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2da4b788f7
gdb/ChangeLog: 2020-06-18 Pedro Alves <palves@redhat.com> * ravenscar-thread.c (ravenscar_thread_target): Update. (ravenscar_thread_target::update_inferior_ptid): Rename to ... (ravenscar_thread_target::add_active_thread): ... this. Don't set m_base_ptid here. Update to avoid referencing inferior_ptid. (ravenscar_thread_target::wait): Don't write to inferior_ptid.
609 lines
18 KiB
C
609 lines
18 KiB
C
/* Ada Ravenscar thread support.
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Copyright (C) 2004-2020 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "defs.h"
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#include "gdbcore.h"
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#include "gdbthread.h"
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#include "ada-lang.h"
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#include "target.h"
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#include "inferior.h"
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#include "command.h"
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#include "ravenscar-thread.h"
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#include "observable.h"
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#include "gdbcmd.h"
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#include "top.h"
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#include "regcache.h"
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#include "objfiles.h"
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/* This module provides support for "Ravenscar" tasks (Ada) when
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debugging on bare-metal targets.
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The typical situation is when debugging a bare-metal target over
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the remote protocol. In that situation, the system does not know
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about high-level concepts such as threads, only about some code
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running on one or more CPUs. And since the remote protocol does not
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provide any handling for CPUs, the de facto standard for handling
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them is to have one thread per CPU, where the thread's ptid has
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its lwp field set to the CPU number (eg: 1 for the first CPU,
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2 for the second one, etc). This module will make that assumption.
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This module then creates and maintains the list of threads based
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on the list of Ada tasks, with one thread per Ada task. The convention
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is that threads corresponding to the CPUs (see assumption above)
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have a ptid_t of the form (PID, LWP, 0), while threads corresponding
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to our Ada tasks have a ptid_t of the form (PID, 0, TID) where TID
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is the Ada task's ID as extracted from Ada runtime information.
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Switching to a given Ada task (or its underlying thread) is performed
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by fetching the registers of that task from the memory area where
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the registers were saved. For any of the other operations, the
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operation is performed by first finding the CPU on which the task
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is running, switching to its corresponding ptid, and then performing
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the operation on that ptid using the target beneath us. */
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/* If true, ravenscar task support is enabled. */
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static bool ravenscar_task_support = true;
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static const char running_thread_name[] = "__gnat_running_thread_table";
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static const char known_tasks_name[] = "system__tasking__debug__known_tasks";
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static const char first_task_name[] = "system__tasking__debug__first_task";
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static const char ravenscar_runtime_initializer[]
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= "system__bb__threads__initialize";
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static const target_info ravenscar_target_info = {
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"ravenscar",
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N_("Ravenscar tasks."),
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N_("Ravenscar tasks support.")
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};
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struct ravenscar_thread_target final : public target_ops
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{
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ravenscar_thread_target ()
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: m_base_ptid (inferior_ptid)
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{
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thread_info *thr = add_active_thread ();
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if (thr != nullptr)
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switch_to_thread (thr);
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}
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const target_info &info () const override
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{ return ravenscar_target_info; }
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strata stratum () const override { return thread_stratum; }
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ptid_t wait (ptid_t, struct target_waitstatus *, int) override;
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void resume (ptid_t, int, enum gdb_signal) override;
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void fetch_registers (struct regcache *, int) override;
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void store_registers (struct regcache *, int) override;
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void prepare_to_store (struct regcache *) override;
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bool stopped_by_sw_breakpoint () override;
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bool stopped_by_hw_breakpoint () override;
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bool stopped_by_watchpoint () override;
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bool stopped_data_address (CORE_ADDR *) override;
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bool thread_alive (ptid_t ptid) override;
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int core_of_thread (ptid_t ptid) override;
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void update_thread_list () override;
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const char *extra_thread_info (struct thread_info *) override;
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std::string pid_to_str (ptid_t) override;
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ptid_t get_ada_task_ptid (long lwp, long thread) override;
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void mourn_inferior () override;
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void close () override
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{
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delete this;
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}
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private:
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/* PTID of the last thread that received an event.
