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[PATCH] S390: Defer PER info update until resume
- From: Andreas Arnez <arnez at linux dot vnet dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Cc: Ulrich Weigand <uweigand at de dot ibm dot com>
- Date: Tue, 10 Mar 2015 11:31:31 +0100
- Subject: [PATCH] S390: Defer PER info update until resume
- Authentication-results: sourceware.org; auth=none
For multi-threaded inferiors on S390 GNU/Linux targets, GDB tried to
update the PER info via ptrace() in a newly attached thread before
assuring that the thread is stopped. Depending on the timing, this
could lead to a GDB internal error. The patch defers the PER info
update until just before resuming the thread.
gdb/ChangeLog:
* s390-linux-nat.c (struct arch_lwp_info): New.
(s390_fix_watch_points): Rename to...
(s390_prepare_to_resume): ...this. Skip the PER info update
unless the watch points have changed.
(s390_refresh_per_info, s390_new_thread): New functions.
(s390_insert_watchpoint): Call s390_refresh_per_info instead of
s390_fix_watch_points.
(s390_remove_watchpoint): Likewise.
(_initialize_s390_nat): Reflect renaming of s390_fix_watch_points.
Register s390_prepare_to_resume.
---
gdb/s390-linux-nat.c | 49 +++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 45 insertions(+), 4 deletions(-)
diff --git a/gdb/s390-linux-nat.c b/gdb/s390-linux-nat.c
index 367b610..9298bcc 100644
--- a/gdb/s390-linux-nat.c
+++ b/gdb/s390-linux-nat.c
@@ -46,6 +46,14 @@
#define PTRACE_SETREGSET 0x4205
#endif
+/* Per-thread arch-specific data. */
+
+struct arch_lwp_info
+{
+ /* Non-zero if the thread's PER info must be re-written. */
+ int per_info_changed;
+};
+
static int have_regset_last_break = 0;
static int have_regset_system_call = 0;
static int have_regset_tdb = 0;
@@ -465,8 +473,10 @@ s390_stopped_by_watchpoint (struct target_ops *ops)
return result;
}
+/* Each time before resuming a thread, update its PER info. */
+
static void
-s390_fix_watch_points (struct lwp_info *lp)
+s390_prepare_to_resume (struct lwp_info *lp)
{
int tid;
@@ -476,6 +486,12 @@ s390_fix_watch_points (struct lwp_info *lp)
CORE_ADDR watch_lo_addr = (CORE_ADDR)-1, watch_hi_addr = 0;
struct watch_area *area;
+ if (lp->arch_private == NULL
+ || !lp->arch_private->per_info_changed)
+ return;
+
+ lp->arch_private->per_info_changed = 0;
+
tid = ptid_get_lwp (lp->ptid);
if (tid == 0)
tid = ptid_get_pid (lp->ptid);
@@ -509,6 +525,30 @@ s390_fix_watch_points (struct lwp_info *lp)
perror_with_name (_("Couldn't modify watchpoint status"));
}
+/* Make sure that LP is stopped and mark its PER info as changed, so
+ the next resume will update it. */
+
+static void
+s390_refresh_per_info (struct lwp_info *lp)
+{
+ if (lp->arch_private == NULL)
+ lp->arch_private = XCNEW (struct arch_lwp_info);
+
+ lp->arch_private->per_info_changed = 1;
+
+ if (!lp->stopped)
+ linux_stop_lwp (lp);
+}
+
+/* When attaching to a new thread, mark its PER info as changed. */
+
+static void
+s390_new_thread (struct lwp_info *lp)
+{
+ lp->arch_private = XCNEW (struct arch_lwp_info);
+ lp->arch_private->per_info_changed = 1;
+}
+
static int
s390_insert_watchpoint (struct target_ops *self,
CORE_ADDR addr, int len, int type,
@@ -527,7 +567,7 @@ s390_insert_watchpoint (struct target_ops *self,
watch_base = area;
ALL_LWPS (lp)
- s390_fix_watch_points (lp);
+ s390_refresh_per_info (lp);
return 0;
}
@@ -556,7 +596,7 @@ s390_remove_watchpoint (struct target_ops *self,
xfree (area);
ALL_LWPS (lp)
- s390_fix_watch_points (lp);
+ s390_refresh_per_info (lp);
return 0;
}
@@ -699,5 +739,6 @@ _initialize_s390_nat (void)
/* Register the target. */
linux_nat_add_target (t);
- linux_nat_set_new_thread (t, s390_fix_watch_points);
+ linux_nat_set_new_thread (t, s390_new_thread);
+ linux_nat_set_prepare_to_resume (t, s390_prepare_to_resume);
}
--
1.9.3