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Based on IRC feedback since commit 6a0da68c036a85a46415aa0dada2421eee7c2269
gdb: add convenience variables around linker namespace debugging
This commit changes the type of the _current_linker_namespace variable
to be a simple integer. This makes it easier to use for expressions,
like breakpoint conditions or printing from a specific namespace once
that is supported, at the cost of making namespace IDs slightly less
consistent.
This is based on PR solib/32960, where no negative feedback was given
for the suggestion.
The commit also changes the usage of "linkage namespaces" to "linker
namespaces" in the NEWS file, to reduce chance of confusion from an end
user.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32960
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Tom Tromey <tom@tromey.com>
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With test-case gdb.base/bp-permanent.exp and gcc 15 I run into:
...
gdb compile failed, bp-permanent.c: In function 'test_signal_nested':
bp-permanent.c:118:20: error: passing argument 2 of 'signal' from \
incompatible pointer type [-Wincompatible-pointer-types]
118 | signal (SIGALRM, test_signal_nested_handler);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
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| void (*)(void)
In file included from bp-permanent.c:20:
/usr/include/signal.h:88:57: note: expected '__sighandler_t' \
{aka 'void (*)(int)'} but argument is of type 'void (*)(void)'
...
Fix this by adding an int parameter to test_signal_nested_handler.
Tested on x86_64-linux.
PR testsuite/32756
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32756
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We don't use any GNU-specific printf args, but this prevents warnings about
%z, observed on MinGW even though every libc anyone is likely to use there
supports %z perfectly well, and we're not stopping using it just because
MinGW complains. Doing this means we stand more chance of seeing *actual*
problems on such platforms without them being drowned in noise.
We turn this off on clang, which doesn't support __gnu_printf__.
Suggested by Eli Zaretskii.
libctf/
PR libctf/31863
* ctf-impl.h (_libctf_printflike_): Use __gnu_printf__.
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In normal deduplicating links, we insert every type (identified by its
unique hash) precisely once. But conflicting types appear in multiple
dicts, so for those, we loop, inserting them into every target dict
in turn (each corresponding to an input dict that type appears in).
But in cu-mapped links, some of those dicts may have been merged into
one: now that we are hiding duplicate conflicting types more
aggressively in such links, we are getting duplicate identical hidden
types turning up in large numbers.
Fix this by eliminating them in cu-mapping phase 1 (the phase in which this
merging takes place), by checking to see if a type with this hash has
already been inserted in this dict and skipping it if so. This is
redundant and a waste of time in other cu-mapping phases and in normal
links, but in cu-mapped links it saves a few tens to hundreds of kilobytes
in kernel-sized links.
libctf/
PR libctf/33047
* ctf-dedup.c (ctf_dedup_emit_type): Check for already-emitted
types in cu-mapping phase 1.
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The previous commits dropped preservation of the non-root flag in ctf_link
and arranged to use it somewhat differently to track conflicting types in
cu-mapped CUs when doing cu-mapped links. This was necessary to prevent
entirely spuriously hidden types from appearing on the output of such links.
Bring it (and the test for it) back. The problem with the previous design
was that it implicitly assumed that the non-root flag it saw on the input
was always meant to be preserved (when in the final phase of cu-mapped links
it merely means that conflicting types were found in intermediate links),
and also that it could figure out what the non-root flag on the input was by
sucking in the non-root flag of the input type corresponding to an output in
the output mapping (which maps type hashes to a corresponding type on some
input).
This method of getting properties of the input type *does* work *if* that
property was one of those hashed by the ctf_dedup_hash_type process. In
that case, every type with a given hash will have the same value for all
hashed-in properties, so it doesn't matter which one is consulted (the
output mapping points at an arbitrary one of those input types). But the
non-root flag is explicitly *not* hashed in: as a comment in
ctf_dedup_rhash_type notes, being non-root is not a property of a type, and
two types (one non-root, one not) can perfectly well be the same type even
though one is visible and one isn't. So just copying the non-root flag from
the output mapping's idea of the input type will copy in a value that is not
stabilized by the hash, so is more-or-less random!
So we cannot do that. We have to do something else, which means we have to
decide what to do if two identical types with different nonroot flag values
pop up. The most sensible thing to do is probably to say that if all
instances of a type are non-root-visible, the linked output should also be
non-root-visible: any root-visible types in that set, and the output type is
root-visible again.
We implement this with a new cd_nonroot_consistency dynhash, which maps type
hashes to the value 0 ("all instances root-visible"), 1 ("all instances
non-root-visible") or 2 ("inconsistent"). After hashing is over, we save a
bit of memory by deleting everything from this hashtab that doesn't have a
value of 1 ("non-root-visible"), then use this to decide whether to emit any
given type as non-root-visible or not.
However... that's not quite enough. In cu-mapped links, we want to
disregard this whole thing because we just hide everything -- but in phase
2, when we take the smushed-together CUs resulting from phase 1 and
deduplicate them against each other, we want to do what the previous commits
implemented and ignore the non-root flag entirely, instead falling back to
preventing clashes by hiding anything that would be considered conflicting.
We extend the existing cu_mapped parameter to various bits of ctf_dedup so
that it is now tristate: 0 means a normal link, 1 means the smush-it-
together phase of cu-mapped links, and 2 means the final phase of cu-mapped
links. We do the hide-conflicting stuff only in phase 2, meaning that
normal links by GNU ld can always respect the value of the nonroot flag put
on types in the input.
(One extra thing added as part of this: you can now efficiently delete the
last value returned by ctf_dynhash_next() by calling
ctf_dynhash_next_remove.)