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This can be useful to determine the associated task that received
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the event, to make it the current task. */
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ptid_t m_base_ptid;
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thread_info *add_active_thread ();
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ptid_t active_task (int cpu);
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bool task_is_currently_active (ptid_t ptid);
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bool runtime_initialized ();
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};
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/* Return true iff PTID corresponds to a ravenscar task. */
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static bool
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is_ravenscar_task (ptid_t ptid)
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{
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/* By construction, ravenscar tasks have their LWP set to zero.
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Also make sure that the TID is nonzero, as some remotes, when
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asked for the list of threads, will return the first thread
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as having its TID set to zero. For instance, TSIM version
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2.0.48 for LEON3 sends 'm0' as a reply to the 'qfThreadInfo'
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query, which the remote protocol layer then treats as a thread
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whose TID is 0. This is obviously not a ravenscar task. */
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return ptid.lwp () == 0 && ptid.tid () != 0;
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}
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/* Given PTID, which can be either a ravenscar task or a CPU thread,
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return which CPU that ptid is running on.
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This assume that PTID is a valid ptid_t. Otherwise, a gdb_assert
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will be triggered. */
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static int
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ravenscar_get_thread_base_cpu (ptid_t ptid)
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{
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int base_cpu;
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if (is_ravenscar_task (ptid))
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{
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struct ada_task_info *task_info = ada_get_task_info_from_ptid (ptid);
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gdb_assert (task_info != NULL);
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base_cpu = task_info->base_cpu;
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}
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else
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{
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/* We assume that the LWP of the PTID is equal to the CPU number. */
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base_cpu = ptid.lwp ();
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}
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return base_cpu;
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}
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/* Given a ravenscar task (identified by its ptid_t PTID), return true
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if this task is the currently active task on the cpu that task is
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running on.
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In other words, this function determine which CPU this task is
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currently running on, and then return nonzero if the CPU in question
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is executing the code for that task. If that's the case, then
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that task's registers are in the CPU bank. Otherwise, the task
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is currently suspended, and its registers have been saved in memory. */
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bool
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ravenscar_thread_target::task_is_currently_active (ptid_t ptid)
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{
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ptid_t active_task_ptid
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= active_task (ravenscar_get_thread_base_cpu (ptid));
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return ptid == active_task_ptid;
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}
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/* Return the CPU thread (as a ptid_t) on which the given ravenscar
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task is running.
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This is the thread that corresponds to the CPU on which the task
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is running. */
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static ptid_t
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get_base_thread_from_ravenscar_task (ptid_t ptid)
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{
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int base_cpu;
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if (!is_ravenscar_task (ptid))
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return ptid;
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base_cpu = ravenscar_get_thread_base_cpu (ptid);
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return ptid_t (ptid.pid (), base_cpu, 0);
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}
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/* Fetch the ravenscar running thread from target memory, make sure
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there's a corresponding thread in the thread list, and return it.
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If the runtime is not initialized, return NULL. */
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thread_info *
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ravenscar_thread_target::add_active_thread ()
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{
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process_stratum_target *proc_target
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= as_process_stratum_target (this->beneath ());
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int base_cpu;
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gdb_assert (!is_ravenscar_task (m_base_ptid));
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base_cpu = ravenscar_get_thread_base_cpu (m_base_ptid);
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if (!runtime_initialized ())
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return nullptr;
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/* Make sure we set m_base_ptid before calling active_task
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as the latter relies on it. */
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ptid_t active_ptid = active_task (base_cpu);
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gdb_assert (active_ptid != null_ptid);
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/* The running thread may not have been added to
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system.tasking.debug's list yet; so ravenscar_update_thread_list
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may not always add it to the thread list. Add it here. */
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thread_info *active_thr = find_thread_ptid (proc_target, active_ptid);
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if (active_thr == nullptr)
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active_thr = add_thread (proc_target, active_ptid);
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return active_thr;
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}
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/* The Ravenscar Runtime exports a symbol which contains the ID of
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the thread that is currently running. Try to locate that symbol
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and return its associated minimal symbol.
