Andrew Burgess [Mon, 1 Feb 2021 11:37:46 +0000 (11:37 +0000)]
sim/rx: avoid pointer arithmetic on void * pointers
Pointer arithmetic on void * pointers results in a GCC warning. Avoid
the warning by casting the pointer to its actual type earlier in the
function.
sim/rx/ChangeLog:
* mem.c (mem_put_blk): Rename parameter, add cast from parameter
type to local type. Remove cast later in the function.
(mem_get_blk): Likewise.
* mem.h (mem_put_blk): Rename parameter to match definition.
(mem_get_blk): Likewise.
Andrew Burgess [Mon, 1 Feb 2021 11:28:09 +0000 (11:28 +0000)]
sim/rx: add some missing includes
In load.c there's some GCC warnings about undefined
functions (bfd_get_elf_phdr_upper_bound and bfd_get_elf_phdrs). To
get the declarations of these functions include 'elf-bfd.h'. This
headers also pulls in other elf related headers, like 'elf/internal.h'
and 'elf/common.h', so these no longer need to be explicitly included
from load.c.
In trace.c and include for trace.h is missing, again this results in
GCC warnings for missing function declarations.
sim/rx/ChangeLog:
* load.c: Replace 'elf/internal.h' and 'elf/common.h' includes
with 'elf-bfd.h' include.
* trace.c: Add 'trace.h' include.
Andrew Burgess [Thu, 28 Jan 2021 17:17:08 +0000 (17:17 +0000)]
sim/rx: fix an issue where we try to modify a const string
While experimenting with switching on warnings for the rx simulator I
discovered this bug. In sim_do_command we get passed a 'const char *'
argument. We create a copy of this string to work with locally, but
then while processing this we accidentally switch back to reference
the original string.
sim/rx/ChangeLog:
* gdb-if.c (sim_do_command): Work with a copy of the command.
Andrew Burgess [Mon, 25 Jan 2021 18:58:37 +0000 (18:58 +0000)]
sim/rx: define sim_memory_map
The rx simulator doesn't define sim_memory_map and so fails to link
with GDB. Define it now to return NULL, this can be extended later to
return an actual memory map if anyone wants this functionality.
Andrew Burgess [Fri, 22 Jan 2021 17:40:19 +0000 (17:40 +0000)]
gdb/tui: fix issue with handling the return character
My initial goal was to fix our gdb/testsuite/lib/tuiterm.exp such that
it would correctly support (some limited) scrolling of the command
window.
What I observe is that when sending commands to the tui command window
in a test script with:
Term::command "p 1"
The command window would be left looking like this:
(gdb)
(gdb) p 1$1 = 1
(gdb)
When I would have expected it to look like this:
(gdb) p 1
$1 = 1
(gdb)
Obviously a bug in our tuiterm.exp library, right???
Wrong!
Turns out there's a bug in GDB.
If in GDB I enable the tui and then type (slowly) the 'p 1\r' (the \r
is pressing the return key at the end of the string), then you do
indeed get the "expected" terminal output.
However, if instead I copy the 'p 1\r' string and paste it into the
tui in one go then I now see the same corrupted output as we do when
using tuiterm.exp.
It turns out the problem is that GDB fails when handling lots of input
arriving quickly with a \r (or \n) on the end.
The reason for this bug is as follows:
When the tui is active the terminal is in no-echo mode, so characters
sent to the terminal are not echoed out again. This means that when
the user types \r, this is not echoed to the terminal.
The characters read in are passed to readline and \r indicates that
the command line is complete and ready to be processed. However, the
\r is not included in readlines command buffer, and is NOT printed by
readline when is displays its buffer to the screen.
So, in GDB we have to manually spot the \r when it is read in and
update the display. Printing a newline character to the output and
moving the cursor to the next line. This is done in tui_getc_1.
Now readline tries to reduce the number of write calls. So if we very
quickly (as in paste in one go) the text 'p 1' to readline (this time
with no \r on the end), then readline will fetch the fist character
and add it to its internal buffer. But before printing the character
out readline checks to see if there's more input incoming. As we
pasted multiple characters, then yes, readline sees the ' ' and adds
this to its buffer, and finally the '1', this too is added to the
buffer.
Now if at this point we take a break, readline sees there is no more
input available, and so prints its buffer out.
Now when we press \r the code in tui_getc_1 kicks in, adds a \n to the
output and moves the cursor to the next line.
But, if instead we paste 'p 1\r' in one go then readline adds 'p 1' to
its buffer as before, but now it sees that there is still more input
available. Now it fetches the '\r', but this triggers the newline
behaviour, we print '\n' and move to the next line - however readline
has not printed its buffer yet!
So finally we end up on the next line. There's no more input
available so readline prints its buffer, then GDB gets passed the
buffer, handles it, and prints the result.
