gdb/amd-dbgapi-target: add trap-on-entry support

gdb/amd-dbgapi-target.c

@@ -220,11 +220,13 @@ struct amd_dbgapi_inferior_info
 {
   explicit amd_dbgapi_inferior_info
     (inferior *inf, bool precise_memory_requested = false,
-     bool precise_alu_exceptions_requested = false)
+     bool precise_alu_exceptions_requested = false,
+     bool trap_on_entry_requested = false)
     : inf (inf)
   {
     precise_memory.requested = precise_memory_requested;
     precise_alu_exceptions.requested = precise_alu_exceptions_requested;
+    trap_on_entry.requested = trap_on_entry_requested;
   }
 
   /* Backlink to inferior.  */
@@ -264,6 +266,9 @@ struct amd_dbgapi_inferior_info
      enablement.  */
   struct dbgapi_feature_request precise_alu_exceptions;
 
+  /* Track the status of trap-on-entry request and enablement.  */
+  struct dbgapi_feature_request trap_on_entry;
+
   gdb::unordered_map<decltype (amd_dbgapi_breakpoint_id_t::handle),
 		     struct breakpoint *>
     breakpoint_map;
@@ -2447,6 +2452,31 @@ set_process_alu_exceptions_precision (amd_dbgapi_inferior_info &info)
 	   get_status_string (status));
 }
 
+/* Set the process' wave launch trap-on-entry mode.  */
+
+static void
+set_process_trap_on_entry (amd_dbgapi_inferior_info &info)
+{
+#if HAVE_DECL_AMD_DBGAPI_PROCESS_ENABLE_TRAPS
+  auto value = (info.trap_on_entry.requested 
+                ? AMD_DBGAPI_WAVE_ENABLE_TRAP_ON_ENTRY
+                : AMD_DBGAPI_WAVE_ENABLE_TRAP_NONE);
+
+  amd_dbgapi_status_t status
+    = amd_dbgapi_process_enable_traps (info.process_id, value, AMD_DBGAPI_WAVE_ENABLE_TRAP_ON_ENTRY);
+#else
+  amd_dbgapi_status_t status = AMD_DBGAPI_STATUS_ERROR_NOT_SUPPORTED;
+#endif
+
+  if (status == AMD_DBGAPI_STATUS_SUCCESS)
+    info.trap_on_entry.enabled = info.trap_on_entry.requested;
+  else if (status == AMD_DBGAPI_STATUS_ERROR_NOT_SUPPORTED)
+	warning (_("AMDGPU enabled traps could not be set."));
+  else
+    error (_("amd_dbgapi_process_enable_traps failed (%s)"),
+	   get_status_string (status));
+}
+
 /* Handle extra initialisation after we have attached to a AMDGPU corefile.  */
 
 static void
@@ -2570,6 +2600,7 @@ attach_amd_dbgapi (inferior *inf)
 
   set_process_memory_precision (info);
   set_process_alu_exceptions_precision (info);
+  set_process_trap_on_entry (info);
 
   /* If GDB is attaching to a process that has the runtime loaded, there will
      already be a "runtime loaded" event available.  Consume it and push the
@@ -2619,10 +2650,11 @@ detach_amd_dbgapi (inferior *inf)
   for (auto &&value : info.breakpoint_map)
     delete_breakpoint (value.second);
 
-  /* Reset the amd_dbgapi_inferior_info, except for precise_memory_mode and
-     precise_alu_exceptions.  */
+  /* Reset the amd_dbgapi_inferior_info, except for precise_memory_mode,
+     precise_alu_exceptions and trap_on_entry.  */
   info = amd_dbgapi_inferior_info (inf, info.precise_memory.requested,
-				   info.precise_alu_exceptions.requested);
+				   info.precise_alu_exceptions.requested,
+				   info.trap_on_entry.requested);
 
   maybe_reset_amd_dbgapi ();
 }
@@ -3058,6 +3090,7 @@ amd_dbgapi_target_inferior_cloned (inferior *original_inferior,
   new_info.precise_memory.requested = orig_info.precise_memory.requested;
   new_info.precise_alu_exceptions.requested
     = orig_info.precise_alu_exceptions.requested;
+  new_info.trap_on_entry.requested = orig_info.trap_on_entry.requested;
 }
 
 /* inferior_execd observer.  */
@@ -3078,6 +3111,8 @@ amd_dbgapi_inferior_execd (inferior *exec_inf, inferior *follow_inf)
   get_amd_dbgapi_inferior_info (follow_inf).precise_alu_exceptions.requested
     = get_amd_dbgapi_inferior_info (exec_inf)
 	.precise_alu_exceptions.requested;
+  get_amd_dbgapi_inferior_info (follow_inf).trap_on_entry.requested
+    = get_amd_dbgapi_inferior_info (exec_inf).trap_on_entry.requested;
 
   attach_amd_dbgapi (follow_inf);
 }
@@ -3099,6 +3134,8 @@ amd_dbgapi_inferior_forked (inferior *parent_inf, inferior *child_inf,
 	= parent_info.precise_memory.requested;
       child_info.precise_alu_exceptions.requested
 	= parent_info.precise_alu_exceptions.requested;
+      child_info.trap_on_entry.requested
+	= parent_info.trap_on_entry.requested;
 
       if (fork_kind != TARGET_WAITKIND_VFORKED)
 	{
@@ -3663,6 +3700,55 @@ get_effective_precise_alu_exception_mode ()
   return info.precise_alu_exceptions.enabled;
 }
 
