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26 commits

Author SHA1 Message Date
Pedro Alves
2954dd2b73 thread_info::executing+resumed -> thread_info::internal_state
While working on Windows non-stop support, I ran into a
very-hard-to-track-down bug.

The problem turned out to be that
infrun.c:proceed_resume_thread_checked resumed an already-executing
thread because the thread was marked as "executing=true,
resumed=false", and that function only skips resuming threads that are
marked resumed=true.  The consequence was that GDB corrupted the
registers of the Windows DLL loader threads, eventually leading to a
GDB+inferior deadlock.

Originally, the "resumed" flag was only ever set when infrun decided
is was ready to process a thread's pending wait status.  infrun has
since evolved to set the resumed flag when we set a thread's executing
flag too.  We are not always consistent throughout in guaranteeing
that a thread is marked resumed=true whenever it is marked
executing=true, though.  For instance, no target code that supports
non-stop mode (linux-nat, remote, and windows-nat with this series) is
making sure that new threads are marked resumed=true when they are
added to the thread list.  They are only marked as {state=running,
executing=true}, the "resumed" flag is not touched.

Making proceed_resume_thread_checked check thr->executing() in
addition to thr->resumed(), feels like papering over a combination of
states that shouldn't happen nowadays.

OTOH, having to have the target backends mark new threads as
resumed=true just feels like too many different states (three) to set:

  add_thread (...);
  set_running (...);
  set_executing (...);
  set_resumed (...);

Yuck.  I think we can do better.

We really have too many "state tracking" flags in a thread.
Basically:

 - whether a thread is "running/stopped/exited" (from the user's
   perspective).  This is the thread_info::state field.

 - whether a thread is "executing" (infrun asked the target to set the
   thread executing).  This is thread_info::executing().

 - whether a thread is "resumed" (infrun wants the thread to be
   resumed, but maybe can't yet because the thread has a pending wait
   status).  This is thread_info::resumed()

"running", "executing", and "resumed" are almost synonyms, so this can
be highly confusing English-wise too.

For "running" vs "executing", in comments, we tipically need to
explain that "running/stopped/exited" is for the user/frontend
perspective, while "executing true/false" is for gdb's internal run
control.

(Also, "executing or not" can also mean something else in GDB's
codebase -- "target has execution" does not mean that threads are
actually running right now -- it's a test for whether we have a live
process vs a core dump!)

One simplification we can do that avoids this running vs executing
ambiguity is to replace the "executing" field with an "internal_state"
field, similar to the thread_info::state field, and make that new
internal_state field reuse the same enum thread_state type that is
used by thread_info::state.  Like:

  struct thread_info
  {
  ...
    /* Frontend/public/external/user view of the thread state.  */
    enum thread_state m_state = THREAD_STOPPED;

    /* The thread's internal state.  When the thread is stopped
       internally while handling an internal event, like a software
       single-step breakpoint, the internal state will be
       THREAD_STOPPED, but the external state will still be
       THREAD_RUNNING.  */
    enum thread_state m_internal_state = THREAD_STOPPED;
  };

(Assume we'd add state() and internal_state() getters.)

With that, every check for thr->executing() is replaced with a
'thr->internal_state() == THREAD_RUNNING' check, and the code is
clearer by design.  There is no confusion between "running" vs
"executing" any more, because they now mean the exact same thing.
Instead, we say e.g., 'thread has (user) state "running", and internal
state "stopped"'.  Or simpler, 'thread is running (from the user's
perspective), but internally stopped'.  That is after all what we
would way in comments today already.

That still leaves the 'resumed' flag, though.  That's the least
obvious one.  Turns out we can get rid of it, and make it a new state
tracked by thread_info::internal_state.  That is, we make
internal_state have its own enumeration type (decoupled from
thread_info::state's type), and convert the resumed true/false flag to
a new enumerator of this new enumeration.  Like so:

  enum thread_int_state
  {
    THREAD_INT_STOPPED,
    THREAD_INT_RUNNING,
 +   THREAD_INT_RESUMED_PENDING_STATUS,
    THREAD_INT_EXITED,
  };

That is what this patch does.  So in summary, we go from:

 thread_info::state {THREAD_STOPPED, THREAD_RUNNING, THREAD_EXITED}
 thread_info::executing {false, true}
 thread_info::resumed {false, true}

to:

 thread_info::state {THREAD_STOPPED, THREAD_RUNNING, THREAD_EXITED}
 thread_info::internal_state {THREAD_INT_STOPPED, THREAD_INT_RUNNING,
                              THREAD_INT_RESUMED_PENDING_STATUS,
			      THREAD_INT_EXITED}

The patch adds getters/setters for both (user) state and
internal_state, and adds assertions around state transitions, ensuring
that internal_state doesn't get out of sync with
thread::have_pending_wait_status().

The code that adds/removes threads from the proc_target's
resumed_with_pending_wait_status list is all centralized within
thread_info::set_internal_state, when we switch to/from the
resumed-pending-status state.  With the assertions in place, it should
be impossible to end up with a THREAD_INT_RUNNING thread with a
pending status.