The solution I think is to put of our special newline insertion code
until we know that readline has finished printing its buffer. Handily
we know when this is - the next thing readline does is pass us the
command line buffer for processing. So all we need to do is hook in
to the command line processing, and before we pass the command line to
GDB's internals we do all of the magic print a newline and move the
cursor to the next line stuff.
Luckily, GDB's interpreter mechanism already provides the hooks we
need to do this. So all I do here is move the newline printing code
from tui_getc_1 into a new function, setup a new input_handler hook
for the tui, and call my new newline printing function.
After this I can enable the tui and paste in 'p 1\r' and see the
correct output.
Also the tuiterm.exp library will now see non-corrupted output.
gdb/ChangeLog:
* tui/tui-interp.c (tui_command_line_handler): New function.
(tui_interp::resume): Register tui_command_line_handler as the
input_handler.
* tui/tui-io.c (tui_inject_newline_into_command_window): New
function.
(tui_getc_1): Delete handling of '\n' and '\r'.
* tui-io.h (tui_inject_newline_into_command_window): Declare.
gdb/testsuite/ChangeLog:
* gdb.tui/scroll.exp: Tighten expected results. Remove comment
about bug in GDB, update expected results, and add more tests.
Andrew Burgess [Fri, 22 Jan 2021 16:25:15 +0000 (16:25 +0000)]
gdb/testsuite: fix implementation of delete line in tuiterm.exp
The implementation of the delete line escape sequence in tuiterm.exp
was wrong. Delete should take a count and then delete COUNT lines at
the current cursor location, all remaining lines in the scroll region
are moved up to replace the deleted lines, with blank lines being
added at the end of the scroll region.
It's not clear to me what "scroll region" means here (or at least how
that is defined), but for now I'm just treating the whole screen as
the scroll region, which seems to work fine.
In contrast the current broken implementation deletes COUNT lines at
the cursor location moving the next COUNT lines up to fill the gap.
The rest of the screen is then cleared.
gdb/testsuite/ChangeLog:
* gdb.tui/scroll.exp: New file.
* gdb.tui/tui-layout-asm-short-prog.exp: Update expected results.
* lib/tuiterm.exp (Term::_csi_M): Delete count lines, scroll
remaining lines up.
(Term::check_region_contents): New proc.
(Term::check_box_contents): Use check_region_contents.
Hannes Domani [Tue, 5 Jan 2021 16:29:02 +0000 (17:29 +0100)]
Don't draw register sub windows outside the visible area
If the regs window is not big enough to show all registers, the
registers whose values changed are always drawn, even if they are not
in the currently visible area.
So this marks the invisible register sub windows with y=0, and skips
their rerender call in check_register_values.
gdb/ChangeLog:
2021-02-07 Hannes Domani <ssbssa@yahoo.de>
* tui/tui-regs.c (tui_data_window::display_registers_from):
Mark invisible register sub windows.
(tui_data_window::check_register_values): Ignore invisible
register sub windows.
Tom de Vries [Sat, 6 Feb 2021 22:22:03 +0000 (23:22 +0100)]
[gdb/testsuite] Fix gdb.tui/tui-layout-asm.exp with -m32
When running test-case gdb.tui/tui-layout-asm.exp with target board
unix/-m32, we run into:
...
FAIL: gdb.tui/tui-layout-asm.exp: scroll to end of assembler (scroll failed)
...
Comparing screen dumps (edited a bit to fit column width) before:
...
0 +--------------------------------------------------------------------+
1 | 0x8049194 <__libc_csu_init+68> call *-0x104(%ebp,%esi,4) |
2 | 0x804919b <__libc_csu_init+75> add $0x1,%esi |
3 | 0x804919e <__libc_csu_init+78> add $0x10,%esp |
4 | 0x80491a1 <__libc_csu_init+81> cmp %esi,%ebx |
5 | 0x80491a3 <__libc_csu_init+83> jne 0x8049188 <__...> |
6 | 0x80491a5 <__libc_csu_init+85> add $0xc,%esp |
7 | 0x80491a8 <__libc_csu_init+88> pop %ebx |
8 | 0x80491a9 <__libc_csu_init+89> pop %esi |
9 | 0x80491aa <__libc_csu_init+90> pop %edi |
10 | 0x80491ab <__libc_csu_init+91> pop %ebp |
11 | 0x80491ac <__libc_csu_init+92> ret |
12 | 0x80491ad lea 0x0(%esi),%esi |
13 | 0x80491b0 <__libc_csu_fini> ret |
14 +--------------------------------------------------------------------+
...
and after:
...
