[PATCH] Conditionally restore displaced stepping state after fork.

[John Baldwin <jhb@FreeBSD.org>]

There is no default method for
gdbarch_displaced_step_restore_all_in_ptid, so calling it
unconditionally for fork events triggered an assertion failure on
platforms that do not support displaced stepping.  To fix, only invoke
the method if the gdbarch supports displaced stepping.

gdb/ChangeLog:

	* infrun.c (handle_inferior_event): Only call
	gdbarch_displaced_step_restore_all_in_ptid if
	gdbarch_supports_displaced_stepping is true.
---
 gdb/ChangeLog | 6 ++++++
 gdb/infrun.c  | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 03910c0634..b0f448a35e 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2021-05-30  John Baldwin  <jhb@FreeBSD.org>
+
+	* infrun.c (handle_inferior_event): Only call
+	gdbarch_displaced_step_restore_all_in_ptid if
+	gdbarch_supports_displaced_stepping is true.
+
 2021-05-27  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* Fix tab after space indentation issues throughout.
diff --git a/gdb/infrun.c b/gdb/infrun.c
index e9624d2a9b..6fd077796f 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -5496,7 +5496,8 @@ handle_inferior_event (struct execution_control_state *ecs)
 	/* If this is a fork (child gets its own address space copy) and some
 	   displaced step buffers were in use at the time of the fork, restore
 	   the displaced step buffer bytes in the child process.  */
-	if (ecs->ws.kind == TARGET_WAITKIND_FORKED)
+	if (ecs->ws.kind == TARGET_WAITKIND_FORKED
+	    && gdbarch_supports_displaced_stepping (gdbarch))
 	  gdbarch_displaced_step_restore_all_in_ptid
 	    (gdbarch, parent_inf, ecs->ws.value.related_pid);
 
-- 
2.31.1