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This patch is required by the following commit
"gdb: Enable displaced stepping with shadow stack on amd64 linux."
Reviewed-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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This patch enables inferior calls to support Intel's Control-Flow
Enforcement Technology (CET), which provides the shadow stack feature
for the x86 architecture.
Following the restriction of the linux kernel, enable inferior calls
for amd64 only.
Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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Inferior calls in GDB reset the current PC to the beginning of the function
that is called. As no call instruction is executed the new return address
needs to be pushed to the shadow stack and the shadow stack pointer needs
to be updated.
This commit adds a new gdbarch method to push an address on the shadow
stack. The method is used to adapt the function 'call_function_by_hand_dummy'
for inferior call shadow stack support.
Reviewed-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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Unwind the $pl3_ssp register.
We now have an updated value for the shadow stack pointer when
moving up or down the frame level. Note that $pl3_ssp can
become unavailable when moving to a frame before the shadow
stack enablement. In the example below, shadow stack is enabled
in the function 'call1'. Thus, when moving to a frame level above
the function, $pl3_ssp will become unavaiable.
Following the restriction of the linux kernel, implement the unwinding
for amd64 linux only.
Before this patch:
~~~
Breakpoint 1, call2 (j=3) at sample.c:44
44 return 42;
(gdb) p $pl3_ssp
$1 = (void *) 0x7ffff79ffff8
(gdb) up
55 call2 (3);
(gdb) p $pl3_ssp
$2 = (void *) 0x7ffff79ffff8
(gdb) up
68 call1 (43);
(gdb) p $pl3_ssp
$3 = (void *) 0x7ffff79ffff8
~~~
After this patch:
~~~
Breakpoint 1, call2 (j=3) at sample.c:44
44 return 42;
(gdb) p $pl3_ssp
$1 = (void *) 0x7ffff79ffff8
(gdb) up
55 call2 (3);
(gdb) p $pl3_ssp
$2 = (void *) 0x7ffff7a00000
(gdb) up
68 call1 (43i);
(gdb) p $pl3_ssp
$3 = <unavailable>
~~~
As we now have an updated value for each selected frame, the
return command is now enabled for shadow stack enabled programs, too.
We therefore add a test for the return command and shadow stack support,
and for an updated shadow stack pointer after a frame level change.
Reviewed-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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Intel's Control-Flow Enforcement Technology (CET) provides the shadow
stack feature for the x86 architecture.
This commit adds support to write and read the shadow-stack node in
corefiles. This helps debugging return address violations post-mortem.
The format is synced with the linux kernel commit "x86: Add PTRACE
interface for shadow stack". As the linux kernel restricts shadow
stack support to 64-bit, apply the fix for amd64 only.
Co-Authored-By: Christina Schimpe <christina.schimpe@intel.com>
Reviewed-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
---
The code and testcase are lightly adapted from:
[PATCH v3 5/9] GDB, gdbserver: aarch64-linux: Initial Guarded Control Stack support
https://sourceware.org/pipermail/gdb-patches/2025-June/218892.html
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This patch adds the user mode register PL3_SSP which is part of the
Intel(R) Control-Flow Enforcement Technology (CET) feature for support
of shadow stack.
For now, only native and remote debugging support for shadow stack
userspace on amd64 linux are covered by this patch including 64 bit and
x32 support. 32 bit support is not covered due to missing Linux kernel
support.
This patch requires fixing the test gdb.base/inline-frame-cycle-unwind
which is failing in case the shadow stack pointer is unavailable.
Such a state is possible if shadow stack is disabled for the current thread
but supported by HW.
This test uses the Python unwinder inline-frame-cycle-unwind.py which fakes
the cyclic stack cycle by reading the pending frame's registers and adding
them to the unwinder:
~~~
for reg in pending_frame.architecture().registers("general"):
val = pending_frame.read_register(reg)
unwinder.add_saved_register(reg, val)
return unwinder
~~~
However, in case the python unwinder is used we add a register (pl3_ssp) that is
unavailable. This leads to a NOT_AVAILABLE_ERROR caught in
gdb/frame-unwind.c:frame_unwind_try_unwinder and it is continued with standard
unwinders. This destroys the faked cyclic behavior and the stack is
further unwinded after frame 5.
In the working scenario an error should be triggered:
~~~
bt
0 inline_func () at /tmp/gdb.base/inline-frame-cycle-unwind.c:49^M
1 normal_func () at /tmp/gdb.base/inline-frame-cycle-unwind.c:32^M
2 0x000055555555516e in inline_func () at /tmp/gdb.base/inline-frame-cycle-unwind.c:45^M
3 normal_func () at /tmp/gdb.base/inline-frame-cycle-unwind.c:32^M
4 0x000055555555516e in inline_func () at /tmp/gdb.base/inline-frame-cycle-unwind.c:45^M
5 normal_func () at /tmp/gdb.base/inline-frame-cycle-unwind.c:32^M
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb) PASS: gdb.base/inline-frame-cycle-unwind.exp: cycle at level 5: backtrace when the unwind is broken at frame 5
~~~
To fix the Python unwinder, we simply skip the unavailable registers.
Also it makes the test gdb.dap/scopes.exp fail. The shadow stack feature is
disabled by default, so the pl3_ssp register which is added with my CET
shadow stack series will be shown as unavailable and we see a TCL error:
~~
>>> {"seq": 12, "type": "request", "command": "variables", "arguments": {"variablesReference": 2, "count": 85}}
Content-Length: 129^M
^M
{"request_seq": 12, "type": "response", "command": "variables", "success": false, "message": "value is not available", "seq": 25}FAIL: gdb.dap/scopes.exp: fetch all registers success
ERROR: tcl error sourcing /tmp/gdb/testsuite/gdb.dap/scopes.exp.
ERROR: tcl error code TCL LOOKUP DICT body
ERROR: key "body" not known in dictionary
while executing
"dict get $val body variables"
(file "/tmp/gdb/testsuite/gdb.dap/scopes.exp" line 152)
invoked from within
"source /tmp/gdb/testsuite/gdb.dap/scopes.exp"
("uplevel" body line 1)
invoked from within
"uplevel #0 source /tmp/gdb/testsuite/gdb.dap/scopes.exp"
invoked from within
"catch "uplevel #0 source $test_file_name" msg"
UNRESOLVED: gdb.dap/scopes.exp: testcase '/tmp/gdb/testsuite/gdb.dap/scopes.exp' aborted due to Tcl error
~~
I am fixing this by enabling the test for CET shadow stack, in case we
detect that the HW supports it:
~~~
# If x86 shadow stack is supported we need to configure GLIBC_TUNABLES
# such that the feature is enabled and the register pl3_ssp is
# available. Otherwise the reqeust to fetch all registers will fail
# with "message": "value is not available".
if { [allow_ssp_tests] } {
append_environment GLIBC_TUNABLES "glibc.cpu.hwcaps" "SHSTK"
}
~~~
Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Reviewed-By: Eli Zaretskii <eliz@gnu.org>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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The XSAVE function set is organized in state components, which are a set of
registers or parts of registers. So-called XSAVE-supported features are
organized using state-component bitmaps, each bit corresponding to a
single state component.
