From: Tankut Baris Aktemur Date: Thu, 14 May 2020 11:59:53 +0000 (+0200) Subject: gdb: protect some 'regcache_read_pc' calls X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=fc75c28ba1ea7353fb6e1e5904c5703a48504b67;p=binutils-gdb.git 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 * 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 * common-regcache.h (regcache_read_pc_protected): New function declaration. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 4f948d57a04..462884ce41e 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,12 @@ +2020-05-14 Tankut Baris Aktemur + + * 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 * ada-lang.c (align_value): Remove. diff --git a/gdb/infrun.c b/gdb/infrun.c index 3c6b201a9fc..5e01336ab09 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 4f079c91a7f..1be794520ec 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 194811e65cb..636a3d34e14 100644 --- a/gdbsupport/ChangeLog +++ b/gdbsupport/ChangeLog @@ -1,3 +1,8 @@ +2020-05-14 Tankut Baris Aktemur + + * common-regcache.h (regcache_read_pc_protected): New function + declaration. + 2020-04-28 Tankut Baris Aktemur * gdb-sigmask.h: Fix typo (pthead_sigmask -> pthread_sigmask). diff --git a/gdbsupport/common-regcache.h b/gdbsupport/common-regcache.h index 18446ff8416..650536e8a88 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);