The thread.c:set_running, thread.c:set_executing, thread.c:set_resumed
global functions are all gone, replaced with new thread.c:set_state
and thread.c:set_internal_state functions.

Tested on x86_64-linux-gnu, native and gdbserver.

Change-Id: I4f5097d68f4694d44e1ae23fea3e9bce45fb078c
commit-id:42ba97d4
2026-04-06 18:50:19 +01:00
Tom Tromey
4abc1ce2cc Update copyright dates to include 2026
This updates the copyright headers to include 2026.  I did this by
running gdb/copyright.py and then manually modifying a few files as
noted by the script.
2026-01-05 13:16:46 -07:00
Tom Tromey
d01e823438 Update copyright dates to include 2025
This updates the copyright headers to include 2025.  I did this by
running gdb/copyright.py and then manually modifying a few files as
noted by the script.

Approved-By: Eli Zaretskii <eliz@gnu.org>
2025-04-08 10:54:39 -06:00
Tom Tromey
054f8e32fe Use gdb set in all_non_exited_process_targets
This changes all_non_exited_process_targets to return
gdb::unordered_set.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
2025-03-11 08:40:06 -06:00
Simon Marchi
18d2988e5d gdb, gdbserver, gdbsupport: remove includes of early headers
Now that defs.h, server.h and common-defs.h are included via the
`-include` option, it is no longer necessary for source files to include
them.  Remove all the inclusions of these files I could find.  Update
the generation scripts where relevant.

Change-Id: Ia026cff269c1b7ae7386dd3619bc9bb6a5332837
Approved-By: Pedro Alves <pedro@palves.net>
2024-03-26 21:13:22 -04:00
Andrew Burgess
1d506c26d9 Update copyright year range in header of all files managed by GDB
This commit is the result of the following actions:

  - Running gdb/copyright.py to update all of the copyright headers to
    include 2024,

  - Manually updating a few files the copyright.py script told me to
    update, these files had copyright headers embedded within the
    file,

  - Regenerating gdbsupport/Makefile.in to refresh it's copyright
    date,

  - Using grep to find other files that still mentioned 2023.  If
    these files were updated last year from 2022 to 2023 then I've
    updated them this year to 2024.

I'm sure I've probably missed some dates.  Feel free to fix them up as
you spot them.
2024-01-12 15:49:57 +00:00
Simon Marchi
7438771288 gdb: remove regcache's address space
While looking at the regcache code, I noticed that the address space
(passed to regcache when constructing it, and available through
regcache::aspace) wasn't relevant for the regcache itself.  Callers of
regcache::aspace use that method because it appears to be a convenient
way of getting the address space for a thread, if you already have the
regcache.  But there is always another way to get the address space, as
the callers pretty much always know which thread they are dealing with.
The regcache code itself doesn't use the address space.

This patch removes anything related to address_space from the regcache
code, and updates callers to get it from the thread in context.  This
removes a bit of unnecessary complexity from the regcache code.

The current get_thread_arch_regcache function gets an address_space for
the given thread using the target_thread_address_space function (which
calls the target_ops::thread_address_space method).  This suggest that
there might have been the intention of supporting per-thread address
spaces.  But digging through the history, I did not find any such case.
Maybe this method was just added because we needed a way to get an
address space from a ptid (because constructing a regcache required an
address space), and this seemed like the right way to do it, I don't
know.

The only implementations of thread_address_space and
process_stratum_target::thread_address_space and
linux_nat_target::thread_address_space, which essentially just return
the inferior's address space.  And thread_address_space is only used in
the current get_thread_arch_regcache, which gets removed.  So, I think
that the thread_address_space target method can be removed, and we can
assume that it's fine to use the inferior's address space everywhere.
Callers of regcache::aspace are updated to get the address space from
the relevant inferior, either using some context they already know
about, or in last resort using the current global context.

So, to summarize:

 - remove everything in regcache related to address spaces
 - in particular, remove get_thread_arch_regcache, and rename
   get_thread_arch_aspace_regcache to get_thread_arch_regcache
 - remove target_ops::thread_address_space, and
   target_thread_address_space
 - adjust all users of regcache::aspace to get the address space another
   way

Change-Id: I04fd41b22c83fe486522af7851c75bcfb31c88c7
2023-11-17 20:01:35 +00:00
Simon Marchi
27b1f19f8f gdb: add inferior::{arch, set_arch}
Make the inferior's gdbarch field private, and add getters and setters.
This helped me by allowing putting breakpoints on set_arch to know when
the inferior's arch was set.  A subsequent patch in this series also
adds more things in set_arch.

Change-Id: I0005bd1ef4cd6b612af501201cec44e457998eec
Reviewed-By: John Baldwin <jhb@FreeBSD.org>
Approved-By: Andrew Burgess <aburgess@redhat.com>
2023-10-10 10:44:35 -04:00
Simon Marchi
9213a6d79a gdb: make find_thread_ptid a process_stratum_target method
Make find_thread_ptid (the overload that takes a process_stratum_target)
a method of process_stratum_target.

