5b6d1e4fa4
This commit adds multi-target support to GDB. What this means is that
with this commit, GDB can now be connected to different targets at the
same time. E.g., you can debug a live native process and a core dump
at the same time, connect to multiple gdbservers, etc.
Actually, the word "target" is overloaded in gdb. We already have a
target stack, with pushes several target_ops instances on top of one
another. We also have "info target" already, which means something
completely different to what this patch does.
So from here on, I'll be using the "target connections" term, to mean
an open process_stratum target, pushed on a target stack. This patch
makes gdb have multiple target stacks, and multiple process_stratum
targets open simultaneously. The user-visible changes / commands will
also use this terminology, but of course it's all open to debate.
User-interface-wise, not that much changes. The main difference is
that each inferior may have its own target connection.
A target connection (e.g., a target extended-remote connection) may
support debugging multiple processes, just as before.
Say you're debugging against gdbserver in extended-remote mode, and
you do "add-inferior" to prepare to spawn a new process, like:
(gdb) target extended-remote :9999
...
(gdb) start
...
(gdb) add-inferior
Added inferior 2
(gdb) inferior 2
[Switching to inferior 2 [<null>] (<noexec>)]
(gdb) file a.out
...
(gdb) start
...
At this point, you have two inferiors connected to the same gdbserver.
With this commit, GDB will maintain a target stack per inferior,
instead of a global target stack.
To preserve the behavior above, by default, "add-inferior" makes the
new inferior inherit a copy of the target stack of the current
inferior. Same across a fork - the child inherits a copy of the
target stack of the parent. While the target stacks are copied, the
targets themselves are not. Instead, target_ops is made a
refcounted_object, which means that target_ops instances are
refcounted, which each inferior counting for a reference.
What if you want to create an inferior and connect it to some _other_
target? For that, this commit introduces a new "add-inferior
-no-connection" option that makes the new inferior not share the
current inferior's target. So you could do:
(gdb) target extended-remote :9999
Remote debugging using :9999
...
(gdb) add-inferior -no-connection
[New inferior 2]
Added inferior 2
(gdb) inferior 2
[Switching to inferior 2 [<null>] (<noexec>)]
(gdb) info inferiors
Num Description Executable
1 process 18401 target:/home/pedro/tmp/main
* 2 <null>
(gdb) tar extended-remote :10000
Remote debugging using :10000
...
(gdb) info inferiors
Num Description Executable
1 process 18401 target:/home/pedro/tmp/main
* 2 process 18450 target:/home/pedro/tmp/main
(gdb)
A following patch will extended "info inferiors" to include a column
indicating which connection an inferior is bound to, along with a
couple other UI tweaks.
Other than that, debugging is the same as before. Users interact with
inferiors and threads as before. The only difference is that
inferiors may be bound to processes running in different machines.
That's pretty much all there is to it in terms of noticeable UI
changes.
On to implementation.
Since we can be connected to different systems at the same time, a
ptid_t is no longer a unique identifier. Instead a thread can be
identified by a pair of ptid_t and 'process_stratum_target *', the
later being the instance of the process_stratum target that owns the
process/thread. Note that process_stratum_target inherits from
target_ops, and all process_stratum targets inherit from
process_stratum_target. In earlier patches, many places in gdb were
converted to refer to threads by thread_info pointer instead of
ptid_t, but there are still places in gdb where we start with a
pid/tid and need to find the corresponding inferior or thread_info
objects. So you'll see in the patch many places adding a
process_stratum_target parameter to functions that used to take only a
ptid_t.
Since each inferior has its own target stack now, we can always find
the process_stratum target for an inferior. That is done via a
inf->process_target() convenience method.
Since each inferior has its own target stack, we need to handle the
"beneath" calls when servicing target calls. The solution I settled
with is just to make sure to switch the current inferior to the
inferior you want before making a target call. Not relying on global
context is just not feasible in current GDB. Fortunately, there
aren't that many places that need to do that, because generally most
code that calls target methods already has the current context
pointing to the right inferior/thread. Note, to emphasize -- there's
no method to "switch to this target stack". Instead, you switch the
current inferior, and that implicitly switches the target stack.
In some spots, we need to iterate over all inferiors so that we reach
all target stacks.
Native targets are still singletons. There's always only a single
instance of such targets.
Remote targets however, we'll have one instance per remote connection.
The exec target is still a singleton. There's only one instance. I
did not see the point of instanciating more than one exec_target
object.
After vfork, we need to make sure to push the exec target on the new
inferior. See exec_on_vfork.
For type safety, functions that need a {target, ptid} pair to identify
a thread, take a process_stratum_target pointer for target parameter
instead of target_ops *. Some shared code in gdb/nat/ also need to
gain a target pointer parameter. This poses an issue, since gdbserver
doesn't have process_stratum_target, only target_ops. To fix this,
this commit renames gdbserver's target_ops to process_stratum_target.
I think this makes sense. There's no concept of target stack in
gdbserver, and gdbserver's target_ops really implements a
process_stratum-like target.
The thread and inferior iterator functions also gain
process_stratum_target parameters. These are used to be able to
iterate over threads and inferiors of a given target. Following usual
conventions, if the target pointer is null, then we iterate over
threads and inferiors of all targets.
I tried converting "add-inferior" to the gdb::option framework, as a
preparatory patch, but that stumbled on the fact that gdb::option does
not support file options yet, for "add-inferior -exec". I have a WIP
patchset that adds that, but it's not a trivial patch, mainly due to
need to integrate readline's filename completion, so I deferred that
to some other time.
In infrun.c/infcmd.c, the main change is that we need to poll events
out of all targets. See do_target_wait. Right after collecting an
event, we switch the current inferior to an inferior bound to the
target that reported the event, so that target methods can be used
while handling the event. This makes most of the code transparent to
multi-targets. See fetch_inferior_event.
infrun.c:stop_all_threads is interesting -- in this function we need
to stop all threads of all targets. What the function does is send an
asynchronous stop request to all threads, and then synchronously waits
for events, with target_wait, rinse repeat, until all it finds are
stopped threads. Now that we have multiple targets, it's not
efficient to synchronously block in target_wait waiting for events out
of one target. Instead, we implement a mini event loop, with
interruptible_select, select'ing on one file descriptor per target.
For this to work, we need to be able to ask the target for a waitable
file descriptor. Such file descriptors already exist, they are the
descriptors registered in the main event loop with add_file_handler,
inside the target_async implementations. This commit adds a new
target_async_wait_fd target method that just returns the file
descriptor in question. See wait_one / stop_all_threads in infrun.c.
The 'threads_executing' global is made a per-target variable. Since
it is only relevant to process_stratum_target targets, this is where
it is put, instead of in target_ops.
