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This is useful information I missed while debugging issues with
the g packet reply.
Reviewed-By: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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On s390x-linux, I run into:
...
(gdb) backtrace
#0 0x000000000100061a in fun_three ()
#1 0x000000000100067a in fun_two ()
#2 0x000003fffdfa9470 in ?? ()
Backtrace stopped: frame did not save the PC
(gdb) FAIL: gdb.base/readnever.exp: backtrace
...
This is really due to a problem handling the fun_three frame. When generating
a backtrace from fun_two, everying looks ok:
...
$ gdb -readnever -q -batch outputs/gdb.base/readnever/readnever \
-ex "b fun_two" \
-ex run \
-ex bt
...
#0 0x0000000001000650 in fun_two ()
#1 0x00000000010006b6 in fun_one ()
#2 0x00000000010006ee in main ()
...
For reference the frame info with debug info (without -readnever) looks like this:
...
$ gdb -q -batch outputs/gdb.base/readnever/readnever \
-ex "b fun_three" \
-ex run \
-ex "info frame"
...
Stack level 0, frame at 0x3fffffff140:
pc = 0x1000632 in fun_three (readnever.c:20); saved pc = 0x100067a
called by frame at 0x3fffffff1f0
source language c.
Arglist at 0x3fffffff140, args: a=10, b=49 '1', c=0x3fffffff29c
Locals at 0x3fffffff140, Previous frame's sp in v0
...
But with -readnever, like this instead:
...
Stack level 0, frame at 0x0:
pc = 0x100061a in fun_three; saved pc = 0x100067a
called by frame at 0x3fffffff140
Arglist at 0xffffffffffffffff, args:
Locals at 0xffffffffffffffff, Previous frame's sp in r15
...
An obvious difference is the "Previous frame's sp in" v0 vs. r15.
Looking at the code:
...
0000000001000608 <fun_three>:
1000608: b3 c1 00 2b ldgr %f2,%r11
100060c: b3 c1 00 0f ldgr %f0,%r15
1000610: e3 f0 ff 50 ff 71 lay %r15,-176(%r15)
1000616: b9 04 00 bf lgr %r11,%r15
...
it becomes clear what is going on. This is an unusual prologue.
Rather than saving r11 (frame pointer) and r15 (stack pointer) to stack,
instead they're saved into call-clobbered floating point registers.
[ For reference, this is the prologue of fun_two:
...
0000000001000640 <fun_two>:
1000640: eb bf f0 58 00 24 stmg %r11,%r15,88(%r15)
1000646: e3 f0 ff 50 ff 71 lay %r15,-176(%r15)
100064c: b9 04 00 bf lgr %r11,%r15
...
where the first instruction stores registers r11 to r15 to stack. ]
Gdb fails to properly analyze the prologue, which causes the problems getting
the frame info.
Fix this by:
- adding handling of the ldgr insn [1] in s390_analyze_prologue, and
- recognizing the insn as saving a register in
s390_prologue_frame_unwind_cache.
This gets us instead:
...
Stack level 0, frame at 0x0:
pc = 0x100061a in fun_three; saved pc = 0x100067a
called by frame at 0x3fffffff1f0
Arglist at 0xffffffffffffffff, args:
Locals at 0xffffffffffffffff, Previous frame's sp in f0
...
and:
...
(gdb) backtrace^M
#0 0x000000000100061a in fun_three ()^M
#1 0x000000000100067a in fun_two ()^M
#2 0x00000000010006b6 in fun_one ()^M
#3 0x00000000010006ee in main ()^M
(gdb) PASS: gdb.base/readnever.exp: backtrace
...
Tested on s390x-linux.
PR tdep/32417
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32417
Approved-By: Andreas Arnez <arnez@linux.ibm.com>
[1] https://www.ibm.com/support/pages/sites/default/files/2021-05/SA22-7871-10.pdf
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In s390_prologue_frame_unwind_cache there are two loops using a hardcoded
constant 16:
...
for (i = 0; i < 16; i++)
if (s390_register_call_saved (gdbarch, S390_R0_REGNUM + i)
...
for (i = 0; i < 16; i++)
if (s390_register_call_saved (gdbarch, S390_F0_REGNUM + i)
...
Fix this by using symbolic constants S390_NUM_GPRS and S390_NUM_FPRS instead.
Tested on s390x-linux, by rebuilding.
Approved-By: Andreas Arnez <arnez@linux.ibm.com>
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ASAN_OPTIONS=verify_asan_link_order=0
After building gdb with asan, and running test-case
gdb.trace/basic-libipa.exp, I got:
...
(gdb) run ^M
Starting program: basic-libipa ^M
[Thread debugging using libthread_db enabled]^M
Using host libthread_db library "/lib64/libthread_db.so.1".^M
==7705==ASan runtime does not come first in initial library list; you should \
either link runtime to your application or manually preload it with \
LD_PRELOAD.^M
[Inferior 1 (process 7705) exited with code 01]^M
(gdb) FAIL: gdb.trace/basic-libipa.exp: runto: run to main
...
Fix this in the same way as in commit 75948417af8 ("[gdb/testsuite] Run two
test-cases with ASAN_OPTIONS=verify_asan_link_order=0").
Tested on x86_64-linux.
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Boolify the field. The 'set_stop_requested' function was already
taking a bool parameter, whose value is assigned to the field.
Approved-By: Andrew Burgess <aburgess@redhat.com>
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I happened to notice that the Ada compiler emitted a warning when
compiling a couple of DAP tests. This wasn't intentional, and this
patch renames the functions to match the filename.
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The regcache_register_size function has one implementation in GDB, and
one in gdbserver. Both of them have a gdb::checked_static_cast to their
corresponding regcache class. This can be avoided by defining a
pure virtual register_size method in the
reg_buffer_common class, which is then implemented by the reg_buffer
class in GDB, and by the regcache class in gdbserver.
Calls to the register_size () function from methods of classes in the
reg_buffer_common hierarchy need to be changed to calls to the newly
defined method, otherwise the compiler complains that a matching method
cannot be found.