0 +--------------------------------------------------------------------+
1 | 0x804919b <__libc_csu_init+75> add $0x1,%esi |
2 | 0x804919e <__libc_csu_init+78> add $0x10,%esp |
3 | 0x80491a1 <__libc_csu_init+81> cmp %esi,%ebx |
4 | 0x80491a3 <__libc_csu_init+83> jne 0x8049188 <__...> |
5 | 0x80491a5 <__libc_csu_init+85> add $0xc,%esp |
6 | 0x80491a8 <__libc_csu_init+88> pop %ebx |
7 | 0x80491a9 <__libc_csu_init+89> pop %esi |
8 | 0x80491aa <__libc_csu_init+90> pop %edi |
9 | 0x80491ab <__libc_csu_init+91> pop %ebp |
10 | 0x80491ac <__libc_csu_init+92> ret |
11 | 0x80491ad lea 0x0(%esi),%esi |
12 | 0x80491b0 <__libc_csu_fini> ret |
13 | 0x80491b1 <__x86.get_pc_thunk.bp> mov (%esp),%ebp |
14 +--------------------------------------------------------------------+
...
it seems the mismatch comes from the extra indentation forced by the longer
<__x86.get_pc_thunk.bp> that was scrolled in.
Fix this by ignoring whitespace when comparing scrolled lines.
Tested on x86_64-linux, using -m64 and -m32.
gdb/testsuite/ChangeLog:
2021-02-06 Tom de Vries <tdevries@suse.de>
PR testsuite/26922
* gdb.tui/tui-layout-asm.exp: Ignore whitespace mismatches when
scrolling.
Mike Frysinger [Tue, 2 Feb 2021 04:51:24 +0000 (23:51 -0500)]
sim: erc32/m32c/rl78: add sim_memory_map stub for gdb
These ports don't use the common sim core, so they weren't providing
a sim_memory_map for gdb, so they failed to link with the new memory
map logic added for the sim. Add stubs to fix.
Mike Frysinger [Mon, 23 Mar 2015 04:44:54 +0000 (00:44 -0400)]
sim: watchpoints: use common sim_pc_get
Few arches implement STATE_WATCHPOINTS()->pc while all of them implement
sim_pc_get. Lets switch the sim-watch core for monitoring pc events to
the sim_pc_get API so this module works for all ports, and then we can
delete this old back channel of snooping in the port's cpu state -- the
code needs the pointer to the pc storage so that it can read out bytes
and compare them to the watchrange.
This also fixes the logic on multi-cpu sims by removing the limitation
of only being able to watch CPU0's state.
Mike Frysinger [Sun, 17 Jan 2021 18:48:08 +0000 (13:48 -0500)]
sim: common: switch AC_CONFIG_HEADERS
The AC_CONFIG_HEADER macro is long deprecated, so switch to the
newer form. This also gets rid of the position limitation, and
drops support for an argument to SIM_AC_COMMON which we haven't
used anywhere.
Mike Frysinger [Sun, 17 Jan 2021 18:39:03 +0000 (13:39 -0500)]
sim: drop use of bfd/configure.host
These settings might have made sense in darker compiler times, but I
think they're largely obsolete now. Looking through the values that
get used in HDEFINES, it's quite limited, and configure itself should
handle them. If we still need something, we can leverage standard
autoconf macros instead, after we get a clear user report.
TDEFINES was never set anywhere and was always empty, so prune that.
This fixes PR27184, a failure to compile gdb due to
cdefs.h being out of sync with glibc on ppc64le targets
which are compiled with -mabi=ieeelongdouble and glibc
2.32.
Likewise, update usage of _GL_ATTRIBUTE_FORMAT_PRINTF to
_GL_ATTRIBUTE_FORMAT_PRINTF_STANDARD.
Likewise, disable newly added rpl_free gnulib api in
gdbserver support libraries.
Likewise, undefine read/write macros before redefining them
on mingw targets.
Likewise, wrap C++ usage of free with GNULIB_NAMESPACE namespace
as needed.
Tom de Vries [Fri, 5 Feb 2021 16:47:07 +0000 (17:47 +0100)]
[gdb/breakpoints] Handle glibc with debuginfo in create_exception_master_breakpoint
The test-case nextoverthrow.exp is failing on targets with unstripped libc.
This is a regression since commit 1940319c0ef "[gdb] Fix internal-error in
process_event_stop_test".
The problem is that this code in create_exception_master_breakpoint:
...
for (objfile *sepdebug = obj->separate_debug_objfile;
sepdebug != nullptr; sepdebug = sepdebug->separate_debug_objfile)
if (create_exception_master_breakpoint_hook (sepdebug))
...
iterates over all the separate debug object files, but fails to handle the
case that obj itself has the debug info we're looking for.
Fix this by using the separate_debug_objfiles () range instead, which does
iterate both over obj and the obj->separate_debug_objfile chain.
Tested on x86_64-linux.
gdb/ChangeLog:
2021-02-05 Tom de Vries <tdevries@suse.de>
PR breakpoints/27330
* breakpoint.c (create_exception_master_breakpoint): Handle case that
glibc object file has debug info.