You'll notice that remote.c includes some FIXME notes. These refer to
the fact that the global arrays that hold data for the remote packets
supported are still globals. For example, if we connect to two
different servers/stubs, then each might support different remote
protocol features. They might even be different architectures, like
e.g., one ARM baremetal stub, and a x86 gdbserver, to debug a
host/controller scenario as a single program. That isn't going to
work correctly today, because of said globals. I'm leaving fixing
that for another pass, since it does not appear to be trivial, and I'd
rather land the base work first. It's already useful to be able to
debug multiple instances of the same server (e.g., a distributed
cluster, where you have full control over the servers installed), so I
think as is it's already reasonable incremental progress.
Current limitations:
- You can only resume more that one target at the same time if all
targets support asynchronous debugging, and support non-stop mode.
It should be possible to support mixed all-stop + non-stop
backends, but that is left for another time. This means that
currently in order to do multi-target with gdbserver you need to
issue "maint set target-non-stop on". I would like to make that
mode be the default, but we're not there yet. Note that I'm
talking about how the target backend works, only. User-visible
all-stop mode works just fine.
- As explained above, connecting to different remote servers at the
same time is likely to produce bad results if they don't support the
exact set of RSP features.
FreeBSD updates courtesy of John Baldwin.
gdb/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
John Baldwin <jhb@FreeBSD.org>
* aarch64-linux-nat.c
(aarch64_linux_nat_target::thread_architecture): Adjust.
* ada-tasks.c (print_ada_task_info): Adjust find_thread_ptid call.
(task_command_1): Likewise.
* aix-thread.c (sync_threadlists, aix_thread_target::resume)
(aix_thread_target::wait, aix_thread_target::fetch_registers)
(aix_thread_target::store_registers)
(aix_thread_target::thread_alive): Adjust.
* amd64-fbsd-tdep.c: Include "inferior.h".
(amd64fbsd_get_thread_local_address): Pass down target.
* amd64-linux-nat.c (ps_get_thread_area): Use ps_prochandle
thread's gdbarch instead of target_gdbarch.
* break-catch-sig.c (signal_catchpoint_print_it): Adjust call to
get_last_target_status.
* break-catch-syscall.c (print_it_catch_syscall): Likewise.
* breakpoint.c (breakpoints_should_be_inserted_now): Consider all
inferiors.
(update_inserted_breakpoint_locations): Skip if inferiors with no
execution.
(update_global_location_list): When handling moribund locations,
find representative inferior for location's pspace, and use thread
count of its process_stratum target.
* bsd-kvm.c (bsd_kvm_target_open): Pass target down.
* bsd-uthread.c (bsd_uthread_target::wait): Use
as_process_stratum_target and adjust thread_change_ptid and
add_thread calls.
(bsd_uthread_target::update_thread_list): Use
as_process_stratum_target and adjust find_thread_ptid,
thread_change_ptid and add_thread calls.
* btrace.c (maint_btrace_packet_history_cmd): Adjust
find_thread_ptid call.
* corelow.c (add_to_thread_list): Adjust add_thread call.
(core_target_open): Adjust add_thread_silent and thread_count
calls.
(core_target::pid_to_str): Adjust find_inferior_ptid call.
* ctf.c (ctf_target_open): Adjust add_thread_silent call.
* event-top.c (async_disconnect): Pop targets from all inferiors.
* exec.c (add_target_sections): Push exec target on all inferiors
sharing the program space.
(remove_target_sections): Remove the exec target from all
inferiors sharing the program space.
(exec_on_vfork): New.
* exec.h (exec_on_vfork): Declare.
* fbsd-nat.c (fbsd_add_threads): Add fbsd_nat_target parameter.
Pass it down.
(fbsd_nat_target::update_thread_list): Adjust.
(fbsd_nat_target::resume): Adjust.
(fbsd_handle_debug_trap): Add fbsd_nat_target parameter. Pass it
down.
(fbsd_nat_target::wait, fbsd_nat_target::post_attach): Adjust.
* fbsd-tdep.c (fbsd_corefile_thread): Adjust
get_thread_arch_regcache call.
* fork-child.c (gdb_startup_inferior): Pass target down to
startup_inferior and set_executing.
* gdbthread.h (struct process_stratum_target): Forward declare.
(add_thread, add_thread_silent, add_thread_with_info)
(in_thread_list): Add process_stratum_target parameter.
(find_thread_ptid(inferior*, ptid_t)): New overload.
(find_thread_ptid, thread_change_ptid): Add process_stratum_target
parameter.
(all_threads()): Delete overload.
(all_threads, all_non_exited_threads): Add process_stratum_target
parameter.
(all_threads_safe): Use brace initialization.
(thread_count): Add process_stratum_target parameter.
(set_resumed, set_running, set_stop_requested, set_executing)
(threads_are_executing, finish_thread_state): Add
process_stratum_target parameter.
(switch_to_thread): Use is_current_thread.
* i386-fbsd-tdep.c: Include "inferior.h".
(i386fbsd_get_thread_local_address): Pass down target.
* i386-linux-nat.c (i386_linux_nat_target::low_resume): Adjust.
* inf-child.c (inf_child_target::maybe_unpush_target): Remove
have_inferiors check.
* inf-ptrace.c (inf_ptrace_target::create_inferior)
(inf_ptrace_target::attach): Adjust.
* infcall.c (run_inferior_call): Adjust.
* infcmd.c (run_command_1): Pass target to
scoped_finish_thread_state.
(proceed_thread_callback): Skip inferiors with no execution.
(continue_command): Rename 'all_threads' local to avoid hiding
'all_threads' function. Adjust get_last_target_status call.
(prepare_one_step): Adjust set_running call.
(signal_command): Use user_visible_resume_target. Compare thread
pointers instead of inferior_ptid.
(info_program_command): Adjust to pass down target.
(attach_command): Mark target's 'thread_executing' flag.
(stop_current_target_threads_ns): New, factored out from ...
(interrupt_target_1): ... this. Switch inferior before making
target calls.
* inferior-iter.h
(struct all_inferiors_iterator, struct all_inferiors_range)
(struct all_inferiors_safe_range)
(struct all_non_exited_inferiors_range): Filter on
process_stratum_target too. Remove explicit.
* inferior.c (inferior::inferior): Push dummy target on target
stack.
(find_inferior_pid, find_inferior_ptid, number_of_live_inferiors):
Add process_stratum_target parameter, and pass it down.
(have_live_inferiors): Adjust.
(switch_to_inferior_and_push_target): New.
(add_inferior_command, clone_inferior_command): Handle
"-no-connection" parameter. Use
switch_to_inferior_and_push_target.