We bring back the ctf-nonroot-linking test with one tweak: linking now works
on mingw as long as you're using the ucrt libc, so re-enable it for better
test coverage on that platform.
libctf/
PR libctf/33047
* ctf-hash.c (ctf_dynhash_next_remove): New.
* ctf-impl.h (struct ctf_dedup) [cd_nonroot_consistency]: New.
* ctf-link.c (ctf_link_deduplicating): Differentiate between
cu-mapped and non-cu-mapped links, even in the final phase.
* ctf-dedup.c (ctf_dedup_hash_type): Callback prototype addition.
Get the non-root flag and pass it down.
(ctf_dedup_rhash_type): Callback prototype addition. Document
restrictions on use of the nonroot flag.
(ctf_dedup_populate_mappings): Populate cd_nonroot_consistency.
(ctf_dedup_hash_type_fini): New function: delete now-unnecessary
values from cd_nonroot_consistency.
(ctf_dedup_init): Initialize it.
(ctf_dedup_fini): Destroy it.
(ctf_dedup): cu_mapping is now cu_mapping_phase. Call
ctf_dedup_hash_type_fini.
(ctf_dedup_emit_type): Use cu_mapping_phase and
cd_nonroot_consistency to propagate the non-root flag into outputs
for normal links, and to do name-based conflict checking only for
phase 2 of cu-mapped links.
(ctf_dedup_emit): cu_mapping is now cu_mapping_phase. Adjust
assertion accordingly.
* testsuite/libctf-writable/ctf-nonroot-linking.c: Bring back.
* testsuite/libctf-writable/ctf-nonroot-linking.lk: Likewise.
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If types are conflicting, they are usually moved into separate child dicts
-- but not always. If they are added to the same dict by the cu-mapping
mechanism (as used e.g. for multi-TU kernel modules), we can easily end
up adding multiple conflicting types with the same name to the same dict.
The mechanism used for turning on the non-root-visible flag in order to do
this had a kludge attached which always hid types with the same name,
whether or not they were conflicting. This is unnecessary and can hide
types that should not be hidden, as well as hiding bugs. Remove it, and
replace it with two different approaches:
- for everything but cu-mapped links (the in-memory first phase of a link
with ctf_link_add_cu_mapping in force), check for duplicate names if
types are conflicting, and mark them as hidden if the names are found.
This will never happen in normal links (in an upcoming commit we will
suppress doing even this much in such cases).
- for cu-mapped links, the only case that merges multiple distinct target
dicts into one, we apply a big hammer and simply hide everything! The
non-root flag will be ignored in the next link phase anyway (which dedups
the cu-mapped pieces against each other), and this way we can be sure
that merging multiple types cannot incur name clashes at this stage.
The result seems to work: the only annoyance is that when enums with
conflicting enumerators are found in a single cu-mapped child (so, really
multiple merged children), you may end up with every instance of that enum
being hidden for reasons of conflictingness. I don't see a real way to
avoid that.
libctf/
PR libctf/33047
* ctf-dedup.c (ctf_dedup_emit_type): Only consider non
conflicting types. Improve type hiding in the presence of clashing
enumerators. Hide everything when doing a cu-mapped link: they will
be unhidden by the next link pass if nonconflicting.
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This reverts commit 87b2f673102884d7c69144c85a26ed5dbaa4f86a.
It is based on a misconception, that hidden types in the deduplicator
input should always be hidden in the output. For cu-mapped links,
and final links following cu-mapped links, this is not true: we want
to hide inputs if they were conflicting on the output and no more.
We will reintroduce the testcase once a better fix is found.
libctf/
PR libctf/33047
* ctf-dedup.c (ctf_dedup_emit_type): Don't respect the nonroot flag.
* testsuite/libctf-writable/ctf-nonroot-linking.c: Removed.
* testsuite/libctf-writable/ctf-nonroot-linking.lk: Removed.
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A commit I recently pushed:
commit 0b5023cc71d3af8b18e10e6599a3f9381bc15265
Date: Sat Apr 12 09:15:53 2025 +0100
gdb/python/guile: user created prefix commands get help list
can trigger a segfault if a user tries to create nested prefix
commands. For example, this will trigger a crash:
(gdb) python gdb.ParameterPrefix("prefix-1", gdb.COMMAND_NONE)
(gdb) python gdb.ParameterPrefix("prefix-1 prefix-2", gdb.COMMAND_NONE)
Fatal signal: Segmentation fault
... etc ...
If the user adds an actual parameter under 'prefix-1' before creating
'prefix-2', then everything is fine:
(gdb) python gdb.ParameterPrefix("prefix-1", gdb.COMMAND_NONE)
(gdb) python gdb.Parameter('prefix-1 param-1', gdb.COMMAND_NONE, gdb.PARAM_BOOLEAN)
(gdb) python gdb.ParameterPrefix("prefix-1 prefix-2", gdb.COMMAND_NONE)
The mistake in the above patch is in how gdbpy_parse_command_name is
used. The BASE_LIST output argument from this function points to the
list of commands for the prefix, not to the prefix command itself.
So when gdbpy_parse_command_name is called for 'prefix-1 prefix-2',
BASE_LIST points to the list of commands associated with 'prefix-1',
not to the actual 'prefix-1' cmd_list_element.
Back in cmdpy_init, from where gdbpy_parse_command_name was called, I
was walking back from the first entry in BASE_LIST to figure out if
this was a "show" prefix command or not. However, if BASE_LIST is
empty then there is no first item, and this would trigger the
segfault.
