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Tom de Vries noticed that a patch in the DWARF scanner rewrite series
caused a regression in parallel_for_each -- it started crashing in the
case where the number of threads is 0 (there was an unchecked use of
"n-1" that was used to size an array).
He also pointed out that there were no tests of parallel_for_each.
This adds a few tests of parallel_for_each, primarily testing that
different settings for the number of threads will work. This test
catches the bug that he found in that series.
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I wanted to see how many threads gdb thought it was using, but
"maint show worker-threads" only reported "unlimited". This patch
adds a show function so that it will now report the number of threads
gdb has started.
Regression tested on x86-64 Fedora 34.
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With current gdb we run into:
...
$ gdb -batch '' ''
: No such file or directory.
pathstuff.cc:132: internal-error: \
gdb::unique_xmalloc_ptr<char> gdb_abspath(const char*): \
Assertion `path != NULL && path[0] != '\0'' failed.
...
Fix this by skipping the call to gdb_abspath in core_target_open in the
empty-string case, such that we have instead:
...
$ gdb -batch '' ''
: No such file or directory.
: No such file or directory.
$
...
Tested on x86_64-linux.
gdb/ChangeLog:
2021-08-30 Tom de Vries <tdevries@suse.de>
PR cli/28290
* gdb/corelow.c (core_target_open): Skip call to gdb_abspath in the
empty-string case.
gdb/testsuite/ChangeLog:
2021-08-30 Tom de Vries <tdevries@suse.de>
PR cli/28290
* gdb.base/batch-exit-status.exp: Add gdb '' and gdb '' '' tests.
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The current syntax of proc arange is:
...
proc arange { arange_start arange_length {comment ""} {seg_sel ""} } {
...
and a typical call looks like:
...
arange $start $len
...
This style is somewhat annoying because if you want to specify the last
parameter, you need to give the default values of all the other optional ones
before as well:
...
arange $start $len "" $seg_sel
...
Update the syntax to:
...
proc arange { options arange_start arange_length } {
parse_options {
{ comment "" }
{ seg_sel "" }
}
...
such that a typical call looks like:
...
arange {} $start $len
...
and a call using seg_sel looks like:
...
arange {
seg_sel $seg_sel
} $start $len
...
Also update proc aranges, which already has an options argument, to use the
new proc parse_options.
Tested on x86_64-linux.
Co-Authored-By: Simon Marchi <simon.marchi@polymtl.ca>
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When comparing the sizes of the index files generated for shlib
outputs/gdb.dwarf2/dw2-zero-range/shr1.sl, I noticed a large difference
between .debug_names:
...
$ gdb -q -batch $shlib -ex "save gdb-index -dwarf-5 ."
$ du -b -h shr1.sl.debug_names shr1.sl.debug_str
61 shr1.sl.debug_names
0 shr1.sl.debug_str
...
and .gdb_index:
...
$ gdb -q -batch $shlib -ex "save gdb-index ."
$ du -b -h shr1.sl.gdb-index
8.2K shr1.sl.gdb-index
...
The problem is that the .gdb_index contains a non-empty symbol table with only
empty entries.
Fix this by making the symbol table empty, such that we have instead:
...
$ du -b -h shr1.sl.gdb-index
184 shr1.sl.gdb-index
...
Tested on x86_64-linux.
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Before commit 5ef670d81fd "[gdb/testsuite] Add dummy start and end CUs in
dwarf assembly" we had in exec outputs/gdb.dlang/watch-loc/watch-loc a D
compilation unit at offset 0xc7:
...
Compilation Unit @ offset 0xc7:
Length: 0x4c (32-bit)
Version: 4
Abbrev Offset: 0x64
Pointer Size: 8
<0><d2>: Abbrev Number: 2 (DW_TAG_compile_unit)
<d3> DW_AT_language : 19 (D)
...
with a corresponding .debug_aranges entry:
...
Offset into .debug_info: 0xc7
Pointer Size: 4
Segment Size: 0
Address Length
004004a7 0000000b
00000000 00000000
...
After that commit we have a dummy CU at offset 0xc7 and the D compilation unit
at offset 0xd2:
...
Compilation Unit @ offset 0xc7:
Length: 0x7 (32-bit)
Version: 4
Abbrev Offset: 0x64
Pointer Size: 8
Compilation Unit @ offset 0xd2:
Length: 0x4c (32-bit)
Version: 4
Abbrev Offset: 0x65
Pointer Size: 8
<0><dd>: Abbrev Number: 2 (DW_TAG_compile_unit)
<de> DW_AT_language : 19 (D)
...
while the .debug_aranges entry still points to 0xc7.
The problem is that the test-case uses a hack (quoting from
commit 75f06e9dc59):
...
[ Note: this is a non-trivial test-case. The file watch-loc-dw.S contains a
.debug_info section, but not an .debug_aranges section or any actual code.
The file watch-loc.c contains code and a .debug_aranges section, but no other
debug section. So, the intent for the .debug_aranges section in watch-loc.c
is to refer to a compilation unit in the .debug_info section in
watch-loc-dw.S. ]
...
and adding the dummy CU caused that hack to stop working.
Fix this by moving the generation of .debug_aranges from watch-loc.c to
watch-loc.exp, such that we have:
...
Offset into .debug_info: 0xd2
Pointer Size: 4
Segment Size: 0
Address Length
004004a7 0000000b
00000000 00000000
...
Tested on x86_64-linux.
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A best practise for DWARF [1] is to generate .debug_aranges entries for CUs
even if they have no address range.
Generate .debug_arange entries for the dummy CUs added by the DWARF assembler.
Tested on x86_64-linux.
[1] http://wiki.dwarfstd.org/index.php?title=Best_Practices
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A couple of test-cases fail when run with target board cc-with-debug-names due
to missing .debug_aranges entries for the CUs added by the dwarf assembler.
