| Age | Commit message (Collapse) | Author | Files | Lines |
|---|
|
Recent commit 32a5aa26256 ("[gdb/testsuite] Fix gdb.ada/float-bits.exp
for powerpc64le") started using command "maint print architecture", which
produces ~275 lines.
Rewrite the corresponding gdb_test_multiple to read line-by-line, to prevent
timeouts on slower test setups.
Note that this doesn't fix a timeout in the test-case on aarch64 due to:
...
gdbarch_dump: read_core_file_mappings = <0x817438>
(gdb) aarch64_dump_tdep: Lowest pc = 0x0x8000
...
Tested on x86_64-linux.
|
|
gdb.reverse/next-reverse-bkpt-over-sr.exp
The tests set a break point with the command break *func. This sets a
breakpoint on the first instruction of the function. PowerPC uses
Global Entry Points (GEP) and Local Entry Points (LEP). The first
instruction in the function is the GEP. The GEP sets up register
r2 before reaching the LEP. When the function is called with func() the
function is entered via the LEP and the test fails because GDB does not
see the breakpoint on the GEP. However, if the function is called via a
function pointer, execution begins at the GEP as the test expects.
Currently finish-reverse-bkpt.exp uses source file finish-reverse.c and
next-reverse-bpkt-over-sr.exp uses source file step-reverse.c A new
source file was created for tests finish-reverse-bkpt.exp and
next-reverse-bkpt-over-sr.exp. The new files use the new function
pointer method to call the functions so the tests will work correctly on
both PowerPC with a GEP and LEP as well as on other systems. The GEP is
the same as the LEP on non PowerPC systems.
The expect files were changed to use the new source files and to set the
initial break point for the rest of the test on the function pointer call
for the function.
This patch fixes two PowerPC test failures in each of the tests
gdb.reverse/finish-reverse-bkpt.exp and
gdb.reverse/next-reverse-bkpt-over-sr.exp.
Patch tested on PowerPC and Intel X86-64 with no regressions.
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
|
|
I noticed that windows_nat_target::interrupt calls registers_changed.
However, I don't think there's any reason to do this, because this
will happen automatically when the inferior stop is processed.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
I belatedly realized that the "the_windows_nat_target" global isn't
really necessary. It's only used in one place, where 'this' would be
simpler and clearer. This patch removes the global entirely.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
It is only used inside frame.c.
Change-Id: I44eb46a5992412f8f8b4954b2284b0ef3b549504
|
|
PR symtab/29105 shows a number of situations where symbol lookup can
result in the expansion of too many CUs.
What happens is that lookup_signed_typename will try to look up a type
like "signed int". In cooked_index_functions::expand_symtabs_matching,
when looping over languages, the C++ case will canonicalize this type
name to be "int" instead. Then this method will proceed to expand
every CU that has an entry for "int" -- i.e., nearly all of them. A
crucial component of this is that the caller, objfile::lookup_symbol,
does not do this canonicalization, so when it tries to find the symbol
for "signed int", it fails -- causing the loop to continue.
This patch fixes the problem by introducing name canonicalization for
C. The idea here is that, by making C and C++ agree on the canonical
name when a symbol name can have multiple spellings, we avoid the bad
behavior in objfile::lookup_symbol (and any other such code -- I don't
know if there is any).
Unlike C++, C only has a few situations where canonicalization is
needed. And, in particular, due to the lack of overloading (thus
avoiding any issues in linespec) and due to the way c-exp.y works, I
think that no canonicalization is needed during symbol lookup -- only
during symtab construction. This explains why lookup_name_info is not
touched.
The stabs reader is modified on a "best effort" basis.
The DWARF reader needed one small tweak in dwarf2_name to avoid a
regression in dw2-unusual-field-names.exp. I think this is adequately
explained by the comment, but basically this is a scenario that should
not occur in real code, only the gdb test suite.
lookup_signed_typename is simplified. It used to search for two
different type names, but now gdb can search just for the canonical
form.
gdb.dwarf2/enum-type.exp needed a small tweak, because the
canonicalizer turns "unsigned integer" into "unsigned int integer".
It seems better here to use the correct C type name.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29105
Tested-by: Simon Marchi <simark@simark.ca>
Reviewed-by: Andrew Burgess <aburgess@redhat.com>
|
|
This refactors cooked_index::do_finalize, reordering an 'if' to make
it a little less redundant. This change makes a subsequent patch
easier to read.