Change-Id: Ib190a925a83c6b93e9c585dc7c6ab65efbdd8629
Reviewed-By: Tom Tromey <tom@tromey.com>
2023-04-04 21:05:31 -04:00
Simon Marchi
287de65625 gdb, gdbserver, gdbsupport: fix whitespace issues
Replace spaces with tabs in a bunch of places.

Change-Id: If0f87180f1d13028dc178e5a8af7882a067868b0
2023-03-09 16:32:00 -05:00
Joel Brobecker
213516ef31 Update copyright year range in header of all files managed by GDB
This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
2023-01-01 17:01:16 +04:00
Pedro Alves
f34652de0b internal_error: remove need to pass __FILE__/__LINE__
Currently, every internal_error call must be passed __FILE__/__LINE__
explicitly, like:

  internal_error (__FILE__, __LINE__, "foo %d", var);

The need to pass in explicit __FILE__/__LINE__ is there probably
because the function predates widespread and portable variadic macros
availability.  We can use variadic macros nowadays, and in fact, we
already use them in several places, including the related
gdb_assert_not_reached.

So this patch renames the internal_error function to something else,
and then reimplements internal_error as a variadic macro that expands
__FILE__/__LINE__ itself.

The result is that we now should call internal_error like so:

  internal_error ("foo %d", var);

Likewise for internal_warning.

The patch adjusts all calls sites.  99% of the adjustments were done
with a perl/sed script.

The non-mechanical changes are in gdbsupport/errors.h,
gdbsupport/gdb_assert.h, and gdb/gdbarch.py.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
Change-Id: Ia6f372c11550ca876829e8fd85048f4502bdcf06
2022-10-19 15:32:36 +01:00
Joel Brobecker
4a94e36819 Automatic Copyright Year update after running gdb/copyright.py
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.

For the avoidance of doubt, all changes in this commits were
performed by the script.
2022-01-01 19:13:23 +04:00
Simon Marchi
82d1f134cc gdb: follow-fork: push target and add thread in target_follow_fork
In the context of ROCm-gdb [1], the ROCm target sits on top of the
linux-nat target.  when a process forks, it needs to carry over some
data from the forking inferior to the fork child inferior.  Ideally, the
ROCm target would implement the follow_fork target_ops method, but there
are some small problems.  This patch fixes these, which helps the ROCm
target, but also makes things more consistent and a bit nicer in
general, I believe.

The main problem is: when follow-fork-mode is "parent",
target_follow_fork is called with the parent as the current inferior.
When it's "child", target_follow_fork is called with the child as the
current inferior.  This means that target_follow_fork is sometimes
called on the parent's target stack and sometimes on the child's target
stack.

The parent's target stack may contain targets above the process target,
such as the ROCm target.  So if follow-fork-child is "parent", the ROCm
target would get notified of the fork and do whatever is needed.  But
the child's target stack, at that moment, only contains the exec and
process target copied over from the parent.  The child's target stack is
set up by follow_fork_inferior, before calling target_follow_fork.  In
that case, the ROCm target wouldn't get notified of the fork.

For consistency, I think it would be good to always call
target_follow_fork on the parent inferior's target stack.  I think it
makes sense as a way to indicate "this inferior has called fork, do
whatever is needed".  The desired outcome of the fork (whether an
inferior is created for the child, do we need to detach from the child)
can be indicated by passed parameter.

I therefore propose these changes:

 - make follow_fork_inferior always call target_follow_fork with the
   parent as the current inferior.  That lets all targets present on the
   parent's target stack do some fork-related handling and push
   themselves on the fork child's target stack if needed.

   For this purpose, pass the child inferior down to target_follow_fork
   and follow_fork implementations.  This is nullptr if no inferior is
   created for the child, because we want to detach from it.

 - as a result, in follow_fork_inferior, detach from the parent inferior
   (if needed) only after the target_follow_fork call.  This is needed
   because we want to call target_follow_fork before the parent's
   target stack is torn down.

 - hand over to the targets in the parent's target stack (including the
   process target) the responsibility to push themselves, if needed, to
   the child's target stack.  Also hand over the responsibility to the
   process target, at the same time, to create the child's initial
   thread (just like we do for follow_exec).

 - pass the child inferior to exec_on_vfork, so we don't need to swap
   the current inferior between parent and child.  Nothing in
   exec_on_vfork depends on the current inferior, after this change.