(_initialize_inferior): Mention "-no-connection" option in
the help of "add-inferior" and "clone-inferior" commands.
* inferior.h: Include "process-stratum-target.h".
(interrupt_target_1): Use bool.
(struct inferior) <push_target, unpush_target, target_is_pushed,
find_target_beneath, top_target, process_target, target_at,
m_stack>: New.
(discard_all_inferiors): Delete.
(find_inferior_pid, find_inferior_ptid, number_of_live_inferiors)
(all_inferiors, all_non_exited_inferiors): Add
process_stratum_target parameter.
* infrun.c: Include "gdb_select.h" and <unordered_map>.
(target_last_proc_target): New global.
(follow_fork_inferior): Push target on new inferior. Pass target
to add_thread_silent. Call exec_on_vfork. Handle target's
reference count.
(follow_fork): Adjust get_last_target_status call. Also consider
target.
(follow_exec): Push target on new inferior.
(struct execution_control_state) <target>: New field.
(user_visible_resume_target): New.
(do_target_resume): Call target_async.
(resume_1): Set target's threads_executing flag. Consider resume
target.
(commit_resume_all_targets): New.
(proceed): Also consider resume target. Skip threads of inferiors
with no execution. Commit resumtion in all targets.
(start_remote): Pass current inferior to wait_for_inferior.
(infrun_thread_stop_requested): Consider target as well. Pass
thread_info pointer to clear_inline_frame_state instead of ptid.
(infrun_thread_thread_exit): Consider target as well.
(random_pending_event_thread): New inferior parameter. Use it.
(do_target_wait): Rename to ...
(do_target_wait_1): ... this. Add inferior parameter, and pass it
down.
(threads_are_resumed_pending_p, do_target_wait): New.
(prepare_for_detach): Adjust calls.
(wait_for_inferior): New inferior parameter. Handle it. Use
do_target_wait_1 instead of do_target_wait.
(fetch_inferior_event): Adjust. Switch to representative
inferior. Pass target down.
(set_last_target_status): Add process_stratum_target parameter.
Save target in global.
(get_last_target_status): Add process_stratum_target parameter and
handle it.
(nullify_last_target_wait_ptid): Clear 'target_last_proc_target'.
(context_switch): Check inferior_ptid == null_ptid before calling
inferior_thread().
(get_inferior_stop_soon): Pass down target.
(wait_one): Rename to ...
(poll_one_curr_target): ... this.
(struct wait_one_event): New.
(wait_one): New.
(stop_all_threads): Adjust.
(handle_no_resumed, handle_inferior_event): Adjust to consider the
event's target.
(switch_back_to_stepped_thread): Also consider target.
(print_stop_event): Update.
(normal_stop): Update. Also consider the resume target.
* infrun.h (wait_for_inferior): Remove declaration.
(user_visible_resume_target): New declaration.
(get_last_target_status, set_last_target_status): New
process_stratum_target parameter.
* inline-frame.c (clear_inline_frame_state(ptid_t)): Add
process_stratum_target parameter, and use it.
(clear_inline_frame_state (thread_info*)): New.
* inline-frame.c (clear_inline_frame_state(ptid_t)): Add
process_stratum_target parameter.
(clear_inline_frame_state (thread_info*)): Declare.
* linux-fork.c (delete_checkpoint_command): Pass target down to
find_thread_ptid.
(checkpoint_command): Adjust.
* linux-nat.c (linux_nat_target::follow_fork): Switch to thread
instead of just tweaking inferior_ptid.
(linux_nat_switch_fork): Pass target down to thread_change_ptid.
(exit_lwp): Pass target down to find_thread_ptid.
(attach_proc_task_lwp_callback): Pass target down to
add_thread/set_running/set_executing.
(linux_nat_target::attach): Pass target down to
thread_change_ptid.
(get_detach_signal): Pass target down to find_thread_ptid.
Consider last target status's target.
(linux_resume_one_lwp_throw, resume_lwp)
(linux_handle_syscall_trap, linux_handle_extended_wait, wait_lwp)
(stop_wait_callback, save_stop_reason, linux_nat_filter_event)
(linux_nat_wait_1, resume_stopped_resumed_lwps): Pass target down.
(linux_nat_target::async_wait_fd): New.
(linux_nat_stop_lwp, linux_nat_target::thread_address_space): Pass
target down.
* linux-nat.h (linux_nat_target::async_wait_fd): Declare.
* linux-tdep.c (get_thread_arch_regcache): Pass target down.
* linux-thread-db.c (struct thread_db_info::process_target): New
field.
(add_thread_db_info): Save target.
(get_thread_db_info): New process_stratum_target parameter. Also
match target.
(delete_thread_db_info): New process_stratum_target parameter.
Also match target.
(thread_from_lwp): Adjust to pass down target.
(thread_db_notice_clone): Pass down target.
(check_thread_db_callback): Pass down target.
(try_thread_db_load_1): Always push the thread_db target.
(try_thread_db_load, record_thread): Pass target down.
(thread_db_target::detach): Pass target down. Always unpush the
thread_db target.
(thread_db_target::wait, thread_db_target::mourn_inferior): Pass
target down. Always unpush the thread_db target.
(find_new_threads_callback, thread_db_find_new_threads_2)
(thread_db_target::update_thread_list): Pass target down.
(thread_db_target::pid_to_str): Pass current inferior down.
(thread_db_target::get_thread_local_address): Pass target down.
(thread_db_target::resume, maintenance_check_libthread_db): Pass
target down.
* nto-procfs.c (nto_procfs_target::update_thread_list): Adjust.
* procfs.c (procfs_target::procfs_init_inferior): Declare.
(proc_set_current_signal, do_attach, procfs_target::wait): Adjust.
(procfs_init_inferior): Rename to ...
(procfs_target::procfs_init_inferior): ... this and adjust.
(procfs_target::create_inferior, procfs_notice_thread)
(procfs_do_thread_registers): Adjust.
* ppc-fbsd-tdep.c: Include "inferior.h".
(ppcfbsd_get_thread_local_address): Pass down target.
* proc-service.c (ps_xfer_memory): Switch current inferior and
program space as well.
(get_ps_regcache): Pass target down.
* process-stratum-target.c
(process_stratum_target::thread_address_space)
(process_stratum_target::thread_architecture): Pass target down.
* process-stratum-target.h
(process_stratum_target::threads_executing): New field.
(as_process_stratum_target): New.
* ravenscar-thread.c
(ravenscar_thread_target::update_inferior_ptid): Pass target down.
(ravenscar_thread_target::wait, ravenscar_add_thread): Pass target
down.