Reviewed-by: Andrew Burgess <aburgess@redhat.com>
|
|
dwarf2_compute_name has a redundant check of the CU's language -- this
is also checked in dwarf2_canonicalize_name. Removing this slightly
simplifies a future patch.
Reviewed-by: Andrew Burgess <aburgess@redhat.com>
|
|
While testing the fix for PR 29105, I noticed I couldn't ctrl-C my way
out of GDB expanding many symtabs. GDB was busy in a loop in
cooked_index_functions::expand_symtabs_matching. Add a QUIT there. I
also happened to see a spot in
cooked_index_functions::expand_matching_symbols where a QUIT would be
useful too, since we iterate over a potentially big number of index
entries and expand CUs in the loop. Add one there too.
Change-Id: Ie1d650381df7f944c16d841b3e592d2dce7306c3
Approved-By: Kevin Buettner <kevinb@redhat.com>
|
|
Pedro mentioned that this prune_threads call in
thread_db_target::update_thread_list was not needed, and it was probably
an oversight to leave it there in the work following commit e8032dde10b
("Push pruning old threads down to the target"). That commit changed
the "find new threads" target operation to "update thread list", making
the target responsible of adding new threads and removing exited
threads, rather than just adding new threads. Commit e8032dde10b moved
the prune_threads calls previously done in common code into each
target's update_thread_list method, in order to keep the existing
behavior, which is why this prune_threads call ended up there.
In the mean time, the linux-nat target was taught to update_thread_list,
and thread_db_target::update_thread_list defers to that for any live
inferior, so the prune_threads call is not needed there. Otherwise, the
thread_db_target::update_thread_list implementation based on
td_ta_thr_iter_p only knows how to add new threads, not how to delete
exited threads, but that is only used for non-live inferiors, where
threads can't exit anyway. So the prune_threads call is not needed for
that case either.
Change-Id: I127fd4f84c25086f97853dadf34c5cec6816840d
Approved-By: Pedro Alves <pedro@palves.net>
|
|
PR compile/29541 points out that some of the C++ tests in gdb.compile
will time out when the glibc debuginfo is installed. This was
interfering with my hacking on gdb by making test runs extremely long,
so I looked into it.
Internally the bug seems to be that gdb tries to convert multiple
symbols named "var" via the compiler interface; one such symbol (I
didn't track it down too far) causes the C++ compiler plugin to crash.
Unfortunately, the crash is reported as a timeout, as the gdb side of
the plugin simply hangs. This seems like a bug in the plugin RPC
mechanism and, worse, apparently when I wrote this stuff I didn't
really consider error reporting very much at all, so gdb can't really
detect failures in the first place.
Anyway... this patch works around the timeout by compiling a simple
test that should provoke this bug, and then using "untested" if it
notices a GCC crash.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29541
|
|
skip_compile_feature_tests checks for "Command not supported on this
host", but this error was removed by commit e8d8cce6 ("Import mkdtemp
gnulib module, fix mingw build"). This patch removes the obsolete
test.
|
|
I noticed that there are two identical copies of
skip_compile_feature_tests in the test suite. This removes one from
gdb.exp, in favor of the one in compile-support.exp.
|
|
When I run the gdb testsuite on a powerpc64le-linux system with (slow) nfs
file system, I run into timeouts due to core generation, like for instance:
...
(gdb) gcore $outputs/gdb.ada/task_switch_in_core/crash.gcore^M
FAIL: gdb.ada/task_switch_in_core.exp: save a corefile (timeout)
...
Fix this by using with_timeout_factor 3 in gdb_gcore_cmd.
Tested on powerpc64le-linux.
Approved-By: Tom Tromey <tom@tromey.com>
|
|
On powerpc64le-linux, I run into:
...
(gdb) print 16llf#4000921fb54442d18469898cc51701b8#^M
$9 = <invalid float value>^M
(gdb) FAIL: gdb.ada/float-bits.exp: print \
16llf#4000921fb54442d18469898cc51701b8#
...
The problem is that we're using a hex string for the 128-bit IEEE quad long
double format, but the actual long double float format is:
...
gdbarch_dump: long_double_format = floatformat_ibm_long_double_little^M
...