   Although this could perhaps be replaced with just having the exec
   target implement follow_fork and push itself in the child's target
   stack, like the process target does... We would just need to make
   sure the process target calls beneath()->follow_fork(...).  I'm not
   sure about this one.

gdb/ChangeLog:

	* target.h (struct target_ops) <follow_fork>: Add inferior*
	parameter.
	(target_follow_fork): Likewise.
	* target.c (default_follow_fork): Likewise.
	(target_follow_fork): Likewise.
	* fbsd-nat.h (class fbsd_nat_target) <follow_fork>: Likewise.
	(fbsd_nat_target::follow_fork): Likewise, and call
	inf_ptrace_target::follow_fork.
	* linux-nat.h (class linux_nat_target) <follow_fork>: Likewise.
	* linux-nat.c (linux_nat_target::follow_fork): Likewise, and
	call inf_ptrace_target::follow_fork.
	* obsd-nat.h (obsd_nat_target) <follow_fork>: Likewise.
	* obsd-nat.c (obsd_nat_target::follow_fork): Likewise, and call
	inf_ptrace_target::follow_fork.
	* remote.c (class remote_target) <follow_fork>: Likewise.
	(remote_target::follow_fork): Likewise, and call
	process_stratum_target::follow_fork.
	* process-stratum-target.h (class process_stratum_target)
	<follow_fork>: New.
	* process-stratum-target.c
	(process_stratum_target::follow_fork): New.
	* target-delegates.c: Re-generate.

[1] https://github.com/ROCm-Developer-Tools/ROCgdb

Change-Id: I460bd0af850f0485e8aed4b24c6d8262a4c69929
2021-08-03 20:26:49 -04:00
Simon Marchi
71a2349005 gdb: optimize selection of resumed thread with pending event
Consider a case where many threads (thousands) keep hitting a breakpoint
whose condition evaluates to false.  random_pending_event_thread is
responsible for selecting a thread from an inferior among all that are
resumed with a pending wait status.  It is currently implemented by
walking the inferior's thread list twice: once to count the number of
candidates and once to select a random one.

Since we now maintain a per target list of resumed threads with pending
event, we can implement this more efficiently by walking that list and
selecting the first thread that matches the criteria
(random_pending_event_thread looks for an thread from a specific
inferior, and possibly a filter ptid).  It will be faster especially in
the common case where there isn't any resumed thread with pending
event.  Currently, we have to iterate the thread list to figure this
out.  With this patch, the list of resumed threads with pending event
will be empty, so it's quick to figure out.

The random selection is kept, but is moved to
process_stratum_target::random_resumed_with_pending_wait_status.  The
same technique is used: do a first pass to count the number of
candidates, and do a second pass to select a random one.  But given that
the list of resumed threads with pending wait statuses will generally be
short, or at least shorter than the full thread list, it should be
quicker.

Note that this isn't completely true, in case there are multiple
inferiors on the same target.  Imagine that inferior A has 10k resumed
threads with pending wait statuses, and random_pending_event_thread is
called with inferior B.  We'll need to go through the list that contains
inferior A's threads to realize that inferior B has no resumed threads
with pending wait status.  But I think that this is a corner /
pathological case.  And a possible fix for this situation would be to
make random_pending_event_thread work per-process-target, rather than
per-inferior.

Change-Id: I1b71d01beaa500a148b5b9797745103e13917325
2021-07-12 20:46:53 -04:00
Simon Marchi
a66f729819 gdb: maintain per-process-target list of resumed threads with pending wait status
Looking up threads that are both resumed and have a pending wait
status to report is something that we do quite often in the fast path
and is expensive if there are many threads, since it currently requires
walking whole thread lists.

The first instance is in maybe_set_commit_resumed_all_targets.  This is
called after handling each event in fetch_inferior_event, to see if we
should ask targets to commit their resumed threads or not.  If at least
one thread is resumed but has a pending wait status, we don't ask the
targets to commit their resumed threads, because we want to consume and
handle the pending wait status first.

The second instance is in random_pending_event_thread, where we want to
select a random thread among all those that are resumed and have a
pending wait status.  This is called every time we try to consume
events, to see if there are any pending events that we we want to
consume, before asking the targets for more events.

To allow optimizing these cases, maintain a per-process-target list of
threads that are resumed and have a pending wait status.

In maybe_set_commit_resumed_all_targets, we'll be able to check in O(1)
if there are any such threads simply by checking whether the list is
empty.

In random_pending_event_thread, we'll be able to use that list, which
will be quicker than iterating the list of threads, especially when
there are no resumed with pending wait status threads.

About implementation details: using the new setters on class
thread_info, it's relatively easy to maintain that list.  Any time the
"resumed" or "pending wait status" property is changed, we check whether
that should cause the thread to be added or removed from the list.

In set_thread_exited, we try to remove the thread from the list, because
keeping an exited thread in that list would make no sense (especially if
the thread is freed).  My first implementation assumed that a process
stratum target was always present when set_thread_exited is called.
That's however, not the case: in some cases, targets unpush themselves
from an inferior and then call "exit_inferior", which exits all the
threads.  If the target is unpushed before set_thread_exited is called
on the threads, it means we could mistakenly leave some threads in the
list.  I tried to see how hard it would be to make it such that targets
have to exit all threads before unpushing themselves from the inferior
(that would seem logical to me, we don't want threads belonging to an
inferior that has no process target).  That seemed quite difficult and
not worth the time at the moment.  Instead, I changed
inferior::unpush_target to remove all threads of that inferior from the
list.