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Return NULL if not found. */
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static struct bound_minimal_symbol
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get_running_thread_msymbol ()
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{
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struct bound_minimal_symbol msym;
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msym = lookup_minimal_symbol (running_thread_name, NULL, NULL);
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if (!msym.minsym)
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/* Older versions of the GNAT runtime were using a different
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(less ideal) name for the symbol where the active thread ID
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is stored. If we couldn't find the symbol using the latest
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name, then try the old one. */
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msym = lookup_minimal_symbol ("running_thread", NULL, NULL);
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return msym;
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}
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/* Return True if the Ada Ravenscar run-time can be found in the
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application. */
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static bool
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has_ravenscar_runtime ()
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{
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struct bound_minimal_symbol msym_ravenscar_runtime_initializer
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= lookup_minimal_symbol (ravenscar_runtime_initializer, NULL, NULL);
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struct bound_minimal_symbol msym_known_tasks
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= lookup_minimal_symbol (known_tasks_name, NULL, NULL);
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struct bound_minimal_symbol msym_first_task
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= lookup_minimal_symbol (first_task_name, NULL, NULL);
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struct bound_minimal_symbol msym_running_thread
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= get_running_thread_msymbol ();
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return (msym_ravenscar_runtime_initializer.minsym
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&& (msym_known_tasks.minsym || msym_first_task.minsym)
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&& msym_running_thread.minsym);
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}
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/* Return True if the Ada Ravenscar run-time can be found in the
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application, and if it has been initialized on target. */
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bool
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ravenscar_thread_target::runtime_initialized ()
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{
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return active_task (1) != null_ptid;
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}
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/* Return the ID of the thread that is currently running.
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Return 0 if the ID could not be determined. */
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static CORE_ADDR
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get_running_thread_id (int cpu)
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{
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struct bound_minimal_symbol object_msym = get_running_thread_msymbol ();
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int object_size;
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int buf_size;
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gdb_byte *buf;
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CORE_ADDR object_addr;
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struct type *builtin_type_void_data_ptr
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= builtin_type (target_gdbarch ())->builtin_data_ptr;
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if (!object_msym.minsym)
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return 0;
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object_size = TYPE_LENGTH (builtin_type_void_data_ptr);
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object_addr = (BMSYMBOL_VALUE_ADDRESS (object_msym)
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+ (cpu - 1) * object_size);
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buf_size = object_size;
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buf = (gdb_byte *) alloca (buf_size);
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read_memory (object_addr, buf, buf_size);
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return extract_typed_address (buf, builtin_type_void_data_ptr);
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}
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void
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ravenscar_thread_target::resume (ptid_t ptid, int step,
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enum gdb_signal siggnal)
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{
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/* If we see a wildcard resume, we simply pass that on. Otherwise,
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arrange to resume the base ptid. */
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inferior_ptid = m_base_ptid;
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if (ptid != minus_one_ptid)
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ptid = m_base_ptid;
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beneath ()->resume (ptid, step, siggnal);
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}
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ptid_t
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ravenscar_thread_target::wait (ptid_t ptid,
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struct target_waitstatus *status,
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int options)
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{
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process_stratum_target *beneath
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= as_process_stratum_target (this->beneath ());
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ptid_t event_ptid;
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if (ptid != minus_one_ptid)
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ptid = m_base_ptid;
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event_ptid = beneath->wait (ptid, status, 0);
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/* Find any new threads that might have been created, and return the
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active thread.