Fix this by using the hex string obtained by compiling test.c:
...
long double a = 5.0e+25L;
...
like so:
...
$ gcc -mlittle test.c -c -g
...
and running gdb:
...
$ gdb -q -batch test.o -ex "p /x a"
$1 = 0xc1e1c000000000004544adf4b7320335
...
and likewise for -mbig:
...
$ gdb -q -batch test.o -ex "p /x a"
$1 = 0x4544adf4b7320335c1e1c00000000000
...
Tested on powerpc64le-linux.
I excercised the case of floatformat_ibm_long_double_big by
using "set endian big" in the test-case.
Note that for this patch to work correctly, recent commit aaa79cd62b8 ("[gdb]
Improve printing of float formats") is required.
PR testsuite/29816
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29816
Approved-By: Tom Tromey <tom@tromey.com>
|
|
On s390x-linux, I run into:
...
DUPLICATE: gdb.arch/s390-multiarch.exp: Linux v2
DUPLICATE: gdb.arch/s390-multiarch.exp: Linux v2
DUPLICATE: gdb.arch/s390-multiarch.exp: Linux v2
...
Fix this by using with_test_prefix.
Tested on s390x-linux.
|
|
--enable-targets=all
On s390x-linux, I run into:
...
DUPLICATE: gdb.arch/s390-disassembler-options.exp: \
show disassembler-options esa
...
First, reproduce this on x86_64-linux with --enable-targets=all, by replacing
the test for 'istarget "s390*-*-*"' with a test for 'get_set_option_choices
"set architecture" "s390"'.
Fix the DUPLICATE by using with_test_prefix.
Also modernize the test-case by using clean_restart instead of gdb_exit/gdb_start.
Tested on x86_64-linux.
|
|
While looking into Ada tasking a little, I noticed that no bounds
checking is done on accesses to the Ada task state names arrays. This
isn't a problem currently, but if the runtime ever added numbers -- or
if there was some kind of runtime corruption -- it could cause a gdb
crash.
This patch adds range checking. It also adds a missing _() call when
printing from the 'task_states' array.
|
|
This changes mi_interp to use ui_file_up rather than explicit
management.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
This renames the fields of cli_interp_base::saved_output_files, as
requested by Simon. I tried to choose names that more obviously
reflect what the field is used for. I also added a couple of
comments.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
Currently, on x86_64, a little endian target, I get:
...
$ gdb -q -batch -ex "maint print architecture" | grep " = floatformat"
gdbarch_dump: bfloat16_format = floatformat_bfloat16_big
gdbarch_dump: double_format = floatformat_ieee_double_big
gdbarch_dump: float_format = floatformat_ieee_single_big
gdbarch_dump: half_format = floatformat_ieee_half_big
gdbarch_dump: long_double_format = floatformat_i387_ext
...
which suggests big endian.
This is due to this bit of code in pformat:
...
/* Just print out one of them - this is only for diagnostics. */
return format[0]->name;
...
Fix this by using gdbarch_byte_order to pick the appropriate index, such that
we have the more accurate:
...
gdbarch_dump: bfloat16_format = floatformat_bfloat16_little
gdbarch_dump: half_format = floatformat_ieee_half_little
gdbarch_dump: float_format = floatformat_ieee_single_little
gdbarch_dump: double_format = floatformat_ieee_double_little
gdbarch_dump: long_double_format = floatformat_i387_ext
...
Tested on x86_64-linux.
|
|
On powerpc64le-linux, I run into:
...
(gdb) PASS: gdb.base/vla-optimized-out.exp: o1: printed optimized out vla
p sizeof (a)^M
$2 = <optimized out>^M
(gdb) FAIL: gdb.base/vla-optimized-out.exp: o1: \
printed size of optimized out vla
...
The problem happens as follows.
In order to find the size of the optimized out vla, gdb needs to evaluate:
...
<155> DW_AT_upper_bound : 13 byte block: f3 1 53 23 1 8 20 24 8 20 26 31 1c \
(DW_OP_GNU_entry_value: (DW_OP_reg3 (r3)); DW_OP_plus_uconst: 1;
DW_OP_const1u: 32; DW_OP_shl; DW_OP_const1u: 32; DW_OP_shra; DW_OP_lit1;
DW_OP_minus)
...
