gdb: fall back on sigpending + sigwait if sigtimedwait is not available
A call to sigwait was introduced that passes nullptr as the second
argument, this call is only reached if sigtimedwait is not supported.
The original patch was written for macOS, I assume on that target
passing nullptr as the second argument is fine.
On my GNU/Linux box, the man-page for sigwait doesn't mention that
nullptr is allowed for the second argument, so my assumption would be
that nullptr is not OK, and, if I change the '#ifdef
HAVE_SIGTIMEDWAIT' introduced by the above patch to '#if 0', and
rebuild on GNU/Linux, I see the same warning that I see on GNU/Hurd.
I propose that we stop passing nullptr as the second argument to
sigwait, and instead pass a valid int pointer. The value returned in
the int can then be used in an assert.
For testing, I (locally) made the change to the #ifdef I mentioned
above, compiled GDB, and ran the usual tests, this meant I was using
sigwait instead on sigtimedwait on GNU/Linux, I saw no regressions.
Jan Beulich [Tue, 4 Jan 2022 09:05:53 +0000 (10:05 +0100)]
x86/Intel: correct VFPCLASSP{S,D} handling when displacement is present
fits_in_disp8() can be called before ambiguous operands get resolved
or rejected (in process_suffix()), which requires that i.memshift be
non-negative to avoid an internal error. This case wasn't covered by 6c0946d0d28d ("x86: correct VFPCLASSP{S,D} operand size handling").
Jan Beulich [Tue, 4 Jan 2022 09:05:17 +0000 (10:05 +0100)]
gas: rework handling of backslashes in quoted symbol names
Strange effects can result from the present handling, e.g.:
.if 1
"backslash\\":
.endif
yields first (correctly) "missing closing `"'" but then also "invalid
character '\' in mnemonic" and further "end of file inside conditional".
Symbols names ending in \ are in principle not expressable with that
scheme.
Instead of recording whether a backslash was seen, inspect the
subsequent character right away. Only accept \\ (meaning a single
backslash in the resulting symbol name) and \" (meaning an embedded
double quote in the resulting symbol name) for now, warning about any
other combination.
While perhaps not necessary immediately, also permit concatenated
strings to form a symbol name. This may become useful if going forward
we would want to support \<octal> or \x<hex> sequences, where closing
and re-opening quotes can be useful to delimit such sequences.
The ELF "Multibyte symbol names" test gets switched away from using
.set, as that would now also mean excluding nios2 and pru. By using
.equiv instead, even the existing #notarget can be dropped. (For h8300
the .section directive additionally needs attributes specified, to avoid
a target specific warning.)
Tom de Vries [Mon, 3 Jan 2022 22:59:30 +0000 (23:59 +0100)]
[gdb/cli] Improve show logging output
Before commit 3b6acaee895 "Update more calls to add_prefix_cmd" we had the
following output for "show logging":
...
$ gdb -q -batch -ex "set trace-commands on" \
-ex "set logging off" \
-ex "show logging" \
-ex "set logging on" \
-ex "show logging"
+set logging off
+show logging
Future logs will be written to gdb.txt.
Logs will be appended to the log file.
Output will be logged and displayed.
Debug output will be logged and displayed.
+set logging on
+show logging
Currently logging to "gdb.txt".
Logs will be appended to the log file.
Output will be logged and displayed.
Debug output will be logged and displayed.
...
After that commit we have instead:
...
+set logging off
+show logging
debugredirect: The logging output mode is off.
file: The current logfile is "gdb.txt".
overwrite: Whether logging overwrites or appends to the log file is off.
redirect: The logging output mode is off.
+set logging on
+show logging
debugredirect: The logging output mode is off.
file: The current logfile is "gdb.txt".
overwrite: Whether logging overwrites or appends to the log file is off.
redirect: The logging output mode is off.
...
which gives less clear output for some subcommands.
OTOH, it's explicit about whether boolean values are on or off.
The new text seems to have been chosen to match the set/show help texts:
...
(gdb) help show logging
Show logging options.