Add a .debug_aranges entry for those CUs.
Tested on x86_64-linux.
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Add a proc aranges such that we can generate .debug_aranges sections in dwarf
assembly using:
...
cu { label cu_label } {
...
}
aranges {} cu_label {
arange $addr $len [<comment>] [$segment_selector]
}
...
Tested on x86_64-linux.
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We can use current dwarf assembly infrastructure to declare a label that marks
the start of the CU header:
...
declare_labels header_start_cu_a
_section ".debug_info"
header_start_cu_a : cu {} {
}
_section ".debug_info"
header_start_cu_b : cu {} {
}
...
on the condition that we switch to the .debug_info section before, which makes
this style of use fragile.
Another way to achieve the same is to use the label as generated by the cu
proc itself:
...
variable _cu_label
cu {} {
}
set header_start_cu_a $_cu_label
cu {} {
}
set header_start_cu_b $_cu_label
...
but again that seems fragile given that adding a new CU inbetween will
silently result in the wrong value for the label.
Add a label option to proc cu such that we can simply do:
...
cu { label header_start_cu_a } {
}
cu { label header_start_cu_b } {
}
...
Tested on x86_64-linux.
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I spotted a couple of stray newlines that were left at the end of
debug message during conversion to the new debug output scheme. These
messages are part of the 'set debug lin-lwp 1' output.
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PR symtab/28160 and PR symtab/27893 concern GDB crashes in the test
suite when using the "fission" target board. They are both caused by
the patches that merge the list of CUs with the list of TUs (and to a
lesser degree by the patches to share DWARF data across objfiles), and
the underlying issue is the same: it turns out that reading a DWO can
cause new type units to be created. This means that the list of
dwarf2_per_cu_data objects depends on precisely which CUs have been
expanded. However, because the type units can be created while
expanding a CU means that the vector of CUs can expand while it is
being iterated over -- a classic mistake. Also, because a TU can be
added later, it means the resize_symtabs approach is incorrect.
This patch fixes resize_symtabs by removing it, and having set_symtab
resize the vector on demand. It fixes the iteration problem by
introducing a safe (index-based) iterator and changing the relevant
spots to use it.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28160
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27893
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dw2-ranges-overlap.exp creates a program where a psymtab has two
address ranges, and a function without debug info whose address is
between these two ranges. Then it sets a breakpoint on this function
and runs to it, expecting that the language should remain "auto; c"
when stopped.
However, this test case also has a "main" function described (briefly)
in the DWARF, and this function is given language C++. Also, a
breakpoint stop sets the current language to the language that was
used when setting the breakpoint.
My new DWARF scanner decides that this "main" is the main program and
sets the current language to C++ at startup, causing this test to
fail.
This patch fixes the test in a simple way, by introducing a new
function that takes the place of "main" in the DWARF. I think this
still exercises the original problem, but also avoids problems with my
branch.
It seemed safe to me to submit this separately.
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With trying to load a non-executable file into gdb, we run into PR26880:
...
$ gdb -q -batch test.c
"0x7ffc87bfc8d0s": not in executable format: \
file format not recognized
...
The problem is caused by using %ps in combination with the error function
(note that confusingly, it does work in combination with the warning
function).
Fix this by using plain "%s" instead.
Tested on x86_64-linux.
gdb/ChangeLog:
2021-08-22 Tom de Vries <tdevries@suse.de>
PR gdb/26880
* gdb/exec.c (exec_file_attach): Use %s instead of %ps in call to
error function.
gdb/testsuite/ChangeLog:
2021-08-22 Tom de Vries <tdevries@suse.de>
PR gdb/26880
* gdb.base/non-executable.exp: New file.
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The test-case gdb.dwarf2/dw2-ranges.exp is the only one in the gdb testsuite
that uses gas-generated stabs.
While the use seems natural alongside the use of gas-generated dwarf in the
same test-case, there are a few known issues, filed on the gdb side as:
- PR symtab/12497 - "stabs: PIE relocation does not work"
- PR symtab/28221 - "[readnow, stabs] FAIL: gdb.dwarf2/dw2-ranges.exp: \
info line func"
and on the gas side as:
- PR gas/28233 - "[gas, --gstabs] Generate stabs more similar to gcc"
The test-case contains a KFAIL for PR12497, but it's outdated and fails to
trigger.
The intention of the test-case is to test gas-generated dwarf, and using
gcc-generated stabs instead of gas-generated stabs works fine.
Supporting compiler-generated stabs is already a corner-case for gdb, and
there's no current commitment/incentive to support/workaround gas-generated
stabs, which can be considered a corner-case of a corner-case.
Work around these problem by using compiler-generated stabs in the test-case.
Tested on x86_64-linux.
gdb/testsuite/ChangeLog:
2021-08-22 Tom de Vries <tdevries@suse.de>
* gdb.dwarf2/dw2-ranges.exp: Use compiler-generated stabs.
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Say one compiles a hello.c:
...
$ gcc -g hello.c
...
On openSUSE Leap 15.2 and Tumbleweed, the CU for hello.c is typically not the
first in .debug_info, nor the last, due to presence of debug information in
objects for sources like:
- ../sysdeps/x86_64/start.S
- init.c
- ../sysdeps/x86_64/crti.S
- elf-init.c
- ../sysdeps/x86_64/crtn.S.
On other systems, say ubuntu 18.04.5, the CU for hello.c is typically the
first and the last in .debug_info.
This difference has caused me to find some errors in the dwarf assembly
using openSUSE, that didn't show up on other platforms.
Force the same situation on other platforms by adding a dummy start
and end CU.