The Intel Software Developer's Manual uses the term xstate_bv for a
state-component bitmap, which is defined as XCR0 | IA32_XSS. The control
register XCR0 only contains a state-component bitmap that specifies user state
components, while IA32_XSS contains a state-component bitmap that specifies
supervisor state components.
Until now, XCR0 is used as input for target description creation in GDB.
However, a following patch will add userspace support for the CET shadow
stack feature by Intel. The CET state is configured in IA32_XSS and consists
of 2 state components:
- State component 11 used for the 2 MSRs controlling user-mode
functionality for CET (CET_U state)
- State component 12 used for the 3 MSRs containing shadow-stack pointers
for privilege levels 0-2 (CET_S state).
Reading the CET shadow stack pointer register on linux requires a separate
ptrace call using NT_X86_SHSTK. To pass the CET shadow stack enablement
state we would like to pass the xstate_bv value instead of xcr0 for target
description creation. To prepare for that, we rename the xcr0 mask
values for target description creation to xstate_bv. However, this
patch doesn't add any functional changes in GDB.
Future states specified in IA32_XSS such as CET will create a combined
xstate_bv_mask including xcr0 register value and its corresponding bit in
the state component bitmap. This combined mask will then be used to create
the target descriptions.
Reviewed-By: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Luis Machado <luis.machado@arm.com>
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This is required for a later commit which requires "bit_SHSTK".
Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Luis Machado <luis.machado@arm.com>
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From: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
The change comes from ARM's GCS series:
[PATCH v3 5/9] GDB, gdbserver: aarch64-linux: Initial Guarded Control Stack support.
We need it for testing coredump files, too. So include it in this patch series.
Abridged-by: Christina Schimpe <christina.schimpe@intel.com>
Approved-By: Luis Machado <luis.machado@arm.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
---
This is the patch mentioned above:
https://sourceware.org/pipermail/gdb-patches/2025-June/218892.html
Minus everything except for the change in gdb.exp's corefind procedure.
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I wrote this as a preparatory patch while attempting to make
objfile::section_iterator use filtered_iterator. It turned out not so
easy, so I have put it aside for now. But now I have this patch, so I
thought I'd send it by itself.
Since the `obj_section *` yielded by the iterator can't be nullptr, I
think it makes sense for the iterator to yield references instead.
Just like you would get if you iterated on an std::vector<obj_section>.
Change-Id: I7bbee50ed52599e64c4f3b06bdbbde597feba9aa
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When running test-case gdb.dwarf2/dw2-linkage-name-trust.exp with target board
cc-with-gdb-index, I get:
...
(gdb) file dw2-linkage-name-trust^M
Reading symbols from dw2-linkage-name-trust...^M
warning: .gdb_index address table has a range (0x4006ac - 0x4006cc) that \
overlaps with an earlier range, ignoring .gdb_index^M
(gdb) delete breakpoints^M
...
Fix this by compiling with nodebug.
Tested on aarch64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
PR testsuite/33315
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33315
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When running test-case gdb.dwarf2/dw2-entry-points.exp with target board
cc-with-gdb-index, I get:
...
(gdb) file dw2-entry-points^M
Reading symbols from dw2-entry-points...^M
warning: .gdb_index address table has a range (0x40066c - 0x4006e4) that \
overlaps with an earlier range, ignoring .gdb_index^M
(gdb) delete breakpoints^M
...
Fix this by copying function bar_helper to barso_helper, and using it where
appropriate.
Tested on aarch64-linux.
Approved-By: Tom Tromey <tom@tromey.com>
PR testsuite/33315
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33315
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For background, see this thread:
https://inbox.sourceware.org/gdb-patches/20250612144607.27507-1-tdevries@suse.de
Tom describes the issue clearly in the above thread, here's what he
said:
Once in a while, when running test-case gdb.base/bp-cmds-continue-ctrl-c.exp,
I run into:
...
Breakpoint 2, foo () at bp-cmds-continue-ctrl-c.c:23^M
23 usleep (100);^M
^CFAIL: $exp: run: stop with control-c (unexpected) (timeout)
FAIL: $exp: run: stop with control-c
...
This is PR python/32167, observed both on x86_64-linux and powerpc64le-linux.
This is not a timeout due to accidental slowness, gdb actually hangs.
The backtrace at the hang is (on cfarm120 running AlmaLinux 9.6):
...
(gdb) bt
#0 0x00007fffbca9dd94 in __lll_lock_wait () from
/lib64/glibc-hwcaps/power10/libc.so.6
#1 0x00007fffbcaa6ddc in pthread_mutex_lock@@GLIBC_2.17 () from
/lib64/glibc-hwcaps/power10/libc.so.6
#2 0x000000001067aee8 in __gthread_mutex_lock ()
at /usr/include/c++/11/ppc64le-redhat-linux/bits/gthr-default.h:749
#3 0x000000001067afc8 in __gthread_recursive_mutex_lock ()
at /usr/include/c++/11/ppc64le-redhat-linux/bits/gthr-default.h:811
#4 0x000000001067b0d4 in std::recursive_mutex::lock ()
at /usr/include/c++/11/mutex:108
#5 0x000000001067b380 in std::lock_guard<std::recursive_mutex>::lock_guard ()
at /usr/include/c++/11/bits/std_mutex.h:229
#6 0x0000000010679d3c in set_quit_flag () at gdb/extension.c:865
#7 0x000000001066b6dc in handle_sigint () at gdb/event-top.c:1264
#8 0x00000000109e3b3c in handler_wrapper () at gdb/posix-hdep.c:70
#9 <signal handler called>
#10 0x00007fffbcaa6d14 in pthread_mutex_lock@@GLIBC_2.17 () from
/lib64/glibc-hwcaps/power10/libc.so.6
#11 0x000000001067aee8 in __gthread_mutex_lock ()
at /usr/include/c++/11/ppc64le-redhat-linux/bits/gthr-default.h:749
#12 0x000000001067afc8 in __gthread_recursive_mutex_lock ()
at /usr/include/c++/11/ppc64le-redhat-linux/bits/gthr-default.h:811
#13 0x000000001067b0d4 in std::recursive_mutex::lock ()
at /usr/include/c++/11/mutex:108
#14 0x000000001067b380 in std::lock_guard<std::recursive_mutex>::lock_guard ()
at /usr/include/c++/11/bits/std_mutex.h:229
#15 0x00000000106799cc in set_active_ext_lang ()
at gdb/extension.c:775
#16 0x0000000010b287ac in gdbpy_enter::gdbpy_enter ()
at gdb/python/python.c:232
#17 0x0000000010a8e3f8 in bpfinishpy_handle_stop ()
at gdb/python/py-finishbreakpoint.c:414
...