List of show logging subcommands:
show logging debugredirect -- Show the logging debug output mode.
show logging file -- Show the current logfile.
show logging overwrite -- \
Show whether logging overwrites or appends to the log file.
show logging redirect -- Show the logging output mode.
...
Make the show logging messages more clear, while still keep the boolean
values explicit, such that we have:
...
$ ./gdb.sh -q -batch -ex "show logging"
logging debugredirect: off: \
Debug output will go to both the screen and the log file.
logging enabled: off: Logging is disabled.
logging file: The current logfile is "gdb.txt".
logging overwrite: off: Logging appends to the log file.
logging redirect: off: Output will go to both the screen and the log file.
...
Tom Tromey [Mon, 3 Jan 2022 18:04:01 +0000 (11:04 -0700)]
Fix use of 'printf' in gdbtypes.c
An earlier patch of mine, commit 64b7cc50 ("Remove
gdb_print_host_address") inadvertently changed a function in
gdbtypes.c to use printf rather than printf_filtered. This patch
fixes the problem.
Tom Tromey [Mon, 3 Jan 2022 16:03:55 +0000 (09:03 -0700)]
Fix regression in page-logging.exp
Simon and Tom pointed out that page-logging.exp failed on their
machines. Tom tracked this down to the "width" setting. Since
there's no need in the test to change the width, it seems simplest to
remove the setting. I confirmed that the test still fails if the fix
is backed out, ensuring that the test is still testing what it
purports to.
Tom Tromey [Mon, 3 Jan 2022 14:55:20 +0000 (07:55 -0700)]
Small indentation fix in eval.c
I noticed that the AdaCore tree had a small divergence in eval.c -- it
had a fix for an indentation problem in binop_promote. I'm checking
in this small fix as obvious.
Tom de Vries [Mon, 3 Jan 2022 14:36:36 +0000 (15:36 +0100)]
[gdb/testsuite] Handle for loop initial decl with gcc 4.8.5
When running test-case gdb.threads/schedlock-thread-exit.exp on a system with
system compiler gcc 4.8.5, I run into:
...
src/gdb/testsuite/gdb.threads/schedlock-thread-exit.c:33:3: error: \
'for' loop initial declarations are only allowed in C99 mode
...
Fix this by:
- using -std=c99, or
- using -std=gnu99, in case that's required, or
- in the case of the jit test-cases, rewriting the for loops.
Tested on x86_64-linux, both with gcc 4.8.5 and gcc 7.5.0.
Tom Tromey [Sun, 2 Jan 2022 19:16:37 +0000 (12:16 -0700)]
Update copying.awk for _initialize declaration patch
Commit 6c265988 ("gdb: add back declarations for _initialize
functions") modified copying.c, but not copying.awk. This patch
updates copying.awk to backport the appropriate fix. This way, if
copying.awk is run again, it will create the correct output.
Tom Tromey [Sun, 2 Jan 2022 17:40:35 +0000 (10:40 -0700)]
Use filtered output in print_i387_ext
print_i387_ext mostly uses filtered output, but one call in the middle
of the function uses the _unfiltered form. This patch fixes this
call. I'm checking this in as obvious.
Alan Modra [Sat, 1 Jan 2022 22:30:17 +0000 (09:00 +1030)]
Update year range in copyright notice of binutils files
The result of running etc/update-copyright.py --this-year, fixing all
the files whose mode is changed by the script, plus a build with
--enable-maintainer-mode --enable-cgen-maint=yes, then checking
out */po/*.pot which we don't update frequently.
The copy of cgen was with commit d1dd5fcc38ead reverted as that commit
breaks building of bfp opcodes files.
Mike Frysinger [Mon, 6 Dec 2021 07:39:42 +0000 (02:39 -0500)]
sim: ppc: drop natural types
These are almost entirely unused. For the very few places using them,
replace with explicit signed types. This matches what was done in the
common sim code.
Mike Frysinger [Sat, 1 Jan 2022 18:13:18 +0000 (13:13 -0500)]
sim: tweak copyright lines for gnulib update-copyright
The regex it uses does not like so many leading spaces which causes
it to think the files lack copyright. Trim them down so the script
can find & update them accordingly.