* record-btrace.c (record_btrace_target::info_record): Adjust.
(record_btrace_target::record_method)
(record_btrace_target::record_is_replaying)
(record_btrace_target::fetch_registers)
(get_thread_current_frame_id, record_btrace_target::resume)
(record_btrace_target::wait, record_btrace_target::stop): Pass
target down.
* record-full.c (record_full_wait_1): Switch to event thread.
Pass target down.
* regcache.c (regcache::regcache)
(get_thread_arch_aspace_regcache, get_thread_arch_regcache): Add
process_stratum_target parameter and handle it.
(current_thread_target): New global.
(get_thread_regcache): Add process_stratum_target parameter and
handle it. Switch inferior before calling target method.
(get_thread_regcache): Pass target down.
(get_thread_regcache_for_ptid): Pass target down.
(registers_changed_ptid): Add process_stratum_target parameter and
handle it.
(registers_changed_thread, registers_changed): Pass target down.
(test_get_thread_arch_aspace_regcache): New.
(current_regcache_test): Define a couple local test_target_ops
instances and use them for testing.
(readwrite_regcache): Pass process_stratum_target parameter.
(cooked_read_test, cooked_write_test): Pass mock_target down.
* regcache.h (get_thread_regcache, get_thread_arch_regcache)
(get_thread_arch_aspace_regcache): Add process_stratum_target
parameter.
(regcache::target): New method.
(regcache::regcache, regcache::get_thread_arch_aspace_regcache)
(regcache::registers_changed_ptid): Add process_stratum_target
parameter.
(regcache::m_target): New field.
(registers_changed_ptid): Add process_stratum_target parameter.
* remote.c (remote_state::supports_vCont_probed): New field.
(remote_target::async_wait_fd): New method.
(remote_unpush_and_throw): Add remote_target parameter.
(get_current_remote_target): Adjust.
(remote_target::remote_add_inferior): Push target.
(remote_target::remote_add_thread)
(remote_target::remote_notice_new_inferior)
(get_remote_thread_info): Pass target down.
(remote_target::update_thread_list): Skip threads of inferiors
bound to other targets. (remote_target::close): Don't discard
inferiors. (remote_target::add_current_inferior_and_thread)
(remote_target::process_initial_stop_replies)
(remote_target::start_remote)
(remote_target::remote_serial_quit_handler): Pass down target.
(remote_target::remote_unpush_target): New remote_target
parameter. Unpush the target from all inferiors.
(remote_target::remote_unpush_and_throw): New remote_target
parameter. Pass it down.
(remote_target::open_1): Check whether the current inferior has
execution instead of checking whether any inferior is live. Pass
target down.
(remote_target::remote_detach_1): Pass down target. Use
remote_unpush_target.
(extended_remote_target::attach): Pass down target.
(remote_target::remote_vcont_probe): Set supports_vCont_probed.
(remote_target::append_resumption): Pass down target.
(remote_target::append_pending_thread_resumptions)
(remote_target::remote_resume_with_hc, remote_target::resume)
(remote_target::commit_resume): Pass down target.
(remote_target::remote_stop_ns): Check supports_vCont_probed.
(remote_target::interrupt_query)
(remote_target::remove_new_fork_children)
(remote_target::check_pending_events_prevent_wildcard_vcont)
(remote_target::remote_parse_stop_reply)
(remote_target::process_stop_reply): Pass down target.
(first_remote_resumed_thread): New remote_target parameter. Pass
it down.
(remote_target::wait_as): Pass down target.
(unpush_and_perror): New remote_target parameter. Pass it down.
(remote_target::readchar, remote_target::remote_serial_write)
(remote_target::getpkt_or_notif_sane_1)
(remote_target::kill_new_fork_children, remote_target::kill): Pass
down target.
(remote_target::mourn_inferior): Pass down target. Use
remote_unpush_target.
(remote_target::core_of_thread)
(remote_target::remote_btrace_maybe_reopen): Pass down target.
(remote_target::pid_to_exec_file)
(remote_target::thread_handle_to_thread_info): Pass down target.
(remote_target::async_wait_fd): New.
* riscv-fbsd-tdep.c: Include "inferior.h".
(riscv_fbsd_get_thread_local_address): Pass down target.
* sol2-tdep.c (sol2_core_pid_to_str): Pass down target.
* sol-thread.c (sol_thread_target::wait, ps_lgetregs, ps_lsetregs)
(ps_lgetfpregs, ps_lsetfpregs, sol_update_thread_list_callback):
Adjust.
* solib-spu.c (spu_skip_standalone_loader): Pass down target.
* solib-svr4.c (enable_break): Pass down target.
* spu-multiarch.c (parse_spufs_run): Pass down target.
* spu-tdep.c (spu2ppu_sniffer): Pass down target.
* target-delegates.c: Regenerate.
* target.c (g_target_stack): Delete.
(current_top_target): Return the current inferior's top target.
(target_has_execution_1): Refer to the passed-in inferior's top
target.
(target_supports_terminal_ours): Check whether the initial
inferior was already created.
(decref_target): New.
(target_stack::push): Incref/decref the target.
(push_target, push_target, unpush_target): Adjust.
(target_stack::unpush): Defref target.
(target_is_pushed): Return bool. Adjust to refer to the current
inferior's target stack.
(dispose_inferior): Delete, and inline parts ...
(target_preopen): ... here. Only dispose of the current inferior.
(target_detach): Hold strong target reference while detaching.
Pass target down.
(target_thread_name): Add assertion.
(target_resume): Pass down target.
(target_ops::beneath, find_target_at): Adjust to refer to the
current inferior's target stack.
(get_dummy_target): New.
(target_pass_ctrlc): Pass the Ctrl-C to the first inferior that
has a thread running.
(initialize_targets): Rename to ...
(_initialize_target): ... this.
* target.h: Include "gdbsupport/refcounted-object.h".
(struct target_ops): Inherit refcounted_object.
(target_ops::shortname, target_ops::longname): Make const.
(target_ops::async_wait_fd): New method.
(decref_target): Declare.
(struct target_ops_ref_policy): New.
(target_ops_ref): New typedef.
(get_dummy_target): Declare function.
(target_is_pushed): Return bool.
* thread-iter.c (all_matching_threads_iterator::m_inf_matches)
(all_matching_threads_iterator::all_matching_threads_iterator):
Handle filter target.
* thread-iter.h (struct all_matching_threads_iterator, struct
all_matching_threads_range, class all_non_exited_threads_range):
Filter by target too. Remove explicit.
* thread.c (threads_executing): Delete.
(inferior_thread): Pass down current inferior.