As of this patch, the list is not used, this is done in the subsequent
patches.

The debug messages in process-stratum-target.c need to print some ptids.
However, they can't use target_pid_to_str to print them without
introducing a dependency on the current inferior (the current inferior
is used to get the current target stack).  For debug messages, I find it
clearer to print the spelled out ptid anyway (the pid, lwp and tid
values).  Add a ptid_t::to_string method that returns a string
representation of the ptid that is meant for debug messages, a bit like
we already have frame_id::to_string.

Change-Id: Iad8f93db2d13984dd5aa5867db940ed1169dbb67
2021-07-12 20:46:53 -04:00
Simon Marchi
294c36eb6a gdb: on exec, delegate pushing / unpushing target and adding thread to target_ops::follow_exec
On "exec", some targets need to unpush themselves from the inferior,
and do some bookkeeping, like forgetting the data associated to the
exec'ing inferior.

One such example is the thread-db target.  It does so in
a special case in thread_db_target::wait, just before returning the
TARGET_WAITKIND_EXECD event to its caller.

We have another such case in the context of rocm-gdb [1], where the
"rocm" target is pushed on top of the linux-nat target.  When an exec
happens, we want to unpush the rocm target from the exec'ing inferior to
close some file descriptors that refer to the pre-exec address space and
forget about that inferior.  We then want to push the target on the
inferior in which execution continues, to open the file descriptors for
the post-exec address space.

I think that a good way to address this cleanly is to do all this in the
target_ops::follow_exec implementations.  Make the
process_stratum_target::follow_exec implementation have the default
behavior of pushing itself to the new inferior's target stack (if
execution continues in a new inferior) and add the initial thread.

remote_target::follow_exec is an example of process target that wants to
do a bit more than the default behavior.  So it calls
process_stratum_target::follow_exec first and does the extra work
second.

linux-thread-db (a non-process target) implements follow_exec to do some
bookeeping (forget about that process' data), before handing down the
event down to the process target (which hits
process_stratum_target::follow_exec).

gdb/ChangeLog:

	* target.h (struct target_ops) <follow_exec>: Add ptid_t
	parameter.
	(target_follow_exec): Likewise.
	* target.c (target_follow_exec): Add ptid_t parameter.
	* infrun.c (follow_exec): Adjust call to target_follow_exec,
	don't push target nor create thread.
	* linux-thread-db.c (class thread_db_target) <follow_exec>: New.
	(thread_db_target::wait): Just return on TARGET_WAITKIND_EXECD.
	(thread_db_target::follow_exec): New.
	* remote.c (class remote_target) <follow_exec>: Add ptid_t parameter.
	(remote_target::follow_exec): Call
	process_stratum_target::follow_exec.
	* target-delegates.c: Re-generate.

Change-Id: I3f96d0ba3ea0dde6540b7e1b4d5cdb01635088c8
2021-05-13 15:29:00 -04:00
Joel Brobecker
3666a04883 Update copyright year range in all GDB files
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...

gdb/ChangeLog

        Update copyright year range in copyright header of all GDB files.
2021-01-01 12:12:21 +04:00
Tankut Baris Aktemur
d890404b63 gdb: introduce 'all_non_exited_process_targets' and 'switch_to_target_no_thread'
Introduce two new convenience functions:

1. all_non_exited_process_targets: returns a collection of all process
stratum targets that have non-exited inferiors on them.  Useful for
iterating targets.

2. switch_to_target_no_thread: switch the context to the first
inferior of the given target, and to no selected thread.

gdb/ChangeLog:
2020-05-14  Tankut Baris Aktemur  <tankut.baris.aktemur@intel.com>

	* process-stratum-target.h: Include <set>.
	(all_non_exited_process_targets, switch_to_target_no_thread): New
	function declarations.
	* process-stratum-target.c (all_non_exited_process_targets)
	(switch_to_target_no_thread): New function implementations.
2020-05-14 13:59:54 +02:00
Pedro Alves
5b6d1e4fa4 Multi-target support
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.
2020-01-10 20:06:08 +00:00
Pedro Alves
5018ce90c1 Make target_ops::has_execution take an 'inferior *' instead of a ptid_t
With the multi-target work, each inferior will have its own target
stack, so to call a target method, we'll need to make sure that the
inferior in question is the current one, otherwise target->beneath()
calls will find the target beneath in the wrong inferior.

In some places, it's much more convenient to be able to check whether
an inferior has execution without having to switch to it in order to
call target_has_execution on the right inferior/target stack, to avoid
side effects with switching inferior/thread/program space.

The current target_ops::has_execution method takes a ptid_t as
parameter, which, in a multi-target world, isn't sufficient to
identify the target.  This patch prepares to address that, by changing
the parameter to an inferior pointer instead.  From the inferior,
we'll be able to query its target stack to tell which target is
beneath.