Tom de Vries [Fri, 5 Feb 2021 16:47:07 +0000 (17:47 +0100)]
[gdb/symtab] Handle DW_TAG_type_unit in process_psymtab_comp_unit
When running test-case gdb.cp/cpexprs-debug-types.exp with target board
unix/gdb:debug_flags=-gdwarf-5, I run into:
...
(gdb) file cpexprs-debug-types^M
Reading symbols from cpexprs-debug-types...^M
ERROR: Couldn't load cpexprs-debug-types into GDB (eof).
ERROR: Couldn't send delete breakpoints to GDB.
ERROR: GDB process no longer exists
GDB process exited with wait status 23054 exp9 0 0 CHILDKILLED SIGABRT SIGABRT
...
We're running into this abort in process_psymtab_comp_unit:
...
switch (reader.comp_unit_die->tag)
{
case DW_TAG_compile_unit:
this_cu->unit_type = DW_UT_compile;
break;
case DW_TAG_partial_unit:
this_cu->unit_type = DW_UT_partial;
break;
default:
abort ();
}
...
because reader.comp_unit_die->tag == DW_TAG_type_unit.
Tom de Vries [Fri, 5 Feb 2021 16:47:07 +0000 (17:47 +0100)]
[gdb/breakpoints] Fix segfault for catch syscall -1
Using a hello world a.out, I run into a segfault:
...
$ gcc hello.c
$ gdb -batch a.out -ex "catch syscall -1" -ex r
Catchpoint 1 (syscall -1)
Aborted (core dumped)
...
Fix this by erroring out if a negative syscall number is used in the
catch syscall command.
Tom Tromey [Fri, 5 Feb 2021 14:11:01 +0000 (07:11 -0700)]
Extract symbol-writing function from parsers
I noticed that several parsers shared the same code to write a symbol
reference to an expression. This patch factors this code out into a
new function.
Regression tested on x86-64 Fedora 32.
gdb/ChangeLog
2021-02-05 Tom Tromey <tom@tromey.com>
* parser-defs.h (write_exp_symbol_reference): Declare.
* parse.c (write_exp_symbol_reference): New function.
* p-exp.y (variable): Use write_exp_symbol_reference.
* m2-exp.y (variable): Use write_exp_symbol_reference.
* f-exp.y (variable): Use write_exp_symbol_reference.
* d-exp.y (PrimaryExpression): Use write_exp_symbol_reference.
* c-exp.y (variable): Use write_exp_symbol_reference.
Tom de Vries [Fri, 5 Feb 2021 09:56:39 +0000 (10:56 +0100)]
[gdb/exp] Fix assert when adding ptr to imaginary unit
I'm running into this assertion failure:
...
$ gdb -batch -ex "p (void *)0 - 5i"
gdbtypes.c:3430: internal-error: \
type* init_complex_type(const char*, type*): Assertion \
`target_type->code () == TYPE_CODE_INT \
|| target_type->code () == TYPE_CODE_FLT' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
...
This is a regression since commit c34e8714662 "Implement complex arithmetic".
Before that commit we had:
...
(gdb) p (void *)0 - 5i
Argument to arithmetic operation not a number or boolean.
...
Fix this in complex_binop by throwing an error, such that we have:
...
(gdb) print (void *)0 - 5i
Argument to complex arithmetic operation not supported.
...
Tested on x86_64-linux.
gdb/ChangeLog:
2021-02-05 Tom de Vries <tdevries@suse.de>
PR exp/27265
* valarith.c (complex_binop): Throw an error if complex type can't
be created.
Tom de Vries [Fri, 5 Feb 2021 08:14:25 +0000 (09:14 +0100)]
[gdb/symtab] Fix duplicate CUs in create_cus_from_debug_names_list
When running test-case gdb.dwarf2/clang-debug-names.exp, I run into the
following warning:
...
(gdb) file clang-debug-names^M
Reading symbols from clang-debug-names...^M
warning: Section .debug_aranges in clang-debug-names has duplicate \
debug_info_offset 0xc7, ignoring .debug_aranges.^M
...
This is caused by a missing return in commit 3ee6bb113af "[gdb/symtab] Fix
incomplete CU list assert in .debug_names".
Fix this by adding the missing return, such that we have instead this warning:
...
(gdb) file clang-debug-names^M
Reading symbols from clang-debug-names...^M
warning: Section .debug_aranges in clang-debug-names \
entry at offset 0 debug_info_offset 0 does not exists, \
ignoring .debug_aranges.^M
...
which is a known problem filed as PR25969 - "Ignoring .debug_aranges with
clang .debug_names".