+/* Callback for "show amdgpu trap-on-entry".  */
+
+static void
+show_trap_on_entry_mode (struct ui_file *file, int from_tty,
+			 struct cmd_list_element *c, const char *value)
+{
+  const amd_dbgapi_inferior_info &info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+
+  gdb_printf (file,
+	      _("AMDGPU wave launch trap-on-entry is %s (currently %s).\n"),
+	      info.trap_on_entry.requested ? "on" : "off",
+	      info.trap_on_entry.enabled ? "enabled" : "disabled");
+}
+
+/* Callback for "set amdgpu trap-on-entry".  */
+
+static void
+set_trap_on_entry_mode (bool value)
+{
+  amd_dbgapi_inferior_info &info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+
+  info.trap_on_entry.requested = value;
+
+  if (info.runtime_state == AMD_DBGAPI_RUNTIME_STATE_LOADED_SUCCESS)
+    set_process_trap_on_entry (info);
+}
+
+/* Get the trap-on-entry requested mode.  */
+
+static bool
+get_trap_on_entry_mode ()
+{
+  const amd_dbgapi_inferior_info &info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+  return info.trap_on_entry.requested;
+}
+
+/* Get the trap-on-entry effective mode.  */
+
+static bool
+get_effective_trap_on_entry_mode ()
+{
+  amd_dbgapi_inferior_info &info
+    = get_amd_dbgapi_inferior_info (current_inferior ());
+  return info.trap_on_entry.enabled;
+}
+
 static const char *
 get_dbgapi_library_file_path ()
 {
@@ -5014,6 +5100,19 @@ running.  If off (default), precise ALU exceptions reporting is disabled."),
   cmds.show->var->set_effective_value_getter<bool>
     (get_effective_precise_alu_exception_mode);
 
+  cmds = add_setshow_boolean_cmd ("trap-on-entry", no_class,
+				  _("Set trap-on-entry mode."),
+				  _("Show trap-on-entry mode."), _("\
+If on, all newly created waves will trap immediately upon launch before\n\
+executing any shader instructions.  If off (default), waves execute normally."),
+				  set_trap_on_entry_mode,
+				  get_trap_on_entry_mode,
+				  show_trap_on_entry_mode,
+				  &set_amdgpu_list, &show_amdgpu_list);
+
+  cmds.show->var->set_effective_value_getter<bool>
+    (get_effective_trap_on_entry_mode);
+
   add_cmd ("version", no_set_class, show_dbgapi_version,
 	   _("Show the ROCdbgapi library version and build information."),
 	   &show_amdgpu_list);

gdb/config.in

@@ -136,6 +136,11 @@
    you don't. */
 #undef HAVE_DECL_ADDR_NO_RANDOMIZE
 
+/* Define to 1 if you have the declaration of
+   `amd_dbgapi_process_enable_traps', and to 0 if you don't.
+   */
+#undef HAVE_DECL_AMD_DBGAPI_PROCESS_ENABLE_TRAPS
+
 /* Define to 1 if you have the declaration of `asprintf', and to 0 if you
    don't. */
 #undef HAVE_DECL_ASPRINTF

gdb/configure

@@ -25437,6 +25437,22 @@ $as_echo "#define HAVE_AMD_DBGAPI 1" >>confdefs.h
 
     TARGET_OBS="$TARGET_OBS amd-dbgapi-target.o"
 
+    save_CPPFLAGS="$CPPFLAGS"
+    CPPFLAGS="$CPPFLAGS $AMD_DBGAPI_CFLAGS"
+    ac_fn_c_check_decl "$LINENO" "amd_dbgapi_process_enable_traps" "ac_cv_have_decl_amd_dbgapi_process_enable_traps" "#include <amd-dbgapi/amd-dbgapi.h>
+"
+if test "x$ac_cv_have_decl_amd_dbgapi_process_enable_traps" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_AMD_DBGAPI_PROCESS_ENABLE_TRAPS $ac_have_decl
+_ACEOF
+
+    CPPFLAGS="$save_CPPFLAGS"
+
     # If --enable-targets=all was provided, use the list of all files depending
     # on amd-dbgapi that is hardcoded in the Makefile.  Else, the appropriate
     # architecture entry in configure.tgt will have added the files to

gdb/configure.ac

@@ -334,6 +334,12 @@ if test "$gdb_require_amd_dbgapi" = true \
     AC_DEFINE(HAVE_AMD_DBGAPI, 1, [Define if amd-dbgapi is being linked in.])
     TARGET_OBS="$TARGET_OBS amd-dbgapi-target.o"
 