(clear_thread_inferior_resources): Pass down thread pointer
instead of ptid_t.
(add_thread_silent, add_thread_with_info, add_thread): Add
process_stratum_target parameter. Use it for thread and inferior
searches.
(is_current_thread): New.
(thread_info::deletable): Use it.
(find_thread_ptid, thread_count, in_thread_list)
(thread_change_ptid, set_resumed, set_running): New
process_stratum_target parameter. Pass it down.
(set_executing): New process_stratum_target parameter. Pass it
down. Adjust reference to 'threads_executing'.
(threads_are_executing): New process_stratum_target parameter.
Adjust reference to 'threads_executing'.
(set_stop_requested, finish_thread_state): New
process_stratum_target parameter. Pass it down.
(switch_to_thread): Also match inferior.
(switch_to_thread): New process_stratum_target parameter. Pass it
down.
(update_threads_executing): Reimplement.
* top.c (quit_force): Pop targets from all inferior.
(gdb_init): Don't call initialize_targets.
* windows-nat.c (windows_nat_target) <get_windows_debug_event>:
Declare.
(windows_add_thread, windows_delete_thread): Adjust.
(get_windows_debug_event): Rename to ...
(windows_nat_target::get_windows_debug_event): ... this. Adjust.
* tracefile-tfile.c (tfile_target_open): Pass down target.
* gdbsupport/common-gdbthread.h (struct process_stratum_target):
Forward declare.
(switch_to_thread): Add process_stratum_target parameter.
* mi/mi-interp.c (mi_on_resume_1): Add process_stratum_target
parameter. Use it.
(mi_on_resume): Pass target down.
* nat/fork-inferior.c (startup_inferior): Add
process_stratum_target parameter. Pass it down.
* nat/fork-inferior.h (startup_inferior): Add
process_stratum_target parameter.
* python/py-threadevent.c (py_get_event_thread): Pass target down.
gdb/gdbserver/ChangeLog:
2020-01-10 Pedro Alves <palves@redhat.com>
* fork-child.c (post_fork_inferior): Pass target down to
startup_inferior.
* inferiors.c (switch_to_thread): Add process_stratum_target
parameter.
* lynx-low.c (lynx_target_ops): Now a process_stratum_target.
* nto-low.c (nto_target_ops): Now a process_stratum_target.
* linux-low.c (linux_target_ops): Now a process_stratum_target.
* remote-utils.c (prepare_resume_reply): Pass the target to
switch_to_thread.
* target.c (the_target): Now a process_stratum_target.
(done_accessing_memory): Pass the target to switch_to_thread.
(set_target_ops): Ajust to use process_stratum_target.
* target.h (struct target_ops): Rename to ...
(struct process_stratum_target): ... this.
(the_target, set_target_ops): Adjust.
(prepare_to_access_memory): Adjust comment.
* win32-low.c (child_xfer_memory): Adjust to use
process_stratum_target.
(win32_target_ops): Now a process_stratum_target.
722 lines
19 KiB
C
722 lines
19 KiB
C
/* Native-dependent code for GNU/Linux i386.
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Copyright (C) 1999-2020 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 "inferior.h"
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#include "gdbcore.h"
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#include "regcache.h"
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#include "elf/common.h"
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#include "nat/gdb_ptrace.h"
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#include <sys/uio.h>
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#include "gregset.h"
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#include "gdb_proc_service.h"
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#include "i386-linux-nat.h"
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#include "i387-tdep.h"
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#include "i386-tdep.h"
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#include "i386-linux-tdep.h"
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#include "gdbsupport/x86-xstate.h"
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#include "x86-linux-nat.h"
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#include "nat/linux-ptrace.h"
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#include "inf-ptrace.h"
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struct i386_linux_nat_target final : public x86_linux_nat_target
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{
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/* Add our register access methods. */
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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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/* Override the default ptrace resume method. */
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void low_resume (ptid_t ptid, int step, enum gdb_signal sig) override;
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};
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static i386_linux_nat_target the_i386_linux_nat_target;
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/* The register sets used in GNU/Linux ELF core-dumps are identical to
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the register sets in `struct user' that is used for a.out
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core-dumps, and is also used by `ptrace'. The corresponding types
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are `elf_gregset_t' for the general-purpose registers (with
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`elf_greg_t' the type of a single GP register) and `elf_fpregset_t'
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for the floating-point registers.
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Those types used to be available under the names `gregset_t' and
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`fpregset_t' too, and this file used those names in the past. But
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those names are now used for the register sets used in the
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`mcontext_t' type, and have a different size and layout. */
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/* Which ptrace request retrieves which registers?
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These apply to the corresponding SET requests as well. */
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#define GETREGS_SUPPLIES(regno) \
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((0 <= (regno) && (regno) <= 15) || (regno) == I386_LINUX_ORIG_EAX_REGNUM)
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#define GETFPXREGS_SUPPLIES(regno) \
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(I386_ST0_REGNUM <= (regno) && (regno) < I386_SSE_NUM_REGS)
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#define GETXSTATEREGS_SUPPLIES(regno) \
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(I386_ST0_REGNUM <= (regno) && (regno) < I386_PKEYS_NUM_REGS)
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/* Does the current host support the GETREGS request? */
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int have_ptrace_getregs =
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#ifdef HAVE_PTRACE_GETREGS
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1
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#else
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0
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#endif
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;
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/* Does the current host support the GETFPXREGS request? The header
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file may or may not define it, and even if it is defined, the
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kernel will return EIO if it's running on a pre-SSE processor.