Alan Modra [Thu, 4 Feb 2021 12:50:42 +0000 (23:20 +1030)]
ld testsuite on x86_64 with --enable-shared
These tests fail since 1c9c9b9b5552, due to not being able to access
some scripts:
FAIL: Absolute non-overflowing relocs
FAIL: ld-i386/iamcu-1
FAIL: ld-i386/iamcu-2
The problem is that when built with --enable-shared the ld-new
executable sits in a .libs/ directory.
* Makefile.am (check-DEJAGNU): Set up ldscripts link in .libs.
* Makefile.in: Regenerate.
Mike Frysinger [Thu, 21 May 2015 15:16:45 +0000 (23:16 +0800)]
sim: riscv: new port
This is a hand-written implementation that should have fairly complete
coverage for the base integer instruction set ("i"), and for the atomic
("a") and integer multiplication+division ("m") extensions. It also
covers 32-bit & 64-bit targets.
The unittest coverage is a bit weak atm, but should get better.
Shahab Vahedi [Tue, 10 Dec 2019 15:25:08 +0000 (16:25 +0100)]
gdb: Use correct feature in tdesc-regs for ARC
tdesc-regs.exp test fails for ARC because the test is not
using the correct XML files as target description. With
this change, the correct directory and files are used.
v2 (after Andrew's remark [1]):
- Update the feature file names again. Test results now:
Test run by shahab on Tue Jan 26 11:31:16 2021
Target is arc-default-elf32
Host is x86_64-unknown-linux-gnu
Simon Marchi [Thu, 4 Feb 2021 18:35:37 +0000 (13:35 -0500)]
gdb: make record-full clear async handler in wait
For the same reason explained in the previous patch (which was for the
record-btrace target), move clearing of the async event handler of the
record-full target to the wait method.
I'm not sure if/where that target needs to re-set its async event
handler in the wait method. Since it only supports a single thread,
there probably can't be multiple events to report at the same time.
Simon Marchi [Thu, 4 Feb 2021 18:35:09 +0000 (13:35 -0500)]
gdb: make record-btrace clear event handler in wait
For the same reason explained in the previous patch (which was for the
remote target), move clearing of the async event handler of the
record-btrace target to the wait method.
The record-btrace target already re-sets its async event handler in its
wait method, so that part doesn't need to be changed:
/* In async mode, we need to announce further events. */
if (target_is_async_p ())
record_btrace_maybe_mark_async_event (moving, no_history);
Simon Marchi [Thu, 4 Feb 2021 18:34:11 +0000 (13:34 -0500)]
gdb: make remote target clear its handler in remote_target::wait
The remote target's remote_async_inferior_event_token is a flag that
tells when it wants the infrun loop to call its wait method. The flag
is cleared in the async_event_handler's callback
(remote_async_inferior_event_handler), just before calling
inferior_event_handler. However, since inferior_event_handler may
actually call another target's wait method, there needs to be code that
checks if we need to re-raise the flag.
It would be simpler instead for remote_target::wait to clear the flag
when it returns an event and there are no more to report after that. If
another target's wait method gets called by inferior_event_handler, the
remote target's flag will stay naturally stay marked.
Note that this is already partially implemented in remote_target::wait,
since the remote target may have multiple events to report (and it can
only report one at the time):
if (target_is_async_p ())
{
remote_state *rs = get_remote_state ();
/* If there are are events left in the queue tell the event loop
to return here. */
if (!rs->stop_reply_queue.empty ())
mark_async_event_handler (rs->remote_async_inferior_event_token);
}
The code in remote_async_inferior_event_handler also checks for pending
events as well, in addition to the stop reply queue, so I've made
remote_target::wait check for that as well. I'm not completely sure
this is ok, since I don't understand very well how the pending events
mechanism works. But I figured it was safer to do this, worst case it
just leads to unnecessary calls to remote_target::wait.
gdb/ChangeLog:
* remote.c (remote_target::wait): Clear async event handler at
beginning, mark if needed at the end.
(remote_async_inferior_event_handler): Don't set or clear async
event handler.
Simon Marchi [Thu, 4 Feb 2021 18:13:30 +0000 (13:13 -0500)]
gdb: make async event handlers clear themselves
The `ready` flag of async event handlers is cleared by the async event
handler system right before invoking the associated callback, in
check_async_event_handlers.
This is not ideal with how the infrun subsystem consumes events: all
targets' async event handler callbacks essentially just invoke
`inferior_event_handler`, which eventually calls `fetch_inferior_event`
and `do_target_wait`. `do_target_wait` picks an inferior at random,
and thus a target at random (it could be the target whose `ready` flag
was cleared, or not), and pulls one event from it.
So it's possible that:
- the async event handler for a target A is called
- we end up consuming an event for target B
- all threads of target B are stopped, target_async(0) is called on it,
so its async event handler is cleared (e.g.
record_btrace_target::async)
As a result, target A still has events to report while its async event
handler is left unmarked, so these events are not consumed. To counter
this, at the end of their async event handler callbacks, targets check
if they still have something to report and re-mark their async event
handler (e.g. remote_async_inferior_event_handler).