Also adds a new inferior::has_execution() method to make callers a bit
more natural to read.

gdb/ChangeLog:
2020-01-10  Pedro Alves  <palves@redhat.com>

	* corelow.c (core_target::has_execution): Change parameter type to
	inferior pointer.
	* inferior.c (number_of_live_inferiors): Use
	inferior::has_execution instead of target_has_execution_1.
	* inferior.h (inferior::has_execution): New.
	* linux-thread-db.c (thread_db_target::update_thread_list): Use
	inferior::has_execution instead of target_has_execution_1.
	* process-stratum-target.c
	(process_stratum_target::has_execution): Change parameter type to
	inferior pointer.  Check the inferior's PID instead of
	inferior_ptid.
	* process-stratum-target.h
	(process_stratum_target::has_execution): Change parameter type to
	inferior pointer.
	* record-full.c (record_full_core_target::has_execution): Change
	parameter type to inferior pointer.
	* target.c (target_has_execution_1): Change parameter type to
	inferior pointer.
	(target_has_execution_current): Adjust.
	* target.h (target_ops::has_execution): Change parameter type to
	inferior pointer.
	(target_has_execution_1): Change parameter type to inferior
	pointer.  Change return type to bool.
	* tracefile.h (tracefile_target::has_execution): Change parameter
	type to inferior pointer.
2020-01-10 20:05:44 +00:00
Joel Brobecker
b811d2c292 Update copyright year range in all GDB files.
gdb/ChangeLog:

        Update copyright year range in all GDB files.
2020-01-01 10:20:53 +04:00
Tom Tromey
a068643d69 Change pid_to_str to return std::string
Currently the target pid_to_str method returns a const char *, so many
implementations have a static buffer that they update.  This patch
changes these methods to return a std::string instead.  I think this
is cleaner and avoids possible gotchas when calling pid_to_str on
different ptids in a single statement.  (Though no such calls exist
currently.)

This also updates various helper functions, and the gdbarch pid_to_str
methods.

I also made a best effort to fix all the callers, but I can't build
some of the *-nat.c files.

Tested by the buildbot.