Co-Authored-By: Simon Marchi <simon.marchi@efficios.com>
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Reviewed-By: Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>
Change-Id: I7f4f74a51e96c42604374e87321ca0e569bc07a3
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On a system with gcc 14.2.0 and gnatmake 13.3.0 I run into:
...
(gdb) PASS: gdb.ada/scalar_storage.exp: print V_LE
get_compiler_info: gcc-14-2-0
print V_BE^M
$2 = (value => 126, another_value => 12, color => red)^M
(gdb) FAIL: gdb.ada/scalar_storage.exp: print V_BE
...
The test-case contains a corresponding kfail:
...
# This requires a compiler fix that is in GCC 14.
if {[gcc_major_version] < 14} {
setup_kfail "DW_AT_endianity on enum types" *-*-*
}
...
which doesn't trigger because it checks the gcc version rather than the
gnatmake version.
Fix this by checking the gnatmake version instead.
Tested on aarch64-linux and x86_64-linux.
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I ran test-case gdb.base/gstack.exp on a machine with kernel.yama.ptrace_scope
set to 1 and ran into:
...
PASS: gdb.base/gstack.exp: spawn gstack
ptrace: Operation not permitted.^M
GSTACK-END^M
PASS: gdb.base/gstack.exp: gstack exits with no error
PASS: gdb.base/gstack.exp: gstack's exit status is 0
FAIL: gdb.base/gstack.exp: got backtrace
...
Fix this by requiring can_spawn_for_attach.
Tested on x86_64-linux.
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gdb.reverse/test_ioctl_TCSETSW.exp
I ran test-case gdb.reverse/test_ioctl_TCSETSW.exp on riscv64-linux, and got:
...
(gdb) record full^M
Process record: the current architecture doesn't support record function.^M
(gdb) FAIL: gdb.reverse/test_ioctl_TCSETSW.exp: record full
...
Fix this by requiring supports_process_record.
Tested on riscv64-linux and x86_64-linux.
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!supports_catch_syscall
I ran test-case gdb.base/reset-catchpoint-cond.exp on riscv64-linux, and got:
...
(gdb) catch syscall write^M
The feature 'catch syscall' is not supported on this architecture yet.^M
(gdb) FAIL: $exp: mode=syscall: catch syscall write
...
Fix this by checking for supports_catch_syscall.
Tested on riscv64-linux and x86_64-linux.
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This renames two maint commands, removing a hyphen from
"check-symtabs" and "check-psymtabs"; that is, moving them under the
existing "maint check" prefix.
Regression tested on x86-64 Fedora 40.
Reviewed-By: Tom de Vries <tdevries@suse.de>
Approved-By: Andrew Burgess <aburgess@redhat.com>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
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Iain pointed out a crash in the DWARF indexer when run on a certain D
program. The DWARF in this case has a nameless enum class; this
causes an assertion failure.
This patch arranges to simply ignore such types. The fact that an
enum class is nameless in this case appears to be a compiler bug.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32518
Approved-By: Tom de Vries <tdevries@suse.de>
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Since commit "gdbserver: allow the --debug command line option to take a
value", gdbserver no longer supports
--debug
--remote-debug
--event-loop-debug.
Instead, --debug now takes a comma separated list of components.
The make check parameter GDBSERVER_DEBUG doesn't support these changes
yet. This patch fixes this, by adding the --debug gdbserver arguments,
as "debug-threads", "debug-remote", "debug-event-loop" or "debug-all" for
GDBSERVER_DEBUG. Replay logging is still enabled by adding the
"replay" GDBSERVER_DEBUG argument. We can also configure "all" to
enable all of the available options.
Now, for instance, we can use it as follows:
make check GDBSERVER_DEBUG="debug-remote,debug-event-loop,replay" RUNTESTFLAGS="--target_board=native-gdbserver" TESTS="gdb.trace/ftrace.exp"
or simply
make check GDBSERVER_DEBUG="all" RUNTESTFLAGS="--target_board=native-gdbserver" TESTS="gdb.trace/ftrace.exp"
to enable all debug options.
Approved-By: Tom Tromey <tom@tromey.com>
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A user was confused by the meaning of signal numbers in the gdb CLI.
For instance, when using "signal 3", exactly which signal is
delivered? Is it always 3, or is it always SIGQUIT?
This patch attempts to clarify the documentation here.
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PR cli/32525 reports that a variable with this DWARF:
..
<2><423>: Abbrev Number: 14 (DW_TAG_variable)
<424> DW_AT_name : var1867
<42a> DW_AT_type : <0x2f8>
<42e> DW_AT_const_value : 8 byte block: 0 0 0 0 0 0 0 0
...
is not shown by info locals.
Fix this by handling LOC_CONST_BYTES in iterate_over_block_locals.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32525
Approved-By: Tom Tromey <tom@tromey.com>
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procfs.c compilation is currently broken on Solaris:
/vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/procfs.c: In member function ‘virtual ptid_t procfs_target::wait(ptid_t, target_waitstatus*, target_wait_flags)’:
/vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/procfs.c:2067:34: error: ‘wait’ is not a member of ‘gdb’; did you mean ‘wait’?
2067 | wait_retval = gdb::wait (&wstat);
| ^~~~
In file included from ../gnulib/import/sys/wait.h:28,
from /usr/include/stdlib.h:16,
from /usr/gcc/14/include/c++/14.2.0/cstdlib:79,
from /vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/../gdbsupport/common-defs.h:99,
from /vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/defs.h:26,
from <command-line>:
/usr/include/sys/wait.h:85:14: note: ‘wait’ declared here
85 | extern pid_t wait(int *);
| ^~~~
/vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/procfs.c:2154:41: error: ‘wait’ is not a member of ‘gdb’; did you mean ‘wait’?