Joel Brobecker [Sat, 1 Jan 2022 15:09:20 +0000 (19:09 +0400)]
Update Copyright year in gdb/testsuite/gdb.arch/powerpc-power10.exp
This commit updates the copyright year range in the script
gdb/testsuite/gdb.arch/powerpc-power10.exp. The update was
performed by running gdb/copyright.py again, to make sure
that the copyright year range will be automatically updated
in years forward.
Joel Brobecker [Sat, 1 Jan 2022 15:07:32 +0000 (19:07 +0400)]
Fix copyright header in gdb/testsuite/gdb.arch/powerpc-power10.exp
The copyright year and holder line is slight malformed, missing
a space after a comma, and this is sufficient for gdb's
copyright.py script to miss this file during its automated
copyright year update.
Joel Brobecker [Sat, 1 Jan 2022 15:03:38 +0000 (19:03 +0400)]
gdb/copyright.py: Add update-netbsd.sh to MULTIPLE_COPYRIGHT_HEADERS
Add gdb/syscalls/update-netbsd.sh to the reminder printed
at the end of the execution listing all the files where
a manual update of the copyright header is needed. This
scripts contains some inline code which includes a copyright
header.
Joel Brobecker [Sat, 1 Jan 2022 15:01:48 +0000 (19:01 +0400)]
Manual copyright year update of various GDB files
This commit updates the copyright year in some files where
we have a copyright year outside of the copyright year,
and thus are not included in gdb's copyright.py script.
Alan Modra [Sat, 1 Jan 2022 03:20:37 +0000 (13:50 +1030)]
Remove unnecessary ELF_MINPAGESIZE defines
The idea of this patch is to make it easy to see which targets (just
sparc) have ELF_MINPAGESIZE != ELF_COMMONPAGESIZE.
* elf32-arm.c (ELF_MINPAGESIZE): Don't define.
* elf32-metag.c: Likewise.
* elfnn-aarch64.c: Likewise.
* elf64-x86-64.c: Likewise. Also don't redefine a bunch of other
macros for l1om elf64-target.h use that are unchanged from default.
Tom Tromey [Fri, 31 Dec 2021 20:28:26 +0000 (13:28 -0700)]
Do not call reinitialize_more_filter from avr_io_reg_read_command
avr_io_reg_read_command is an ordinary gdb command, and so should not
be calling reinitialize_more_filter. This patch removes it. I'm
checking this in as obvious. Tested by rebuilding.
Tamar Christina [Fri, 31 Dec 2021 11:42:07 +0000 (11:42 +0000)]
ld: fix coff PE SEH
COFF_WITH_pex64 and COFF_WITH_peAArch64 can't be true at the same time.
That means that two conditionals that control the sorting of the .pdata section
became a falsum.
The testsuite doesn't catch this because the linker does the sorting and to link
you require library support from the unwinder so we can't test from binutils in
isolation.
bfd/ChangeLog:
2021-12-31 Tamar Christina <tamar.christina@arm.com>
Tom Tromey [Wed, 29 Dec 2021 18:05:51 +0000 (11:05 -0700)]
Use filtered output in show callbacks
"show" command callbacks, like most ordinary gdb commands, should use
filtered output. I found a few that did not, so this patch changes
them to use the filtered form.
Tom Tromey [Tue, 28 Dec 2021 21:10:11 +0000 (14:10 -0700)]
Consistently Use ui_file parameter to show callbacks
I happened to notice that one "show" callback was printing to
gdb_stdout rather than to the passed-in ui_file parameter. I went
through all such callbacks and fixed them to consistently use the
ui_file.
Tom Tromey [Mon, 27 Dec 2021 01:36:36 +0000 (18:36 -0700)]
Use debug_prefixed_printf_cond_nofunc in index-cache
This changes index-cache.c to use debug_prefixed_printf_cond_nofunc.
As a side effect, logs are now written to gdb_stdlog. This is part of
PR gdb/7233.
