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authorTankut Baris Aktemur <tankut.baris.aktemur@intel.com>2020-05-14 13:59:53 +0200
committerTankut Baris Aktemur <tankut.baris.aktemur@intel.com>2020-05-14 13:59:53 +0200
commitfc75c28ba1ea7353fb6e1e5904c5703a48504b67 (patch)
tree5b1a59f1c2cb60a34c7ca6b34e7868aaac49c975
parent9d95b8e9d631e76eb152c86003db6b89e913bdd9 (diff)
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gdb: protect some 'regcache_read_pc' calls
It possible that a thread whose PC we attempt to read is already dead. In this case, 'regcache_read_pc' errors out. This impacts the "proceed" execution flow, where GDB quits early before having a chance to check if there exists a pending event. To remedy, keep going with a 0 value for the PC if 'regcache_read_pc' fails. Because the value of PC before resuming a thread is mostly used for storing and checking the next time the thread stops, this tolerance is expected to be harmless for a dead thread/process. gdb/ChangeLog: 2020-05-14 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com> * regcache.c (regcache_read_pc_protected): New function implementation that returns 0 if the PC cannot read via 'regcache_read_pc'. * infrun.c (proceed): Call 'regcache_read_pc_protected' instead of 'regcache_read_pc'. (keep_going_pass_signal): Ditto. gdbsupport/ChangeLog: 2020-05-14 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com> * common-regcache.h (regcache_read_pc_protected): New function declaration.
-rw-r--r--gdb/ChangeLog9
-rw-r--r--gdb/infrun.c7
-rw-r--r--gdb/regcache.c18
-rw-r--r--gdbsupport/ChangeLog5
-rw-r--r--gdbsupport/common-regcache.h5
5 files changed, 41 insertions, 3 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 4f948d5..462884c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2020-05-14 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
+
+ * regcache.c (regcache_read_pc_protected): New function
+ implementation that returns 0 if the PC cannot read via
+ 'regcache_read_pc'.
+ * infrun.c (proceed): Call 'regcache_read_pc_protected'
+ instead of 'regcache_read_pc'.
+ (keep_going_pass_signal): Ditto.
+
2020-05-13 Tom Tromey <tromey@adacore.com>
* ada-lang.c (align_value): Remove.
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 3c6b201..5e01336 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -2995,7 +2995,8 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
gdbarch = regcache->arch ();
const address_space *aspace = regcache->aspace ();
- pc = regcache_read_pc (regcache);
+ pc = regcache_read_pc_protected (regcache);
+
thread_info *cur_thr = inferior_thread ();
/* Fill in with reasonable starting values. */
@@ -3122,7 +3123,7 @@ proceed (CORE_ADDR addr, enum gdb_signal siggnal)
advanced. Must do this before resuming any thread, as in
all-stop/remote, once we resume we can't send any other packet
until the target stops again. */
- cur_thr->prev_pc = regcache_read_pc (regcache);
+ cur_thr->prev_pc = regcache_read_pc_protected (regcache);
{
scoped_restore save_defer_tc = make_scoped_defer_target_commit_resume ();
@@ -7929,7 +7930,7 @@ keep_going_pass_signal (struct execution_control_state *ecs)
/* Save the pc before execution, to compare with pc after stop. */
ecs->event_thread->prev_pc
- = regcache_read_pc (get_thread_regcache (ecs->event_thread));
+ = regcache_read_pc_protected (get_thread_regcache (ecs->event_thread));
if (ecs->event_thread->control.trap_expected)
{
diff --git a/gdb/regcache.c b/gdb/regcache.c
index 4f079c9..1be7945 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -1220,6 +1220,24 @@ regcache_read_pc (struct regcache *regcache)
return pc_val;
}
+/* See gdbsupport/common-regcache.h. */
+
+CORE_ADDR
+regcache_read_pc_protected (regcache *regcache)
+{
+ CORE_ADDR pc;
+ try
+ {
+ pc = regcache_read_pc (regcache);
+ }
+ catch (const gdb_exception_error &ex)
+ {
+ pc = 0;
+ }
+
+ return pc;
+}
+
void
regcache_write_pc (struct regcache *regcache, CORE_ADDR pc)
{
diff --git a/gdbsupport/ChangeLog b/gdbsupport/ChangeLog
index 194811e..636a3d3 100644
--- a/gdbsupport/ChangeLog
+++ b/gdbsupport/ChangeLog
@@ -1,3 +1,8 @@
+2020-05-14 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
+
+ * common-regcache.h (regcache_read_pc_protected): New function
+ declaration.
+
2020-04-28 Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
* gdb-sigmask.h: Fix typo (pthead_sigmask -> pthread_sigmask).
diff --git a/gdbsupport/common-regcache.h b/gdbsupport/common-regcache.h
index 18446ff..650536e 100644
--- a/gdbsupport/common-regcache.h
+++ b/gdbsupport/common-regcache.h
@@ -56,6 +56,11 @@ extern int regcache_register_size (const struct regcache *regcache, int n);
extern CORE_ADDR regcache_read_pc (struct regcache *regcache);
+/* Read the PC register. If PC cannot be read, return 0.
+ This is a wrapper around 'regcache_read_pc'. */
+
+extern CORE_ADDR regcache_read_pc_protected (regcache *regcache);
+
/* Read a raw register into a unsigned integer. */
extern enum register_status regcache_raw_read_unsigned
(struct regcache *regcache, int regnum, ULONGEST *val);