The solution it to extend gdbpy_parse_command_name to also return the
prefix cmd_list_element in addition to the existing values. With this
done, and cmdpy_init updated, the segfault is now avoided.
There's a new test that would trigger the crash without the patch.
And, of course, the above commit also broke guile in the exact same
way. And the fix is exactly the same. And there's a guile test too.
NOTE: We should investigate possibly sharing some of this boiler plate
helper code between Python and Guile. But not in this commit.
Approved-By: Tom Tromey <tom@tromey.com>
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Since commit d462550c91c ("gdb/testsuite: also compile foll-exec.exp as C++"),
we run into:
...
Running gdb.base/exec-invalid-sysroot.exp ...
gdb compile failed, foll-exec.c: In function 'main':
foll-exec.c:35:52: error: 'EXECD_PROG' undeclared (first use in this function)
printf ("foll-exec is about to execlp(%s)...\n", EXECD_PROG);
^~~~~~~~~~
foll-exec.c:35:52: note: each undeclared identifier is reported only once \
for each function it appears in
...
Fix this by default-defining EXECD_PROG to "execd-prog".
Tested on x86_64-linux.
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According to the zlib FAQ (*1), zlib does not support compressed data
larger than 4 GiB when the compiler's long type is 32 bits. Therefore,
we need to report an error if a zlib-compressed debug section exceeds
4 GiB on LLP64 machines.
(*1) https://zlib.net/zlib_faq.html#faq32
Signed-off-by: Rui Ueyama <rui314@gmail.com>
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Fix PR libsframe/Bug 33051 - ASAN: heap-buffer-overflow
../../src/libsframe/sframe.c:1054 in
sframe_get_funcdesc_with_addr_internal
The previous commit 9d2a24349e2 (libsframe: correct binary search for
SFrame FDE) adapted the binary search logic in
sframe_get_funcdesc_with_addr_internal. Adjusting the upper end of the
search index was missed.
The search must only be done for FDEs starting at index 0 and up until
num_fdes - 1. Prior logic of searching (before commit 9d2a24349e2) was
a bit different.
libsframe/
* sframe.c: Use the correct high index.
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For a long time, Fedora GDB has carried a test that performs some
basic testing that GDB can handle 'catch exec' related commands for a
C++ executable.
The exact motivation for this test has been lost in the mists of time,
but looking at the test script, the concern seems to be that GDB would
have problems inserting C++ related internal breakpoints if a non C++
process is execd from a C++ one.
There's no actual GDB fix associated with the Fedora test. This
usually means that the issue was fixed upstream long ago. This patch
does seem to date from around 2010ish (or maybe earlier).
Having a look through the upstream tests, I cannot see anything that
covers this sort of thing (C++ to C exec calls), and I figure it
cannot hurt to have some additional testing in this area, and so I
wrote this patch.
I've taken the existing foll-exec.exp test, which compiles a C
executable and then execs a different C executable, and split it into
two copies.
We now have foll-exec-c.exp and foll-exec-c++.exp. These tests
compile a C and C++ executable respectively. Then within each of
these scripts both a C and C++ helper application is built, which can
then be execd from the main test executable.
And so, we now cover 4 cases, the initial executable can be C or C++,
and the execd process can be C or C++.
As expected, everything passes. This is just increasing test
coverage.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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This commit allows a user to enable or disable dwarf support at
compilation time. To do that, a new configure option is introduced, in
the form of --enable-gdb-dwarf-support (and the accompanying --disable
version). By default, dwarf support is enabled, so no behavior changes
occur if a user doesn't use the new feature. If support is disabled, no
.c files inside the dwarf2/ subfolder will be compiled into the final
binary.
To achieve this, this commit also introduces the new macro
DWARF_FORMAT_AVAILABLE, which guards the definitions of functions
exported from the dwarf reader. If the macro is not defined, there are a
couple behaviors that exported functions may have:
* no-ops: several functions are used to register things at
initialization time, like unwinders. These are turned into no-ops
because the user hasn't attempted to read DWARF yet, there's no point
in warning that DWARF is unavailable.
* warnings: similar to the previous commit, if dwarf would be read or
used, the funciton will emit the warning "No dwarf support available."
* throw exceptions: If the code that calls a function expects an
exceptin in case of errors, and has a try-catch block, an error with
the previous message is thrown.
I believe that the changed functions should probalby be moved to the
dwarf2/public.h header, but that require a much larger refactor, so it
is left as a future improvement.
Finally, the --enable-gdb-compile configure option has been slightly
changed, since compile requires dwarf support. If compile was requested
and dwarf was disabled, configure will throw an error. If the option was
not used, support will follow what was requested for dwarf (warning the
user of what is decided).
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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This commit aims to allow a user to enable or disable mdebug support at
compilation time. To do that, a new configure option is added, called
--enable-gdb-mdebug-support (and the accompanying --disable version). By
default, support is enabled, and if a user decides to disable support,
the file mdebugread.c won't be compiled in the final binary, and the
macro MDEBUG_FORMAT_AVAILABLE won't be defined.
That macro is used to control the definitions of mdebug reading, either
the actual definition in mdebugread.c, or a static inline version that
only emits the following warning:
> No mdebug support available.