Tested on x86_64-linux.
gdb/testsuite/ChangeLog:
2021-08-22 Tom de Vries <tdevries@suse.de>
PR testsuite/28235
* lib/dwarf.exp (Dwarf::dummy_cu): New proc.
(Dwarf::assemble): Add dummy start and end CU.
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When running test-case gdb.dwarf2/dw2-ranges-psym.exp with target board
-readnow, I run into:
...
(gdb) file dw2-ranges-psym^M
Reading symbols from dw2-ranges-psym...^M
Expanding full symbols from dw2-ranges-psym...^M
(gdb) set complaints 0^M
(gdb) FAIL: gdb.dwarf2/dw2-ranges-psym.exp: No complaints
...
The problem is that the regexp expects a gdb prompt immediately after the
"Reading symbols" line.
Fix this by updating the regexp.
Tested on x86_64-linux.
gdb/testsuite/ChangeLog:
2021-08-22 Tom de Vries <tdevries@suse.de>
* lib/gdb.exp (gdb_load_no_complaints): Update regexp to allow
"Expanding full symbols" Line.
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Trivial patch to use bool instead of int.
Change-Id: I9e5f8ee4305272a6671cbaaaf2f0484eff0d1ea5
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scan_dyntag is unnecessarily duplicated in solib-svr4.c and solib-dsbt.c.
Move this function to solib.c and rename it to gdb_bfd_scan_elf_dyntag.
Also add it to solib.h so it is included in both solib-svr4 and solib-dsbt.
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Add a method to set the gcc target options for the ppc64 targets.
This change sets an empty value, which allows the gcc
default values (-mcmodel=medium) be used, instead of -mcmodel=large
which is set by the default_gcc_target_options hook.
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Add methods to set the target triplet so we can
find the proper gcc when our gcc is named of
the form powerpc64{le}-<foo>-gcc or ppc64{le}-<foo>-gcc.
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If I debug a single-thread program and look at the infrun debug logs, I
see:
[infrun] start_step_over: stealing global queue of threads to step, length = 2
That makes no sense... turns out there's a buglet in
thread_step_over_chain_length, "num" should be initialized to 0. I
think this bug is a leftover from an earlier version of the code (not
merged upstream) that manually walked the list, where the first item was
implicitly counted (hence the 1).
Change-Id: I0af03aa93509aed36528be5076894dc156a0b5ce
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The r_ldsomap field is specific to Solaris (part of librtld_db), and
should never be accessed for Linux. glibc is planning to add a field
to support multiple namespaces. But there will be no r_ldsomap when
r_version is bumped to 2. Add linux_[ilp32|lp64]_fetch_link_map_offsets
to set r_ldsomap_offset to -1 and use them for Linux targets.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=28236
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On an internal test case, using an arm-elf target, commit ba5bc3e5a92
("Make DWARF evaluator return a single struct value") causes a
regression. (It doesn't happen for any of the other cross targets
that I test when importing upstream gdb.)
I don't know if there's an upstream gdb test case showing the same
problem... I can only really run native tests with dejagnu AFAIK.
The failure manifests like this:
Breakpoint 1, file_1.export_1 (param_1=<error reading variable: Unable to access DWARF register number 64>, str=...) at [...]/file_1.adb:5
Whereas when it works it looks like:
Breakpoint 1, file_1.export_1 (param_1=99.0, str=...) at [...]/file_1.adb:5
The difference is that the new code uses the passed-in gdbarch,
whereas the old code used the frame's gdbarch, when handling
DWARF_VALUE_REGISTER.
This patch restores the use of the frame's arch.
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Commit 0579205aec4 ("Simplify dwarf_expr_context class interface")
caused a regression in the internal AdaCore test suite. I didn't try
to reproduce this with the GDB test suite, but the test is identical
to gdb.dwarf2/dynarr-ptr.exp.
The problem is that this change:
case DW_OP_push_object_address:
/* Return the address of the object we are currently observing. */
- if (this->data_view.data () == nullptr
- && this->obj_address == 0)
+ if (this->m_addr_info == nullptr)
... slightly changes the logic here. In particular, it's possible for
the caller to pass in a non-NULL m_addr_info, but one that looks like:
(top) p *this.m_addr_info
$15 = {
type = 0x29b7a70,
valaddr = {
m_array = 0x0,
m_size = 0
},
addr = 0,
next = 0x0
}
In this case, an additional check is needed. With the current code,
what happens instead is that the computation computes an incorrect
address -- but one that does not fail in read_memory, due to the
precise memory map of the embedded target in question.
This patch restores the old logic.
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As breakpoint_modified observer is currently notified upon breakpoint stop
before handling auto-disabling when enable count is reached, the observer
is never notified of the disabling.
The problem affects:
- The MI interpreter enabled= value when reporting =breakpoint-modified
- A Python event handler for breakpoint_modified using the "enabled"
member of its parameter
- insight: breakpoint GUI window is not properly updated upon auto-disable
This patch moves the observer notification after the auto-disabling
code and implements corresponding tests for the MI and Python cases.
Fixes https://sourceware.org/bugzilla/show_bug.cgi?id=23336
Change-Id: I0c50df4789334071e5390cb46b3ca0d4a7f83c61
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While working on the testsuite, I ended up noticing that GDB fails to
produce a full backtrace from a thread waiting in pthread_join. When
selecting the waiting thread and using the 'bt' command, the following
result can be observed:
(gdb) bt
#0 0x0000003ff7fccd20 in __futex_abstimed_wait_common64 () from /lib/riscv64-linux-gnu/libpthread.so.0
#1 0x0000003ff7fc43da in __pthread_clockjoin_ex () from /lib/riscv64-linux-gnu/libpthread.so.0
Backtrace stopped: frame did not save the PC
On my platform, I do not have debug symbols for glibc, so I need to rely
on prologue analysis in order to unwind stack.