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My instinct is to attach this to some architecture- or
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target-specific data structure, but really, a particular GDB
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process can only run on top of one kernel at a time. So it's okay
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for this to be a simple variable. */
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int have_ptrace_getfpxregs =
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#ifdef HAVE_PTRACE_GETFPXREGS
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-1
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#else
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0
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#endif
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;
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/* Accessing registers through the U area, one at a time. */
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/* Fetch one register. */
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static void
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fetch_register (struct regcache *regcache, int regno)
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{
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pid_t tid;
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int val;
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gdb_assert (!have_ptrace_getregs);
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if (i386_linux_gregset_reg_offset[regno] == -1)
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{
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regcache->raw_supply (regno, NULL);
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return;
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}
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tid = get_ptrace_pid (regcache->ptid ());
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errno = 0;
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val = ptrace (PTRACE_PEEKUSER, tid,
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i386_linux_gregset_reg_offset[regno], 0);
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if (errno != 0)
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error (_("Couldn't read register %s (#%d): %s."),
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gdbarch_register_name (regcache->arch (), regno),
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regno, safe_strerror (errno));
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regcache->raw_supply (regno, &val);
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}
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/* Store one register. */
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static void
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store_register (const struct regcache *regcache, int regno)
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{
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pid_t tid;
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int val;
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gdb_assert (!have_ptrace_getregs);
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if (i386_linux_gregset_reg_offset[regno] == -1)
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return;
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tid = get_ptrace_pid (regcache->ptid ());
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errno = 0;
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regcache->raw_collect (regno, &val);
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ptrace (PTRACE_POKEUSER, tid,
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i386_linux_gregset_reg_offset[regno], val);
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if (errno != 0)
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error (_("Couldn't write register %s (#%d): %s."),
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gdbarch_register_name (regcache->arch (), regno),
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regno, safe_strerror (errno));
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}
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/* Transfering the general-purpose registers between GDB, inferiors
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and core files. */
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/* Fill GDB's register array with the general-purpose register values
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in *GREGSETP. */
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void
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supply_gregset (struct regcache *regcache, const elf_gregset_t *gregsetp)
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{
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const gdb_byte *regp = (const gdb_byte *) gregsetp;
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int i;
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for (i = 0; i < I386_NUM_GREGS; i++)
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regcache->raw_supply (i, regp + i386_linux_gregset_reg_offset[i]);
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if (I386_LINUX_ORIG_EAX_REGNUM
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< gdbarch_num_regs (regcache->arch ()))
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regcache->raw_supply
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(I386_LINUX_ORIG_EAX_REGNUM,
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regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
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}
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/* Fill register REGNO (if it is a general-purpose register) in
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*GREGSETPS with the value in GDB's register array. If REGNO is -1,
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do this for all registers. */
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void
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fill_gregset (const struct regcache *regcache,
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elf_gregset_t *gregsetp, int regno)
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{
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gdb_byte *regp = (gdb_byte *) gregsetp;
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int i;
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for (i = 0; i < I386_NUM_GREGS; i++)
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if (regno == -1 || regno == i)
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regcache->raw_collect (i, regp + i386_linux_gregset_reg_offset[i]);
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if ((regno == -1 || regno == I386_LINUX_ORIG_EAX_REGNUM)
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&& I386_LINUX_ORIG_EAX_REGNUM
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< gdbarch_num_regs (regcache->arch ()))
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regcache->raw_collect
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(I386_LINUX_ORIG_EAX_REGNUM,
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regp + i386_linux_gregset_reg_offset[I386_LINUX_ORIG_EAX_REGNUM]);
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}
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#ifdef HAVE_PTRACE_GETREGS
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/* Fetch all general-purpose registers from process/thread TID and
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store their values in GDB's register array. */
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static void
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fetch_regs (struct regcache *regcache, int tid)
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{
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elf_gregset_t regs;
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elf_gregset_t *regs_p = ®s;
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if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0)
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{
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if (errno == EIO)
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{
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/* The kernel we're running on doesn't support the GETREGS
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request. Reset `have_ptrace_getregs'. */
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have_ptrace_getregs = 0;
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return;
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}
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perror_with_name (_("Couldn't get registers"));
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}
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supply_gregset (regcache, (const elf_gregset_t *) regs_p);
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}
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/* Store all valid general-purpose registers in GDB's register array
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into the process/thread specified by TID. */
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static void
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store_regs (const struct regcache *regcache, int tid, int regno)
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{
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elf_gregset_t regs;
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if (ptrace (PTRACE_GETREGS, tid, 0, (int) ®s) < 0)
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perror_with_name (_("Couldn't get registers"));
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fill_gregset (regcache, ®s, regno);
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if (ptrace (PTRACE_SETREGS, tid, 0, (int) ®s) < 0)
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perror_with_name (_("Couldn't write registers"));
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}
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#else
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static void fetch_regs (struct regcache *regcache, int tid) {}
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static void store_regs (const struct regcache *regcache, int tid, int regno) {}
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#endif
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/* Transfering floating-point registers between GDB, inferiors and cores. */
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/* Fill GDB's register array with the floating-point register values in
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*FPREGSETP. */
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void
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supply_fpregset (struct regcache *regcache, const elf_fpregset_t *fpregsetp)
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{
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i387_supply_fsave (regcache, -1, fpregsetp);
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}
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/* Fill register REGNO (if it is a floating-point register) in
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*FPREGSETP with the value in GDB's register array. If REGNO is -1,
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do this for all registers. */
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void
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fill_fpregset (const struct regcache *regcache,
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elf_fpregset_t *fpregsetp, int regno)
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{
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i387_collect_fsave (regcache, regno, fpregsetp);
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}
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#ifdef HAVE_PTRACE_GETREGS
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/* Fetch all floating-point registers from process/thread TID and store
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thier values in GDB's register array. */
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static void
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fetch_fpregs (struct regcache *regcache, int tid)
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{
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elf_fpregset_t fpregs;
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if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
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perror_with_name (_("Couldn't get floating point status"));
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supply_fpregset (regcache, (const elf_fpregset_t *) &fpregs);
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}
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/* Store all valid floating-point registers in GDB's register array
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into the process/thread specified by TID. */
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static void
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store_fpregs (const struct regcache *regcache, int tid, int regno)
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{
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elf_fpregset_t fpregs;
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if (ptrace (PTRACE_GETFPREGS, tid, 0, (int) &fpregs) < 0)
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perror_with_name (_("Couldn't get floating point status"));
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fill_fpregset (regcache, &fpregs, regno);
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if (ptrace (PTRACE_SETFPREGS, tid, 0, (int) &fpregs) < 0)
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perror_with_name (_("Couldn't write floating point status"));
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}
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#else
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static void
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fetch_fpregs (struct regcache *regcache, int tid)
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{
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}
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static void
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store_fpregs (const struct regcache *regcache, int tid, int regno)
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{
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}
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#endif
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/* Transfering floating-point and SSE registers to and from GDB. */
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/* Fetch all registers covered by the PTRACE_GETREGSET request from
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process/thread TID and store their values in GDB's register array.
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Return non-zero if successful, zero otherwise. */
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static int
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fetch_xstateregs (struct regcache *regcache, int tid)
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{
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char xstateregs[X86_XSTATE_MAX_SIZE];
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struct iovec iov;
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if (have_ptrace_getregset != TRIBOOL_TRUE)
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return 0;
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iov.iov_base = xstateregs;
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iov.iov_len = sizeof(xstateregs);
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if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
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&iov) < 0)
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perror_with_name (_("Couldn't read extended state status"));
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i387_supply_xsave (regcache, -1, xstateregs);
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return 1;
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}
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/* Store all valid registers in GDB's register array covered by the
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PTRACE_SETREGSET request into the process/thread specified by TID.