Ideally, we'd like to guard the entirity of mdebugread in the macro, but
the alpha-mdebug-tdep file uses those directly, and I don't think we
should restrict alpha hosts to requiring that debug format compiled in,
nor do I understand the tdep file enough to be comfortable disentangling
the requirements.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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Currently, mipscoff_symfile_read uses a single minimal_symbol_reader to
get all minimal symbols from mdebug-formatted debuginfo, and from
alphacoff. This pattern has been around since minimal_symbol_reader has
been introduced, and from own research, there's no need to use the same
reader. This made it so mipscoff_symfile_read could call
mdebug_build_psymtabs directly, since the latter needs a reference to
the minsym reader object. The issue is that future commits need a
unified entrance point to read debuginfo, and this pattern is very
different to how elf does mdebug reading.
In fact, the elf mdebug reader does some preparatory steps and then
calls mdebug_build_psymtabs, so what the mips version does is just
spread these preparatory steps through the mipscoff function instead.
To make it easier for future commits to query debuginfo support
dynamically (as opposed to assuming things at compile time), this commit
introduces a new mipsmdebug_build_psymtabs function, which does similar
preparatory steps as elfmdebug_build_psymtabs. It is added to
mdebugread.c to help with maintaining a separation between reading an
objfile (in mipsread.c) and its debuginfo (mdebug), so that in the
future we have an easier time selectively disabling debuginfo formats
at compilation time. This should have no visible changes for the end
user.
The new function must receive the pointers to ecoff_debug_swap and
ecoff_debug_info because finding those structures based on the bfd
object necessitates including the headers libcoff.h and libecoff.h,
and those headers can't be included at the same time as libaout.h
- which mdebugread.c already uses.
Approved-By: Tom Tromey <tom@tromey.com>
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PR 33019
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Consider GDB's builtin prefix set/show prefix sub-commands, if they
are invoked with no sub-command name then they work like this:
(gdb) show print
print address: Printing of addresses is on.
print array: Pretty formatting of arrays is off.
print array-indexes: Printing of array indexes is off.
print asm-demangle: Demangling of C++/ObjC names in disassembly listings is off.
... cut lots of lines ...
(gdb) set print
List of set print subcommands:
set print address -- Set printing of addresses.
set print array -- Set pretty formatting of arrays.
set print array-indexes -- Set printing of array indexes.
set print asm-demangle -- Set demangling of C++/ObjC names in disassembly listings.
... cut lots of lines ...
Type "help set print" followed by set print subcommand name for full documentation.
Type "apropos word" to search for commands related to "word".
Type "apropos -v word" for full documentation of commands related to "word".
Command name abbreviations are allowed if unambiguous.
(gdb)
That is 'show print' lists the values of all settings under the
'print' prefix, and 'set print' lists the help text for all settings
under the 'set print' prefix.
Now, if we try to create something similar using the Python API:
(gdb) python gdb.ParameterPrefix("my-prefix", gdb.COMMAND_NONE)
(gdb) python gdb.Parameter("my-prefix foo", gdb.COMMAND_OBSCURE, gdb.PARAM_BOOLEAN)
(gdb) show my-prefix
(gdb) set my-prefix
Neither 'show my-prefix' or 'set my-prefix' gives us the same details
relating to the sub-commands that we get with the builtin prefix
commands.
This commit aims to address this.
Currently, in cmdpy_init, when a new command is created, we always set
the commands callback function to cmdpy_function. It is within
cmdpy_function that we spot that the command is a prefix command, and
that there is no gdb.Command.invoke method, and so return early.
This commit changes things so that the rules are now:
1. For NON prefix commands, we continue to use cmdpy_function.
2. For prefix commands that do have a gdb.Command.invoke
method (i.e. can handle unknown sub-commands), continue to use
cmdpy_function.
3. For all other prefix commands, don't use cmdpy_function, instead
use GDB's normal callback function for set/show prefixes.
This requires splitting the current call to add_prefix_cmd into either
a call to add_prefix_cmd, add_show_prefix_cmd, or
add_basic_prefix_cmd, as appropriate.
After these changes, we now see this:
(gdb) python gdb.ParameterPrefix("my-prefix", gdb.COMMAND_NONE) │
(gdb) python gdb.Parameter("my-prefix foo", gdb.COMMAND_OBSCURE, gdb.PARAM_BOOLEAN)
(gdb) show my-prefix │
my-prefix foo: The current value of 'my-prefix foo' is "off".
(gdb) set my-prefix
List of "set my-prefix" subcommands:
set my-prefix foo -- Set the current value of 'my-prefix foo'.
Type "help set my-prefix" followed by subcommand name for full documentation.
Type "apropos word" to search for commands related to "word".
Type "apropos -v word" for full documentation of commands related to "word".
Command name abbreviations are allowed if unambiguous.
(gdb)
Which matches how a prefix defined within GDB would act.
I have made the same changes to the Guile API.
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This removes a trailing backslash from a comment in
dw2-ranges-psym-warning.exp. This backslash causes Emacs to try to
reindent the next line. This happens because comments are weird in
Tcl -- they are not exactly syntactic and the backslash still acts as
a line-continuation marker here.
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libsframe/doc/
* sframe-spec.texi: Include date with each publication.
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In Ada, a field can have a dynamic bit offset in its enclosing record.
In DWARF 3, this was handled using a dynamic
DW_AT_data_member_location, combined with a DW_AT_bit_offset -- this
combination worked out ok because in practice GNAT only needs a
dynamic byte offset with a fixed offset within the byte.
However, this approach was deprecated in DWARF 4 and then removed in
DWARF 5. No replacement approach was given, meaning that in strict
mode there is no way to express this.
