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* [binutils-gdb] displaced_step_finish: Don't fetch the regcache of exited threads
@ 2023-12-20 21:21 Pedro Alves
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From: Pedro Alves @ 2023-12-20 21:21 UTC (permalink / raw)
To: gdb-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=249d08128787e4e0a977079aa09516d73f196f77
commit 249d08128787e4e0a977079aa09516d73f196f77
Author: Pedro Alves <pedro@palves.net>
Date: Fri Dec 1 13:31:00 2023 +0000
displaced_step_finish: Don't fetch the regcache of exited threads
displaced_step_finish can be called with event_status.kind ==
TARGET_WAITKIND_THREAD_EXITED, and in that case it is not possible to
get at the already-exited thread's registers.
This patch moves the get_thread_regcache calls to branches that
actually need it, where we know the thread is still alive.
It also adds an assertion to get_thread_regcache, to help catching
these broken cases sooner.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Change-Id: I63b5eacb3e02a538fc5087c270d8025adfda88c3
Diff:
---
gdb/infrun.c | 19 ++++++++++++-------
gdb/regcache.c | 2 ++
2 files changed, 14 insertions(+), 7 deletions(-)
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 6dc0a2bb9a5..76693a30611 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2021,8 +2021,6 @@ displaced_step_finish (thread_info *event_thread,
const target_waitstatus &event_status)
{
/* Check whether the parent is displaced stepping. */
- struct regcache *regcache = get_thread_regcache (event_thread);
- struct gdbarch *gdbarch = regcache->arch ();
inferior *parent_inf = event_thread->inf;
/* If this was a fork/vfork/clone, this event indicates that the
@@ -2040,10 +2038,15 @@ displaced_step_finish (thread_info *event_thread,
gdbarch_displaced_step_restore_all_in_ptid. This is not enforced
during gdbarch validation to support architectures which support
displaced stepping but not forks. */
- if (event_status.kind () == TARGET_WAITKIND_FORKED
- && gdbarch_supports_displaced_stepping (gdbarch))
- gdbarch_displaced_step_restore_all_in_ptid
- (gdbarch, parent_inf, event_status.child_ptid ());
+ if (event_status.kind () == TARGET_WAITKIND_FORKED)
+ {
+ struct regcache *parent_regcache = get_thread_regcache (event_thread);
+ struct gdbarch *gdbarch = parent_regcache->arch ();
+
+ if (gdbarch_supports_displaced_stepping (gdbarch))
+ gdbarch_displaced_step_restore_all_in_ptid
+ (gdbarch, parent_inf, event_status.child_ptid ());
+ }
displaced_step_thread_state *displaced = &event_thread->displaced_step_state;
@@ -2082,11 +2085,13 @@ displaced_step_finish (thread_info *event_thread,
child hasn't been added to the inferior list yet at this
point. */
+ struct regcache *parent_regcache = get_thread_regcache (event_thread);
+ struct gdbarch *gdbarch = parent_regcache->arch ();
struct regcache *child_regcache
= get_thread_arch_regcache (parent_inf, event_status.child_ptid (),
gdbarch);
/* Read PC value of parent. */
- CORE_ADDR parent_pc = regcache_read_pc (regcache);
+ CORE_ADDR parent_pc = regcache_read_pc (parent_regcache);
displaced_debug_printf ("write child pc from %s to %s",
paddress (gdbarch,
diff --git a/gdb/regcache.c b/gdb/regcache.c
index 6140a05f02b..1217fe7240b 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -430,6 +430,8 @@ get_thread_regcache (process_stratum_target *target, ptid_t ptid)
struct regcache *
get_thread_regcache (thread_info *thread)
{
+ gdb_assert (thread->state != THREAD_EXITED);
+
return get_thread_regcache (thread->inf->process_target (),
thread->ptid);
}
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2023-12-20 21:21 [binutils-gdb] displaced_step_finish: Don't fetch the regcache of exited threads Pedro Alves
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