Tom Tromey [Sun, 26 Dec 2021 21:03:41 +0000 (14:03 -0700)]
Use debug_prefixed_printf_cond_nofunc in machoread
This changes machoread.c to use debug_prefixed_printf_cond_nofunc. As
a side effect, the logs are now written to gdb_stdlog. This is part
of PR gdb/7233.
Tom Tromey [Sun, 26 Dec 2021 20:41:36 +0000 (13:41 -0700)]
Use correct stream for process record output
The process record code often emits unfiltered output. In some cases,
this output ought to go to gdb_stderr (but see below). In other
cases, the output is guarded by a logging variable and so ought to go
to gdb_stdlog. This patch makes these changes.
Note that in many cases, the output to stderr is followed by a
"return -1", which is how process record indicates an error. It seems
to me that calling error here would be preferable, because, in many
cases, that's all the caller does when it sees a -1. However, I
haven't made this change.
Tom Tromey [Mon, 27 Dec 2021 17:53:16 +0000 (10:53 -0700)]
Fix logging redirection bug with pager
I noticed yesterday that if gdb output is redirected to a file, the
pager will still be active. This is irritating, because the output
isn't actually visible -- just the pager prompt. Looking in bugzilla,
I found that this had been filed 17 years ago, as PR cli/8798.
This patch fixes the bug. It changes the pagination code to query the
particular ui-file to see if paging is allowable. The ui-file
implementations are changed so that only the stdout implementation and
a tee (where one sub-file is stdout) can page.
Tom Tromey [Wed, 22 Dec 2021 17:30:16 +0000 (10:30 -0700)]
Remove unusual use of core_addr_eq and core_addr_hash
gdbtypes.h uses core_addr_eq and core_addr_hash in a weird way: taking
the address of a member and then passing this (as a void*) to these
functions.
It seems better to simply inline the ordinary code here. CORE_ADDR is
a scalar so it can be directly compared, and the identity hash
function seems safe to assume as well.
After this, core_addr_eq and core_addr_hash are unused, so this patch
removes them.
Lancelot SIX [Mon, 6 Dec 2021 10:23:42 +0000 (05:23 -0500)]
gdb: Copy inferior properties in clone-inferior
This commit ensures that the following settings are cloned from one
inferior to the new one when processing the clone-inferior command:
- inferior-tty
- environment variables
- cwd
- args
Some of those parameters can be passed as command line arguments to GDB
(-args and -tty), so one could expect the clone-inferior to respect
those flags. The following debugging session illustrates that:
gdb -nx -quiet -batch \
-ex "show args" \
-ex "show inferior-tty" \
-ex "clone-inferior" \
-ex "inferior 2" \
-ex "show args" \
-ex "show inferior-tty" \
-tty=/some/tty \
-args echo foo bar
Argument list to give program being debugged when it is started is "foo bar".
Terminal for future runs of program being debugged is "/some/tty".
[New inferior 2]
Added inferior 2.
[Switching to inferior 2 [<null>] (/bin/echo)]
Argument list to give program being debugged when it is started is "".
Terminal for future runs of program being debugged is "".
The other properties this commit copies on clone (i.e. CWD and the
environment variables) are included since they are related (in the sense
that they influence the runtime behavior of the program) even if they
cannot be directly set using command line switches.
There is a chance that this patch changes existing user workflow. I
think that this change is mostly harmless. If users want to start a new
inferior based on an existing one, they probably already propagate those
settings to the new inferior in some way.
Alan Modra [Mon, 20 Dec 2021 14:39:13 +0000 (01:09 +1030)]
gas reloc sorting
In some cases, eg. riscv_pre_output_hook, gas generates out-of-order
relocations. Various places in the linker assume relocs are sorted
by increasing r_offset, which is normally the case. Provide
GAS_SORT_RELOCS to handle unsorted relocs.
Tom Tromey [Wed, 22 Dec 2021 17:28:37 +0000 (10:28 -0700)]
Remove gdb_print_host_address
gdb_print_host_address is just a simple wrapper around
fprintf_filtered. However, it is readily replaced in all callers by a
combination of %s and call to host_address_to_string. This also
simplifies the code, so I think it's worthwhile to remove this
function.