When trying to evaluate DW_OP_GNU_entry_value, it looks for a call site
matching the pc, but doesn't find it:
...
$ gdb -q -batch outputs/gdb.base/vla-optimized-out/vla-optimized-out-o1 \
-ex "break f1" -ex run -ex "set debug entry-values 1" -ex "print sizeof (a)"
Breakpoint 1 at 0x1000067c: file vla-optimized-out.c, line 34.
Breakpoint 1, f1 (i=5) at vla-optimized-out.c:34
34 }
DW_OP_entry_value resolving cannot find DW_TAG_call_site 0x100006b0 in main
$1 = <optimized out>
....
The call site lookup fails because the call site label .LVL4:
...
bl f1 # 11 *call_value_nonlocal_aixdi [length = 8]
nop
.LVL4:
...
is not placed directly after the bl insn. This is gcc PR target/107909.
However, after manually fixing the .s file we have instead:
...
Cannot find matching parameter at DW_TAG_call_site 0x10000690 at main
$1 = <optimized out>
...
due to the fact that the call site has no call site parameters.
The call site does have a reference to the corresponding function f1, with
parameter i, for which we find location list entries:
...
0037 1000067c 10000680 (DW_OP_reg3 (r3))
004a 10000680 10000690 (DW_OP_GNU_entry_value: (DW_OP_reg3 (r3));
DW_OP_stack_value)
...
and we could use the fact that the current pc is in the 1000067c-10000680
range, and that that the range starts at the start of the function, to deduce
that DW_OP_GNU_entry_value: (DW_OP_reg3 (r3)) == DW_OP_reg3 (r3).
But that's a non-trivial enhancement, filed as enhancement PR symtab/29836.
Fix this by allowing <optimized out> for target powerpc and the gcc compiler.
Reviewed-By: Carl Love <cel@us.ibm.com>
Tested-By: Carl Love <cel@us.ibm.com>
PR testsuite/29813
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29813
|
|
In the failure seen by Philippe here:
https://inbox.sourceware.org/gdb-patches/20221120173024.3647464-1-philippe.waroquiers@skynet.be/
gdb_unload crashed GDB, leaving no trace in the test results. Change it
to use gdb_test_multiple, so that it leaves an UNRESOLVED result. I
think it is good practice anyway.
Make it return the result of gdb_test_multiple directly, change
gdb.python/py-objfile.exp accordingly.
Change gdb.base/endian.exp as well to avoid duplicate test names.
Change gdb.base/gnu-debugdata.exp to avoid recording a test result,
since gdb_unload does it already now.
Change-Id: I59a1e4947691330797e6ce23277942547c437a48
Approved-By: Tom de Vries <tdevries@suse.de>
|
|
In the failure seen by Philippe here:
https://inbox.sourceware.org/gdb-patches/20221120173024.3647464-1-philippe.waroquiers@skynet.be/
... the testsuite only outputs PASSes, and an ERROR, resulting from an
uncaught exception. This is a bit sneaky, because ERRORs are not
reported in the test summary. In certain circumstances, it can be easy
to miss.
Normally, gdb_test_multiple outputs an UNRESOLVED when GDB crashes. But
this is only if it manages to send the command, and it's that command
that crashes GDB. Here, the ERROR is due to the fact that GDB had
already crashed by the time we entered gdb_test_multiple and tried to
send a command. GDB was crashed by the previous "file" command, sent by
gdb_unload. Because gdb_unload uses bare expect, it didn't record a
test failure when crashing GDB (this will be addressed separately).
In this patch, I propose to make gdb_test_multiple call unresolved
directly and return -1 send_gdb fails. This way, if GDB is already
crashed by the time we enter gdb_test_multiple, it will leave a trace in
the test results in the form of an UNRESOLVED. It will also spare us
the not-so-useful-in-my-opinion TCL backtrace.
Before, it looks like:
ERROR: Couldn't send python print(objfile.filename) to GDB.
ERROR: : spawn id exp9 not open
while executing
"expect {
-i exp9 -timeout 10
-re ".*A problem internal to GDB has been detected" {
fail "$message (GDB internal error)"
gdb_internal_error..."
("uplevel" body line 1)
invoked from within
"uplevel $body" NONE : spawn id exp9 not open
And after:
Couldn't send python print(objfile.filename) to GDB.