What happens here is the following:
- the gdbpy_enter constructor attempts to set the current extension language
to python using set_active_ext_lang
- set_active_ext_lang attempts to lock ext_lang_mutex
- while doing so, it is interrupted by sigint_wrapper (the SIGINT handler),
handling a SIGINT
- sigint_wrapper calls handle_sigint, which calls set_quit_flag, which also
tries to lock ext_lang_mutex
- since std::recursive_mutex::lock is not async-signal-safe, things go wrong,
resulting in a hang.
The hang bisects to commit 8bb8f834672 ("Fix gdb.interrupt race"), which
introduced the lock, making PR python/32167 a regression since gdb 15.1.
Commit 8bb8f834672 fixes PR dap/31263, a race reported by ThreadSanitizer:
...
WARNING: ThreadSanitizer: data race (pid=615372)
Read of size 1 at 0x00000328064c by thread T19:
#0 set_active_ext_lang(extension_language_defn const*) gdb/extension.c:755
#1 scoped_disable_cooperative_sigint_handling::scoped_disable_cooperative_sigint_handling()
gdb/extension.c:697
#2 gdbpy_interrupt gdb/python/python.c:1106
#3 cfunction_vectorcall_NOARGS <null>
Previous write of size 1 at 0x00000328064c by main thread:
#0 scoped_disable_cooperative_sigint_handling::scoped_disable_cooperative_sigint_handling()
gdb/extension.c:704
#1 fetch_inferior_event() gdb/infrun.c:4591
...
Location is global 'cooperative_sigint_handling_disabled' of size 1 at 0x00000328064c
...
SUMMARY: ThreadSanitizer: data race gdb/extension.c:755 in \
set_active_ext_lang(extension_language_defn const*)
...
The problem here is that gdb.interrupt is called from a worker thread, and its
implementation, gdbpy_interrupt races with the main thread on some variable.
The fix presented here is based on the fix that Tom proposed, but
fills in the missing Mingw support.
The problem is basically split into two: hosts that support unix like
signals, and Mingw, which doesn't support signals.
For signal supporting hosts, I've adopted the approach that Tom
suggests, gdbpy_interrupt uses kill() to send SIGINT to the GDB
process. This is then handled in the main thread as if the user had
pressed Ctrl+C. For these hosts no locking is required, so the
existing lock is removed. However, everywhere the lock currently
exists I've added an assert:
gdb_assert (is_main_thread ());
If this assert ever triggers then we're setting or reading the quit
flag on a worker thread, this will be a problem without the mutex.
For Mingw, the current mutex is retained. This is fine as there are
no signals, so no chance of the mutex acquisition being interrupted by
a signal, and so, deadlock shouldn't be an issue.
To manage the complexity of when we need an assert, and when we need
the mutex, I've created 'struct ext_lang_guard', which can be used as
a RAII object. This object either performs the assertion check, or
acquires the mutex, depending on the host.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32167
Co-Authored-By: Tom de Vries <tdevries@suse.de>
Approved-By: Tom Tromey <tom@tromey.com>
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I think it's uninteresting to step into gdb::ref_ptr::get, so add a skip
entry for it. I am adding just one to get the party started, but there
are certainly more like this that we could skip.
Change-Id: Ib074535c96a62137de63bbe58ff168a1e913688f
Approved-By: Tom Tromey <tom@tromey.com>
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I don't know if this is true on all platforms, but from what I can see
on Linux, the dump commands don't output anything. Use
gdb_test_no_output, which should be a bit more robust than checking for
some specific error patterns.
Change-Id: Idc82298c4752ba7808659dfea2f8324c8a97052d
Approved-By: Tom Tromey <tom@tromey.com>
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The manual claims that the -list-features and -list-target-features MI
commands return their result in a field named "result". The field is
actually named "features", and always has been since the introduction of
these commands in 084344d and c6ebd6c. See mi_cmd_list_features and
mi_cmd_list_target_features in gdb/mi/mi-main.c.
Approved-By: Tom Tromey <tom@tromey.com>
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Even though the core_find proc will log a warning, it's better to log
"untested" and then terminate the test. This will help to avoid
silently skipped tests, when running the testsuite. Most of the tests
already do that. This patch adds the missing ones.
Approved-By: Luis Machado <luis.machado.foss@gmail.com>
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In this commit:
commit dbd05b9edcf760a7001985f89bc760358a3c19d7
Date: Wed Aug 20 10:45:09 2025 +0100
gdb/python: check return value of PyObject_New in all cases
I missed a call to PyObject_New in python/py-disasm.c, which this
commit addresses.
Unlike the previous commit, the call to PyObject_New in py-disasm.c is
contained within the scoped_disasm_info_object class, which makes it
harder to check for NULL and return.
So in this commit I've rewritten the scoped_disasm_info_object class,
moving the call to PyObject_New out into gdbpy_print_insn, which is
the only place that scoped_disasm_info_object was being used.
As scoped_disasm_info_object is no longer responsible for creating the
underlying Python object, I figured that I might as well move the
initialisation of that object out of scoped_disasm_info_object too.
With that done, the scoped_disasm_info_object now has just one task,
invalidating the existing disasm_info_object at the end of the scope.
So I renamed scoped_disasm_info_object to
scoped_invalidate_disasm_info, which reflects its only task.
I made a couple of other small adjustments that were requested during
review, these are both in the same code area: updating
disasm_info_fill to take an object reference rather than a pointer,
and removing the local variable insn_disas_obj from gdbpy_print_insn,
and inline its value at the one place it was used.
There should be no user visible changes after this commit. Except for
the PyObject_New call, which now has proper error checking. But in
the working case, nothing should have changed.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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nullptr
Change-Id: Iae17492f468efba7b76463a6ff8526171e412040
Reviewed-By: Tom de Vries <tdevries@suse.de>
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While looking at test-case gdb.tui/tui-missing-src.exp I noticed that
gdb_compile is used to compile multiple sources:
...
if { [gdb_compile "${srcfiles}" "${binfile}" \
executable {debug additional_flags=-O0}] != "" } {
...
meaning there are no separate compile and link steps, as is required for
fission [1].
Fix this by using build_executable instead.
Tested on aarch64-linux.
[1] https://gcc.gnu.org/wiki/DebugFission
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During testing of bare-metal applications on QEMU for RISC-V, it was discovered
that the instructions wfi, sfence.vma, sret, and mret were not supported. This
patch introduces support for these instructions. Additionally, it wraps
fetch_instruction function in a try-catch block to gracefully handle errors
that may occur when attempting to read invalid address.
Reviewed-By: Guinevere Larsen <guinevere@redhat.com>
Approved-By: Andrew Burgess <aburgess@redhat.com>
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The Linaro CI reported a regression in test-case
gdb.dwarf2/macro-source-path-clang14-dw4.exp due to recent commit 81e5a23c7b8
("[gdb/testsuite] Fix require dwarf2_support check in some test-cases").