This is a DWARF bug, see
https://dwarfstd.org/issues/250501.1.html
In a discussion on the DWARF mailing list, a couple people mentioned
that compilers could use the obvious extension of a dynamic
DW_AT_data_bit_offset. I've implemented this for LLVM:
https://github.com/llvm/llvm-project/pull/141106
In preparation for that landing, this patch implements support for
this construct in gdb.
New in v2: renamed some constants and added a helper method, per
Simon's review.
New in v3: more renamings.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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It is possible, when creating a shared memory segment (i.e. with
shmget), that the id of the segment will be zero.
When looking at the segment in /proc/PID/smaps, the inode field of the
entry holds the shared memory segment id.
And so, it can be the case that an entry (in the smaps file) will have
an inode of zero.
When GDB generates a core file, with the generate-core-file (or its
gcore alias) command, the shared memory segment should be written into
the core file.
Fedora GDB has, since 2008, carried a patch that tests this case.
There is no fix for GDB associated with the test, and unfortunately,
the motivation for the test has been lost to the mists of time. This
likely means that a fix was merged upstream without a suitable test,
but I've not been able to find and relevant commit. The test seems to
be checking that the shared memory segment with id zero, is being
written to the core file.
While looking at this test and trying to work out if it should be
posted upstream, I saw that GDB does appear to write the shared memory
segment into the core file (as expected), which is good. However, GDB
still isn't getting this case exactly right, there appears to be no
NT_FILE entry for the shared memory mapping if the mapping had an id
of zero.
In gcore_memory_sections (gcore.c) we call back into linux-tdep.c (via
the gdbarch_find_memory_regions call) to correctly write the shared
memory segment into the core file, however, in
linux_make_mappings_corefile_notes, when we use
linux_find_memory_regions_full to create the NT_FILE note, we call
back in to dump_note_entry_p for each mapping, and in here we reject
any mapping with a zero inode.
The result of this, is that, for a shared memory segment with a
non-zero id, after loading the core file, the shared memory segment
will appear in the 'proc info mappings' output. But, for a shared
memory segment with a zero id, the segment will not appear in the
'proc info mappings' output.
I initially tried just dropping the inode check in this function (see
previous commit 1e21c846c27, which I then reverted in commit
998165ba99a.
The problem with dropping the inode check is that the special kernel
mappings, e.g. '[vvar]' would now get a NT_FILE entry. In fact, any
special entry except '[vdso]' and '[vsyscall]' which are specifically
checked for in dump_note_entry_p would get a NT_FILE entry, which is
not correct.
So, instead, I propose that if the inode is zero, and the filename
starts with '[' and finished with ']' then we should not create a
NT_FILE entry. But otherwise a zero inode should not prevent a
NT_FILE entry being created.
The test for this change is a bit tricky. The original Fedora
test (mentioned above) has a loop that tries to grab the shared memory
mapping with id zero. This was, unfortunately, not very reliable.
I tried to make this more reliable by going multi-threaded, and
waiting for longer, see my proposal here:
https://inbox.sourceware.org/gdb-patches/0d389b435cbb0924335adbc9eba6cf30b4a2c4ee.1741776651.git.aburgess@redhat.com
But this was still not great. On further testing this was only
passing (i.e. managing to find the shared memory mapping with id zero)
about 60% of the time.
However, I realised that GDB finds the shared memory id by reading the
/proc/PID/smaps file. But we don't really _need_ the shared memory id
for anything, we just use the value (as an inode) to decide if the
segment should be included in the core file or not. The id isn't even
written to the core file. So, if we could intercept the read of the
smaps file, then maybe, we could lie to GDB, and tell it that the id
was zero, and then see how GDB handles this.
And luckily, we can do that using a preload library!
We already have a test that uses a preload library to modify GDB, see
gdb.threads/attach-slow-waitpid.exp.
So, I have created a new preload library. This one intercepts open,
open64, close, read, and pread. When GDB attempts to open
/proc/PID/smaps, the library spots this and loads the file contents
into a memory buffer. The buffer is then modified to change the id of
any shared memory mapping to zero. Any reads from this file are
served from the modified memory buffer.
I tested on x86-64, AArch64, PPC, s390, and ARM, all running various
versions of GNU/Linux. The requirement for open64() came from my ARM
testing. The other targets used plain open().
And so, the test is now simple. Start GDB with the preload library in
place, start the inferior and generate a core file. Then restart GDB,
load the core file, and check the shared memory mapping was included.
This test will fail with an unpatched GDB, and succeed with the patch
applied.
Tested-By: Guinevere Larsen <guinevere@redhat.com>
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Suppose a function returns a struct and a method of that struct is
called. E.g.:
struct S
{
int a;
int get () { return a; }
};
S f ()
{
S s;
s.a = 42;
return s;
}
...
int z = f().get();
...
GDB is able to evaluate the expression:
(gdb) print f().get()
$1 = 42
However, type-checking the expression fails:
(gdb) ptype f().get()
Attempt to take address of value not located in memory.
This happens because the `get` function takes an implicit `this`
pointer, which in this case is the value returned by `f()`, and GDB
wants to get an address for that value, as if passing the implicit
this pointer. However, during type-checking, the struct value
returned by `f()` is a `not_lval`.
A similar issue exists for union types, where methods called on
temporary union objects would fail type-checking in the same way.
Address the problems by handling `TYPE_CODE_STRUCT` and
`TYPE_CODE_UNION` in `evaluate_subexp_for_address_base`.
With this change, for struct's method call, we get
(gdb) ptype f().get()
type = int
Add new test cases to file gdb.cp/chained-calls.exp to test this change.
Regression-tested in X86-64 Linux.