2154 | int temp = gdb::wait (&wstat);
| ^~~~
/usr/include/sys/wait.h:85:14: note: ‘wait’ declared here
85 | extern pid_t wait(int *);
| ^~~~
/vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/procfs.c: In function ‘void unconditionally_kill_inferior(procinfo*)’:
/vol/src/gnu/gdb/hg/gdb-16-branch/git/gdb/procfs.c:2566:12: error: ‘wait’ is not a member of ‘gdb’; did you mean ‘wait’?
2566 | gdb::wait (NULL);
| ^~~~
/usr/include/sys/wait.h:85:14: note: ‘wait’ declared here
85 | extern pid_t wait(int *);
| ^~~~
The use of gdb::wait was introduced in
commit 4e4dfc4728622d83c5d600949024449e21de868a
Author: Tom de Vries <tdevries@suse.de>
Date: Fri Nov 22 17:44:29 2024 +0100
[gdb] Add gdb::wait
but obviously never tested.
Fixed by including gdbsupport/eintr.h to provide the declaration.
Tested on amd64-pc-solaris2.11 and sparcv9-sun-solaris2.11.
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The DAP initialize request has a "linesStartAt1" option, where the
client can indicate that it prefers whether line numbers be 0-based or
1-based.
This patch implements this. I audited all the line-related code in
the DAP implementation.
Note that while a similar option exists for column numbers, gdb
doesn't handle these yet, so nothing is done here.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32468
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Consider this Rust tuple:
let tuple_tuple = ((23i32, 24i32), 25i32);
Here, the value is a tuple whose first element is also a tuple.
You should be able to print this with:
(gdb) print tuple_tuple.0.1
However, currently the Rust lexer sees "0.1" as a floating-point
number.
This patch fixes the problem by introducing a special case in the
lexer: when parsing a field expression, the parser informs the lexer
that a number should be handled as a decimal integer only.
This change then lets us remove the decimal integer special case from
lex_number.
v2: I realized that the other DECIMAL_INTEGER cases aren't needed any
more.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32472
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This removes the "then" keyword from the test suite. Andrew did this
once before, but some new ones crept in.
This also adds braces to the "if" conditions and normalizes the
failures to just use "return".
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Recent commit 6ab5d62ebc5 ("[gdb] Fix compilation error in event-top.c") did:
...
fd_copy (fd_set *dst, const fd_set *src, int n)
{
FD_ZERO (dst);
for (int i = 0; i < n; ++i)
- if (FD_ISSET (i, src))
+ if (FD_ISSET (i, (fd_set *)src))
...
but according to [1] only const_cast may be used to cast away constness.
Fix this by using const_cast.
Tested by rebuilding on x86_64-linux.
[1] https://en.cppreference.com/w/cpp/language/const_cast
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This applies some more cleanups to add_symbol_overload_list_qualified,
consolidating calls to get_selected_block.
It also moves the symtab expansion call after the code that walks up
from the selected block, merging two loops.
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The code in dwarf2/read.c:new_symbol that handles Ada 'import' symbols
has a bug. It uses the current scope, which by default this is the
file scope -- even for a global symbol like:
<1><1186>: Abbrev Number: 4 (DW_TAG_variable)
<1187> DW_AT_name : (indirect string, offset: 0x1ad2): pkg__imported_var_ada
...
<1196> DW_AT_external : 1
This disagrees with the scope computed by the DWARF indexer.
Now, IMO new_symbol and its various weirdness really has to go. And,
ideally, this information would come from the indexer rather than
perhaps being erroneously recomputed. But meanwhile, this patch fixes
the issue at hand.
This came up while working on another change that exposes the bug.
Reviewed-By: Tom de Vries <tdevries@suse.de>
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A recent discussion about what commands are allowed during
gdb.Breakpoint.stop, made me wonder if there would be less restrictions if
we'd do those commands as part of a breakpoint command list instead.
Attribute gdb.Breakpoint.commands is a string with gdb commands, so I
tried implementing a new class PyCommandsBreakpoint, derived from
gdb.Breakpoint, that supports a py_commands method.
My original idea was to forbid setting PyCommandsBreakpoint.commands, and do:
...
def py_commands(self):
print("VAR: %d" % self.var)
self.var += 1
gdb.execute("continue")
...
but as it turns out 'gdb.execute("continue")' does not behave the same way as
continue. I've filed PR python/32454 about this.
So the unsatisfactory solution is to first execute
PyCommandsBreakpoint.py_commands:
...
def py_commands(self):
print("VAR: %d" % self.var)
self.var += 1
...
and then:
...
self.commands = "continue"
...
I was hoping for a better outcome, but having done the work of writing this, I
suppose it has use as a test-case, perhaps also as an example of how to work
around PR python/32454.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32454
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On s390x-linux, with test-case gdb.base/finish-pretty.exp I ran into:
...
(gdb) finish
Run till exit from #0 foo () at finish-pretty.c:28
main () at finish-pretty.c:40
40 return v.a + v.b;
Value returned has type: struct s. Cannot determine contents
(gdb) FAIL: $exp: finish foo prettyprinted function result
...
The function being finished is foo, which returns a value of type struct s.
The ABI [1] specifies:
- that the value is returned in a storage buffer allocated by the caller, and
- that the address of this buffer is passed as a hidden argument in r2.
GDB fails to print the value when finishing foo, because it doesn't know the
address of the buffer.
Implement the gdbarch_get_return_buf_addr hook for s390x to fix this.
This is based on ppc_sysv_get_return_buf_addr, the only other implementation
of gdbarch_get_return_buf_addr. For readability I've factored out
dwarf_reg_on_entry.
There is one difference with ppc_sysv_get_return_buf_addr: only
NO_ENTRY_VALUE_ERROR is caught. If this patch is approved, I intend to submit
a follow-up patch to fix this in ppc_sysv_get_return_buf_addr as well.
The hook is not guaranteed to work, because it attempts to get the value r2
had at function entry.
The hook can be called after function entry, and the ABI doesn't guarantee
that r2 is the same throughout the function.
Using -fvar-tracking adds debug information, which allows the hook to succeed
more often, and indeed after adding this to the test-case, it passes.
Do likewise in one more test-case.