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Only do it if the program is still alive, though. Otherwise,
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this causes problems when debugging through the remote protocol,
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because we might try switching threads (and thus sending packets)
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after the remote has disconnected. */
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if (status->kind != TARGET_WAITKIND_EXITED
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&& status->kind != TARGET_WAITKIND_SIGNALLED)
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{
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m_base_ptid = event_ptid;
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this->update_thread_list ();
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return this->add_active_thread ()->ptid;
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}
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return m_base_ptid;
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}
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/* Add the thread associated to the given TASK to the thread list
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(if the thread has already been added, this is a no-op). */
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static void
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ravenscar_add_thread (struct ada_task_info *task)
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{
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if (find_thread_ptid (current_inferior (), task->ptid) == NULL)
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add_thread (current_inferior ()->process_target (), task->ptid);
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}
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void
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ravenscar_thread_target::update_thread_list ()
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{
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/* Do not clear the thread list before adding the Ada task, to keep
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the thread that the process stratum has included into it
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(m_base_ptid) and the running thread, that may not have been included
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to system.tasking.debug's list yet. */
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iterate_over_live_ada_tasks (ravenscar_add_thread);
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}
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ptid_t
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ravenscar_thread_target::active_task (int cpu)
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{
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CORE_ADDR tid = get_running_thread_id (cpu);
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if (tid == 0)
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return null_ptid;
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else
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return ptid_t (m_base_ptid.pid (), 0, tid);
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}
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const char *
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ravenscar_thread_target::extra_thread_info (thread_info *tp)
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{
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return "Ravenscar task";
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}
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bool
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ravenscar_thread_target::thread_alive (ptid_t ptid)
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{
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/* Ravenscar tasks are non-terminating. */
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return true;
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}
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std::string
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ravenscar_thread_target::pid_to_str (ptid_t ptid)
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{
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return string_printf ("Thread %#x", (int) ptid.tid ());
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}
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void
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ravenscar_thread_target::fetch_registers (struct regcache *regcache, int regnum)
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{
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ptid_t ptid = regcache->ptid ();
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if (runtime_initialized ()
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&& is_ravenscar_task (ptid)
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&& !task_is_currently_active (ptid))
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{
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struct gdbarch *gdbarch = regcache->arch ();
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struct ravenscar_arch_ops *arch_ops
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= gdbarch_ravenscar_ops (gdbarch);
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arch_ops->fetch_registers (regcache, regnum);
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}
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else
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beneath ()->fetch_registers (regcache, regnum);
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}
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void
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ravenscar_thread_target::store_registers (struct regcache *regcache,
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int regnum)
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{
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ptid_t ptid = regcache->ptid ();
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if (runtime_initialized ()
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&& is_ravenscar_task (ptid)
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&& !task_is_currently_active (ptid))
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{
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struct gdbarch *gdbarch = regcache->arch ();
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struct ravenscar_arch_ops *arch_ops
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= gdbarch_ravenscar_ops (gdbarch);
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arch_ops->store_registers (regcache, regnum);