The linux_nat target does not suffer from this because it doesn't use an
async event handler at the moment. It only uses a pipe registered with
the event loop. It is written to in the SIGCHLD handler (and in other
spots that want to get target wait method called) and read from in
the target's wait method. So if linux_nat happened to be target A in
the example above, the pipe would just stay readable, and the event loop
would wake up again, until linux_nat's wait method is finally called and
consumes the contents of the pipe.
I think it would be nicer if targets using async_event_handler worked in
a similar way, where the flag would stay set until the target's wait
method is actually called. As a first step towards that, this patch
moves the responsibility of clearing the ready flags of async event
handlers to the invoked callback.
All async event handler callbacks are modified to clear their ready flag
before doing anything else. So in practice, nothing changes with this
patch. It's only the responsibility of clearing the flag that is
shifted toward the callee.
Nick Alcock [Fri, 29 Jan 2021 13:33:11 +0000 (13:33 +0000)]
libctf: always name nameless types "", never NULL
The ctf_type_name_raw and ctf_type_aname_raw functions, which return the
raw, unadorned name of CTF types, have one unfortunate wrinkle: they
return NULL not only on error but when returning the name of types
without a name in writable dicts. This was unintended: it not only
makes it impossible to reliably tell if a given call to
ctf_type_name_raw failed (due to a bad string offset say), but also
complicates all its callers, who now have to check for both NULL and "".
The written-out form of CTF has no concept of a NULL pointer instead of
a string: all null strings are strtab offset 0, "". So the more we can
do to remove this distinction from the writable form, the less complex
the rest of our code needs to be.
Armour against NULL in multiple places, arranging to return "" from
ctf_type_name_raw if offset 0 is passed in, and removing a risky
optimization from ctf_str_add* that avoided doing anything if a NULL was
passed in: this added needless irregularity to the functions' API
surface, since "" and NULL should be treated identically, and in the
case of ctf_str_add_ref, we shouldn't skip adding the passed-in REF to
the list of references to be updated no matter what the content of the
string happens to be.
This means we can simplify the deduplicator a tiny bit, also fixing a
bug (latent when used by ld) where if the input dict was writable,
we failed to realise when types were nameless and could end up creating
deeply unhelpful synthetic forwards with no name, which we just banned
a few commits ago, so the link failed.
libctf/ChangeLog
2021-01-27 Nick Alcock <nick.alcock@oracle.com>
* ctf-string.c (ctf_str_add): Treat adding a NULL as adding "".
(ctf_str_add_ref): Likewise.
(ctf_str_add_external): Likewise.
* ctf-types.c (ctf_type_name_raw): Always return "" for offset 0.
* ctf-dedup.c (ctf_dedup_multiple_input_dicts): Don't armour
against NULL name.
(ctf_dedup_maybe_synthesize_forward): Likewise.
Nick Alcock [Wed, 27 Jan 2021 19:55:45 +0000 (19:55 +0000)]
libctf: prohibit nameless ints, floats, typedefs and forwards
Now that "anonymous typedef nodes" have been extirpated, we can mandate
that things that have names in C must have names in CTF too. (Unlike
the no-forwards embarrassment, the deduplicator does nothing special
with names: types that have names in C will have the same name in CTF.
So we can assume that the CTF rules and the C rules are the same.)
include/ChangeLog
2021-01-27 Nick Alcock <nick.alcock@oracle.com>
Nick Alcock [Wed, 27 Jan 2021 19:41:49 +0000 (19:41 +0000)]
libctf: rip out dead code handling typedefs with no name
There is special code in libctf to handle typedefs with no name, which
the code calls "anonymous typedef nodes".
These monsters are obviously not something C programs can include: the
whole point of a ttypedef is to introduce a new name. Looking back at
the history of DWARF in GCC, the only thing (outside C++ anonymous
namespaces) which can generate a DW_TAG_typedef without a DW_AT_name is
obsolete code to handle the long-removed -feliminate-dwarf2-dups option.
Looking at OpenSolaris, typedef nodes with no name couldn't be generated
by the DWARF->CTF converter at all (and its deduplicator barfed on
them): the only reason for the existence of this code is a special case
working around a peculiarity of stabs whereby types could sometimes be
referenced before they were introduced.
We don't need to carry code in libctf to handle special cases in an
obsolete OpenSolaris converter (that yields a format that isn't readable
by libctf anyway). So drop it.
libctf/ChangeLog
2021-01-27 Nick Alcock <nick.alcock@oracle.com>
* ctf-open.c (init_types): Rip out code to check anonymous typedef
nodes.
* ctf-create.c (ctf_add_reftype): Likewise.
* ctf-lookup.c (refresh_pptrtab): Likewise.