UNRESOLVED: gdb.python/py-objfile.exp: objfile.filename after objfile is unloaded
Change-Id: I72af8dc0d687826fc3f76911c27a9e5f91b677ba
Approved-By: Tom de Vries <tdevries@suse.de>
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the testsuite
library files (in boards/, config/, and lib/). Previous commits have
removed all uses of the 'then' keyword from the test script files,
this commit just cleans up the library files.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the remaining
gdb.*/*.exp scripts. Previous commits have done the bulk of this
removal, this commit just handles the remaining directories that each
contain a low number of instances.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.multi/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.fortran/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.disasm/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.reverse/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.trace/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.threads/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.python/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.cp/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.arch/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.base/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The canonical form of 'if' in modern TCL is 'if {} {}'. But there's
still a bunch of places in the testsuite where we make use of the
'then' keyword, and sometimes these get copies into new tests, which
just spreads poor practice.
This commit removes all use of the 'then' keyword from the gdb.ada/
test script directory.
There should be no changes in what is tested after this commit.
|
|
The gdb.fortran/nested-funcs.exp test script has DOS line endings. I
can see no reason why this script needs DOS line endings.
Convert to UNIX line endings.
There should be no change in what is tested after this commit.
|
|
When using the "set logging" commands, cli_interp_base::set_logging
will send gdb_stdlog output (among others) to the tee it makes for
gdb_stdout. However, this has the side effect of also causing logging
to use the pager. This is PR gdb/29787.
This patch fixes the problem by keeping stderr and stdlog separate
from stdout, preserving the rule that only gdb_stdout should page.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29787
|
|
Right now, tee_file owns the second stream it writes to. This is done
for the convenience of the users. In a subsequent patch, this will no
longer be convenient, so this patch moves the responsibility for
ownership to the users of tee_file.
|
|
CLI redirect uses a global variable, 'saved_output'. However, globals
are generally bad, and there is no need for this one -- it can be a
member of cli_interp_base. This patch makes this change.
|
|
The out label is unused since wait_for_debug_event is in a different thread.
|
|
Looks like this was missed in the async mode implementation.
|
|
Older gcc versions (here 4.9.2) can't handle auto for a lambda parameter:
../../gdb/windows-nat.c: In member function 'void windows_nat_target::delete_thread(ptid_t, DWORD, bool)':
../../gdb/windows-nat.c:629:12: error: use of 'auto' in lambda parameter declaration only available with -std=c++1y or -std=gnu++1y [-Werror]
[=] (auto &th)
^
|
|
For i686 the CreateThread entry point function needs the WINAPI (stdcall)
calling convention:
../../gdb/windows-nat.c: In constructor 'windows_nat_target::windows_nat_target()':
../../gdb/windows-nat.c:450:56: error: invalid user-defined conversion from 'windows_nat_target::windows_nat_target()::<lambda(LPVOID)>' to 'LPTHREAD_START_ROUTINE' {aka 'long unsigned int (__attribute__((stdcall)) *)(void*)'} [-fpermissive]
450 | HANDLE bg_thread = CreateThread (nullptr, 64 * 1024, fn, this, 0, nullptr);
| ^~
../../gdb/windows-nat.c:444:13: note: candidate is: 'constexpr windows_nat_target::windows_nat_target()::<lambda(LPVOID)>::operator DWORD (*)(LPVOID)() const' (near match)
444 | auto fn = [] (LPVOID self) -> DWORD
| ^
../../gdb/windows-nat.c:444:13: note: no known conversion from 'DWORD (*)(LPVOID)' {aka 'long unsigned int (*)(void*)'} to 'LPTHREAD_START_ROUTINE' {aka 'long unsigned int (__attribute__((stdcall)) *)(void*)'}
Since it's not possible to change the calling convention of a lambda, I've
moved it to a separate function.
|
|
In disasm.h we define a set of types that are used by the various
disassembler classes to hold callback functions before passing the
callbacks into libopcodes.
Because libopcodes is C code, and on some (many?) targets, C code is
compiled without exception support, it is important that GDB not try
to throw an exception over libopcode code.
In the previous commit all the existing callbacks were marked as
noexcept, however, this doesn't protect us from a future change to GDB
either adding a new callback that is not noexcept, or removing the
noexcept keyword from an existing callback.
In this commit I mark all the callback types as noexcept. This means
that GDB's disassembler classes will no longer compile if we try to
pass a callback that is not marked as noexcept.