Tom Tromey [Tue, 21 Dec 2021 23:24:16 +0000 (16:24 -0700)]
Move gdb_bfd_errmsg to gdb_bfd.c
gdb_bfd.c contains most of gdb's BFD-related utility functions.
However, gdb_bfd_errmsg is in utils.c. It seemed better to me to move
this out of util.[ch] and into the BFD-related file instead.
Nelson Chu [Fri, 24 Dec 2021 07:10:38 +0000 (15:10 +0800)]
RISC-V: Rewrite the csr testcases.
Maskray (Fangrui Song) had suggested me before that we should combine
multiple testcases into one file as possible as we can. So that we can
more easily understand what these test cases are testing, and easier to
maintain. Therefore, this patch rewrites all csr testcases, to make them
more clean.
gas/
* testsuite/gas/riscv/csr-fail-nonexistent.d: Renamed from
priv-reg-fail-nonexistent testcase.
* testsuite/gas/riscv/csr-fail-nonexistent.: Likewise.
* testsuite/gas/riscv/csr-fail-nonexistent.s: Likewise.
* testsuite/gas/riscv/csr-insns-pseudo-noalias.d: Renamed from
priv-reg-pseudo testcase.
* testsuite/gas/riscv/csr-insns-pseudo.d: Likewise.
* testsuite/gas/riscv/csr-insns-pseudo.s: Likewise.
* testsuite/gas/riscv/csr-insns-read-only.d: Renamed from
priv-reg-fail-read-only-02 testcase.
* testsuite/gas/riscv/csr-insns-read-only.l: Likewise.
* testsuite/gas/riscv/csr-insns-read-only.s: Likewise.
* testsuite/gas/riscv/h-ext-32.d: Moved hypervisor csrs to csr.s.
* testsuite/gas/riscv/h-ext-32.s: Likewise.
* testsuite/gas/riscv/h-ext-64.d: Likewise.
* testsuite/gas/riscv/h-ext-64.s: Likewise.
* testsuite/gas/riscv/csr.s: Renamed from priv-reg.s, and then
added the hypervisor csrs.
* testsuite/gas/riscv/csr-version-1p9p1.d: The csr testcase when
the privileged spec is 1.9.1. Also tested all invalid csr warnings
when -mcsr-check is enabled.
* testsuite/gas/riscv/csr-version-1p9p1.l: Likewise.
* testsuite/gas/riscv/csr-version-1p10.d: Likewise, but the
privileged spec is 1.10..
* testsuite/gas/riscv/csr-version-1p10.l: Likewise.
* testsuite/gas/riscv/csr-version-1p11.d: Likewise, but the
privileged spec is 1.11.
* testsuite/gas/riscv/csr-version-1p11.l: Likewise.
* testsuite/gas/riscv/csr-version-1p12.d: Likewise, but the
privileged spec is 1.12.
* testsuite/gas/riscv/csr-version-1p12.l: Likewise.
* testsuite/gas/riscv/priv-reg*: Removed or Renamed.
Vineet Gupta [Tue, 21 Dec 2021 02:34:12 +0000 (18:34 -0800)]
RISC-V: Hypervisor ext: drop Privileged Spec 1.9.1 implementation/tests
This makes way for a clean 1.12 based Hypervisor Ext support.
There are no known implementors of 1.9.1 H-ext. (Per Jim, kendryte k210
is based on priv spec 1.9.1, but it seems unlikely that they implemented
H-ext).
Signed-off-by: Vineet Gupta <vineetg@rivosinc.com> Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com> Reviewed-by: Nelson Chu <nelson.chu@sifive.com>
gas/
* testsuite/gas/riscv/csr-dw-regnums.d: Drop the hypervisor csrs
defined in the privileged spec 1.9.1.
* testsuite/gas/riscv/csr-dw-regnums.s: Likewise.
* testsuite/gas/riscv/priv-reg-fail-read-only-01.s: Likewise.
* testsuite/gas/riscv/priv-reg-fail-version-1p10.l: Likewise.