Here is what the function prologue looks like:
(gdb) disassemble __pthread_clockjoin_ex
Dump of assembler code for function __pthread_clockjoin_ex:
0x0000003ff7fc42de <+0>: addi sp,sp,-144
0x0000003ff7fc42e0 <+2>: sd s5,88(sp)
0x0000003ff7fc42e2 <+4>: auipc s5,0xd
0x0000003ff7fc42e6 <+8>: ld s5,-2(s5) # 0x3ff7fd12e0
0x0000003ff7fc42ea <+12>: ld a5,0(s5)
0x0000003ff7fc42ee <+16>: sd ra,136(sp)
0x0000003ff7fc42f0 <+18>: sd s0,128(sp)
0x0000003ff7fc42f2 <+20>: sd s1,120(sp)
0x0000003ff7fc42f4 <+22>: sd s2,112(sp)
0x0000003ff7fc42f6 <+24>: sd s3,104(sp)
0x0000003ff7fc42f8 <+26>: sd s4,96(sp)
0x0000003ff7fc42fa <+28>: sd s6,80(sp)
0x0000003ff7fc42fc <+30>: sd s7,72(sp)
0x0000003ff7fc42fe <+32>: sd s8,64(sp)
0x0000003ff7fc4300 <+34>: sd s9,56(sp)
0x0000003ff7fc4302 <+36>: sd a5,40(sp)
As far as prologue analysis is concerned, the most interesting part is
done at address 0x0000003ff7fc42ee (<+16>): 'sd ra,136(sp)'. This stores
the RA (return address) register on the stack, which is the information
we are looking for in order to identify the caller.
In the current implementation of the prologue scanner, GDB stops when
hitting 0x0000003ff7fc42e6 (<+8>) because it does not know what to do
with the 'ld' instruction. GDB thinks it reached the end of the
prologue but have not yet reached the important part, which explain
GDB's inability to unwind past this point.
The section of the prologue starting at <+4> until <+12> is used to load
the stack canary[1], which will then be placed on the stack at <+36> at
the end of the prologue.
In order to have the prologue properly handled, this commit proposes to
add support for the ld instruction in the RISC-V prologue scanner.
I guess riscv32 would use lw in such situation so this patch also adds
support for this instruction.
With this patch applied, gdb is now able to unwind past pthread_join:
(gdb) bt
#0 0x0000003ff7fccd20 in __futex_abstimed_wait_common64 () from /lib/riscv64-linux-gnu/libpthread.so.0
#1 0x0000003ff7fc43da in __pthread_clockjoin_ex () from /lib/riscv64-linux-gnu/libpthread.so.0
#2 0x0000002aaaaaa88e in bar() ()
#3 0x0000002aaaaaa8c4 in foo() ()
#4 0x0000002aaaaaa8da in main ()
I have had a look to see if I could reproduce this easily, but in my
simple testcases using '-fstack-protector-all', the canary is loaded
after the RA register is saved. I do not have a reliable way of
generating a prologue similar to the problematic one so I forged one
instead.
The testsuite have been run on riscv64 ubuntu 21.01 with no regression
observed.
[1] https://en.wikipedia.org/wiki/Buffer_overflow_protection#Canaries
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Philippe Blain pointed out that the gdb documentation does not mention
that Pygments may be used for source highlighting. This patch updates
the docs to reflect how highlighting is actually done.
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I noticed that gdbarch_selftest::operator() leaked the value returned by
gdbarch_printable_names. Make gdbarch_printable_names return an
std::vector and update callers. That makes it easier for everyone
involved, less manual memory management.
Change-Id: Ia8fc028bdb91f787410cca34f10bf3c5a6da1498
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The test steps into func2 and than does an up to get back to the previous
frame. The test checks that the line number you are at after the up command
is greater than the line where the function was called from. The
assembly/codegen for the powerpc target includes a NOP after the
branch-link.
func2 (); /* Break at func2 call site. /
10000694: 59 00 00 48 bl 100006ec
10000698: 00 00 00 60 nop
return 0; / Break to end. */
1000069c: 00 00 20 39 li r9,0
The PC at the instruction following the branch-link is 0x10000698 which
GDB.find_pc_line() maps to the same line number as the bl instruction.
GDB did move past the branch-link location thus making forward progress.
The following proposed fix adds an additional PC check to see if forward
progress was made. The line test is changed from greater than to greater
than or equal.
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As CSKY arch has not parsed target-description.xml in csky_gdbarch_init,
when a remote server, like csky-qemu or gdbserver, send a target-description.xml
to gdb, tdesc_has_registers will return ture, but tdesc_register_name (gdbarch, 0)
will return NULL, so a cmd "info registers r0" will not work.
Function of parsing target-description.xml will be add later for CSKY arch,
now it is temporarily removed to allow me to do other supported tests.
2021-07-15 Jiangshuai Li <jiangshuai_li@c-sky.com>
* csky-tdep.c : not using tdesc funtions in csky_register_name
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As discussed previously, a.out support is now quite deprecated, and in
some cases removed, in both Binutils itself and NetBSD, so this legacy
default makes little sense. `netbsdelf*` and `netbsdaout*` still work
allowing the user to be explicit about there choice. Additionally, the
configure script warns about the change as Nick Clifton requested.
One possible concern was the status of NetBSD on NS32K, where only a.out
was supported. But per [1] NetBSD has removed support, and if it were to
come back, it would be with ELF. The binutils implementation is
therefore marked obsolete, per the instructions in the last message.
With that patch and this one applied, I have confirmed the following:
--target=i686-unknown-netbsd
--target=i686-unknown-netbsdelf
builds completely
--target=i686-unknown-netbsdaout
properly fails because target is deprecated.