Nick Alcock [Sat, 16 Jan 2021 16:49:29 +0000 (16:49 +0000)]
libctf, ld: fix symtypetab and var section population under ld -r
The variable section in a CTF dict is meant to contain the types of
variables that do not appear in the symbol table (mostly file-scope
static declarations). We implement this by having the compiler emit
all potential data symbols into both sections, then delete those
symbols from the variable section that correspond to data symbols the
linker has reported.
Unfortunately, the check for this in ctf_serialize is wrong: rather than
checking the set of linker-reported symbols, we check the set of names
in the data object symtypetab section: if the linker has reported no
symbols at all (usually if ld -r has been run, or if a non-linker
program that does not use symbol tables is calling ctf_link) this will
include every single symbol, emptying the variable section completely.
Worse, when ld -r is in use, we want to force writeout of every
symtypetab entry on the inputs, in an indexed section, whether or not
the linker has reported them, since this isn't a final link yet and the
symbol table is not finalized (and may grow more symbols than the linker
has yet reported). But the check for this is flawed too: we were
relying on ctf_link_shuffle_syms not having been called if no symbols
exist, but that function is *always* called by ld even when ld -r is in
use: ctf_link_add_linker_symbol is the one that's not called when there
are no symbols.
We clearly need to rethink this. Using the emptiness of the set of
reported symbols as a test for ld -r is just ugly: the linker already
knows if ld -r is underway and can just tell us. So add a new linker
flag CTF_LINK_NO_FILTER_REPORTED_SYMS that is set to stop the linker
filtering the symbols in the symtypetab sections using the set that the
linker has reported: use the presence or absence of this flag to
determine whether to emit unindexed symtabs: we only remove entries from
the variable section when filtering symbols, and we only remove them if
they are in the reported symbol set, fixing the case where no symbols
are reported by the linker at all.
(The negative sense of the new CTF_LINK flag is intentional: the common
case, both for ld and for simple tools that want to do a ctf_link with
no ELF symbol table in sight, is probably to filter out symbols that no
linker has reported: i.e., for the simple tools, all of them.)
There's another wrinkle, though. It is quite possible for a non-linker
to add symbols to a dict via ctf_add_*_sym and then write it out via the
ctf_write APIs: perhaps it's preparing a dict for a later linker
invocation. Right now this would not lead to anything terribly
meaningful happening: ctf_serialize just assumes it was called via
ctf_link if symbols are present. So add an (internal-to-libctf) flag
that indicates that a writeout is happening via ctf_link_write, and set
it there (propagating it to child dicts as needed). ctf_serialize can
then spot when it is not being called by a linker, and arrange to always
write out an indexed, sorted symtypetab for fastest possible future
symbol lookup by name in that case. (The writeouts done by ld -r are
unsorted, because the only thing likely to use those symtabs is the
linker, which doesn't benefit from symtypetab sorting.)
Tests added for all three linking cases (ld -r, ld -shared, ld), with a
bit of testsuite framework enhancement to stop it unconditionally
linking the CTF to be checked by the lookup program with -shared, so
tests can now examine CTF linked with -r or indeed with no flags at all,
though the output filename is still foo.so even in this case.
Another test added for the non-linker case that endeavours to determine
whether the symtypetab is sorted by examining the order of entries
returned from ctf_symbol_next: nobody outside libctf should rely on
this ordering, but this test is not outside libctf :)
include/ChangeLog
2021-01-26 Nick Alcock <nick.alcock@oracle.com>
ld/ChangeLog
2021-01-26 Nick Alcock <nick.alcock@oracle.com>
* ldlang.c (lang_merge_ctf): Set CTF_LINK_NO_FILTER_REPORTED_SYMS
when appropriate.
libctf/ChangeLog
2021-01-27 Nick Alcock <nick.alcock@oracle.com>
* ctf-impl.c (_libctf_nonnull_): Add parameters.
(LCTF_LINKING): New flag.
(ctf_dict_t) <ctf_link_flags>: Mention it.
* ctf-link.c (ctf_link): Keep LCTF_LINKING set across call.
(ctf_write): Likewise, including in child dictionaries.
(ctf_link_shuffle_syms): Make sure ctf_dynsyms is NULL if there
are no reported symbols.
* ctf-create.c (symtypetab_delete_nonstatic_vars): Make sure
the variable has been reported as a symbol by the linker.
(symtypetab_skippable): Mention relationship between SYMFP and the
flags.
(symtypetab_density): Adjust nonnullity. Exit early if no symbols
were reported and force-indexing is off (i.e., we are doing a
final link).
(ctf_serialize): Handle the !LCTF_LINKING case by writing out an
indexed, sorted symtypetab (and allow SYMFP to be NULL in this
case). Turn sorting off if this is a non-final link. Only delete
nonstatic vars if we are filtering symbols and the linker has
reported some.