* testsuite/gas/riscv/priv-reg-fail-version-1p11.l: Likewise.
* testsuite/gas/riscv/priv-reg-version-1p10.d: Likewise.
* testsuite/gas/riscv/priv-reg-version-1p11.d: Likewise.
* testsuite/gas/riscv/priv-reg-version-1p9p1.d: Likewise.
* testsuite/gas/riscv/priv-reg.s: Likewise.
include/
* opcode/riscv-opc.h: Drop the hypervisor csrs defined in the
privileged spec 1.9.1.
Andrew Burgess [Thu, 23 Dec 2021 15:48:47 +0000 (15:48 +0000)]
gdb/testsuite: resolve some duplicate testnames in gdb.mi
Set of fixes to resolve some duplicate test names in the gdb.mi/
directory. There should be no real test changes after this set of
fixes, they are all either:
- Adding with_test_prefix type constructs to make test names unique,
or
- Changing the test name to be more descriptive, or better reflect
the test being run.
Andrew Burgess [Mon, 4 Oct 2021 14:48:11 +0000 (15:48 +0100)]
gdb/remote: handle attach when stop packet lacks thread-id
Bug PR gdb/28405 reports a regression when using attach with an
extended-remote target. In this case the target is not including a
thread-id in the stop packet it sends back after the attach.
The problem is that when GDB processes the stop packet, it sees that
there is no thread-id and so has to "guess" which thread the stop
should apply to.
In this case the target only has one thread, so really, there's no
guessing needed, but GDB still runs through the same process, this
shouldn't cause us any problems.
However, after the above commit, GDB now expects itself to be more
internally consistent, specifically, only a thread that GDB thinks is
resumed, can be a candidate for having stopped.
It turns out that, when GDB attaches to a process through an
extended-remote target, the threads of the process being attached too,
are not, initially, marked as resumed.
And so, when GDB tries to figure out which thread the stop might apply
too, it finds no threads in the processes marked resumed, and so an
assert triggers.
In extended_remote_target::attach we create a new thread with a call
to add_thread_silent, rather than remote_target::remote_add_thread,
the reason is that calling the latter will result in a call to
'add_thread' rather than 'add_thread_silent'. However,
remote_target::remote_add_thread includes additional
actions (i.e. calling remote_thread_info::set_resumed and set_running)
which are missing from extended_remote_target::attach. These missing
calls are what would serve to mark the new thread as resumed.
In this commit I propose that we add an extra parameter to
remote_target::remote_add_thread. This new parameter will force the
new thread to be added with a call to add_thread_silent. We can now
call remote_add_thread from the ::attach method, the extra
actions (listed above) will now be performed, and the thread will be
left in the correct state.
Additionally, in PR gdb/28405, a segfault is reported. This segfault
triggers when 'set debug remote 1' is used before trying to reproduce
the original assertion failure. The cause of this is in
remote_target::select_thread_for_ambiguous_stop_reply, where we do
this:
remote_debug_printf ("first resumed thread is %s",
pid_to_str (first_resumed_thread->ptid).c_str ());
remote_debug_printf ("is this guess ambiguous? = %d", ambiguous);
gdb_assert (first_resumed_thread != nullptr);
Notice that when debug printing is on we dereference
first_resumed_thread before we assert that the pointer is not
nullptr. This is the cause of the segfault, and is resolved by moving
the assert before the debug printing code.
I've extended an existing test, ext-attach.exp, so that the original
test is run multiple times; we run in the original mode, as normal,
but also, we now run with different packets disabled in gdbserver. In
particular, disabling Tthread would trigger the assertion as it was
reported in the original bug. I also run the test in all-stop and
non-stop modes now for extra coverage, we also run the tests with
target-async enabled, and disabled.
Andrew Burgess [Mon, 13 Dec 2021 16:56:16 +0000 (16:56 +0000)]
gdb: on x86-64 non-trivial C++ objects are returned in memory
Fixes PR gdb/28681. It was observed that after using the `finish`
command an incorrect value was displayed in some cases. Specifically,
this behaviour was observed on an x86-64 target.