--target=vax-unknown-netbsdaout builds completely except for gas, where
the target is deprecated.
[1]: https://mail-index.netbsd.org/tech-toolchain/2021/07/19/msg004025.html
---
bfd/config.bfd | 43 +++++++++++++--------
bfd/configure.ac | 5 +--
binutils/testsuite/binutils-all/nm.exp | 2 +-
binutils/testsuite/lib/binutils-common.exp | 7 +---
config/picflag.m4 | 4 +-
gas/configure.tgt | 9 +++--
gas/testsuite/gas/arm/blx-bl-convert.d | 2 +-
gas/testsuite/gas/arm/blx-local-thumb.d | 2 +-
gas/testsuite/gas/sh/basic.exp | 2 +-
gdb/configure.host | 34 +++++++----------
gdb/configure.tgt | 2 +-
gdb/testsuite/gdb.asm/asm-source.exp | 6 +--
intl/configure | 2 +-
ld/configure.tgt | 44 +++++++++++-----------
ld/testsuite/ld-arm/arm-elf.exp | 4 +-
ld/testsuite/ld-elf/elf.exp | 2 +-
ld/testsuite/ld-elf/shared.exp | 4 +-
libiberty/configure | 4 +-
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Currently, when GDB hits an internal error, and the user selects to
dump core, the recently added feature to write a backtrace to the
console will kick in, and print a backtrace as well as dumping the
core.
This was certainly not my intention when adding the backtrace on fatal
signal functionality, this feature was intended to produce a backtrace
when GDB crashes due to some fatal signal, internal errors should have
continued to behave as they did before, unchanged.
In this commit I set the signal disposition of SIGABRT back to SIG_DFL
just prior to the call to abort() that GDB uses to trigger the core
dump, this prevents GDB reaching the code that writes the backtrace to
the console.
I've also added a test that checks we don't see a backtrace on the
console after an internal error.
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Register handlers for SIGBUS, SIGFPE, and SIGABRT. All of these
signals are setup as fatal signals that will cause GDB to terminate.
However, by passing these signals through the handle_fatal_signal
function, a user can arrange to see a backtrace when GDB
terminates (see maint set backtrace-on-fatal-signal).
In normal use of GDB there should be no user visible changes after
this commit. Only if GDB terminates with one of the above signals
will GDB change slightly, potentially printing a backtrace before
aborting.
I've added new tests for SIGFPE, SIGBUS, and SIGABRT.
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This commit adds a new maintenance feature, the ability to print
a (limited) backtrace if GDB dies due to a fatal signal.
The backtrace is produced using the backtrace and backtrace_symbols_fd
functions which are declared in the execinfo.h header, and both of
which are async signal safe. A configure check has been added to
check for these features, if they are not available then the new code
is not compiled into GDB and the backtrace will not be printed.
The motivation for this new feature is to aid in debugging GDB in
situations where GDB has crashed at a users site, but the user is
reluctant to share core files, possibly due to concerns about what
might be in the memory image within the core file. Such a user might
be happy to share a simple backtrace that was written to stderr.
The production of the backtrace is on by default, but can switched off
using the new commands:
maintenance set backtrace-on-fatal-signal on|off
maintenance show backtrace-on-fatal-signal
Right now, I have hooked this feature in to GDB's existing handling of
SIGSEGV only, but this will be extended to more signals in a later
commit.
One additional change I have made in this commit is that, when we
decide GDB should terminate due to the fatal signal, we now
raise the same fatal signal rather than raising SIGABRT.
Currently, this is only effecting our handling of SIGSEGV. So,
previously, if GDB hit a SEGV then we would terminate GDB with a
SIGABRT. After this commit we will terminate GDB with a SIGSEGV.
This feels like an improvement to me, we should still get a core dump,
but in many shells, the user will see a more specific message once GDB
exits, in bash for example "Segmentation fault" rather than "Aborted".
Finally then, here is an example of the output a user would see if GDB
should hit an internal SIGSEGV:
Fatal signal: Segmentation fault
----- Backtrace -----
./gdb/gdb[0x8078e6]
./gdb/gdb[0x807b20]
/lib64/libpthread.so.0(+0x14b20)[0x7f6648c92b20]
/lib64/libc.so.6(__poll+0x4f)[0x7f66484d3a5f]
./gdb/gdb[0x1540f4c]
./gdb/gdb[0x154034a]
./gdb/gdb[0x9b002d]
./gdb/gdb[0x9b014d]
./gdb/gdb[0x9b1aa6]
./gdb/gdb[0x9b1b0c]
./gdb/gdb[0x41756d]
/lib64/libc.so.6(__libc_start_main+0xf3)[0x7f66484041a3]
./gdb/gdb[0x41746e]
---------------------
A fatal error internal to GDB has been detected, further
debugging is not possible. GDB will now terminate.
This is a bug, please report it. For instructions, see:
<https://www.gnu.org/software/gdb/bugs/>.
Segmentation fault (core dumped)
It is disappointing that backtrace_symbols_fd does not actually map
the addresses back to symbols, this appears, in part, to be due to GDB
not being built with -rdynamic as the manual page for
backtrace_symbols_fd suggests, however, even when I do add -rdynamic
to the build of GDB I only see symbols for some addresses.
We could potentially look at alternative libraries to provide the
backtrace (e.g. libunwind) however, the solution presented here, which
is available as part of glibc is probably a good baseline from which
we might improve things in future.
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The async_init_signals has, for some time, dealt with async and sync
signals, so removing the async prefix makes sense I think.
Additionally, as pointed out by Pedro:
.....
The comments relating to SIGTRAP and SIGQUIT within this function are
out of date.