At least, that's the idea. Unfortunately, it's not that easy.
Before C++17, the noexcept keyword on a function typedef would be
ignored, thus:
using func_type = void (*) (void) noexcept;
void
a_func ()
{
throw 123;
}
void
some_func (func_type f)
{
f ();
}
int
main ()
{
some_func (a_func);
return 0;
}
Will compile just fine for C++11 and C++14 with GCC. Clang on the
other hand complains that 'noexcept' should not appear on function
types, but then does appear to correctly complain that passing a_func
is a mismatch in the set of exceptions that could be thrown.
Switching to C++17 and both GCC and Clang correctly point out that
passing a_func is an invalid conversion relating to the noexcept
keyword. Changing a_func to:
void
a_func () noexcept
{ /* Nothing. */ }
And for C++17 both GCC and Clang compile this just fine.
My conclusion then is that adding the noexcept keyword to the function
types is pointless while GDB is not compiled as C++17, and silencing
the warnings would require us to jump through a bunch of hoops.
And so, in this commit, I define a macro LIBOPCODE_CALLBACK_NOEXCEPT,
this macro expands to noexcept when compiling for C++17, but otherwise
expands to nothing. I then add this macro to the function types.
I've compiled GDB as the default C++11 and also forced the compile to
C++17. When compiling as C++17 I spotted a few additional places
where callbacks needed to be marked noexcept (these fixes were merged
into the previous commit, but this confirmed to be that the macro is
working as expected).
|
|
While working on another patch, Simon pointed out that GDB could be
improved by marking the functions passed to the disassembler as
noexcept.
https://sourceware.org/pipermail/gdb-patches/2022-October/193084.html
The reason this is important is the on some hosts, libopcodes, being C
code, will not be compiled with support for handling exceptions. As
such, an attempt to throw an exception over libopcodes code will cause
GDB to terminate.
See bug gdb/29712 for an example of when this happened.
In this commit all the functions that are passed to the disassembler,
and which might be used as callbacks by libopcodes are marked
noexcept.
Ideally, I would have liked to change these typedefs:
using read_memory_ftype = decltype (disassemble_info::read_memory_func);
using memory_error_ftype = decltype (disassemble_info::memory_error_func);
using print_address_ftype = decltype (disassemble_info::print_address_func);
using fprintf_ftype = decltype (disassemble_info::fprintf_func);
using fprintf_styled_ftype = decltype (disassemble_info::fprintf_styled_func);
which are declared in disasm.h, as including the noexcept keyword.
However, when I tried this, I ran into this warning/error:
In file included from ../../src/gdb/disasm.c:25:
../../src/gdb/disasm.h: In constructor ‘gdb_printing_disassembler::gdb_printing_disassembler(gdbarch*, ui_file*, gdb_disassemble_info::read_memory_ftype, gdb_disassemble_info::memory_error_ftype, gdb_disassemble_info::print_address_ftype)’:
../../src/gdb/disasm.h:116:3: error: mangled name for ‘gdb_printing_disassembler::gdb_printing_disassembler(gdbarch*, ui_file*, gdb_disassemble_info::read_memory_ftype, gdb_disassemble_info::memory_error_ftype, gdb_disassemble_info::print_address_ftype)’ will change in C++17 because the exception specification is part of a function type [-Werror=noexcept-type]
116 | gdb_printing_disassembler (struct gdbarch *gdbarch,
| ^~~~~~~~~~~~~~~~~~~~~~~~~
So I've left that change out. This does mean that if somebody adds a
new use of the disassembler classes in the future, and forgets to mark
the callbacks as noexcept, this will compile fine. We'll just have to
manually check for that during review.
|
|
Bug gdb/29712 identifies a problem with the Python disassembler API.
In some cases GDB will try to throw an exception through the
libopcodes disassembler code, however, not all targets include
exception unwind information when compiling C code, for targets that
don't include this information GDB will terminate when trying to pass
the exception through libopcodes.