Consider this test program:
struct A
{
int i;
A ()
{ this->i = 0; }
A (const A& a)
{ this->i = a.i; }
};
A
func (int i)
{
A a;
a.i = i;
return a;
}
int
main ()
{
A a = func (3);
return a.i;
}
And this GDB session:
$ gdb -q ex.x
Reading symbols from ex.x...
(gdb) b func
Breakpoint 1 at 0x401115: file ex.cc, line 14.
(gdb) r
Starting program: /home/andrew/tmp/ex.x
Breakpoint 1, func (i=3) at ex.cc:14
14 A a;
(gdb) finish
Run till exit from #0 func (i=3) at ex.cc:14
main () at ex.cc:23
23 return a.i;
Value returned is $1 = {
i = -19044
}
(gdb) p a
$2 = {
i = 3
}
(gdb)
Notice how after the `finish` the contents of $1 are junk, but, when I
immediately ask for the value of `a`, I get back the correct value.
The problem here is that after the finish command GDB calls the
function amd64_return_value to figure out where the return value can
be found (on x86-64 targets anyway).
This function makes the wrong choice for the struct A in our case, as
sizeof(A) <= 8, then amd64_return_value decides that A will be
returned in a register. GDB then reads the return value register an
interprets the contents as an instance of A.
Unfortunately, A is not trivially copyable (due to its copy
constructor), and the sys-v specification for argument and return
value passing, says that any non-trivial C++ object should have space
allocated for it by the caller, and the address of this space is
passed to the callee as a hidden first argument. The callee should
then return the address of this space as the return value.
And so, the register that GDB is treating as containing an instance of
A, actually contains the address of an instance of A (in this case on
the stack), this is why GDB shows the incorrect result.
The call stack within GDB for where we actually go wrong is this:
And it is in amd64_classify_aggregate that we should be classifying
the type as AMD64_MEMORY, instead of as AMD64_INTEGER as we currently
do (via a call to amd64_classify_aggregate_field).
At the top of amd64_classify_aggregate we already have this logic:
Which handles some easy cases where we know a struct will be placed
into memory, that is (a) the struct is more than 16-bytes in size,
or (b) the struct has any unaligned fields.
All we need then, is to add a check here to see if the struct is
trivially copyable. If it is not then we know the struct will be
passed in memory.
This solved the example from the bug, and my small example above. So
then I started adding some more extensive tests to the GDB testsuite,
and I ran into a problem. I hit this error:
Inside the unaligned field check we try to get the bit position of
each field. Unfortunately, in some cases the field location is not
FIELD_LOC_KIND_BITPOS, but is FIELD_LOC_KIND_DWARF_BLOCK.
An example that shows this bug is:
struct B
{
short j;
};
struct A : virtual public B
{
short i;
A ()
{ this->i = 0; }
A (const A& a)
{ this->i = a.i; }
};
A
func (int i)
{
A a;
a.i = i;
return a;
}
int
main ()
{
A a = func (3);
return a.i;
}
It is the virtual base class, B, that causes the problem. The base
class is represented, within GDB, as a field within A. However, the
location type for this field is a DWARF_BLOCK.
I spent a little time trying to figure out how to convert the
DWARF_BLOCK to a BITPOS, however, I realised that, in this case at
least, conversion is not needed.
The C++ standard says that a class is not trivially copyable if it has
any virtual base classes. And so, in this case, even if I could
figure out the BITPOS for the virtual base class fields, I know for
sure that I would immediately fail the trivially_copyable check. So,
lets just reorder the checks in amd64_classify_aggregate to:
I notice that we only catch the exception so we can call
set_executing, and this is the same call to set_executing that we need
to perform in the non-exception return path.
This would be much cleaner if we could use SCOPE_EXIT to avoid the
try/catch, so lets do that.
While cleaning this up, I also applied a similar patch to
record-full.c, though there's no try/catch in that case, but using
SCOPE_EXIT makes the code safe if, in the future, we do start throwing
exceptions.
There should be no user visible changes after this commit.