The problem is that the "require dwarf2_support" in its new location doesn't
work because proc dwarf2_support is not defined.
I didn't notice this because I tested all gdb.dwarf2 test-cases together, and
a different test-case had already imported the proc.
Fix this by moving load_lib dwarf.exp earlier.
Tested on x86_64-linux.
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Similar to a previous patch, if the gdb executable is in fact a libtool
wrapper, we need to get the path to the real executable to load it in
the top-level gdb.
With this change, the test runs on Cygwin, although I do see two
failures:
FAIL: gdb.gdb/index-file.exp: debug_names files are identical
FAIL: gdb.gdb/index-file.exp: debug_str files are identical
Change-Id: Ie06d1ece67e61530e5b664e65b5ef0edccaf6afa
Reviewed-By: Keith Seitz <keiths@redhat.com>
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When running gdb.gdb/selftest.exp on Cygwin, the test eventually times
out on this command:
(gdb) PASS: gdb.gdb/selftest.exp: printed version as pointer
continue
Continuing.
[New Thread 4804.0x1728]
[New Thread 4804.0x2f24]
[New Thread 4804.0x934]
[New Thread 4804.0x23a8]
[New Thread 4804.0x2cf4]
[New Thread 4804.0x1408]
[New Thread 4804.0x2c90]
[New Thread 4804.0xc58]
[New Thread 4804.0x1d40]
[New Thread 4804.0x1824]
GNU gdb (GDB) 17.0.50.20250530-git
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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Type "show copying" and "show warranty" for details.
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Type "show configuration" for configuration details.
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For help, type "help".
Type "apropos word" to search for commands related to "word".
(gdb) [New Thread 4804.0x2c64]
[New Thread 4804.0x23c4]
[New Thread 4804.0x2814]
[Thread 4804.0x1200 exited with code 0]
[Thread 4804.0x293c exited with code 0]
[Thread 4804.0x2c9c exited with code 0]
FAIL: gdb.gdb/selftest.exp: xgdb is at prompt (timeout)
The problem is the new thread notification, and the fact that the test
expects the prompt to be the last thing in the buffer. To avoid the
thread events interfering with the test, disable them, they are not
useful here.
With this patch, gdb.gdb/selftest.exp mostly runs fine on Cygwin, the
only remaining problem appears to be:
(gdb) PASS: gdb.gdb/selftest.exp: send ^C to child process
signal SIGINT
Continuing with signal SIGINT.
PASS: gdb.gdb/selftest.exp: send SIGINT signal to child process, top GDB message
FAIL: gdb.gdb/selftest.exp: send SIGINT signal to child process, bottom GDB message (timeout)
Change-Id: I0b1df0503c1961c042c8de559b4d223c5d3cb95c
Reviewed-By: Keith Seitz <keiths@redhat.com>
|
|
When building GDB on Cygwin, gdb/gdb.exe is a libtool wrapper (which
happens to be a PE executable). The real executable is at
gdb/.libs/gdb.exe. The "does gdb have debug info test" that
_selftest_setup does is bogus, because it loads the libtool wrapper
(which doesn't have debug info), doesn't see any debug info, and thus
the test is skipped.
The "correct" way to deal with libtool wrappers is to run the shell
command you want to run under `libtool --mode=execute`. That will
replace any path resembling to a libtool wrapper with the real
executable path. But it will also add to the environment the library
paths necessary for this executable to find the libraries it needs.
Therefore, modify the `do_self_tests` proc to:
- run the top-level GDB commands under `libtool --mode=execute`
- pass the path to the inferior GDB on the command-line of the
top-level, so that it gets replaced with the real executable's path
However, the "file" command was previously used to detect the presence
of debug info in the GDB executable. It's not easy to implement this
check when loading the executable directly on the command line. So, add
a separate proc, _selftest_check_executable_debug_info, that spawns a
temporary GDB and does the debug info check through the file command.
This proc uses libtool to obtain the path to the real executable.
When building, we use the bundled libtool.m4 at the top of the tree.
This means that the libtool system package, and therefore the libtool
binary, might not be available. Check for the presence of the libtool
binary first, and only do the conversion if it is found. If it is not
found, the test should still work on platforms that don't require the
conversion.
With this commit, the test runs on Cygwin, even though there are
failures later.
Change-Id: Ie7b712cdc84671a5a017655a7e41687ff23f906c
Reviewed-By: Keith Seitz <keiths@redhat.com>
|
|
In the ROCm-GDB testing process, we hit a problem that is a combination
of these 3 factors:
1. In the downstream ROCm-GDB packages, the gdb executable is built with
a relative RUNPATH:
0x000000000000001d (RUNPATH) Library runpath: [${ORIGIN}/../lib]
This is done so that the installation is relocatable (the whole ROCm
directory can be copied around) and things still work. For instance,
the rocgdb executable needs to be able to find the libraries it
needs, such as `librocm-dbgapi.so.0`. The relative runpath allows
that.
2. For testing, we run the testsuite against the gdb executable
installed from one of those packages. It is possible to ./configure
the testsuite directory on its own, and then do:
$ make check RUNTESTFLAGS="GDB=/opt/rocm/bin/rocgdb"
3. The selftests (such as gdb.gdb/selftest.exp) copy the GDB under test
to the standard output directory, before trying to debug it.
The problem is that the gdb executable under test that has been copied
can't find the libraries it needs.
With this patch, I propose that we don't copy the gdb executable, but
debug it in place instead. The comment removed in this patch says "in
case this OS doesn't like to edit its own text space", and has been
there since forever in some form. But it's not clear if there is a host
OS (where we intend to run this test) that needs this nowadays. I would
bet that there isn't. If there is in fact a GDB host OS (where we
intend to run this test) that needs it, we can reinstate the copying,
but as an opt-in operation.
Another situation where this change helps is on Windows, where
gdb/gdb.exe is a libtool wrapper (the real executable is at
gdb/.libs/gdb.exe). Copying gdb/gdb.exe doesn't accomplish anything
useful. The next patch does further changes to account for the libtool
wrapper case.
I tested on Linux and Cygwin, more testing would be welcome.
Change-Id: Id4148517d4fc4ecdd49f099c12003e3d16c6a93d
Reviewed-By: Keith Seitz <keiths@redhat.com>
|
|
The function to stop at is always main. Remove the parameter and
hard-code main in _selftest_setup.
Change-Id: Ibbbf598203b1658305eb6bc631d029652c10edac
Reviewed-By: Keith Seitz <keiths@redhat.com>
|
|
Rename some procs in lib/selftest-support.exp that are only used
internally, to make it a bit clearer that they are just internal
helpers.