To explain what GDB is trying to do, consider the following trivial
use of the Python disassembler API:
class ExampleDisassembler(gdb.disassembler.Disassembler):
class MyInfo(gdb.disassembler.DisassembleInfo):
def __init__(self, info):
super().__init__(info)
def read_memory(self, length, offset):
return super().read_memory(length, offset)
def __init__(self):
super().__init__("ExampleDisassembler")
def __call__(self, info):
info = self.MyInfo(info)
return gdb.disassembler.builtin_disassemble(info)
This disassembler doesn't add any value, it defers back to GDB to do
all the actual work, but it serves to allow us to discuss the problem.
The problem occurs when a Python exception is raised by the
MyInfo.read_memory method. The MyInfo.read_memory method is called
from the C++ function gdbpy_disassembler::read_memory_func. The C++
stack at the point this function is called looks like this:
#0 gdbpy_disassembler::read_memory_func (memaddr=4198805, buff=0x7fff9ab9d2a8 "\220ӹ\232\377\177", len=1, info=0x7fff9ab9d558) at ../../src/gdb/python/py-disasm.c:510
#1 0x000000000104ba06 in fetch_data (info=0x7fff9ab9d558, addr=0x7fff9ab9d2a9 "ӹ\232\377\177") at ../../src/opcodes/i386-dis.c:305
#2 0x000000000104badb in ckprefix (ins=0x7fff9ab9d100) at ../../src/opcodes/i386-dis.c:8571
#3 0x000000000104e28e in print_insn (pc=4198805, info=0x7fff9ab9d558, intel_syntax=-1) at ../../src/opcodes/i386-dis.c:9548
#4 0x000000000104f4d4 in print_insn_i386 (pc=4198805, info=0x7fff9ab9d558) at ../../src/opcodes/i386-dis.c:9949
#5 0x00000000004fa7ea in default_print_insn (memaddr=4198805, info=0x7fff9ab9d558) at ../../src/gdb/arch-utils.c:1033
#6 0x000000000094fe5e in i386_print_insn (pc=4198805, info=0x7fff9ab9d558) at ../../src/gdb/i386-tdep.c:4072
#7 0x0000000000503d49 in gdbarch_print_insn (gdbarch=0x5335560, vma=4198805, info=0x7fff9ab9d558) at ../../src/gdb/gdbarch.c:3351
#8 0x0000000000bcc8c6 in disasmpy_builtin_disassemble (self=0x7f2ab07f54d0, args=0x7f2ab0789790, kw=0x0) at ../../src/gdb/python/py-disasm.c:324
### ... snip lots of frames as we pass through Python itself ...
#22 0x0000000000bcd860 in gdbpy_print_insn (gdbarch=0x5335560, memaddr=0x401195, info=0x7fff9ab9e3c8) at ../../src/gdb/python/py-disasm.c:783
#23 0x00000000008995a5 in ext_lang_print_insn (gdbarch=0x5335560, address=0x401195, info=0x7fff9ab9e3c8) at ../../src/gdb/extension.c:939
#24 0x0000000000741aaa in gdb_print_insn_1 (gdbarch=0x5335560, vma=0x401195, info=0x7fff9ab9e3c8) at ../../src/gdb/disasm.c:1078
#25 0x0000000000741bab in gdb_disassembler::print_insn (this=0x7fff9ab9e3c0, memaddr=0x401195, branch_delay_insns=0x0) at ../../src/gdb/disasm.c:1101
So gdbpy_disassembler::read_memory_func is called from the libopcodes
disassembler to read memory, this C++ function then calls into user
supplied Python code to do the work.
If the user supplied Python code raises an gdb.MemoryError exception
indicating the memory read failed, this is fine. The C++ code
converts this exception back into a return value that libopcodes can
understand, and returns to libopcodes.
However, if the user supplied Python code raises some other exception,
what we want is for this exception to propagate through GDB and appear
as if raised by the call to gdb.disassembler.builtin_disassemble. To
achieve this, when gdbpy_disassembler::read_memory_func spots an
unknown Python exception, we must pass the information about this
exception from frame #0 to frame #8 in the above backtrace. Frame #8
is the C++ implementation of gdb.disassembler.builtin_disassemble, and
so it is this function that we want to re-raise the unknown Python
exception, so the user can, if they want, catch the exception in their
code.
The previous mechanism by which the exception was passed was to pack
the details of the Python exception into a C++ exception, then throw
the exception from frame #0, and catch the exception in frame #8,
unpack the details of the Python exception, and re-raise it.
However, this relies on the exception passing through frames #1 to #7,
some of which are in libopcodes, which is C code, and so, might not be
compiled with exception support.