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Return non-zero if successful, zero otherwise. */
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static int
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store_xstateregs (const struct regcache *regcache, int tid, int regno)
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{
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char xstateregs[X86_XSTATE_MAX_SIZE];
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struct iovec iov;
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if (have_ptrace_getregset != TRIBOOL_TRUE)
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return 0;
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iov.iov_base = xstateregs;
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iov.iov_len = sizeof(xstateregs);
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if (ptrace (PTRACE_GETREGSET, tid, (unsigned int) NT_X86_XSTATE,
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&iov) < 0)
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perror_with_name (_("Couldn't read extended state status"));
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i387_collect_xsave (regcache, regno, xstateregs, 0);
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if (ptrace (PTRACE_SETREGSET, tid, (unsigned int) NT_X86_XSTATE,
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(int) &iov) < 0)
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perror_with_name (_("Couldn't write extended state status"));
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return 1;
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}
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#ifdef HAVE_PTRACE_GETFPXREGS
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/* Fetch all registers covered by the PTRACE_GETFPXREGS request from
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process/thread TID and store their values in GDB's register array.
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Return non-zero if successful, zero otherwise. */
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static int
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fetch_fpxregs (struct regcache *regcache, int tid)
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{
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elf_fpxregset_t fpxregs;
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if (! have_ptrace_getfpxregs)
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return 0;
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if (ptrace (PTRACE_GETFPXREGS, tid, 0, (int) &fpxregs) < 0)
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{
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if (errno == EIO)
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{
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have_ptrace_getfpxregs = 0;
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return 0;
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}
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perror_with_name (_("Couldn't read floating-point and SSE registers"));
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}
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i387_supply_fxsave (regcache, -1, (const elf_fpxregset_t *) &fpxregs);
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return 1;
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}
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/* Store all valid registers in GDB's register array covered by the
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PTRACE_SETFPXREGS request into the process/thread specified by TID.
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Return non-zero if successful, zero otherwise. */
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static int
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store_fpxregs (const struct regcache *regcache, int tid, int regno)
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{
|
||
elf_fpxregset_t fpxregs;
|
||
|
||
if (! have_ptrace_getfpxregs)
|
||
return 0;
|
||
|
||
if (ptrace (PTRACE_GETFPXREGS, tid, 0, &fpxregs) == -1)
|
||
{
|
||
if (errno == EIO)
|
||
{
|
||
have_ptrace_getfpxregs = 0;
|
||
return 0;
|
||
}
|
||
|
||
perror_with_name (_("Couldn't read floating-point and SSE registers"));
|
||
}
|
||
|
||
i387_collect_fxsave (regcache, regno, &fpxregs);
|
||
|
||
if (ptrace (PTRACE_SETFPXREGS, tid, 0, &fpxregs) == -1)
|
||
perror_with_name (_("Couldn't write floating-point and SSE registers"));
|
||
|
||
return 1;
|
||
}
|
||
|
||
#else
|
||
|
||
static int
|
||
fetch_fpxregs (struct regcache *regcache, int tid)
|
||
{
|
||
return 0;
|
||
}
|
||
|
||
static int
|
||
store_fpxregs (const struct regcache *regcache, int tid, int regno)
|
||
{
|
||
return 0;
|
||
}
|
||
|
||
#endif /* HAVE_PTRACE_GETFPXREGS */
|
||
|
||
|
||
/* Transferring arbitrary registers between GDB and inferior. */
|
||
|
||
/* Fetch register REGNO from the child process. If REGNO is -1, do
|
||
this for all registers (including the floating point and SSE
|
||
registers). */
|
||
|
||
void
|
||
i386_linux_nat_target::fetch_registers (struct regcache *regcache, int regno)
|
||
{
|
||
pid_t tid;
|
||
|
||
/* Use the old method of peeking around in `struct user' if the
|
||
GETREGS request isn't available. */
|
||
if (!have_ptrace_getregs)
|
||
{
|
||
int i;
|
||
|
||
for (i = 0; i < gdbarch_num_regs (regcache->arch ()); i++)
|
||
if (regno == -1 || regno == i)
|
||
fetch_register (regcache, i);
|
||
|
||
return;
|
||
}
|
||
|
||
tid = get_ptrace_pid (regcache->ptid ());
|
||
|
||
/* Use the PTRACE_GETFPXREGS request whenever possible, since it
|
||
transfers more registers in one system call, and we'll cache the
|
||
results. But remember that fetch_fpxregs can fail, and return
|
||
zero. */
|
||
if (regno == -1)
|
||
{
|
||
fetch_regs (regcache, tid);
|
||
|
||
/* The call above might reset `have_ptrace_getregs'. */
|
||
if (!have_ptrace_getregs)
|
||
{
|
||
fetch_registers (regcache, regno);
|
||
return;
|
||
}
|
||
|
||
if (fetch_xstateregs (regcache, tid))
|
||
return;
|
||
if (fetch_fpxregs (regcache, tid))
|
||
return;
|
||
fetch_fpregs (regcache, tid);
|
||
return;
|
||
}
|
||
|
||
if (GETREGS_SUPPLIES (regno))