gdb/ChangeLog
2019-03-13  Tom Tromey  <tromey@adacore.com>

	* i386-gnu-nat.c (i386_gnu_nat_target::fetch_registers)
	(i386_gnu_nat_target::store_registers): Update.
	* target-debug.h (target_debug_print_std_string): New macro.
	* x86-linux-nat.c (x86_linux_nat_target::enable_btrace): Update.
	* windows-tdep.c (display_one_tib): Update.
	* tui/tui-stack.c (tui_make_status_line): Update.
	* top.c (print_inferior_quit_action): Update.
	* thread.c (thr_try_catch_cmd): Update.
	(add_thread_with_info): Update.
	(thread_target_id_str): Update.
	(thr_try_catch_cmd): Update.
	(thread_command): Update.
	(thread_find_command): Update.
	* record-btrace.c (record_btrace_target::info_record)
	(record_btrace_resume_thread, record_btrace_target::resume)
	(record_btrace_cancel_resume, record_btrace_step_thread)
	(record_btrace_target::wait, record_btrace_target::wait)
	(record_btrace_target::wait, record_btrace_target::stop): Update.
	* progspace.c (print_program_space): Update.
	* process-stratum-target.c
	(process_stratum_target::thread_address_space): Update.
	* linux-fork.c (linux_fork_mourn_inferior)
	(detach_checkpoint_command, info_checkpoints_command)
	(linux_fork_context): Update.
	(linux_fork_detach): Update.
	(class scoped_switch_fork_info): Update.
	(delete_checkpoint_command): Update.
	* infrun.c (follow_fork_inferior): Update.
	(follow_fork_inferior): Update.
	(proceed_after_vfork_done): Update.
	(handle_vfork_child_exec_or_exit): Update.
	(follow_exec): Update.
	(displaced_step_prepare_throw): Update.
	(displaced_step_restore): Update.
	(start_step_over): Update.
	(resume_1): Update.
	(clear_proceed_status_thread): Update.
	(proceed): Update.
	(print_target_wait_results): Update.
	(do_target_wait): Update.
	(context_switch): Update.
	(stop_all_threads): Update.
	(restart_threads): Update.
	(finish_step_over): Update.
	(handle_signal_stop): Update.
	(switch_back_to_stepped_thread): Update.
	(keep_going_pass_signal): Update.
	(print_exited_reason): Update.
	(normal_stop): Update.
	* inferior.c (inferior_pid_to_str): Change return type.
	(print_selected_inferior): Update.
	(add_inferior): Update.
	(detach_inferior): Update.
	* dummy-frame.c (fprint_dummy_frames): Update.
	* dcache.c (dcache_info_1): Update.
	* btrace.c (btrace_enable, btrace_disable, btrace_teardown)
	(btrace_fetch, btrace_clear): Update.
	* linux-tdep.c (linux_core_pid_to_str): Change return type.
	* i386-cygwin-tdep.c (i386_windows_core_pid_to_str): Change return
	type.
	* fbsd-tdep.c (fbsd_core_pid_to_str): Change return type.
	* sol2-tdep.h (sol2_core_pid_to_str): Change return type.
	* sol2-tdep.c (sol2_core_pid_to_str): Change return type.
	* gdbarch.c, gdbarch.h: Rebuild.
	* gdbarch.sh (core_pid_to_str): Change return type.
	* windows-nat.c (struct windows_nat_target) <pid_to_str>: Change
	return type.
	(windows_nat_target::pid_to_str): Change return type.
	(windows_delete_thread): Update.
	(windows_nat_target::attach): Update.
	(windows_nat_target::files_info): Update.
	* target-delegates.c: Rebuild.
	* sol-thread.c (class sol_thread_target) <pid_to_str>: Change
	return type.
	(sol_thread_target::pid_to_str): Change return type.
	* remote.c (class remote_target) <pid_to_str>: Change return
	type.
	(remote_target::pid_to_str): Change return type.
	(extended_remote_target::attach, remote_target::remote_stop_ns)
	(remote_target::remote_notif_remove_queued_reply)
	(remote_target::push_stop_reply, remote_target::disable_btrace):
	Update.
	(extended_remote_target::attach): Update.
	* remote-sim.c (struct gdbsim_target) <pid_to_str>: Change return
	type.
	(gdbsim_target::pid_to_str): Change return type.
	* ravenscar-thread.c (struct ravenscar_thread_target)
	<pid_to_str>: Change return type.
	(ravenscar_thread_target::pid_to_str): Change return type.
	* procfs.c (class procfs_target) <pid_to_str>: Change return
	type.
	(procfs_target::pid_to_str): Change return type.
	(procfs_target::attach): Update.
	(procfs_target::detach): Update.
	(procfs_target::fetch_registers): Update.
	(procfs_target::store_registers): Update.
	(procfs_target::wait): Update.
	(procfs_target::files_info): Update.
	* obsd-nat.c (obsd_nat_target::pid_to_str): Change return type.
	* nto-procfs.c (struct nto_procfs_target) <pid_to_str>: Change
	return type.
	(nto_procfs_target::pid_to_str): Change return type.
	(nto_procfs_target::files_info, nto_procfs_target::attach): Update.
	* linux-thread-db.c (class thread_db_target) <pid_to_str>: Change
	return type.
	* linux-nat.c (linux_nat_target::pid_to_str): Change return type.
	(exit_lwp): Update.
	(attach_proc_task_lwp_callback, get_detach_signal)
	(detach_one_lwp, resume_lwp, linux_nat_target::resume)
	(linux_nat_target::resume, wait_lwp, stop_callback)
	(maybe_clear_ignore_sigint, stop_wait_callback, status_callback)
	(save_stop_reason, select_event_lwp, linux_nat_filter_event)
	(linux_nat_wait_1, resume_stopped_resumed_lwps)
	(linux_nat_target::wait, linux_nat_stop_lwp): Update.
	* inf-ptrace.c (inf_ptrace_target::pid_to_str): Change return
	type.
	(inf_ptrace_target::attach): Update.
	(inf_ptrace_target::files_info): Update.
	* go32-nat.c (struct go32_nat_target) <pid_to_str>: Change return
	type.
	(go32_nat_target::pid_to_str): Change return type.
	* gnu-nat.c (gnu_nat_target::pid_to_str): Change return type.
	(gnu_nat_target::wait): Update.
	(gnu_nat_target::wait): Update.
	(gnu_nat_target::resume): Update.
	* fbsd-nat.c (fbsd_nat_target::pid_to_str): Change return type.
	(fbsd_nat_target::wait): Update.
	* darwin-nat.c (darwin_nat_target::pid_to_str): Change return
	type.
	(darwin_nat_target::attach): Update.
	* corelow.c (class core_target) <pid_to_str>: Change return type.
	(core_target::pid_to_str): Change return type.
	* target.c (normal_pid_to_str): Change return type.
	(default_pid_to_str): Likewise.
	(target_pid_to_str): Change return type.
	(target_translate_tls_address): Update.
	(target_announce_detach): Update.
	* bsd-uthread.c (struct bsd_uthread_target) <pid_to_str>: Change
	return type.
	(bsd_uthread_target::pid_to_str): Change return type.
	* bsd-kvm.c (class bsd_kvm_target) <pid_to_str>: Change return
	type.
	(bsd_kvm_target::pid_to_str): Change return type.
	* aix-thread.c (class aix_thread_target) <pid_to_str>: Change
	return type.
	(aix_thread_target::pid_to_str): Change return type.
	* target.h (struct target_ops) <pid_to_str>: Change return type.
	(target_pid_to_str, normal_pid_to_str): Likewise.
	* obsd-nat.h (class obsd_nat_target) <pid_to_str>: Change return
	type.
	* linux-nat.h (class linux_nat_target) <pid_to_str>: Change return
	type.
	* inf-ptrace.h (struct inf_ptrace_target) <pid_to_str>: Change
	return type.
	* gnu-nat.h (struct gnu_nat_target) <pid_to_str>: Change return
	type.
	* fbsd-nat.h (class fbsd_nat_target) <pid_to_str>: Change return
	type.
	* darwin-nat.h (class darwin_nat_target) <pid_to_str>: Change
	return type.
2019-03-13 13:50:13 -06:00
Joel Brobecker
42a4f53d2b Update copyright year range in all GDB files.
This commit applies all changes made after running the gdb/copyright.py
script.

Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.

gdb/ChangeLog:

	Update copyright year range in all GDB files.
2019-01-01 10:01:51 +04:00
Pedro Alves
f3d11a9a96 Convert default_child_has_foo functions to process_stratum_target methods
This patch converts the default_child_has_foo functions to
process_stratum_target methods.  This simplifies "regular"
non-inf_child process_stratum targets, since they no longer have to
override the target_ops::has_foo methods to call the default_child_foo
functions.  A couple targets need to override the new defaults
(corelow and tracefiles), but it still seems like a good tradeoff,
since those are expected to be little different (target doesn't run).

gdb/ChangeLog:
2018-11-30  Pedro Alves  <palves@redhat.com>

	* corelow.c (core_target) <has_all_memory, has_execution>: New
	overrides.
	* inf-child.c (inf_child_target::has_all_memory)
	(inf_child_target::has_memory, inf_child_target::has_stack)
	(inf_child_target::has_registers)
	(inf_child_target::has_execution): Delete.
	* inf-child.h (inf_child_target) <has_all_memory, has_memory,
	has_stack, has_registers, has_execution>: Delete.
	* process-stratum-target.c
	(process_stratum_target::has_all_memory)
	(process_stratum_target::has_memory)
	(process_stratum_target::has_stack)
	(process_stratum_target::has_registers)
	(process_stratum_target::has_execution): New.
	* process-stratum-target.h (process_stratum_target)
	<has_all_memory, has_memory, has_stack, has_registers,
	has_execution>: New method overrides.
	* ravenscar-thread.c (ravenscar_thread_target) <has_all_memory,
	has_memory, has_stack, has_registers, has_execution>: Delete.
	* remote-sim.c (gdbsim_target) <has_stack, has_registers,
	has_execution>: Delete.
	* remote.c (remote_target) <has_all_memory, has_memory, has_stack,
	has_registers, has_execution>: Delete.
	* target.c (default_child_has_all_memory)
	(default_child_has_memory, default_child_has_stack)
	(default_child_has_registers, default_child_has_execution):
	Delete.
	* target.h (default_child_has_all_memory)
	(default_child_has_memory, default_child_has_stack)
	(default_child_has_registers, default_child_has_execution):
	Delete.
	* tracefile.h (tracefile_target) <has_execution>: New override.
2018-11-30 16:28:11 +00:00
Pedro Alves
3b3dac9b3f Introduce process_stratum_target
This adds a base class that all process_stratum targets inherit from.

default_thread_address_space/default_thread_architecture only make
sense for process_stratum targets, so they are transformed to
process_stratum_target methods/overrides.

gdb/ChangeLog:
2018-11-30  Pedro Alves  <palves@redhat.com>

	* Makefile.in (COMMON_SFILES): Add process-stratum-target.c.
	* bsd-kvm.c: Include "process-stratum-target.h".
	(bsd_kvm_target): Now inherits from process_stratum_target.
	(bsd_kvm_target::bsd_kvm_target): Default it.
	* corelow.c: Include "process-stratum-target.h".
	(core_target): Now inherits from process_stratum_target.
	(core_target::core_target): Don't set to_stratum here.
	* inf-child.c (inf_child_target::inf_child_target): Delete.
	* inf-child.h: Include "process-stratum-target.h".
	(inf_child_target): Inherit from process_stratum_target.
	(inf_child_target) <inf_child_target>: Default it.
	<can_async_p, supports_non_stop, supports_disable_randomization>:
	Delete overrides.
	* process-stratum-target.c: New file.
	* process-stratum-target.h: New file.
	* remote-sim.c: Include "process-stratum-target.h".
	(gdbsim_target): Inherit from process_stratum_target.
	<gdbsim_target>: Default it.
	* remote.c: Include "process-stratum-target.h".
	(remote_target): Inherit from process_stratum_target.
	<remote_target>: Default it.
	* target.c (default_thread_address_space)
	(default_thread_architecture): Delete.
	* target.h (target_ops) <thread_architecture>: Now returns NULL by
	default.
	<thread_address_space>: Ditto.
	* test-target.h: Include "process-stratum-target.h" instead of
	"target.h".
	(test_target_ops): Inherit from process_stratum_target.
	<test_target_ops>: Default it.
	* tracefile.c (tracefile_target::tracefile_target): Delete.
	* tracefile.h: Include "process-stratum-target.h".
	(tracefile_target): Inherit from process_stratum_target.
	<tracefile_target>: Default it.
	* target-delegates.c: Regenerate.
2018-11-30 16:27:26 +00:00