The comments for SIGTRAP talk about the signal disposition (SIG_IGN)
being passed to the inferior, meaning the signal disposition being
inherited by GDB's fork children. However, we now call
restore_original_signals_state prior to forking, so the comment on
SIGTRAP is redundant.
The comments for SIGQUIT are similarly out of date, further, the
comment on SIGQUIT talks about problems with BSD4.3 and vfork,
however, we have not supported BSD4.3 for several years now.
Given the above, it seems that changing the disposition of SIGTRAP is
no longer needed, so I've deleted the signal() call for SIGTRAP.
Finally, the header comment on the function now called
gdb_init_signals was getting quite out of date, so I've updated it
to (hopefully) better reflect reality.
There should be no user visible change after this commit.
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This commit fixes the smallest of small possible bug related to signal
handling. If we look in async_init_signals we see code like this:
signal (SIGQUIT, handle_sigquit);
sigquit_token =
create_async_signal_handler (async_do_nothing, NULL, "sigquit");
Then if we look in handle_sigquit we see code like this:
mark_async_signal_handler (sigquit_token);
signal (sig, handle_sigquit);
Finally, in mark_async_signal_handler we have:
async_handler_ptr->ready = 1;
Where async_handler_ptr will be sigquit_token.
What this means is that if a SIGQUIT arrive in async_init_signals
after handle_sigquit has been registered, but before sigquit_token has
been initialised, then GDB will most likely crash.
The chance of this happening is tiny, but fixing this is trivial, just
ensure we call create_async_signal_handler before calling signal, so
lets do that.
There are no tests for this. Trying to land a signal in the right
spot is pretty hit and miss. I did try changing the current HEAD GDB
like this:
signal (SIGQUIT, handle_sigquit);
raise (SIGQUIT);
sigquit_token =
create_async_signal_handler (async_do_nothing, NULL, "sigquit");
And confirmed that this did result in a crash, after my change I tried
this:
sigquit_token =
create_async_signal_handler (async_do_nothing, NULL, "sigquit");
signal (SIGQUIT, handle_sigquit);
raise (SIGQUIT);
And GDB now starts up just fine.
gdb/ChangeLog:
* event-top.c (async_init_signals): For each signal, call signal
only after calling create_async_signal_handler.
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GDB's SIGFPE handling is broken, this is PR gdb/16505 and
PR gdb/17891.
We currently try to use an async event token to process SIGFPE. So,
when a SIGFPE arrives the signal handler calls
mark_async_signal_handler then returns, effectively ignoring the
signal (for now).
The intention is that later the event loop will see that the async
token associated with SIGFPE has been marked and will call the async
handler, which just throws an error.
The problem is that SIGFPE is not safe to ignore. Ignoring a
SIGFPE (unless it is generated artificially, e.g. by raise()) is
undefined behaviour, after ignoring the signal on many targets we
return to the instruction that caused the SIGFPE to be raised, which
immediately causes another SIGFPE to be raised, we get stuck in an
infinite loop. The behaviour is certainly true on x86-64.
To view this behaviour I simply added some dummy code to GDB that
performed an integer divide by zero, compiled this on x86-64
GNU/Linux, ran GDB and saw GDB hang.
In this commit, I propose to remove all special handling of SIGFPE and
instead just let GDB make use of the default SIGFPE action, that is,
to terminate the process.
The only user visible change here should be:
- If a user sends a SIGFPE to GDB using something like kill,
previously GDB would just print an error and remain alive, now GDB
will terminate. This is inline with what happens if the user
sends GDB a SIGSEGV from kill though, so I don't see this as an
issue.
- If a bug in GDB causes a real SIGFPE, previously the users GDB
session would hang. Now the GDB session will terminate. Again,
this is inline with what happens if GDB receives a SIGSEGV due to
an internal bug.
In bug gdb/16505 there is mention that it would be nice if GDB did
more than just terminate when receiving a fatal signal. I haven't
done that in this commit, but later commits will move in that
direction.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=16505
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=17891
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I noticed that the fission-reread.exp test case can cause a complaint
when run with --target_board=cc-with-debug-names:
warning: Section .debug_aranges in [...]/fission-reread has duplicate debug_info_offset 0x0, ignoring .debug_aranges.
The bug here is that this executable has both .debug_info and
.debug_types, and both have a CU at offset 0x0. This triggers the
duplicate warning.
Because .debug_types doesn't provide any address ranges, these CUs can
be ignored. That is, this bug turns out to be another regression from
the info/types merger patch.
This patch fixes the problem by having this loop igore type units.
fission-reread.exp is updated to test for the bug.
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While debugging another patch series, I wanted to dump an addrmap. I
came up with this patch, which generalizes the addrmap-dumping code
from psymtab.c and moves it to addrmap.c. psymtab.c is changed to use
the new code.
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I spotted what I think is a buglet in proceed_after_vfork_done. After a
vfork child exits or execs, we resume all the threads of the parent. To
do so, we iterate on all threads using iterate_over_threads with the
proceed_after_vfork_done callback. Each thread is resumed if the
following condition is true:
if (thread->ptid.pid () == pid
&& thread->state == THREAD_RUNNING
&& !thread->executing
&& !thread->stop_requested
&& thread->stop_signal () == GDB_SIGNAL_0)
where `pid` is the pid of the vfork parent. This is not multi-target
aware: since it only filters on pid, if there is an inferior with the
same pid in another target, we could end up resuming a thread of that
other inferior. The chances of the stars aligning for this to happen
are tiny, but still.
Fix that by iterating only on the vfork parent's threads, instead of on
all threads. This is more efficient, as we iterate on just the required
threads (inferiors have their own thread list), and we can drop the pid
check. The resulting code is also more straightforward in my opinion,
so it's a win-win.