|
||
{
|
||
fetch_regs (regcache, tid);
|
||
return;
|
||
}
|
||
|
||
if (GETXSTATEREGS_SUPPLIES (regno))
|
||
{
|
||
if (fetch_xstateregs (regcache, tid))
|
||
return;
|
||
}
|
||
|
||
if (GETFPXREGS_SUPPLIES (regno))
|
||
{
|
||
if (fetch_fpxregs (regcache, tid))
|
||
return;
|
||
|
||
/* Either our processor or our kernel doesn't support the SSE
|
||
registers, so read the FP registers in the traditional way,
|
||
and fill the SSE registers with dummy values. It would be
|
||
more graceful to handle differences in the register set using
|
||
gdbarch. Until then, this will at least make things work
|
||
plausibly. */
|
||
fetch_fpregs (regcache, tid);
|
||
return;
|
||
}
|
||
|
||
internal_error (__FILE__, __LINE__,
|
||
_("Got request for bad register number %d."), regno);
|
||
}
|
||
|
||
/* Store register REGNO back into the child process. If REGNO is -1,
|
||
do this for all registers (including the floating point and SSE
|
||
registers). */
|
||
void
|
||
i386_linux_nat_target::store_registers (struct regcache *regcache, int regno)
|
||
{
|
||
pid_t tid;
|
||
|
||
/* Use the old method of poking around in `struct user' if the
|
||
SETREGS request isn't available. */
|
||
if (!have_ptrace_getregs)
|
||
{
|
||
int i;
|
||
|
||
for (i = 0; i < gdbarch_num_regs (regcache->arch ()); i++)
|
||
if (regno == -1 || regno == i)
|
||
store_register (regcache, i);
|
||
|
||
return;
|
||
}
|
||
|
||
tid = get_ptrace_pid (regcache->ptid ());
|
||
|
||
/* Use the PTRACE_SETFPXREGS requests whenever possible, since it
|
||
transfers more registers in one system call. But remember that
|
||
store_fpxregs can fail, and return zero. */
|
||
if (regno == -1)
|
||
{
|
||
store_regs (regcache, tid, regno);
|
||
if (store_xstateregs (regcache, tid, regno))
|
||
return;
|
||
if (store_fpxregs (regcache, tid, regno))
|
||
return;
|
||
store_fpregs (regcache, tid, regno);
|
||
return;
|
||
}
|
||
|
||
if (GETREGS_SUPPLIES (regno))
|
||
{
|
||
store_regs (regcache, tid, regno);
|
||
return;
|
||
}
|
||
|
||
if (GETXSTATEREGS_SUPPLIES (regno))
|
||
{
|
||
if (store_xstateregs (regcache, tid, regno))
|
||
return;
|
||
}
|
||
|
||
if (GETFPXREGS_SUPPLIES (regno))
|
||
{
|
||
if (store_fpxregs (regcache, tid, regno))
|
||
return;
|
||
|
||
/* Either our processor or our kernel doesn't support the SSE
|
||
registers, so just write the FP registers in the traditional
|
||
way. */
|
||
store_fpregs (regcache, tid, regno);
|
||
return;
|
||
}
|
||
|
||
internal_error (__FILE__, __LINE__,
|
||
_("Got request to store bad register number %d."), regno);
|
||
}
|
||
|
||
|
||
/* Called by libthread_db. Returns a pointer to the thread local
|
||
storage (or its descriptor). */
|
||
|
||
ps_err_e
|
||
ps_get_thread_area (struct ps_prochandle *ph,
|
||
lwpid_t lwpid, int idx, void **base)
|
||
{
|
||
unsigned int base_addr;
|
||
ps_err_e result;
|
||
|
||
result = x86_linux_get_thread_area (lwpid, (void *) idx, &base_addr);
|
||
|
||
if (result == PS_OK)
|
||
*(int *) base = base_addr;
|
||
|
||
return result;
|
||
}
|
||
|
||
|
||
/* The instruction for a GNU/Linux system call is:
|
||
int $0x80
|
||
or 0xcd 0x80. */
|
||
|
||
static const unsigned char linux_syscall[] = { 0xcd, 0x80 };
|
||
|
||
#define LINUX_SYSCALL_LEN (sizeof linux_syscall)
|
||
|
||
/* The system call number is stored in the %eax register. */
|
||
#define LINUX_SYSCALL_REGNUM I386_EAX_REGNUM
|
||
|
||
/* We are specifically interested in the sigreturn and rt_sigreturn
|
||
system calls. */
|
||
|
||
#ifndef SYS_sigreturn
|
||
#define SYS_sigreturn 0x77
|
||
#endif
|
||
#ifndef SYS_rt_sigreturn
|
||
#define SYS_rt_sigreturn 0xad
|
||
#endif
|
||
|
||
/* Offset to saved processor flags, from <asm/sigcontext.h>. */
|
||
#define LINUX_SIGCONTEXT_EFLAGS_OFFSET (64)
|
||
|
||
/* Resume execution of the inferior process.
|
||
If STEP is nonzero, single-step it.
|
||
If SIGNAL is nonzero, give it that signal. */
|
||
|
||
void
|
||
i386_linux_nat_target::low_resume (ptid_t ptid, int step, enum gdb_signal signal)
|
||
{
|
||
int pid = ptid.lwp ();
|
||
int request;
|
||
|
||
if (catch_syscall_enabled () > 0)
|
||
request = PTRACE_SYSCALL;
|
||
else
|
||
request = PTRACE_CONT;
|
||
|
||
if (step)
|
||
{
|
||
struct regcache *regcache = get_thread_regcache (this, ptid);
|
||
struct gdbarch *gdbarch = regcache->arch ();
|
||
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
|
||
ULONGEST pc;
|
||
gdb_byte buf[LINUX_SYSCALL_LEN];
|
||
|
||
request = PTRACE_SINGLESTEP;
|
||
|
||
regcache_cooked_read_unsigned (regcache,
|
||
gdbarch_pc_regnum (gdbarch), &pc);
|
||
|
||
/* Returning from a signal trampoline is done by calling a
|
||
special system call (sigreturn or rt_sigreturn, see
|
||
i386-linux-tdep.c for more information). This system call
|
||
restores the registers that were saved when the signal was
|
||
raised, including %eflags. That means that single-stepping
|
||
won't work. Instead, we'll have to modify the signal context
|
||
that's about to be restored, and set the trace flag there. */
|
||
|
||
/* First check if PC is at a system call. */
|
||
if (target_read_memory (pc, buf, LINUX_SYSCALL_LEN) == 0
|
||
&& memcmp (buf, linux_syscall, LINUX_SYSCALL_LEN) == 0)
|
||
{
|
||
ULONGEST syscall;
|
||
regcache_cooked_read_unsigned (regcache,
|
||
LINUX_SYSCALL_REGNUM, &syscall);
|
||
|
||
/* Then check the system call number. */
|
||
if (syscall == SYS_sigreturn || syscall == SYS_rt_sigreturn)
|
||
{
|
||
ULONGEST sp, addr;
|
||
unsigned long int eflags;
|
||
|
||
regcache_cooked_read_unsigned (regcache, I386_ESP_REGNUM, &sp);
|
||
if (syscall == SYS_rt_sigreturn)
|
||
addr = read_memory_unsigned_integer (sp + 8, 4, byte_order)
|
||
+ 20;
|
||
else
|
||
addr = sp;
|
||
|
||
/* Set the trace flag in the context that's about to be
|
||
restored. */
|
||
addr += LINUX_SIGCONTEXT_EFLAGS_OFFSET;
|
||
read_memory (addr, (gdb_byte *) &eflags, 4);
|
||
eflags |= 0x0100;
|
||
write_memory (addr, (gdb_byte *) &eflags, 4);
|
||
}
|
||
}
|
||
}
|
||
|
||
if (ptrace (request, pid, 0, gdb_signal_to_host (signal)) == -1)
|
||
perror_with_name (("ptrace"));
|
||
}
|
||
|
||
void
|
||
_initialize_i386_linux_nat (void)
|
||
{
|
||
linux_target = &the_i386_linux_nat_target;
|
||
|
||
/* Add the target. */
|
||
add_inf_child_target (linux_target);
|
||
}
|