Change-Id: Icd399ac42698209fbc8e798bf43a7d8464aa848c
Reviewed-By: Keith Seitz <keiths@redhat.com>
|
|
pre-commit pointed out that gdbarch_components.py had a minor
formatting issue, according to the official version of 'black'. This
patch corrects the oversight.
|
|
There is a bug in expect, see:
https://sourceforge.net/p/expect/patches/26/
which causes empty substring matches from a regexp to instead return
the complete input buffer. To reproduce this bug, try this command:
expect -c 'spawn sh -c "echo -n -e \"abc\""; \
expect -re "(a?)(a)(bc)"; \
puts "\n"; \
for { set i 1 } { $i < 4 } { incr i } { \
puts -nonewline "($i): \""; \
puts -nonewline $expect_out($i,string); \
puts "\"" \
}'
For a working expect the output looks like:
spawn sh -c echo -n -e "abc"
abc
(1): ""
(2): "a"
(3): "bc"
But for a broken expect the output looks like:
spawn sh -c echo -n -e "abc"
abc
(1): "abc"
(2): "a"
(3): "bc"
Notice that (1) is now returning the complete input buffer rather than
the empty string, this is wrong.
This is not the first time this bug has impacted GDB's testsuite,
this commit seems to be working around the same problem:
commit e579b537353cd91cb8fac1eaeb69901d4936766f
Date: Sat Aug 16 20:32:37 2025 +0200
[gdb/testsuite] Fix TUI tests on freebsd
I recently pushed this commit:
commit 3825c972a636852600b47c242826313f4b9963b8
Date: Wed Jun 18 15:02:29 2025 +0100
gdb: allow gdb.Color to work correctly with pagination
Which added gdb.python/py-color-pagination.exp. Bug PR gdb/33321 was
then created as the test was failing on some hosts. Turns out, this
is same expect bug.
The fix presented here is the same as for e579b537353cd91cb8, avoid
using optional regexp substrings at the start of a regexp, and instead
use two separate regexp patterns. With this change in place, the test
now passes on all hosts.
There's no change in what is being tested after this commit.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33321
Approved-By: Tom de Vries <tdevries@suse.de>
|
|
On msys2-ucrt64, with test-case gdb.server/non-existing-program.exp I get:
...
(gdb) quit^M
gdb_caching_proc allow_xml_test caused gdb_exit to be called
gdb_caching_proc allow_xml_test marked as called
gdb_caching_proc get_mount_point_map marked as called
builtin_spawn gdbserver stdio non-existing-program^M
Error creating process "non-existing-program " (error 2): \
The system cannot find the file specified.^M^M
Exiting^M^M
FAIL: gdb.server/non-existing-program.exp: gdbserver exits cleanly
...
This happens because this regexp fails to match:
...
# This is what we get on Windows.
-re "Error creating process\r\n\r\nExiting\r\n" {
...
Fix this by updating the regexp.
Tested on x86_64-w64-mingw32 (msys2-ucrt64).
|
|
Say we disable startup-with-shell, we get:
...
(gdb) run `echo 8`^M
Starting program: a2-run `echo 8`^M
[Thread debugging using libthread_db enabled]^M
Using host libthread_db library "/lib64/libthread_db.so.1".^M
usage: factorial <number>^M
[Inferior 1 (process 10787) exited with code 01]^M
(gdb) FAIL: gdb.base/a2-run.exp: run "a2-run" with shell (timeout)
...
Fix this by only doing this test if startup-with-shell is supported.
This fixes the test-case on msys2-ucrt64, where startup-with-shell is not
supported.
Likewise in other test-cases.
Tested on x86_64-linux.
|
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I ran test-case gdb.python/py-color-pagination.exp with make-check-all.sh and
noticed failures when using remote host.
So I grepped to find all test-cases using with_ansi_styling_terminal and ran
them with host/target board local-remote-host-native.
Fix the failing test-cases using require {!is_remote host}.
Tested on x86_64-linux.
|
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Update gdbpy_create_ptid_object (python/py-infthread.c) to return a
gdbpy_ref<> rather than a 'PyObject *'. This reduces the chances that
a caller will leak an object, though no such memory leaks are fixed in
this commit, this is just a code improvement patch.
There should be no user visible changes after this commit.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
In corelow.c, in the function rename_vmcore_idle_reg_sections, the
argument ABFD holds the core file bfd pointer. When this function is
called current_program_space->core_bfd() is passed as the argument
value.
Within this function, we sometimes use the function argument, and
sometimes access current_program_space->core_bfd() directly.
This is confusing, and unnecessary. Lets not do that.
I've renamed the argument to cbfd (for Core file BFD), and then
updated the function to make use of this argument throughout. This
reduces the number of accesses to global state, which is, I think, a
good thing.
There should be no user visible changes after this commit.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
This commit changes the signature of the gdbarch_core_info_proc method
so that it takes a 'struct bfd *' as an extra argument. This argument
is used to pass through the core file bfd pointer.
Now, in corelow.c, when calling gdbarch_core_info_proc, we can pass
through current_program_space->core_bfd() as the argument. Within the
implementations, (Linux and FreeBSD) we can use this argument rather
than having to access the core file through current_program_space.
This reduces the use of global state, which I think is a good thing.
There should be no user visible changes after this commit.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
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|
The function linux_read_core_file_mappings is passed an argument CBFD,
which is the BFD for the core file. In
core_target::build_file_mappings, where the function is called, we
pass current_program_space->core_bfd() as the argument.
However, in linux_read_core_file_mappings, in some places we use the
CBFD argument, and in other places we directly use
current_program_space->core_bfd(). This is confusing, and
unnecessary. Lets not do that.
Standardise on just using CBFD. This removes some references to
global state in favour of passing the global state in as an argument,
I think this is a good thing.
There should be no user visible changes after this commit.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
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Implement support for XOP instructions [1] in amd64_get_insn_details.
The encoding scheme is documented here [2]. Essentially it's a variant of the
VEX3 encoding scheme, with:
- 0x8f as the first byte instead of 0xc4, and
- an opcode map >= 8.
The changes are roughly the same as the XOP part of an earlier submission [3],
hence the tag.
The only real difference is that that patch proposed to implement xop_prefix_p
using:
...
return pfx[0] == 0x8f && (pfx[1] & 0x38);
...
which tries to resolve the conflict between the XOP prefix (starts with 0x8f)
and the POP instruction (opcode 0x8f) by detecting that it's not a POP
instruction.
Instead, use the way AMD has resolved this conflict in the specification, by
checking for opcode map >= 8:
...
gdb_byte m = pfx[1] & 0x1f;
return pfx[0] == 0x8f && m >= 8;
...
Tested on x86_64-linux.
Co-Authored-By: Jan Beulich <jbeulich@suse.com>
Reviewed-By: Klaus Gerlicher<klaus.gerlicher.@intel.com>
[1] https://en.wikipedia.org/wiki/XOP_instruction_set
[2] https://www.amd.com/content/dam/amd/en/documents/archived-tech-docs/programmer-references/43479.pdf
[3] https://sourceware.org/pipermail/gdb-patches/2019-February/155347.html
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I noticed a possible memory leak in gdbpy_create_ptid_object, in
py-infthread.c. We create a Tuple, and hold the reference in a
'PyObject*' local.