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Remove the unused 'struct expression *exp' parameter from
evaluate_subexp_for_address_base and also do some format cleanup.
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With test-case gdb.base/maint.exp, I ran into:
...
(gdb) file maint^M
Reading symbols from maint...^M
(gdb) mt set per-command on^M
(gdb) Time for "DWARF indexing worker": ...^M
Time for "DWARF indexing worker": ...^M
Time for "DWARF indexing worker": ...^M
Time for "DWARF indexing worker": ...^M
Time for "DWARF skeletonless type units": ...^M
Time for "DWARF add parent map": ...^M
Time for "DWARF finalize worker": ...^M
Time for "DWARF finalize worker": ...^M
Time for "DWARF finalize worker": ...^M
Time for "DWARF finalize worker": ...^M
Time for "DWARF finalize worker": ...^M
FAIL: $exp: warnings: per-command: mt set per-command on (timeout)
mt set per-command off^M
2025-05-31 09:33:44.711 - command started^M
(gdb) PASS: $exp: warnings: per-command: mt set per-command off
...
I didn't manage to reproduce this by rerunning the test-case, but it's fairly
easy to reproduce using a file with more debug info, for instance gdb:
...
$ gdb -q -batch -ex "file build/gdb/gdb" -ex "mt set per-command on"
...
Due to the default "mt dwarf synchronous" == off, the file command starts
building the cooked index in the background, and returns immediately without
waiting for the result.
The subsequent "mt set per-command on" implies "mt set per-command time on",
which switches on displaying of per-command execution time.
The "Time for" lines are the result of those two commands, but these lines
shouldn't be there because "mt per-command time" == off at the point of
issuing the file command.
Fix this by capturing the per_command_time variable, and using the captured
value instead.
Tested on x86_64-linux.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
PR cli/33039
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33039
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This comment refers to the field location kind enum, even though call
sites were moved to their own enum in 7eb21cc70224 ("Change
call_site_target to use custom type and enum"). Update it.
Change-Id: I089923170c919853efb2946529221a4b55e720c1
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With the quoted filename completion work that I did last year the
deprecated_filename_completer function will now only complete a single
word as a filename, for example:
(gdb) save breakpoints /tm<TAB>
The 'save breakpoints' command uses the deprecated_filename_completer
completion function. In the above '/tm' will complete to '/tmp/' as
expected. However, if you try this:
(gdb) save breakpoints /tmp/ /tm<TAB>
The second '/tm' will not complete for GDB 16.x, but will complete
with GDB 15.x as GDB 15.x is before my changes were merged.
What's actually happening here is that, before my changes, the
filename completion was breaking words on white space, so in the above
the first '/tmp/' and the second '/tm' are seen as separate words for
completion, the second word is therefore seen as the start of a new
filename.
After my changes, deprecated_filename_completer allows spaces to be
part of the filename, so in the above, GDB is actually trying to
complete a filename '/tmp/ /tm' which likely doesn't exist, and so
completion stops.
This change for how deprecated_filename_completer works makes sense,
commands like 'save breakpoints' take their complete command arguments
and treat it as a single filename, so given this:
(gdb) save breakpoints /tmp/ /tm<ENTER>
GDB really will try to save breakpoints to a file called '/tmp/ /tm',
weird as that may seem. How GDB interprets the command arguments
didn't change with my completion patches, I simply brought completion
into line with how GDB interprets the arguments.
The patches I'm talking about here are this set:
* 4076f962e8c gdb: split apart two different types of filename completion
* dc22ab49e9b gdb: deprecated filename_completer and associated functions
* 35036875913 gdb: improve escaping when completing filenames
* 1d1df753977 gdb: move display of completion results into completion_result class
* bbbfe4af4fb gdb: simplify completion_result::print_matches
* 2bebc9ee270 gdb: add match formatter mechanism for 'complete' command output
* f2f866c6ca8 gdb: apply escaping to filenames in 'complete' results
* 8f87fcb1daf gdb: improve gdb_rl_find_completion_word for quoted words
* 67b8e30af90 gdb: implement readline rl_directory_rewrite_hook callback
* 1be3b2e82f7 gdb: extend completion of quoted filenames to work in brkchars phase
* 9dedc2ac713 gdb: fix for completing a second filename for a command
* 4339a3ffc39 gdb: fix filename completion in the middle of a line
Bug PR gdb/32982 identifies a problem with the shell command;
completion broke between 15.x and 16.x. The shell command also uses
deprecated_filename_completer for completion. But consider a shell
command line:
(gdb) shell ls /tm<TAB>
The arguments to the shell command are 'ls /tm' at the point <TAB> is
pressed. Under the old 15.x completion GDB would split the words on
white space and then try to complete '/tm' as a filename.
Under the 16.x model, GDB completes all the arguments as a single
filename, that is 'ls /tm', which is unlikely to match any filenames,
and so completion fails.
The fix is to write a custom completion function for the shell_command
function (cli/cli-cmds.c), this custom completion function will skip
forward to find the last word in the arguments, and then try to
complete that, so in the above example, GDB will skip over 'ls ', and
then tries to complete '/tm', which is exactly what we want.
Given that the filenames passed to the shell command are forwarded to
an actual shell, I have switched over the new quoted filename
completion function for the shell command, this means that white space
within a filename will be escaped with a backslash by the completion
function, which is likely what the user wants, this means the filename
will arrive in the (actual) shell as a single word, rather than
splitting on white space and arriving as two words.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32982
Reviewed-By: Tom Tromey <tom@tromey.com>
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DAP requests have a "defer_stop_events" option that is intended to
defer the emission of any "stopped" event until after the current
request completes. This was needed to handle async continues like
"finish &".