Tested on s390x-linux.
Fixes:
- gdb.ada/finish-large.exp
- gdb.base/finish-pretty.exp
- gdb.base/retval-large-struct.exp
- gdb.cp/non-trivial-retval.exp
- gdb.ada/array_return.exp
AFAICT, I've also enabled the hook for s390 and from the ABI I get the
impression that it should work, but I haven't been able to test it.
[1] https://github.com/IBM/s390x-abi
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Running selftest help_doc_invariants.
help doc broken invariant: command 'signal-event' help doc has over-long line
Self test failed: self-test failed at unittests/command-def-selftests.c:121
The reason is that doc string of 'signal-event' doesn't have
newlines at end of its line. Fix by adding newlines.
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CXX event-top.o
In file included from d:\usr\include\winsock2.h:69,
from ./../gdbsupport/gdb_select.h:30,
from event-top.c:43:
event-top.c: In function 'fd_set* fd_copy(fd_set*, const fd_set*, int)':
event-top.c:1279:22: error: invalid conversion from 'const fd_set*' to 'fd_set*' [-fpermissive]
1279 | if (FD_ISSET (i, src))
| ^
| |
| const fd_set*
d:\usr\include\winsock.h:164:50: note: initializing argument 2 of 'int __FD_ISSET(SOCKET, fd_set*)'
164 | __CRT_ALIAS int __FD_ISSET( SOCKET __fd, fd_set *__set )
| ~~~~~~~~^~~~~
Use an explicit type cast to prevent this.
* gdb/event-top.c (fd_copy): Type-cast in call to FD_ISSET.
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The Linaro CI reported a regression on arm-linux in test-case
gdb.base/sigstep.exp following commit 7b46460a619 ("[gdb/symtab] Apply
workaround for PR gas/31115 a bit more") [1]:
...
(gdb) return^M
Make __default_sa_restorer return now? (y or n) n^M
Not confirmed^M
(gdb) FAIL: $exp: return from handleri: \
leave signal trampoline (got interactive prompt)
...
After installing package glibc-debuginfo and adding --with-separate-debug-dir
to the configure flags, I managed to reproduce the FAIL.
The regression seems to be a progression in the sense that the function name
for the signal trampoline is found.
After reading up on the signal trampoline [2] and the return command [3], my
understanding is that forced returning from the signal trampoline is
potentially unsafe, given that for instance the process signal mask won't be
restored.
Fix this by:
- rather than using the name, using "signal trampoline" in the query, and
- adding a warning about returning from a signal trampoline,
giving us:
...
(gdb) return^M
warning: Returning from signal trampoline does not fully restore pre-signal \
state, such as process signal mask.^M
Make signal trampoline return now? (y or n) y^M
87 dummy = 0; dummy = 0; while (!done);^M
(gdb) PASS: $exp: return from handleri: leave signal trampoline (in main)
...
Tested on x86_64-linux.
Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
[1] https://linaro.atlassian.net/browse/GNU-1459
[2] https://man7.org/linux/man-pages/man2/sigreturn.2.html
[3] https://sourceware.org/gdb/current/onlinedocs/gdb.html/Returning.html
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I ran make-check-all.sh with gdb.linespec/explicit.exp, and the only problems
were found with target board stabs.
With target board unix the test-case runs in two seconds, but with target
board stabs it takes 12 seconds due to a timeout.
Stabs support in gdb has been unmaintained for a while, and there's an ongoing
discussion to deprecate and remove it (PR symtab/31210).
It seems unnecessary to excercise this unmaintained feature in
make-check-all.sh, so drop it.
Tested on x86_64-linux.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31210
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fnmatch is called with the FNM_FILE_NAME flag so that `skip -gfi /usr/*`
doesn't match /usr/include/*. This makes the file matching feature not
useful for STL headers that reside in multiple directories. In
addition, the user cannot use a single `*` to match multiple leading
path components.
Let's drop the FNM_FILE_NAME flag and remove the assertion from
gdb_filename_fnmatch (originally for the auto-load feature).
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This changes gdbpy_lookup_static_symbols to pass the 'flags' parameter
to expand_symtabs_matching. This should refine the search somewhat.
Note this is "just" a performance improvement, as the loop over
symtabs already checks 'flags'.
v2 also removes 'SEARCH_GLOBAL_BLOCK' and updates py-symbol.exp to
verify that this works properly. Thanks to Tom for this insight.
Co-Authored-By: Tom de Vries <tdevries@suse.de>
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This commit a new section for the next release branch, and renames
the section of the current branch, now that it has been cut.
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Now that the GDB 16 branch has been created,
this commit bumps the version number in gdb/version.in to
17.0.50.DATE-git
For the record, the GDB 16 branch was created
from commit ee29a3c4ac7adc928ae6ed1fed3b59c940a519a4.
Also, as a result of the version bump, the following changes
have been made in gdb/testsuite:
* gdb.base/default.exp: Change $_gdb_major to 17.
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There are two tests that fail in gdb.base/startup-with-shell.exp when
using the native-extended-remote board. I plan to fix these issues,
and I've posted a series that does just that:
https://inbox.sourceware.org/gdb-patches/cover.1730731085.git.aburgess@redhat.com
But until that series is reviewed, I thought I'd merge this commit,
which marks the FAIL as XFAIL and links them to the relevant bug
number.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28392
Tested-By: Guinevere Larsen <guinevere@redhat.com>
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This commit implements the gdbarch_core_parse_exec_context method for
FreeBSD.
This is much simpler than for Linux. On FreeBSD, at least the
version (13.x) that I have installer, there are additional entries in
the auxv vector that point directly to the argument and environment
vectors, this makes it trivial to find this information.
If these extra auxv entries are not available on earlier FreeBSD, then
that's fine. The fallback behaviour will be for GDB to act as it
always has up to this point, you'll just not get the extra
functionality.
Other differences compared to Linux are that FreeBSD has
AT_FREEBSD_EXECPATH instead of AT_EXECFN, the AT_FREEBSD_EXECPATH is
the full path to the executable. On Linux AT_EXECFN is the command
the user typed, so this can be a relative path.