If we then fail to create any of the tuple contents we perform an
early exit, returning nullptr, this will leak the Tuple object.
Currently, we create the Tuple as the first action in the function,
but we don't really need the tuple until the end of the function.
In this commit I have:
1. Moved creation of the Tuple until the end of the function, just
before we need it.
2. Stored the Tuple reference in a gdbpy_ref<>. This is not
strictly needed any more, but is (I think) good practice as
future changes to the function will not need to worry about
releasing the Tuple object.
3. Taken the opportunity to replace a NULL with nullptr in this
function.
4. Inlined the local variable declarations to the point of first
use.
There should be no user visible changes after this commit.
No tests as I have no idea how to make gdb_py_object_from_longest (and
friends) fail, and so trigger the memory leak. I suspect we'd never
actually see this leak in the real world, but it doesn't hurt to clean
these things up.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
(1) Description of Problem:
When debugging the following code, the execution result of
the backtrace command is incorrect.
$ cat test.S
.text
.globl fun1
.type fun1, @function
fun1:
or $r12,$r0,$r0
or $r4,$r12,$r0
jr $r1
.globl fun
.type fun, @function
fun:
addi.d $r3,$r3,-16
st.d $r1,$r3,8
bl fun1
or $r12,$r4,$r0
or $r4,$r12,$r0
ld.d $r1,$r3,8
addi.d $r3,$r3,16
jr $r1
.globl main
.type main, @function
main:
addi.d $r3,$r3,-16
st.d $r1,$r3,8
bl fun
nop
ld.d $r1,$r3,8
addi.d $r3,$r3,16
jr $r1
$ gcc test.S -o test
$ gdb test
...
(gdb) b fun1
Breakpoint 1 at 0x748
(gdb) r
Breakpoint 1, 0x0000555555554748 in fun1 ()
(gdb) bt
#0 0x0000555555554748 in fun1 ()
#1 0x0000555555554758 in fun ()
#2 0x0000555555554758 in fun ()
#3 0x0000555555554758 in fun ()
....
--Type <RET> for more, q to quit, c to continue without paging
(2) Root Cause Analysis:
The return address of fun() in r1(ra) is saved on the stack:
addi.d $r3,$r3,-16
st.d $r1,$r3,8
The bl instruction in fun () will call the fun1 () and save
the value of pc+4 to r1(ra).
bl fun1
or $r12,$r4,$r0
Because registers such as fp and ra saved in the stack of the sub-function
are not recorded in current code. When trace back fun() to main(), the pc
of the previous frame to be read from ra register instead of the saved location
on the stack. At this time, the value of ra register in fun() is already the
address of the next instruction after the bl. So it is impossible to trace
back to the main().
(3) Solution:
Record the location of ra, fp, s0 to s8 on the stack to ensure the correct
execution of backtrace.
(4) Test:
$ gdb test
...
(gdb) b fun1
Breakpoint 1 at 0x748
(gdb) r
Breakpoint 1, 0x0000555555554748 in fun1 ()
(gdb) bt
#0 0x0000555555554748 in fun1 ()
#1 0x0000555555554758 in fun ()
#2 0x0000555555554778 in main ()
Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
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(1) Description of Problem:
When debugging the following code, the execution result of
nexti command is incorrect.
$ cat test.S
.text
.globl fun
.type fun, @function
fun:
or $r12,$r0,$r0
or $r4,$r12,$r0
jr $r1
.globl main
.type main, @function
main:
addi.d $r3,$r3,-16
st.d $r1,$r3,8
bl fun
or $r12,$r4,$r0
or $r4,$r12,$r0
ld.d $r1,$r3,8
addi.d $r3,$r3,16
jr $r1
$ gcc test.S -o test
$ gdb test
...
(gdb) set disassemble-next-line on
(gdb) start
...
Temporary breakpoint 1, 0x0000555555554754 in main ()
=> 0x0000555555554754 <main+8>: 57ffefff bl -20 # 0x555555554740 <fun>
(gdb) ni
0x0000555555554740 in fun ()
=> 0x0000555555554740 <fun+0>: 0015000c move $t0, $zero
(2) Root Cause Analysis:
In the internal execution flow of the ni command, a single-step will be
executed first. After that, it will enter process_event_stop_test (),
some conditions are judged in this function.
if ((get_stack_frame_id (frame)
!= ecs->event_thread->control.step_stack_frame_id)
&& get_frame_type (frame) != SIGTRAMP_FRAME
&& ((frame_unwind_caller_id (frame)
== ecs->event_thread->control.step_stack_frame_id)
&& ((ecs->event_thread->control.step_stack_frame_id
!= outer_frame_id)
|| (ecs->event_thread->control.step_start_function
!= find_pc_function (ecs->event_thread->stop_pc ())))))
{
...
if (ecs->event_thread->control.step_over_calls == STEP_OVER_ALL)
...
else
insert_step_resume_breakpoint_at_caller (frame);
}
Here, it will be judged whether a sub-function has been called based on
whether the frame id before the single step is not equal to the current
frame id and whether there is a calling relationship.
If a sub-function is called at this time and the current operation is nexti,
it will not stop immediately. Instead, insert_step_resume_breakpoint_at_caller()
will be called to complete the execution of the sub-function and then stop.
In above debugging examples, the executable program being debugged is compiled
from an asm source file that does not contain dwarf information. Therefore, the
frame id of the function is calculated by loongarch_frame_unwind rather than
dwarf2_frame_unwind. However, loongarch_scan_prologue() has not yet recorded
stack information in loongarch_frame_cache, this will cause problems in some
operations related to the frame id information.
(3) Solution:
Improve loongarch_scan_prologue() to record the stack information in
loongarch_frame_cache. And improve the loongarch_frame_unwind_stop_reason()
through the information recorded in loongarch_frame_cache.
(4) Test:
After this patch:
$ gdb test
(gdb) set disassemble-next-line on
(gdb) start
Temporary breakpoint 1, 0x0000555555554754 in main ()
=> 0x0000555555554754 <main+8>: 57ffefff bl -20 # 0x555555554740 <fun>
(gdb) ni
0x0000555555554758 in main ()
=> 0x0000555555554758 <main+12>: 0015008c move $t0, $a0
(gdb) ni
0x000055555555475c in main ()
=> 0x000055555555475c <main+16>: 00150184 move $a0, $t0
Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
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In the current code, loongarch_frame_unwind is a LoongArch prologue unwinder,
it contains the required member functions, but they do not calculate a valid
frame id through prologue of a function frame. Refactor these functions and
use loongarch_frame_cache to record the information of the function frame.
No functional change intended.
Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
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Add the definition of loongarch_frame_cache for loongarch_frame_unwind,
this is preparation for later patch on LoongArch.