This commit proposes an alternative solution that does not rely on
throwing a C++ exception.
When we spot an unhandled Python exception in frame #0, we will store
the details of this exception within the gdbpy_disassembler object
currently in use. Then we return to libopcodes a value indicating
that the memory_read failed.
libopcodes will now continue to disassemble as though that memory read
failed (with one special case described below), then, when we
eventually return to disasmpy_builtin_disassemble we check to see if
there is an exception stored in the gdbpy_disassembler object. If
there is then this exception can immediately be installed, and then we
return back to Python, when the user will be able to catch the
exception.
There is one extra change in gdbpy_disassembler::read_memory_func.
After the first call that results in an exception being stored on the
gdbpy_disassembler object, any future calls to the ::read_memory_func
function will immediately return as if the read failed. This avoids
any additional calls into user supplied Python code.
My thinking here is that should the first call fail with some unknown
error, GDB should not keep trying with any additional calls. This
maintains the illusion that the exception raised from
MyInfo.read_memory is immediately raised by
gdb.disassembler.builtin_disassemble. I have no tests for this change
though - to trigger this issue would rely on a libopcodes disassembler
that will try to read further memory even after the first failed
read. I'm not aware of any such disassembler that currently does
this, but that doesn't mean such a disassembler couldn't exist in the
future.
With this change in place the gdb.python/py-disasm.exp test should now
pass on AArch64.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29712
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
I noticed that execution_control_state has a 'reset' method, and
there's also a 'reset_ecs' function that calls it. This patch cleans
this area up a little by adding a parameter to the constructor and (a
change Simon suggested) removing the reset method. Some extraneous
variables are also removed, like:
- struct execution_control_state ecss;
- struct execution_control_state *ecs = &ecss;
Here 'ecs' is never changed, so this patch removes it entirely in
favor of just using the object everywhere.
Regression tested on x86-64 Fedora 34.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
|
|
From glibc 2.35 and later, the "map_failed" stap probe is no longer
included in glibc. The removal of the probe looks like an accident,
but it was caused by a glibc commit which meant that the "map_failed"
probe could no longer be reached; the compiler then helpfully
optimised out the probe.
In GDB, in solib-svr4.c, we have a list of probes that we look for
related to the shared library loading detection. If any of these
probes are missing then GDB will fall back to the non-probe based
mechanism for detecting shared library loading. The "map_failed"
probe is include in the list of required probes.
This means that on glibc 2.35 (or later) systems, GDB is going to
always fall back to the non-probes based mechanism for detecting
shared library loading.
I raised a glibc bug to discuss this issue:
https://sourceware.org/bugzilla/show_bug.cgi?id=29818
But, whatever the ultimate decision from the glibc team, given there
are version of glibc in the wild without the "map_failed" probe, we
probably should update GDB to handle this situation.
The "map_failed" probe is already a little strange, very early
versions of glibc didn't include this probe, so, in some cases, if
this probe is missing GDB is happy to ignore it. This is fine, the
action associated with this probe inside GDB is DO_NOTHING, this means
the probe isn't actually required in order for GDB to correctly detect
the loading of shared libraries.
In this commit I propose changing the rules so that any probe whose
action is DO_NOTHING, is optional.
There is one possible downside to this change, and that concerns 'set
stop-on-solib-events on'. If a probe is removed from glibc, but the
old style breakpoint based mechanism is still in place within glibc
for that same event, then GDB will stop when using the old style
non-probe based mechanism, but not when using the probes based
mechanism.
For the map_failed case this is not a problem, both the map_failed
probe, and the call to the old style breakpoint location were
optimised out, and so neither event (probes based, or breakpoint
based) will trigger. This would only become an issue if glibc removed
a probe, but left the breakpoint in place (this would almost certainly
be a bug in glibc).
For now, I'm proposing that we just don't worry about this. Because
some probes have actions that are not DO_NOTHING, then we know the
user will always seem _some_ stops when a shared library is
loaded/unloaded, and (I'm guessing), in most cases, that's all they
care about. I figure when someone complains then we can figure out
what the right solution is then.
With this commit in place, then, when using a glibc 2.35 or later
system, GDB will once again use the stap probes for shared library
detection.
Reviewed-By: Lancelot SIX <lancelot.six@amd.com>
|