However, I noticed that sometimes DAP tests can fail, because a stop
event does arrive before the response to the "stepOut" request. I've
only noticed this when the machine is fairly loaded -- for instance
when I'm regression-testing a series, it may occur in some of the
tests mid-series.
I believe the problem is that the implementation in the "request"
function is incorrect -- the flag is set when "request" is invoked,
but instead it must be deferred until the request itself is run. That
is, the setting must be captured in one of the wrapper functions.
Following up on this, Simon pointed out that introducing a delay
before sending a request's response will cause test case failures.
That is, there's a race here that is normally hidden.
Investigation showed that that deferred requests can't force event
deferral. This patch implements this; but more testing showed many
more race failures. Some of these are due to how the test suite is
written.
Anyway, in the end I took the radical approach of deferring all events
by default. Most DAP requests are asynchronous by nature, so this
seemed ok. The only case I found that really required this is
pause.exp, where the test (rightly) expects to see a 'continued' event
while performing an inferior function call.
I went through all events and all requests and tried to convince
myself that this patch will cause acceptable behavior in every case.
However, it's hard to be completely sure about this approach. Maybe
there are cases that do still need an event before the response, but
we just don't have tests for them.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32685
Acked-By: Simon Marchi <simon.marchi@efficios.com>
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This allows an interpreter to override internal calls to
gdb_do_one_event in case the former needs to handle alternate event
sources.
The default action is to call gdb_do_one_event and this is not overriden
in current internal interpreters. However this feature allows to easily
embed Tcl/Tk in insight that needs to concurrently handle Tcl events for
GUI handling.
In all cases, an interpreter event servicing method must call
gdb_do_one_event at some point.
All internal event servicing calls from gdb now direct to the
interpreter-specific method rather than gdb_do_one_event itself.
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At commit 34b0776fd73^, flake8 reports the following F405 warnings:
...
$ pre-commit run flake8 --file gdb/python/lib/gdb/__init__.py
flake8...................................................................Failed
- hook id: flake8
- exit code: 1
F405 'flush' may be undefined, or defined from star imports: _gdb
F405 'write' may be undefined, or defined from star imports: _gdb
F405 'STDOUT' may be undefined, or defined from star imports: _gdb
F405 'STDERR' may be undefined, or defined from star imports: _gdb
...
F405 'selected_inferior' may be undefined, or defined from star imports: _gdb
F405 'execute' may be undefined, or defined from star imports: _gdb
F405 'parameter' may be undefined, or defined from star imports: _gdb
...
The F405s are addressed by commit 34b0776fd73 ('Suppress some "undefined"
warnings from flake8').
The problem indicated by the first F405 is that the use of flush here:
...
class _GdbFile(object):
...
def flush(self):
flush(stream=self.stream)
...
cannot be verified by flake8. It concludes that either, flush is undefined,
or it is defined by this "star import":
...
from _gdb import * # noqa: F401,F403
...
In this particular case, indeed flush is defined by the star import.
This can be addressed by simply adding:
...
flush(stream=self.stream) # noqa: F405
...
but that has only effect for flake8, so other analyzers may report the same
problem.
The commit 34b0776fd73 addresses it instead by adding an "import _gdb" and
adding a "_gdb." prefix:
...
_gdb.flush(stream=self.stream)
...
This introduces a second way to specify _gdb names, but the first one still
remains, and occasionally someone will use the first one, which then requires
fixing once flake8 is run [1].
While this works to silence the warnings, there is a problem: if a developer
makes a typo:
...
_gdb.flash(stream=self.stream)
...
this is not detected by flake8.
This matters because although the python import already complains:
...
$ gdb -q -batch -ex "python import gdb"
Exception ignored in: <gdb._GdbFile object at 0x7f6186d4d7f0>
Traceback (most recent call last):
File "__init__.py", line 63, in flush
_gdb.flash(stream=self.stream)
AttributeError: module '_gdb' has no attribute 'flash'
...
that doesn't trigger if the code is hidden behind some control flow:
...
if _var_mostly_false:
flash(stream=self.stream)
...
Instead, fix the F405s by reverting commit 34b0776fd73 and adding a second
import of _gdb alongside the star import which lists the names used locally:
...
from _gdb import * # noqa: F401,F403
+from _gdb import (
+ STDERR,
+ STDOUT,
+ Command,
+ execute,
+ flush,
+ parameter,
+ selected_inferior,
+ write,
+)
...
This gives the following warnings for the flash typo:
...
31:1: F401 '_gdb.flush' imported but unused
70:5: F811 redefinition of unused 'flush' from line 31
71:9: F405 'flash' may be undefined, or defined from star imports: _gdb
...
The benefits of this approach compared to the previous one are that:
- the typo is noticed, and
- when using a new name, the F405 fix needs to be done once (by adding it to
the explicit import list), while previously the fix had to be applied to
each use (by adding the "_gdb." prefix).
Tested on x86_64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
[1] Commit 475799b692e ("Fix some pre-commit nits in gdb/__init__.py")
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If thread-local storage is unavailable, bfd_thread_init should fail,
because in this case BFD can't be used from multiple threads -- it
relies on TLS working.
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On openSUSE Tumbleweed ppc64le-linux using gcc 14.3.0, with a gdb 16.3 based
package and test-case gdb.ada/finish-var-size.exp, I run into:
...