Signed-off-by: Hui Li <lihui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
|
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VEX and EVEX-encoded instructions generally require a ModR/M byte, with the
notable exception of vzeroall and vzeroupper (opcode 0x77), which do not
use ModR/M.
This change sets need_modrm = 1 for VEX instructions, and adds an exception
for instructions where *insn == 0x77, following Intel’s SDM.
EVEX has no exceptions and thus always sets need_modrm to 1.
Additionally, the legacy twobyte_has_modrm table cannot be used for VEX and
EVEX instructions, as these encodings have different requirements and
exceptions. The logic is now explicit for VEX/EVEX handling.
Add vpblendw to selftest amd64_insn_decode.
The Intel SDM says the following:
1. Intel® 64 and IA-32 Architectures Software Developer’s Manual
Section 2.2.1.2 — Instruction Prefixes
"The VEX prefix is a multi-byte prefix that replaces several legacy prefixes
and opcode bytes. The VEX prefix is not an opcode; it is a prefix that
modifies the instruction that follows."
Section 2.2.1.3 — Opcode Bytes
"The opcode byte(s) follow any instruction prefixes (including VEX). The
opcode specifies the operation to be performed."
Section 2.2.2 — Instruction Format
"If a VEX prefix is present, it is processed as a single prefix, and the
opcode bytes follow immediately after the VEX prefix."
Source: Intel® SDM Vol. 2A, Section 2.2.1.2 and 2.2.2 (See Vol. 2A,
PDF pages 2-4, 2-5, and 2-7)
2. ModRM Byte Requirement
Intel® SDM Vol. 2A, Table 2-2 — VEX Prefix Encoding
"Most VEX-encoded instructions require a ModRM byte, except for a few
instructions such as VZEROALL and VZEROUPPER."
Source: Intel® SDM Vol. 2A, Table 2-2 (See Vol. 2A, PDF page 2-13)
Approved-By: Tom de Vries <tdevries@suse.de>
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|
On x86_64-freebsd, I ran into trouble with test-case
gdb.dwarf2/macro-source-path-clang14-dw4.exp (and similar), and I managed to
reproduce the problem on x86_64-linux by making dwarf2_support return 0.
The failure looks like:
...
UNSUPPORTED: $exp: require failed: dwarf2_support
UNRESOLVED: $exp: testcase aborted due to invalid command name: do_test
ERROR: tcl error sourcing $exp.
...
I fixed a similar problem in commit 3e488d8ccd0 ("[gdb/testsuite] Fix
gdb.dwarf2/dw-form-strx-out-of-bounds.exp with make-check-all.sh").
Fix this by moving "require dwarf2_support" from
gdb.dwarf2/macro-source-path.exp.tcl to the files including it.
Tested on x86_64-linux.
|
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On s390x, a big-endian machine, I'm seeing these test failures:
FAIL: gdb.base/dump.exp: array as memory, tekhex; file restored ok
FAIL: gdb.base/dump.exp: array as memory, tekhex; value restored ok
FAIL: gdb.base/dump.exp: array as value, tekhex; file restored ok
FAIL: gdb.base/dump.exp: array as value, tekhex; value restored ok
FAIL: gdb.base/dump.exp: array copy, tekhex; file restored ok
FAIL: gdb.base/dump.exp: array copy, tekhex; value restored ok
FAIL: gdb.base/dump.exp: array partial, tekhex; file restored ok
FAIL: gdb.base/dump.exp: array partial, tekhex; value restored ok
FAIL: gdb.base/dump.exp: dump array as memory, tekhex
FAIL: gdb.base/dump.exp: dump array as value, tekhex
FAIL: gdb.base/dump.exp: dump struct as memory, tekhex
FAIL: gdb.base/dump.exp: dump struct as value, tekhex
FAIL: gdb.base/dump.exp: reload array as memory, tekhex; value restored ok
FAIL: gdb.base/dump.exp: reload array as value, tekhex; value restored ok
FAIL: gdb.base/dump.exp: reload struct as memory, tekhex; value restored ok
FAIL: gdb.base/dump.exp: reload struct as value, tekhex; value restored ok
FAIL: gdb.base/dump.exp: struct as memory, tekhex; file restored ok
FAIL: gdb.base/dump.exp: struct as memory, tekhex; value restored ok
FAIL: gdb.base/dump.exp: struct as value, tekhex; file restored ok
FAIL: gdb.base/dump.exp: struct as value, tekhex; value restored ok
FAIL: gdb.base/dump.exp: struct copy, tekhex; file restored ok
FAIL: gdb.base/dump.exp: struct copy, tekhex; value restored ok
It turns out that there's a subtle bug in move_section_contents in
bfd/tekhex.c. The bug is that when attempting to write a buffer that
starts with a zero byte, the function will return false, an error
condition, without writing anything. But it also doesn't set
bfd_error, so GDB ends up displaying whatever the last unrelated error
was, e.g.:
warning: writing dump file '.../intstr1.tekhex' (No such file or directory)
When I investigated this, the bfd error was set during failure to
open a separate debug file for the test case, which is totally
unrelated to this problem.
The reason this fails on big endian machines is that the test case
writes out structs and arrays of int initialized to small values. On
little endian machines, the small integer is the first byte, so the
error doesn't occur. On big endian machines, a zero byte occurs
first, triggering the error.
On the GDB side of things, I've made a one line change to the test
case to cause the error to also happen on little endian machines. I
simply shift value of the first field in the struct left by 16 bits.
That leaves at least one zero byte on both sides of the non-zero part
of the int. I shifted it by 16 because, for a moment, there was a
question in my mind about what would happen with a second zero byte,
but it turns out that it's not a problem.
On the bfd side of things, take a look at move_section_contents() and
find_chunk() in tekhex.c. The scenario is this: we enter
move_section_contents with locationp pointing at a character buffer
whose first byte is zero. The 'get' parameter is false, i.e. we're
writing, not reading. The other critical fact is that the
abfd->tdata.tekhex_data->data is NULL (0).
I'm going to go through the execution path pretty much line by line
with commentary below the line(s) just executed.
char *location = (char *) locationp;
bfd_vma prev_number = 1; /* Nothing can have this as a high bit. */
I can't say that the comment provides the best explanation about
what's happening, but the gist is this: later on, chunk_number will
have it's low bits masked away, therefore no matter what it is, it
can't possibly be equal to prev_number when it's set to 1.
struct data_struct *d = NULL;
BFD_ASSERT (offset == 0);
for (addr = section->vma; count != 0; count--, addr++)
{
Set d to NULL and enter the loop.