Change-Id: I14647da72e2bf65592e82fbe6efb77a413a4be3a
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Before Guile v2.1 [1], calls to `scm_make_smob_type' implicitly added
the created class to the exports list of (oop goops); v2.1+ does not
implicitly create bindings in any modules. This means that the GDB
manual subsection documenting exported types is not quite right when GDB
is linked against Guile <v2.1 (types are exported from (oop goops))
instead of (gdb)) and incorrect when linked against Guile v2.1+ (types
are not bound to any variables at all!).
There is a range of cases in which it's necessary or convenient to be
able to refer to a GDB smob type, for instance:
- Pattern matching based on the type of a value.
- Defining GOOPS methods handling values from GDB (GOOPS methods
typically use dynamic dispatch based on the types of the arguments).
- Type-checking assertions when applying some defensive programming on
an interface.
- Generally any other situation one might encounter in a dynamically
typed language that might need some introspection.
If you're more familiar with Python, it would be quite similar to being
unable to refer to the classes exported from the GDB module (which is to
say: not crippling for the most part, but makes certain tasks more
difficult than necessary).
This commit makes a small change to GDB's smob registration machinery
to make sure registered smobs get exported from the current
module. This will likely cause warnings to the user about conflicting
exports if they load both (gdb) and (oop goops) from a GDB linked
against Guile v2.0, but it shouldn't impact functionality (and seemed
preferable to trying to un-export bindings from (oop goops) if v2.0
was detected).
[1]: This changed with Guile commit
28d0871b553a3959a6c59e2e4caec1c1509f8595
gdb/ChangeLog:
2021-06-07 George Barrett <bob@bob131.so>
* guile/scm-gsmob.c (gdbscm_make_smob_type): Export registered
smob type from the current module.
gdb/testsuite/ChangeLog:
2021-06-07 George Barrett <bob@bob131.so>
* gdb.guile/scm-gsmob.exp (test exports): Add tests to make
sure the smob types currently listed in the GDB manual get
exported from the (gdb) module.
Change-Id: I7dcd791276b48dfc9edb64fc71170bbb42a6f6e7
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I found a few .c files that rely on objfiles.h, but that only include
it indirectly, via dwarf2/read.h -> psympriv.h. If that include is
removed (something my new DWARF indexer series does), then the build
will break.
It seemed harmless and correct to add these includes now, making the
eventual series a little smaller.
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When reading a .gdb_index that contains a non-empty symbol table with only
empty entries, gdb doesn't recognize it as empty.
Fix this by recognizing that the constant pool is empty, and then setting the
symbol table to empty.
Tested on x86_64-linux.
gdb/ChangeLog:
2021-08-01 Tom de Vries <tdevries@suse.de>
PR symtab/28159
* dwarf2/read.c (read_gdb_index_from_buffer): Handle symbol table
filled with empty entries.
gdb/testsuite/ChangeLog:
2021-08-01 Tom de Vries <tdevries@suse.de>
PR symtab/28159
* gdb.dwarf2/dw2-zero-range.exp: Remove kfail.
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The way that init.c is generated does not allow for an initialization
function to be conditionally defined -- doing so will result in a link
error.
This patch fixes a build problem that arises from such a conditional
definition. It can be reproduce with --disable-unit-tests.
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In PR28004 the following warning / Internal error is reported:
...
$ gdb -q -batch \
-iex "set sysroot $(pwd -P)/repro" \
./repro/gdb \
./repro/core \
-ex bt
...
Program terminated with signal SIGABRT, Aborted.
#0 0x00007ff8fe8e5d22 in raise () from repro/usr/lib/libc.so.6
[Current thread is 1 (LWP 1762498)]
#1 0x00007ff8fe8cf862 in abort () from repro/usr/lib/libc.so.6
warning: (Internal error: pc 0x7ff8feb2c21d in read in psymtab, \
but not in symtab.)
warning: (Internal error: pc 0x7ff8feb2c218 in read in psymtab, \
but not in symtab.)
...
#2 0x00007ff8feb2c21e in __gnu_debug::_Error_formatter::_M_error() const \
[clone .cold] (warning: (Internal error: pc 0x7ff8feb2c21d in read in \
psymtab, but not in symtab.)
) from repro/usr/lib/libstdc++.so.6
...
The warning is about the following:
- in find_pc_sect_compunit_symtab we try to find the address
(0x7ff8feb2c218 / 0x7ff8feb2c21d) in the symtabs.
- that fails, so we try again in the partial symtabs.
- we find a matching partial symtab
- however, the partial symtab has a full symtab, so
we should have found a matching symtab in the first step.
The addresses are:
...
(gdb) info sym 0x7ff8feb2c218
__gnu_debug::_Error_formatter::_M_error() const [clone .cold] in \
section .text of repro/usr/lib/libstdc++.so.6
(gdb) info sym 0x7ff8feb2c21d
__gnu_debug::_Error_formatter::_M_error() const [clone .cold] + 5 in \
section .text of repro/usr/lib/libstdc++.so.6
...
which correspond to unrelocated addresses 0x9c218 and 0x9c21d:
...
$ nm -C repro/usr/lib/libstdc++.so.6.0.29 | grep 000000000009c218
000000000009c218 t __gnu_debug::_Error_formatter::_M_error() const \
[clone .cold]
...
which belong to function __gnu_debug::_Error_formatter::_M_error() in
/build/gcc/src/gcc/libstdc++-v3/src/c++11/debug.cc.
The partial symtab that is found for the addresses is instead the one for
/build/gcc/src/gcc/libstdc++-v3/src/c++98/bitmap_allocator.cc, which is
incorrect.
This happens as follows.
The bitmap_allocator.cc CU has DW_AT_ranges at .debug_rnglist offset 0x4b50:
...