Andrew Burgess [Tue, 7 Dec 2021 10:43:38 +0000 (10:43 +0000)]
gdb/doc: add some index entries relating to mi-async setting
I noticed that the mi-async setting was not referenced from the index
in any way, this commit tries to rectify that a bit.
The @cindex lines I think are not controversial, these same index
entries are used elsewhere in the manual for async related topics (see
@node Background Execution).
The only bit that might be controversial is that I've added a @kindex
entry for 'set mi-async' when the command is documented as '-gdb-set
mi-async' (with a similar difference for the show/-gdb-show).
My reasoning here is that nothing else is indexed under -gdb-set or
-gdb-show, and as -gdb-set/-gdb-show are just the MI equivalent for
set/show anything that is documented under set/show can be adjusted
using -gdb-set/-gdbshow, and so, I've tried to keep the index
consistent for mi-async.
Andrew Burgess [Sat, 11 Dec 2021 10:35:36 +0000 (10:35 +0000)]
gdb: convert 'set debug lin-lwp' to a boolean command
Convert the 'set debug lin-lwp' command to a boolean. Adds a new
LINUX_NAT_SCOPED_DEBUG_ENTER_EXIT macro, and makes use of it in one
place (linux_nat_target::stop).
The manual entry for 'set debug lin-lwp' is already vague about
exactly what arguments this command takes, and the description talks
about turning debug on and off, so I don't think there's any updates
required there.
I have updated the doc strings shown when the users enters 'help show
debug lin-lwp' or 'help show debug lin-lwp'. The old title lines used
to talk about the 'GNU/Linux lwp module', but this debug flag is now
used for any native linux target debug, so we now talk about
'GNU/Linux native target'. The body string for this setting has been
changed from 'Enables printf debugging output.' to 'When on, print
debug messages relating to the GNU/Linux native target.', the old
value looks like a cut&paste error to me.
Andrew Burgess [Fri, 12 Nov 2021 10:30:27 +0000 (10:30 +0000)]
gdb: add threads debugging switch
Add new commands:
set debug threads on|off
show debug threads
Prints additional debug information relating to thread creation and
deletion.
GDB already announces when threads are created of course.... most of
the time, but sometimes threads are added silently, in which case this
debug message is the only mechanism to see the thread being added.
Also, though GDB does announce when a thread exits, it doesn't
announce when the thread object is deleted, I've added a debug message
for that.
Additionally, having message printed through the debug system will
cause the messages to be nested to an appropriate depth when other
debug sub-systems are turned on (especially things like `infrun` and
`lin-lwp`).
Simon Marchi [Tue, 21 Dec 2021 03:30:37 +0000 (22:30 -0500)]
gdbarch-components.py: change empty "params" tuples to empty lists
During review, it was suggested to change the "params" parameter from a
tuple to a list, for esthetic reasons. The empty ones are still tuples
though, they should probably be changed to be empty lists, for
consistency. It does not change anything in the script result.
Jan Beulich [Tue, 21 Dec 2021 08:31:04 +0000 (09:31 +0100)]
x86: -mfence-as-lock-add=yes doesn't work for 16-bit mode
Rather than trying to fix this (which would require making an assumption
on the upper half of %esp being zero), simply issue an error. While at
it, since the generated code is in conflict with -momit-lock-prefix=yes,
issue an error in that case as well.
Tom Tromey [Sat, 11 Dec 2021 21:57:17 +0000 (14:57 -0700)]
Remove print_spaces
This removes the print_spaces helper function, in favor of using the
"*%s" idiom that's already used in many places in gdb. One spot (in
symmisc.c) is changed to use print_spaces_filtered, because the rest
of that function is using filtered output. (This highlights one way
that the printf idiom is better -- this error is harder to make when
using that.)
Tom Tromey [Sat, 11 Dec 2021 22:10:14 +0000 (15:10 -0700)]
Make n_spaces return a const char *
n_spaces keeps the spaces in a static buffer. If a caller overwrites
these, it may give an incorrect result to a subsequent caller. So,
make the return type const to help avoid this outcome.