This difference is handy as on FreeBSD we don't parse the mapped files
from the core file (are they even available?). So having the EXECPATH
means we can use that as the absolute path to the executable.
However, if the user ran a symlink then AT_FREEBSD_EXECPATH will be
the absolute path to the symlink, not to the underlying file. This is
probably a good thing, but it does mean there is one case we test on
Linux that fails on FreeBSD.
On Linux if we create a symlink to an executable, then run the symlink
and generate a corefile. Now delete the symlink and load the core
file. On Linux GDB will still find (and open) the original
executable. This is because we use the mapped file information to
find the absolute path to the executable, and the mapped file
information only stores the real file names, not symlink names.
This is a total edge case, I only added the deleted symlink test
originally because I could see that this would work on Linux. Though
it is neat that Linux finds this, I don't feel too bad that this fails
on FreeBSD.
Other than this, everything seems to work on x86-64 FreeBSD (13.4)
which is all I have setup right now. I don't see why other
architectures wouldn't work too, but I haven't tested them.
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GDB already has a limited mechanism for auto-loading the executable
corresponding to a core file, this can be found in the function
locate_exec_from_corefile_build_id in corelow.c.
However, this approach uses the build-id of the core file to look in
either the debug directory (for a symlink back to the executable) or
by asking debuginfod. This is great, and works fine if the core file
is a "system" binary, but often, when I'm debugging a core file, it's
part of my development cycle, so there's no build-id symlink in the
debug directory, and debuginfod doesn't know about the binary either,
so GDB can't auto load the executable....
... but the executable is right there!
This commit builds on the earlier commits in this series to make GDB
smarter.
On GNU/Linux, when we parse the execution context from the core
file (see linux-tdep.c), we already grab the command pointed to by
AT_EXECFN. If this is an absolute path then GDB can use this to
locate the executable, a build-id check ensures we've found the
correct file. With this small change GDB suddenly becomes a lot
better at auto-loading the executable for a core file.
But we can do better! Often the AT_EXECFN is not an absolute path.
If it is a relative path then we check for this path relative to the
core file. This helps if a user does something like:
$ ./build/bin/some_prog
Aborted (core dumped)
$ gdb -c corefile
In this case the core file in the current directory will have an
AT_EXECFN value of './build/bin/some_prog', so if we look for that
path relative to the location of the core file this might result in a
hit, again, a build-id check ensures we found the right file.
But we can do better still! What if the user moves the core file? Or
the user is using some tool to manage core files (e.g. the systemd
core file management tool), and the user downloads the core file to a
location from which the relative path no longer works?
Well in this case we can make use of the core file's mapped file
information (the NT_FILE note). The executable will be included in
the mapped file list, and the path within the mapped file list will be
an absolute path. We can search for mapped file information based on
an address within the mapped file, and the auxv vector happens to
include an AT_ENTRY value, which is the entry address in the main
executable. If we look up the mapped file containing this address
we'll have the absolute path to the main executable, a build-id check
ensures this really is the file we're looking for.
It might be tempting to jump straight to the third approach, however,
there is one small downside to the third approach: if the executable
is a symlink then the AT_EXECFN string will be the name of the
symlink, that is, the thing the user asked to run. The mapped file
entry will be the name of the actual file, i.e. the symlink target.
When we auto-load the executable based on the third approach, the file
loaded might have a different name to that which the user expects,
though the build-id check (almost) guarantees that we've loaded the
correct binary.
But there's one more thing we can check for!
If the user has placed the core file and the executable into a
directory together, for example, as might happen with a bug report,
then neither the absolute path check, nor the relative patch check
will find the executable. So GDB will also look for a file with the
right name in the same directory as the core file. Again, a build-id
check is performed to ensure we find the correct file.
Of course, it's still possible that GDB is unable to find the
executable using any of these approaches. In this case, nothing
changes, GDB will check in the debug info directory for a build-id
based link back to the executable, and if that fails, GDB will ask
debuginfod for the executable. If this all fails, then, as usual, the
user is able to load the correct executable with the 'file' command,
but hopefully, this should be needed far less from now on.
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We have a few tests that load core files, which depend on GDB not
auto-loading the executable that matches the core file. One of these
tests (corefile-buildid.exp) exercises GDB's ability to load the
executable via the build-id links in the debug directory, while the
other two tests are just written assuming that GDB hasn't auto-loaded
the executable.
In the next commit, GDB is going to get better at finding the
executable for a core file, and as a consequence these tests could
start to fail if the testsuite is being run using a compiler that adds
build-ids by default, and is on a target (currently only Linux) with
the improved executable auto-loading.
To avoid these test failures, this commit updates some of the tests.
coredump-filter.exp and corefile.exp are updated to unload the
executable should it be auto-loaded. This means that the following
output from GDB will match the expected patterns. If the executable
wasn't auto-loaded then the new step to unload is harmless.
The corefile-buildid.exp test needed some more significant changes.
For this test it is important that the executable be moved aside so
that GDB can't locate it, but we do still need the executable around
somewhere, so that the debug directory can link to it. The point of
the test is that the executable _should_ be auto-loaded, but using the
debug directory, not using GDB's context parsing logic.
While looking at this test I noticed two additional problems, first we
were creating the core file more times than we needed. We only need
to create one core file for each test binary (total two), while we
previously created one core file for each style of debug info
directory (total four). The extra core files should be identical, and
were just overwriting each other, harmless, but still pointless work.
The other problem is that after running an earlier test we modified
the test binary in order to run a later test. This means it's not
possible to manually re-run the first test as the binary for that test
is destroyed.
As part of the rewrite in this commit I've addressed these issues.
This test does change many of the test names, but there should be no
real changes in what is being tested after this commit. However, when
the next commit is added, and GDB gets better at auto-loading the
executable for a core file, these tests should still be testing what
is expected.
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Extend the core file context parsing mechanism added in the previous
commit to also store the environment parsed from the core file.