(gdb) finish^M
Run till exit from #0 pck.get (value=true) at pck.adb:19^M
0x0000000100004a20 in p () at finish-var-size/p.adb:18^M
18 V : Result_T := Get (True);^M
Value returned is $1 = <error reading variable: \
Cannot access memory at address 0x0>^M
(gdb) FAIL: gdb.ada/finish-var-size.exp: finish
...
Function pck.get returns type Result_T:
...
type Array_Type is array (1 .. 64) of Integer;
type Maybe_Array (Defined : Boolean := False) is
record
Arr : Array_Type;
Arr2 : Array_Type;
end record;
type Result_T (Defined : Boolean := False) is
record
case Defined is
when False =>
Arr : Maybe_Array;
when True =>
Payload : Boolean;
end case;
end record;
...
and uses r3 as address of the return value, which means
RETURN_VALUE_STRUCT_CONVENTION, but while executing finish_command we do:
...
return_value
= gdbarch_return_value_as_value (gdbarch,
read_var_value (sm->function, nullptr,
callee_frame),
val_type, nullptr, nullptr, nullptr);
...
and get:
...
(gdb) p return_value
$1 = RETURN_VALUE_REGISTER_CONVENTION
...
This is caused by this check in ppc64_sysv_abi_return_value:
...
/* In the ELFv2 ABI, aggregate types of up to 16 bytes are
returned in registers r3:r4. */
if (tdep->elf_abi == POWERPC_ELF_V2
&& valtype->length () <= 16
...
which succeeds because valtype->length () == 0.
Fix this by also checking for !TYPE_HAS_DYNAMIC_LENGTH (valtype).
[ I also tested a version of this patch using "!is_dynamic_type (valtype)"
instead, but ran into a regression in test-case gdb.ada/variant-record.exp,
because type T:
...
Length : constant Positive := 8;
subtype Name_T is String (1 .. Length);
type A_Record_T is
record
X1 : Natural;
X2 : Natural;
end record;
type Yes_No_T is (Yes, No);
type T (Well : Yes_No_T := Yes) is
record
case Well is
when Yes =>
Name : Name_T;
when No =>
Unique_Name : A_Record_T;
end case;
end record;
...
while being dynamic, also has a non-zero size, and is small enough to be
returned in registers r3:r4. ]
Fixing this causes the test-case to fail with the familiar:
...
warning: Cannot determine the function return value.
Try compiling with -fvar-tracking.
...
and indeed using -fvar-tracking makes the test-case pass.
Tested on ppc64le-linux.
PR tdep/33000
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33000
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This horrible testcase (cleaned up from oss-fuzz)
r=x*2
x=r-r
.weakref r,x
r=r-5
triggers resolve_symbol_value "gas_assert (final_val == 0)" in weakref
handling.
* read.c (assign_symbol): Clear weakrefr.
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Some 64-bit compilers have a 32-bit long, which could result in an
endless loop if uncompressed_size is larger than 4G.
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z_stream's avail_in and avail_out are defined as "unsigned int", so it
cannot decode an entire compressed stream in one pass if the stream is
larger than 4 GiB. The simplest solution to this problem is to use zlib's
convenient uncompress2() function, which handles the details for us.
Signed-off-by: Rui Ueyama <rui314@gmail.com>
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I noticed that there's no particular reason to allocate the
macro_scope objects on the heap. They can be passed around by value
just as easily.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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If configure decides that thread-local storage isn't available, it
does not define "TLS". However, this is used unconditionally in a
definition. So, define it if it isn't already defined.
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The PR fuzzer testcase creates a SHT_NOBITS .debug_info section, then
triggers a bug in --compress-debug-sections=zlib whereby sh_name is
set to -1 in elf_fake_sections as a flag to indicate the name is not
set yet (may change to zdebug_*), but the section never hits the debug
compression code in assign_file_positions_for_non_load_sections that
is responsible for setting sh_name.
PR 33020
* elf.c (_bfd_elf_init_reloc_shdr): Rename delay_st_name_p
param to delay_sh_name_p.
(elf_fake_sections): Rename delay_st_name_p to delay_sh_name_p.
Don't set delay_sh_name_p for no contents debug sections.
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illegal memory access does not occur."
This reverts commit 429fb15134cfbdafe2b203086ee05d827726b63b.
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With some compilers, only __x86_64__ is defined so use that
instead of __x86_64.
gprofng/ChangeLog
2025-05-30 Andrew Pinski <quic_apinski@quicinc.com>
* common/core_pcbe.c: s/__x86_64/__x86_64__/.
* common/cpu_frequency.h: Likewise.
* common/cpuid.c: Likewise.
* common/gp-defs.h: Likewise.
* common/hwctable.c: Likewise.
* libcollector/libcol-i386-dis.c: Likewise.
* libcollector/libcol_util.h: Likewise.
Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
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When I did the big expression conversion, I left some helper functions
lying around, primarily because the conversion was already quite large
and I didn't want to add on.
This patch removes a couple such helpers, turning them into methods on
the appropriate operation objects.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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While (mistakenly) grepping for DW_AT_compile_unit, I found this typo.
Change-Id: I04d97d7b1b27eacfca9da3853711b6092d330575
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removed by garbage collection
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I believe we previously agreed that the minimum supported Python
version should be 3.4. This patch makes this change, harmonizing the
documentation (which was inconsistent about the minimum version) and
the code.
New in v2: rebased, and removed a pre-3.4 workaround from __init__.py.
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-by: Kevin Buettner <kevinb@redhat.com>
Acked-By: Tom de Vries <tdevries@suse.de>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31870
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