From: Tom Tromey Date: Fri, 7 Aug 2020 16:26:45 +0000 (-0600) Subject: Wrap xfer_partial and enable_btrace for Ravenscar X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2080266b77a21c07b5051055181e6ebcbdedcd8b;p=binutils-gdb.git Wrap xfer_partial and enable_btrace for Ravenscar A gdb crash showed that the xfer_partial target method was not wrapped for Ravenscar. This caused remote.c to call remote::set_general_thread with a Ravenscar "fake" ptid, which showed up later as an event ptid. I went through all the target methods and looked to see which ones could call set_general_thread or set_continue_thread (but not set_general_process, as I think Ravenscar targets aren't multi-inferior). This patch wraps the two that I found. xfer_partial requires special treatment, because it can be called recursively via get_base_thread_from_ravenscar_task. To avoid a recursive call, this patch changes update_thread_list to record all tasks in the m_cpu_map, and changes get_thread_base_cpu to prefer this map. This avoids some memory reads. It was unclear to me whether enable_btrace really makes sense for Ravenscar; but at the same time it seemed harmless to add this patch. gdb/ChangeLog 2020-08-07 Tom Tromey * ravenscar-thread.c (xfer_partial, enable_btrace, add_thread): New methods. (ravenscar_thread_target::get_thread_base_cpu): Check m_cpu_map first. (ravenscar_thread_target::add_thread): Rename from ravenscar_add_thread. (ravenscar_thread_target::update_thread_list): Use a lambda. (ravenscar_thread_target::xfer_partial): New method. --- diff --git a/gdb/ChangeLog b/gdb/ChangeLog index cfa38cf301a..e67b386b418 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,14 @@ +2020-08-07 Tom Tromey + + * ravenscar-thread.c (xfer_partial, enable_btrace, add_thread): + New methods. + (ravenscar_thread_target::get_thread_base_cpu): Check m_cpu_map + first. + (ravenscar_thread_target::add_thread): Rename from + ravenscar_add_thread. + (ravenscar_thread_target::update_thread_list): Use a lambda. + (ravenscar_thread_target::xfer_partial): New method. + 2020-08-07 Tom Tromey * ada-lang.h (ada_task_list_iterator_ftype): Now a diff --git a/gdb/ravenscar-thread.c b/gdb/ravenscar-thread.c index dbcd4de81f8..a67a5e9a368 100644 --- a/gdb/ravenscar-thread.c +++ b/gdb/ravenscar-thread.c @@ -103,6 +103,13 @@ struct ravenscar_thread_target final : public target_ops bool stopped_data_address (CORE_ADDR *) override; + enum target_xfer_status xfer_partial (enum target_object object, + const char *annex, + gdb_byte *readbuf, + const gdb_byte *writebuf, + ULONGEST offset, ULONGEST len, + ULONGEST *xfered_len) override; + bool thread_alive (ptid_t ptid) override; int core_of_thread (ptid_t ptid) override; @@ -113,6 +120,14 @@ struct ravenscar_thread_target final : public target_ops ptid_t get_ada_task_ptid (long lwp, long thread) override; + struct btrace_target_info *enable_btrace (ptid_t ptid, + const struct btrace_config *conf) + override + { + ptid = get_base_thread_from_ravenscar_task (ptid); + return beneath ()->enable_btrace (ptid, conf); + } + void mourn_inferior () override; void close () override @@ -134,6 +149,7 @@ private: bool runtime_initialized (); int get_thread_base_cpu (ptid_t ptid); ptid_t get_base_thread_from_ravenscar_task (ptid_t ptid); + void add_thread (struct ada_task_info *task); /* This maps a TID to the CPU on which it was running. This is needed because sometimes the runtime will report an active task @@ -170,16 +186,18 @@ ravenscar_thread_target::get_thread_base_cpu (ptid_t ptid) if (is_ravenscar_task (ptid)) { - struct ada_task_info *task_info = ada_get_task_info_from_ptid (ptid); + /* Prefer to not read inferior memory if possible, to avoid + reentrancy problems with xfer_partial. */ + auto iter = m_cpu_map.find (ptid.tid ()); - if (task_info != NULL) - base_cpu = task_info->base_cpu; + if (iter != m_cpu_map.end ()) + base_cpu = iter->second; else { - auto iter = m_cpu_map.find (ptid.tid ()); + struct ada_task_info *task_info = ada_get_task_info_from_ptid (ptid); - gdb_assert (iter != m_cpu_map.end ()); - base_cpu = iter->second; + gdb_assert (task_info != NULL); + base_cpu = task_info->base_cpu; } } else @@ -383,11 +401,14 @@ ravenscar_thread_target::wait (ptid_t ptid, /* Add the thread associated to the given TASK to the thread list (if the thread has already been added, this is a no-op). */ -static void -ravenscar_add_thread (struct ada_task_info *task) +void +ravenscar_thread_target::add_thread (struct ada_task_info *task) { if (find_thread_ptid (current_inferior (), task->ptid) == NULL) - add_thread (current_inferior ()->process_target (), task->ptid); + { + ::add_thread (current_inferior ()->process_target (), task->ptid); + m_cpu_map[task->ptid.tid ()] = task->base_cpu; + } } void @@ -398,7 +419,10 @@ ravenscar_thread_target::update_thread_list () (m_base_ptid) and the running thread, that may not have been included to system.tasking.debug's list yet. */ - iterate_over_live_ada_tasks (ravenscar_add_thread); + iterate_over_live_ada_tasks ([=] (struct ada_task_info *task) + { + this->add_thread (task); + }); } ptid_t @@ -541,6 +565,26 @@ ravenscar_thread_target::core_of_thread (ptid_t ptid) return beneath ()->core_of_thread (inferior_ptid); } +/* Implement the target xfer_partial method. */ + +enum target_xfer_status +ravenscar_thread_target::xfer_partial (enum target_object object, + const char *annex, + gdb_byte *readbuf, + const gdb_byte *writebuf, + ULONGEST offset, ULONGEST len, + ULONGEST *xfered_len) +{ + scoped_restore save_ptid = make_scoped_restore (&inferior_ptid); + /* Calling get_base_thread_from_ravenscar_task can read memory from + the inferior. However, that function is written to prefer our + internal map, so it should not result in recursive calls in + practice. */ + inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid); + return beneath ()->xfer_partial (object, annex, readbuf, writebuf, + offset, len, xfered_len); +} + /* Observer on inferior_created: push ravenscar thread stratum if needed. */ static void