+    save_CPPFLAGS="$CPPFLAGS"
+    CPPFLAGS="$CPPFLAGS $AMD_DBGAPI_CFLAGS"
+    AC_CHECK_DECLS([amd_dbgapi_process_enable_traps], [], [],
+		   [[#include <amd-dbgapi/amd-dbgapi.h>]])
+    CPPFLAGS="$save_CPPFLAGS"
+
     # If --enable-targets=all was provided, use the list of all files depending
     # on amd-dbgapi that is hardcoded in the Makefile.  Else, the appropriate
     # architecture entry in configure.tgt will have added the files to

gdb/doc/gdb.texinfo

@@ -3654,12 +3654,12 @@ Adds @var{n} inferiors ready to execute the same program as inferior
 @var{infno}; @var{n} defaults to 1, and @var{infno} defaults to the
 number of the current inferior.  This command copies the values of the
 @var{args}, @w{@var{inferior-tty}}, @var{cwd}, @w{@code{amdgpu
-precise-memory}} and @w{@code{amdgpu precise-alu-exceptions}} properties
-from the current inferior to the new one.  It also propagates changes
-the user made to environment variables using the @w{@code{set
-environment}} and @w{@code{unset environment}} commands.  This is a
-convenient command when you want to run another instance of the inferior
-you are debugging.
+precise-memory}}, @w{@code{amdgpu precise-alu-exceptions}} and
+@w{@code{amdgpu trap-on-entry}} properties from the current inferior to
+the new one.  It also propagates changes the user made to environment
+variables using the @w{@code{set environment}} and @w{@code{unset
+environment}} commands.  This is a convenient command when you want to
+run another instance of the inferior you are debugging.
 
 @smallexample
 (@value{GDBP}) info inferiors
@@ -30074,6 +30074,78 @@ Display the currently requested and effective @acronym{AMD}
 
 @end table
 
+@subsubsection @acronym{AMD} @acronym{GPU} Forcing Waves to Trap on Entry
+
+By default, @acronym{AMD} @acronym{GPU} waves execute freely once they are
+created, and are only stopped when they hit a breakpoint or report an
+exception.  It can be useful to instead have every wave stop as soon as it
+enters a kernel, for example to inspect any activity on the device.
+
+The following commands can be used to control whether waves trap on entry:
+
+@table @code
+
+@kindex set amdgpu trap-on-entry
+@cindex AMD GPU trap-on-entry
+@item set amdgpu trap-on-entry @var{mode}
+Controls whether @acronym{AMD} @acronym{GPU} waves trap when they enter a
+kernel:
+
+@table @code
+
+@item off
+The program executes normally.  This is the default.
+
+@item on
+Request that the program breaks at every kernel entry on the devices.
+
+The trap-on-entry mode can be changed at any time in the life of the
+program.  If the trap-on-entry mode is updated before the inferior
+is started, the update request is recorded and applies as soon as
+possible.  For example:
+
+@smallexample
+(@value{GDBP}) set amdgpu trap-on-entry on
+(@value{GDBP}) show amdgpu trap-on-entry
+AMDGPU wave launch trap-on-entry is on (currently disabled).
+(@value{GDBP}) start
+Temporary breakpoint 1 at 0x218cc9: file /tmp/trap-on-entry.cpp, line 46.
+Starting program: /tmp/a.out
+[Thread debugging using libthread_db enabled]
+Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
+
+Temporary breakpoint 1, main (argc=1, argv=0x7fffffffe628) at /tmp/trap-on-entry.cpp:46
+46	  if (argc != 2)
+(@value{GDBP}) show amdgpu trap-on-entry
+AMDGPU wave launch trap-on-entry is on (currently enabled).
+@end smallexample
+
+Any activity on the GPU can thus be captured:
+
+@smallexample
+(@value{GDBP}) continue
+Continuing.
+
+Thread 15 "do_an_addition" received signal SIGTRAP, Trace/breakpoint trap.
+[Switching to thread 15, lane 0 (AMDGPU Lane 1:2:2:9/0 (0,0,0)[0,0,0])]
+do_an_addition () at /tmp/trap-on-entry.cpp:23
+23    @{
+@end smallexample
+
+This feature may expose some internal components from the runtime, which
+may add clutter to the debugging session.  It is advised to ensure these
+are initialized prior to enabling it.
+
+@end table
+
+@kindex show amdgpu trap-on-entry
+@cindex AMD GPU trap-on-entry
+@item show amdgpu trap-on-entry
+Display the currently requested and effective @acronym{AMD}
+@acronym{GPU} trap-on-entry setting.
+
+@end table
+
 @subsubsection @acronym{AMD} @acronym{GPU} Logging
 
 The @samp{set debug amd-dbgapi-lib log-level @var{level}} command can be used