/* Get high bits of address. */
bfd_vma chunk_number = addr & ~(bfd_vma) CHUNK_MASK;
bfd_vma low_bits = addr & CHUNK_MASK;
Use CHUNK_MASK, which is 0x1fff, to obtain the chunk number, i.e.
whatever's left after masking off the low 13 bits of addr, and
low_bits, which are the low 13 bits of addr. chunk_number matters for
understanding this bug, low_bits does not. Remember that no matter
what addr is, once you mask off the low 13 bits, it can't be equal to 1.
bool must_write = !get && *location != 0;
!get is true, *location != 0 is false, therefore the conjunction is
false, and furthermore must_write is false. I.e. even though we are
writing, we don't transfer zero bytes to the chunk - this is why
must_write is false. (The reason this works is that a chunk, once
allocated, is zero'd as part of the allocation using bfd_zalloc.
Therefore we can skip transferring zero bytes and, if enough of them
are skipped one after another, chunk allocation simply doesn't happen.
That's a good thing.)
if (chunk_number != prev_number || (!d && must_write))
For the reason provided above, chunk_number != prev_number is true.
The other part of the disjunction doesn't matter since the first part
is true. This means that the if-block is entered.
/* Different chunk, so move pointer. */
d = find_chunk (abfd, chunk_number, must_write);
find_chunk is entered with must_write set to false. Now, remember
where we left off here, because we're going to switch to find_chunk.
static struct data_struct *
find_chunk (bfd *abfd, bfd_vma vma, bool create)
{
(Above 3 lines indented to distinguish code from commentary.)
When we enter find_chunk, create is false because must_write was false.
struct data_struct *d = abfd->tdata.tekhex_data->data;
d is set to NULL since abfd->tdata.texhex_data->data is NULL (one of
the conditions for the scenario).
vma &= ~CHUNK_MASK;
while (d && (d->vma) != vma)
d = d->next;
d is NULL, so the while loop doesn't execute.
if (!d && create)
...
d is NULL so !d is true, but create is false, so the condition
evaluates to false, meaning that the if-block is skipped.
return d;
find_chunk returns NULL, since d is NULL.
Back in move_section_contents:
if (!d)
return false;
d is NULL (because that's what find_chunk returned), so
move_section_contents returns false at this point.
Note that find_section_contents has allocated no memory, nor even
tried to transfer any bytes beyond the first (zero) byte. This
is a bug.
The key to understanding this bug is to observe that find_chunk can
return NULL to indicate that no chunk was found. This is especially
important for the read (get=true) case. But it can also be NULL
to indicate a memory allocation error. I toyed around with the
idea of using a different value to distinguish these cases, i.e.
something like (struct data_struct *) -1, but although bfd contains
plenty of code where -1 is used to indicate various interesting
conditions for scalars, there's no prior art where this is done
for a pointer. Therefore the idea was discarded in favor of
modifying this statement:
if (!d)
return false;
to:
if (!d && must_write)
return false;
This works because, in find_chunk, the only way to return a NULL
memory allocation error is for must_write / create to be true. When
it is true, if bfd_zalloc successfully allocates a chunk, then that
(non-NULL) chunk will be returned at the end of the function. When it
fails, it'll return NULL early. The point is that when bfd_zalloc()
fails and returns NULL, must_write (in move_section_contents) / create
(in find_chunk) HAD to be true. That provides us with an easy test
back in move_section_contents to distinguish a memory-allocation-NULL
from a block-not-found-NULL.
The other NULL return case happens when the end of the function is
reached when either searching for a chunk to read or attempting to
find a chunk to write when abfd->tdata.tekhex_data->data is NULL. But
for the latter case, must_write was false, which does not (now, with
the above fix) trigger the early return of false.
(Alan Modra approved the bfd/tekhex.c change.)
Approved-By: Simon Marchi <simon.marchi@efficios.com> (GDB)
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Change-Id: I3d39ee767a3b2b743b3a90386fb30a6703e9733e
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We can't put a breakpoint in the middle of a ll/sc atomic sequence,
handle the instructions sc.q, llacq.{w/d}, screl.{w/d} newly added
in the LoongArch Reference Manual v1.10 so a ll/sc atomic sequence
using them won't loop forever being debugged.
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
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This commit allows gdb.Color objects to be used to style output from
GDB commands written in Python, and the styled output should work
correctly with pagination.
There are two parts to fixing this:
First, GDB needs to be able to track the currently applied style
within the page_file class. This means that style changes need to be
achieved with calls to pager_file::emit_style_escape.
Now usually, GDB does this by calling something like fprintf_styled,
which takes care to apply the style for us. However, that's not
really an option here as a gdb.Color isn't a full style, and as the
gdb.Color object is designed to be converted directly into escape
sequences that can then be printed, we really need a solution that
works with this approach.
However pager_file::puts already has code in place to handle escape
sequences. Right now all this code does is spot the escape sequence
and append it to the m_wrap_buffer. But in this commit I propose that
we go one step further, parse the escape sequence back into a
ui_file_style object in pager_file::puts, and then we can call
pager_file::emit_style_escape.
If the parsing doesn't work then we can just add the escape sequence
to m_wrap_buffer as we did before.
But wait, how can this work if a gdb.Color isn't a full style? Turns
out that's not a problem. We only ever emit the escape sequence for
those parts of a style that need changing, so a full style that sets
the foreground color will emit the same escape sequence as a gdb.Color
for the foreground. When we convert the escape sequence back into a
ui_file_style, then we get a style with everything set to default,
except the foreground color.
I had hoped that this would be all that was needed. But unfortunately
this doesn't work because of the second problem...
... the implementation of the Python function gdb.write() calls
gdb_printf(), which calls gdb_vprintf(), which calls ui_file::vprintf,
which calls ui_out::vmessage, which calls ui_out::call_do_message, and
finally we reach cli_ui_out::do_message. This final do_message
function does this:
ui_file *stream = m_streams.back ();
stream->emit_style_escape (style);
stream->puts (str.c_str ());
stream->emit_style_escape (ui_file_style ());
If we imagine the case where we are emitting a style, triggered from
Python like this:
gdb.write(gdb.Color('red').escape_sequence(True))
the STYLE in this case will be the default ui_file_style(), and STR
will hold the escape sequence we are writing.
After the first change, where pager_file::puts now calls
pager_file::emit_style_escape, the current style of STREAM will have
been updated. But this means that the final emit_style_escape will
now restore the default style.
The fix for this is to avoid using the high level gdb_printf from
gdb.write(), and instead use gdb_puts instead. The gdb_puts function
doesn't restore the default style, which means our style modification
survives.
There's a new test included. This test includes what appears like a
pointless extra loop (looping over a single value), but this makes
sense given the origin of this patch. I've pulled this commit from a
longer series:
https://inbox.sourceware.org/gdb-patches/cover.1755080429.git.aburgess@redhat.com
I want to get this bug fix merged before GDB 17 branches, but the
longer series is not getting reviews, so for now I'm just merging this
one fix. Once the rest of the series gets merged, I'll be extending
the test, and the loop (mentioned above) will now loop over more
values.
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I noticed an out-of-date comment in rust-parse.c.
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