_ILL
-	  || ecs->ws.sig () == GDB_SIGNAL_SEGV
+	  || (ecs->ws.sig () == GDB_SIGNAL_SEGV
+	      && !gdbarch_imprecise_pagefault_reporting
+	        (current_inferior ()->arch ()))
 	  || ecs->ws.sig () == GDB_SIGNAL_EMT))
     {
       struct regcache *regcache = get_thread_regcache (ecs->event_thread);
-- 
2.34.1

Intel Deutschland GmbH
Registered Address: Am Campeon 10, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Sean Fennelly, Jeffrey Schneiderman, Tiffany Doon Silva
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928