This environment can then be injected into the inferior object.
The benefit of this is that when examining a core file in GDB, the
'show environment' command will now show the environment extracted
from a core file.
Consider this example:
$ env -i GDB_TEST_VAR=FOO ./gen-core
Segmentation fault (core dumped)
$ gdb -c ./core.1669829
...
[New LWP 1669829]
Core was generated by `./gen-core'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000000000401111 in ?? ()
(gdb) show environment
GDB_TEST_VAR=foo
(gdb)
There's a new test for this functionality.
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Add a new gdbarch method which can read the execution context from a
core file. An execution context, for this commit, means the filename
of the executable used to generate the core file and the arguments
passed to the executable.
In later commits this will be extended further to include the
environment in which the executable was run, but this commit is
already pretty big, so I've split that part out into a later commit.
Initially this new gdbarch method is only implemented for Linux
targets, but a later commit will add FreeBSD support too.
Currently when GDB opens a core file, GDB reports the command and
arguments used to generate the core file. For example:
(gdb) core-file ./core.521524
[New LWP 521524]
Core was generated by `./gen-core abc def'.
However, this information comes from the psinfo structure in the core
file, and this struct only allows 80 characters for the command and
arguments combined. If the command and arguments exceed this then
they are truncated.
Additionally, neither the executable nor the arguments are quoted in
the psinfo structure, so if, for example, the executable was named
'aaa bbb' (i.e. contains white space) and was run with the arguments
'ccc' and 'ddd', then when this core file was opened by GDB we'd see:
(gdb) core-file ./core.521524
[New LWP 521524]
Core was generated by `./aaa bbb ccc ddd'.
It is impossible to know if 'bbb' is part of the executable filename,
or another argument.
However, the kernel places the executable command onto the user stack,
this is pointed to by the AT_EXECFN entry in the auxv vector.
Additionally, the inferior arguments are all available on the user
stack. The new gdbarch method added in this commit extracts this
information from the user stack and allows GDB to access it.
The information on the stack is writable by the user, so a user
application can start up, edit the arguments, override the AT_EXECFN
string, and then dump core. In this case GDB will report incorrect
information, however, it is worth noting that the psinfo structure is
also filled (by the kernel) by just copying information from the user
stack, so, if the user edits the on stack arguments, the values
reported in psinfo will change, so the new approach is no worse than
what we currently have.
The benefit of this approach is that GDB gets to report the full
executable name and all the arguments without the 80 character limit,
and GDB is aware which parts are the executable name, and which parts
are arguments, so we can, for example, style the executable name.
Another benefit is that, now we know all the arguments, we can poke
these into the inferior object. This means that after loading a core
file a user can 'show args' to see the arguments used. A user could
even transition from core file debugging to live inferior debugging
using, e.g. 'run', and GDB would restart the inferior with the correct
arguments.
Now the downside: finding the AT_EXECFN string is easy, the auxv entry
points directly too it. However, finding the arguments is a little
trickier. There's currently no easy way to get a direct pointer to
the arguments. Instead, I've got a heuristic which I believe should
find the arguments in most cases. The algorithm is laid out in
linux-tdep.c, I'll not repeat it here, but it's basically a search of
the user stack, starting from AT_EXECFN.
If the new heuristic fails then GDB just falls back to the old
approach, asking bfd to read the psinfo structure for us, which gives
the old 80 character limited answer.
For testing, I've run this series on (all GNU/Linux) x86-64. s390,
ppc64le, and the new test passes in each case. I've done some very
basic testing on ARM which does things a little different than the
other architectures mentioned, see ARM specific notes in
linux_corefile_parse_exec_context_1 for details.
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This fixes PR 31331:
https://sourceware.org/bugzilla/show_bug.cgi?id=31331
Currently, enum-flags.h is suppressing the warning
-Wenum-constexpr-conversion coming from recent versions of Clang.
This warning is intended to be made a compiler error
(non-downgradeable) in future versions of Clang:
https://github.com/llvm/llvm-project/issues/59036
The rationale is that casting a value of an integral type into an
enumeration is Undefined Behavior if the value does not fit in the
range of values of the enum:
https://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1766
Undefined Behavior is not allowed in constant expressions, leading to
an ill-formed program.
In this case, in enum-flags.h, we are casting the value -1 to an enum
of a positive range only, which is UB as per the Standard and thus not
allowed in a constexpr context.
The purpose of doing this instead of using std::underlying_type is
because, for C-style enums, std::underlying_type typically returns
"unsigned int". However, when operating with it arithmetically, the
enum is promoted to *signed* int, which is what we want to avoid.
This patch solves this issue as follows:
* Use std::underlying_type and remove the custom enum_underlying_type.
* Ensure that operator~ is called always on an unsigned integer. We do
this by casting the input enum into std::size_t, which can fit any
unsigned integer. We have the guarantee that the cast is safe,
because we have checked that the underlying type is unsigned. If the
enum had negative values, the underlying type would be signed.
This solves the issue with C-style enums, but also solves a hidden
issue: enums with underlying type of std::uint8_t or std::uint16_t are
*also* promoted to signed int. Now they are all explicitly casted
to the largest unsigned int type and operator~ is safe to use.
* There is one more thing that needs fix. Currently, operator~ is
implemented as follows:
return (enum_type) ~underlying(e);
After applying ~underlying(e), the result is a very large value,
which we then cast to "enum_type". This cast is Undefined Behavior
if the large value does not fit in the range of the enum. For
C++ enums (scoped and/or with explicit underlying type), the range
of the enum is the entire range of the underlying type, so the cast
is safe. However, for C-style enums, the range is the smallest
bit-field that can hold all the values of the enumeration. So the
range is a lot smaller and casting a large value to the enum would
invoke Undefined Behavior.
To solve this problem, we create a new trait
EnumHasFixedUnderlyingType, to ensure operator~ may only be called
on C++-style enums. This behavior is roughly the same as what we
had on trunk, but relying on different properties of the enums.