00004b50 0000000000000000 0000000000000056
00004b5a 00000000000a4790 00000000000a479c
00004b64 00000000000a47a0 00000000000a47ac
...
When reading the first range 0x0..0x56, it doesn't trigger the "start address
of zero" complaint here:
...
/* A not-uncommon case of bad debug info.
Don't pollute the addrmap with bad data. */
if (range_beginning + baseaddr == 0
&& !per_objfile->per_bfd->has_section_at_zero)
{
complaint (_(".debug_rnglists entry has start address of zero"
" [in module %s]"), objfile_name (objfile));
continue;
}
...
because baseaddr != 0, which seems incorrect given that when loading the
shared library individually in gdb (and consequently baseaddr == 0), we do see
the complaint.
Consequently, we run into this case in dwarf2_get_pc_bounds:
...
if (low == 0 && !per_objfile->per_bfd->has_section_at_zero)
return PC_BOUNDS_INVALID;
...
which then results in this code in process_psymtab_comp_unit_reader being
called with cu_bounds_kind == PC_BOUNDS_INVALID, which sets the set_addrmap
argument to 1:
...
scan_partial_symbols (first_die, &lowpc, &highpc,
cu_bounds_kind <= PC_BOUNDS_INVALID, cu);
...
and consequently, the CU addrmap gets build using address info from the
functions.
During that process, addrmap_set_empty is called with a range that includes
0x9c218 and 0x9c21d:
...
(gdb) p /x start
$7 = 0x9989c
(gdb) p /x end_inclusive
$8 = 0xb200d
...
but it's called for a function at DIE 0x54153 with DW_AT_ranges at 0x40ae:
...
000040ae 00000000000b1ee0 00000000000b200e
000040b9 000000000009989c 00000000000998c4
000040c3 <End of list>
...
and neither range includes 0x9c218 and 0x9c21d.
This is caused by this code in partial_die_info::read:
...
if (dwarf2_ranges_read (ranges_offset, &lowpc, &highpc, cu,
nullptr, tag))
has_pc_info = 1;
...
which pretends that the function is located at addresses 0x9989c..0xb200d,
which is indeed not the case.
This patch fixes the first problem encountered: fix the "start address of
zero" complaint warning by removing the baseaddr part from the condition.
Same for dwarf2_ranges_process.
The effect is that:
- the complaint is triggered, and
- the warning / Internal error is no longer triggered.
This does not fix the observed problem in partial_die_info::read, which is
filed as PR28200.
Tested on x86_64-linux.
Co-Authored-By: Simon Marchi <simon.marchi@polymtl.ca>
gdb/ChangeLog:
2021-07-29 Simon Marchi <simon.marchi@polymtl.ca>
Tom de Vries <tdevries@suse.de>
PR symtab/28004
* gdb/dwarf2/read.c (dwarf2_rnglists_process, dwarf2_ranges_process):
Fix zero address complaint.
* gdb/testsuite/gdb.dwarf2/dw2-zero-range-shlib.c: New test.
* gdb/testsuite/gdb.dwarf2/dw2-zero-range.c: New test.
* gdb/testsuite/gdb.dwarf2/dw2-zero-range.exp: New file.
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[PATCH] GDB Testsuite, update compile-cplus.exp
Update the gdb.compile/compile-cplus.exp test to
handle errors generated when passing bad arguments
into the gdb-compile command.
This matches changes made to gdb.compile/compile.exp
in the past as part of
"Migrate rest of compile commands to new options framework"
e6ed716cd5514c08b9d7c469d185b1aa177dbc22
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[gdb] Handle .TOC. sections during gdb-compile for rs6000 target.
When we encounter a .TOC. symbol in the object we are loading,
we need to associate this with the .toc section in order to
properly resolve other symbols in the object. IF a .toc section
is not found, iterate the sections until we find one with the
SEC_ALLOC flag. If that also fails, fall back to using
the *ABS* section, pointed to by bfd_abs_section_ptr.
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native-extended-gdbserver
In gdb.base/attach.exp, proc do_attach_failure_tests, we attach to a
process. When then try to attach to the same process in another
inferior, expecting it to fail. We then come back to the first inferior
and try to kill it, to clean up the test. When using the
native-extended-gdbserver board, this "kill" test passes, even though it
didn't actually work:
add-inferior
[New inferior 2]
Added inferior 2 on connection 1 (extended-remote localhost:2347)
(gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: add empty inferior 2
inferior 2
[Switching to inferior 2 [<null>] (<noexec>)]
(gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: switch to inferior 2
attach 817032
Attaching to process 817032
Attaching to process 817032 failed
(gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: fail to attach again
inferior 1
[Switching to inferior 1 [process 817032] (/home/simark/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/attach/attach)]
[Switching to thread 1.1 (Thread 817032.817032)]
#0 main () at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/attach.c:19
19 while (! should_exit)
(gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: switch to inferior 1
kill
Kill the program being debugged? (y or n) y
Remote connection closed <==== That's unexpected
(gdb) PASS: gdb.base/attach.exp: do_attach_failure_tests: exit after attach failures
When the second attach fails, gdbserver seems to break the connection
(it hangs up on the existing remote target) and start listening again
for incoming connections. This is documented in PR 19558 [1].
Make the expected output regexp for the kill command tighter (it
currently accepts anything). Use "set confirm off" so we don't have to
deal with the confirmation. And to be really sure the extended-remote
target still works, try to run the inferior again after killing. The
now tests are kfail'ed when the target is gdbserver.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=19558
gdb/testsuite/ChangeLog:
* gdb.base/attach.exp (do_attach_failure_tests): Make kill
regexp tighter, run inferior after killing it. Kfail when
target is gdbserver.
Change-Id: I99c5cd3968ce2ec962ace35b016f842a243b7a0d
|