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}
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else
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beneath ()->store_registers (regcache, regnum);
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}
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void
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ravenscar_thread_target::prepare_to_store (struct regcache *regcache)
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{
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ptid_t ptid = regcache->ptid ();
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if (runtime_initialized ()
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&& is_ravenscar_task (ptid)
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&& !task_is_currently_active (ptid))
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{
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/* Nothing. */
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}
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else
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beneath ()->prepare_to_store (regcache);
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}
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/* Implement the to_stopped_by_sw_breakpoint target_ops "method". */
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bool
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ravenscar_thread_target::stopped_by_sw_breakpoint ()
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{
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scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
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inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
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return beneath ()->stopped_by_sw_breakpoint ();
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}
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/* Implement the to_stopped_by_hw_breakpoint target_ops "method". */
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bool
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ravenscar_thread_target::stopped_by_hw_breakpoint ()
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{
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scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
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inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
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return beneath ()->stopped_by_hw_breakpoint ();
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}
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/* Implement the to_stopped_by_watchpoint target_ops "method". */
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bool
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ravenscar_thread_target::stopped_by_watchpoint ()
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{
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scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
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inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
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return beneath ()->stopped_by_watchpoint ();
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}
|
|
|
|
/* Implement the to_stopped_data_address target_ops "method". */
|
|
|
|
bool
|
|
ravenscar_thread_target::stopped_data_address (CORE_ADDR *addr_p)
|
|
{
|
|
scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
|
|
inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
|
|
return beneath ()->stopped_data_address (addr_p);
|
|
}
|
|
|
|
void
|
|
ravenscar_thread_target::mourn_inferior ()
|
|
{
|
|
m_base_ptid = null_ptid;
|
|
target_ops *beneath = this->beneath ();
|
|
unpush_target (this);
|
|
beneath->mourn_inferior ();
|
|
}
|
|
|
|
/* Implement the to_core_of_thread target_ops "method". */
|
|
|
|
int
|
|
ravenscar_thread_target::core_of_thread (ptid_t ptid)
|
|
{
|
|
scoped_restore save_ptid = make_scoped_restore (&inferior_ptid);
|
|
inferior_ptid = get_base_thread_from_ravenscar_task (inferior_ptid);
|
|
return beneath ()->core_of_thread (inferior_ptid);
|
|
}
|
|
|
|
/* Observer on inferior_created: push ravenscar thread stratum if needed. */
|
|
|
|
static void
|
|
ravenscar_inferior_created (struct target_ops *target, int from_tty)
|
|
{
|
|
const char *err_msg;
|
|
|
|
if (!ravenscar_task_support
|
|
|| gdbarch_ravenscar_ops (target_gdbarch ()) == NULL
|
|
|| !has_ravenscar_runtime ())
|
|
return;
|
|
|
|
err_msg = ada_get_tcb_types_info ();
|
|
if (err_msg != NULL)
|
|
{
|
|
warning (_("%s. Task/thread support disabled."), err_msg);
|
|
return;
|
|
}
|
|
|
|
target_ops_up target_holder (new ravenscar_thread_target ());
|
|
push_target (std::move (target_holder));
|
|
}
|
|
|
|
ptid_t
|
|
ravenscar_thread_target::get_ada_task_ptid (long lwp, long thread)
|
|
{
|
|
return ptid_t (m_base_ptid.pid (), 0, thread);
|
|
}
|
|
|
|
/* Command-list for the "set/show ravenscar" prefix command. */
|
|
static struct cmd_list_element *set_ravenscar_list;
|
|
static struct cmd_list_element *show_ravenscar_list;
|
|
|
|
/* Implement the "show ravenscar task-switching" command. */
|
|
|
|
static void
|
|
show_ravenscar_task_switching_command (struct ui_file *file, int from_tty,
|
|
struct cmd_list_element *c,
|
|
const char *value)
|
|
{
|
|
if (ravenscar_task_support)
|
|
fprintf_filtered (file, _("\
|
|
Support for Ravenscar task/thread switching is enabled\n"));
|
|
else
|
|
fprintf_filtered (file, _("\
|
|
Support for Ravenscar task/thread switching is disabled\n"));
|
|
}
|
|
|
|
/* Module startup initialization function, automagically called by
|
|
init.c. */
|
|
|
|
void _initialize_ravenscar ();
|
|
void
|
|
_initialize_ravenscar ()
|
|
{
|
|
/* Notice when the inferior is created in order to push the
|
|
ravenscar ops if needed. */
|
|
gdb::observers::inferior_created.attach (ravenscar_inferior_created);
|
|
|
|
add_basic_prefix_cmd ("ravenscar", no_class,
|
|
_("Prefix command for changing Ravenscar-specific settings."),
|
|
&set_ravenscar_list, "set ravenscar ", 0, &setlist);
|
|
|
|
add_show_prefix_cmd ("ravenscar", no_class,
|
|
_("Prefix command for showing Ravenscar-specific settings."),
|
|
&show_ravenscar_list, "show ravenscar ", 0, &showlist);
|
|
|
|
add_setshow_boolean_cmd ("task-switching", class_obscure,
|
|
&ravenscar_task_support, _("\
|
|
Enable or disable support for GNAT Ravenscar tasks."), _("\
|
|
Show whether support for GNAT Ravenscar tasks is enabled."),
|
|
_("\
|
|
Enable or disable support for task/thread switching with the GNAT\n\
|
|
Ravenscar run-time library for bareboard configuration."),
|
|
NULL, show_ravenscar_task_switching_command,
|
|
&set_ravenscar_list, &show_ravenscar_list);
|
|
}
|