* Once this is implemented, the following tests fail to compile:
CHECK_VALID (true, int, true ? EF () : EF2 ())
This is because it expects the enums to be promoted to signed int,
instead of unsigned int (which is the true underlying type).
I propose to remove these tests altogether, because:
- The comment nearby say they are not very important.
- Comparing 2 enums of different type like that is strange, relies
on integer promotions and thus hurts readability. As per comments
in the related PR, we likely don't want this type of code in gdb
code anyway, so there's no point in testing it.
- Most importantly, this type of comparison will be ill-formed in
C++26 for regular enums, so enum_flags does not need to emulate
that.
Since this is the only place where the warning was suppressed, remove
also the corresponding macro in include/diagnostics.h.
The change has been tested by running the entire gdb test suite
(make check) and comparing the results (testsuite/gdb.sum) against
trunk. No noticeable differences have been observed.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31331
Tested-by: Keith Seitz <keiths@redhat.com>
Approved-By: Tom Tromey <tom@tromey.com>
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Compilation will fail with -Werror=vla, which seems to be the default.
Note that we don't need to allocate num_threads + 1 since the matching
algorithm works only on the num_threads as returned by task_threads.
Change-Id: I276928d0ff3c52c7c7fe4edb857e5789cdabfcf7
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This commit adds support for a `gstack' command which Fedora has
been carrying for many years. gstack is a natural counterpart to
the gcore command. Whereas gcore dumps a core file, gstack prints
stack traces of a running process.
There are many improvements over Fedora's version of this script.
The dependency on procfs is gone; gstack will run anywhere gdb
runs. The only runtime dependencies are bash and awk.
The script includes suggestions from gdb/32325 to include
versioning and help. [If this approach to gdb/32325 is acceptable,
I could propagate the solution to gcore/gdb-add-index.]
I've rewritten the documentation, integrating it into the User Manual.
The manpage is now output using this one source.
Example run (on x86_64 Fedora 40)
$ gstack --help
Usage: gstack [-h|--help] [-v|--version] PID
Print a stack trace of a running program
-h, --help Print this message then exit.
-v, --version Print version information then exit.
$ gstack -v
GNU gstack (GDB) 16.0.50.20241119-git
$ gstack 12345678
Process 12345678 not found.
$ gstack $(pidof emacs)
Thread 6 (Thread 0x7fd5ec1c06c0 (LWP 2491423) "pool-spawner"):
#0 0x00007fd6015ca3dd in syscall () at /lib64/libc.so.6
#1 0x00007fd60b31eccd in g_cond_wait () at /lib64/libglib-2.0.so.0
#2 0x00007fd60b28a61b in g_async_queue_pop_intern_unlocked () at /lib64/libglib-2.0.so.0
#3 0x00007fd60b2f1a03 in g_thread_pool_spawn_thread () at /lib64/libglib-2.0.so.0
#4 0x00007fd60b2f0813 in g_thread_proxy () at /lib64/libglib-2.0.so.0
#5 0x00007fd6015486d7 in start_thread () at /lib64/libc.so.6
#6 0x00007fd6015cc60c in clone3 () at /lib64/libc.so.6
#7 0x0000000000000000 in ??? ()
Thread 5 (Thread 0x7fd5eb9bf6c0 (LWP 2491424) "gmain"):
#0 0x00007fd6015be87d in poll () at /lib64/libc.so.6
#1 0x0000000000000001 in ??? ()
#2 0xffffffff00000001 in ??? ()
#3 0x0000000000000001 in ??? ()
#4 0x000000002104cfd0 in ??? ()
#5 0x00007fd5eb9be320 in ??? ()
#6 0x00007fd60b321c34 in g_main_context_iterate_unlocked.isra () at /lib64/libglib-2.0.so.0
Thread 4 (Thread 0x7fd5eb1be6c0 (LWP 2491425) "gdbus"):
#0 0x00007fd6015be87d in poll () at /lib64/libc.so.6
#1 0x0000000020f9b558 in ??? ()
#2 0xffffffff00000003 in ??? ()
#3 0x0000000000000003 in ??? ()
#4 0x00007fd5d8000b90 in ??? ()
#5 0x00007fd5eb1bd320 in ??? ()
#6 0x00007fd60b321c34 in g_main_context_iterate_unlocked.isra () at /lib64/libglib-2.0.so.0
Thread 3 (Thread 0x7fd5ea9bd6c0 (LWP 2491426) "emacs"):
#0 0x00007fd6015ca3dd in syscall () at /lib64/libc.so.6
#1 0x00007fd60b31eccd in g_cond_wait () at /lib64/libglib-2.0.so.0
#2 0x00007fd60b28a61b in g_async_queue_pop_intern_unlocked () at /lib64/libglib-2.0.so.0
#3 0x00007fd60b28a67c in g_async_queue_pop () at /lib64/libglib-2.0.so.0
#4 0x00007fd603f4d0d9 in fc_thread_func () at /lib64/libpangoft2-1.0.so.0
#5 0x00007fd60b2f0813 in g_thread_proxy () at /lib64/libglib-2.0.so.0
#6 0x00007fd6015486d7 in start_thread () at /lib64/libc.so.6
#7 0x00007fd6015cc60c in clone3 () at /lib64/libc.so.6
#8 0x0000000000000000 in ??? ()
Thread 2 (Thread 0x7fd5e9e6d6c0 (LWP 2491427) "dconf worker"):
#0 0x00007fd6015be87d in poll () at /lib64/libc.so.6
#1 0x0000000000000001 in ??? ()
#2 0xffffffff00000001 in ??? ()
#3 0x0000000000000001 in ??? ()
#4 0x00007fd5cc000b90 in ??? ()
#5 0x00007fd5e9e6c320 in ??? ()
#6 0x00007fd60b321c34 in g_main_context_iterate_unlocked.isra () at /lib64/libglib-2.0.so.0
Thread 1 (Thread 0x7fd5fcc45280 (LWP 2491417) "emacs"):
#0 0x00007fd6015c9197 in pselect () at /lib64/libc.so.6
#1 0x0000000000000000 in ??? ()
Since this is essentially a complete rewrite of the original
script and documentation, I've chosen to only keep a 2024 copyright date.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Tom Tromey <tom@tromey.com>
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This patch is a few minor cleanups to rust-lang.c: renaming a
badly-named local variable, moving a couple of declarations into 'for'
headers, and using 'bool' in one spot.
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Consider operate-and-get-next [1] in bash:
...
$ <echo 1>echo 1<enter>
1
$ <echo 2>echo 2<enter>
2
$ <Ctrl-r>(reverse-i-search)`': <echo 1>echo 1<Ctrl-o>
1
$ echo 2<Ctrl-o>
2
$ echo 1
...
So, typing Ctrl-o:
- executes the recalled command, and
- prefills the next one (which then can be executed again with Ctrl-o).
We have the same functionality in gdb, but when recalling the last command
from history with bash we have no prefill:
...
$ <echo 1>echo 1<enter>
1
$ <Ctrl-r>(reverse-i-search)`': <echo 1>echo 1<Ctrl-o>
1
$
...
but with gdb do we have a prefill:
...
(gdb) echo 1\n
1
(gdb) <Ctrl-r>(reverse-i-search)`': <echo 1>echo 1\n<Ctrl-o>
1
(gdb) echo 1\n
...
Following the principle of least surprise [2], I think gdb should do what bash
does.
Fix this by:
- signalling this case in gdb_rl_operate_and_get_next using
"operate_saved_history = -1", and
- handling operate_saved_history == -1 in
gdb_rl_operate_and_get_next_completion.
Tested on aarch64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
PR cli/32485
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32485
[1] https://www.man7.org/linux/man-pages/man3/readline.3.html
[2] https://en.wikipedia.org/wiki/Principle_of_least_astonishment
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This changes one spot in ada-lang.c to use block::is_static_block
rather than a hand-rolled implementation. Note this also fixes the
call -- what is currently written there is wrong.
Approved-By: Tom de Vries <tdevries@suse.de>
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gdbpy_lookup_static_symbols is missing an error check for the case
where symbol_to_symbol_object returns NULL.
Approved-By: Tom de Vries <tdevries@suse.de>
|
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On openSUSE Leap 15.6 ppc64le-linux, with gdb.linespec/explicit.exp I run
into:
...
(gdb) b -source thread_pointer.h FAIL: $exp: complete after -source: tab complete "b -source thr"
Quit^M
...
The test-case already contains a related workaround:
...
# Get rid of symbols from shared libraries, otherwise
# "b -source thr<tab>" could find some system library's
# source.
gdb_test_no_output "nosharedlibrary"
...
but that doesn't work in this case because the debug info is in the executable
itself:
...
The File Name Table (offset 0xb5):
Entry Dir Time Size Name
1 0 0 0 abi-note.c
2 1 0 0 types.h
3 2 0 0 stdint-intn.h
4 2 0 0 stdint-uintn.h
5 3 0 0 elf.h
6 4 0 0 thread_pointer.h
...
due to debug info in some glibc object file.
Fix this by:
- using -nostdlib, ensuring only debug info from the three test-case sources
is present in the executable, and
- adding a _start wrapping main.
Tested on x86_64-linux and ppc64le-linux.
Reviewed-By: Keith Seitz <keiths@redhat.com>
PR testsuite/31229
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31229
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Introduce an RSP packet, 'x', for reading from the remote server
memory in binary format. The binary write packet, 'X' already exists.
The 'x' packet is essentially the same as 'm', except that the
returned data is in binary format. For transferring relatively large
data from the memory of the remote process, the 'x' packet can reduce the
transfer costs.
For example, without this patch, fetching ~100MB of data from a remote
target takes
(gdb) dump binary memory temp.o 0x00007f3ba4c576c0 0x00007f3bab709400
2024-03-13 16:17:42.626 - command started
2024-03-13 16:18:24.151 - command finished
Command execution time: 32.136785 (cpu), 41.525515 (wall)
(gdb)
whereas with this patch, we obtain
(gdb) dump binary memory temp.o 0x00007fec39fce6c0 0x00007fec40a80400
2024-03-13 16:20:48.609 - command started
2024-03-13 16:21:16.873 - command finished
Command execution time: 20.447970 (cpu), 28.264202 (wall)
(gdb)
We see improvements not only when reading bulk data as above, but also
when making a large number of small memory access requests.
For example, without this patch:
(gdb) pipe x/100000xw $pc | wc -l
2024-03-13 16:04:57.112 - command started
25000
2024-03-13 16:05:10.798 - command finished
Command execution time: 9.952364 (cpu), 13.686581 (wall)
With this patch:
(gdb) pipe x/100000xw $pc | wc -l
2024-03-13 16:06:48.160 - command started
25000
2024-03-13 16:06:57.750 - command finished
Command execution time: 6.541425 (cpu), 9.589839 (wall)
(gdb)
Another example, where we create a core file of a GDB process.
(gdb) gcore /tmp/core.1
...
Command execution time: 85.496967 (cpu), 133.224373 (wall)
vs.
(gdb) gcore /tmp/core.1
...
Command execution time: 48.328885 (cpu), 115.032289 (wall)
Regression-tested on X86-64 using the unix (default) and
native-extended-gdbserver board files.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Tom Tromey <tom@tromey.com>
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Revise a sentence to avoid misinterpretation. Move @cindex entries
before the text they index. Refer to trace frames regarding partial
reads.
Approved-By: Eli Zaretskii <eliz@gnu.org>
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The current gdb-add-index manual page is a bit out-of-date. This
commit fixes a few deficiencies:
- gdb-add-index does not use objdump; it uses objcopy and readelf
- missing info on environment variables (in appropriate ENVIRONMENT section).
- missing mention of -dwarf-5 option
- adds important notice about FILENAME being writable
- explains exit status
- the script adds appropriate section(s) to the file; it does not
output new files with the section(s)
Approved-By: Eli Zaretskii <eliz@gnu.org>
|