* testsuite/libctf-regression/nonstatic-var-section-ld-r*:
New test of variable and symtypetab section population when
ld -r is used.
* testsuite/libctf-regression/nonstatic-var-section-ld-executable.lk:
Likewise, when ld of an executable is used.
* testsuite/libctf-regression/nonstatic-var-section-ld.lk:
Likewise, when ld -shared alone is used.
* testsuite/libctf-regression/nonstatic-var-section-ld*.c:
Lookup programs for the above.
* testsuite/libctf-writable/symtypetab-nonlinker-writeout.*: New
test, testing survival of symbols across ctf_write paths.
* testsuite/lib/ctf-lib.exp (run_lookup_test): New option,
nonshared, suppressing linking of the SOURCE with -shared.
Alan Modra [Thu, 4 Feb 2021 03:26:34 +0000 (13:56 +1030)]
PR27311, (symbol from plugin): undefined reference, hidden sym
bfd/
PR 27311
* elflink.c (elf_link_add_object_symbols): Don't pull in as-needed
libraries for IR references on pass over libraries after LTO
recompilation.
ld/
* testsuite/ld-plugin/pr27311d.c: New test.
* testsuite/ld-plugin/lto.exp: Rename pr27311 to pr27311-1, compile
and link new test as pr27311-2.
Alan Modra [Wed, 3 Feb 2021 05:27:35 +0000 (15:57 +1030)]
Re: PR27311, ld.bfd (symbol from plugin): undefined reference
This does exactly the same as making decisions based on an override
in _bfd_elf_add_default_symbol, and is simpler.
PR 27311
* elflink.c (_bfd_elf_add_default_symbol): Revert last two changes.
(elf_link_add_object_symbols): Here too. Don't pull in as-needed
libraries when H is an indirect symbol after calling
_bfd_elf_add_default_symbol.
Alan Modra [Sun, 31 Jan 2021 15:34:41 +0000 (02:04 +1030)]
pr27270 and pr27284, ar segfaults and wrong file mode
PR 27270
PR 27284
PR 26945
* ar.c: Don't include libbfd.h.
(write_archive): Replace xmalloc+strcpy with xstrdup. Use
bfd_stat rather than fstat on iostream. Move stat and fd tests
outside of _WIN32 ifdef. Delete skip_stat variable.
* arsup.c (temp_name, real_ofd): New static variables.
(ar_open): Use make_tempname and bfd_fdopenw.
(ar_save): Adjust to suit ar_open changes. Move stat output
of _WIN32 ifdef.
* objcopy.c: Don't include libbfd.h.
(copy_file): Use bfd_stat.
Alan Modra [Wed, 3 Feb 2021 00:27:12 +0000 (10:57 +1030)]
PR27311 again, ld.bfd (symbol from plugin): undefined reference
bfd/
PR 27311
* elflink.c (_bfd_elf_add_default_symbol): Clear override when
undecorated symbol will have a different version.
ld/
* testsuite/ld-ifunc/ifunc.exp (libpr16467b.so, libpr16467bn.so):
Link with --as-needed.
Pedro Alves [Mon, 11 Jan 2021 20:01:58 +0000 (20:01 +0000)]
detach in all-stop with threads running
A following patch will add a testcase that has a number of threads
constantly stepping over a breakpoint, and then has GDB detach the
process, while threads are running. If we have more than one inferior
running, and we detach from just one of the inferiors, we expect that
the remaining inferior continues running. However, in all-stop, if
GDB needs to pause the target for the detach, nothing is re-resuming
the other inferiors after the detach. "info threads" shows the
threads as running, but they really aren't. This fixes it.
gdb/ChangeLog:
* infcmd.c (detach_command): Hold strong reference to target, and
if all-stop on entry, restart threads on exit.
* infrun.c (switch_back_to_stepped_thread): Factor out bits to ...
(restart_stepped_thread): ... this new function. Also handle
trap_expected.
(restart_after_all_stop_detach): New function.
* infrun.h (restart_after_all_stop_detach): Declare.
Pedro Alves [Mon, 11 Jan 2021 23:11:57 +0000 (23:11 +0000)]
detach with in-line step over in progress
A following patch will add a testcase that has a number of threads
constantly stepping over a breakpoint, and then has GDB detach the
process. That testcase exercises both "set displaced-stepping
on/off". Testing with "set displaced-stepping off" reveals that GDB
does not handle the case of the user typing "detach" just while some
thread is in the middle of an in-line step over. If that thread
belongs to the inferior that is being detached, then the step-over
never finishes, and threads of other inferiors are never re-resumed.
This fixes it.
Pedro Alves [Sun, 13 Dec 2020 01:35:05 +0000 (01:35 +0000)]
detach and breakpoint removal
A following patch will add a testcase that has a number of threads
constantly stepping over a breakpoint, and then has GDB detach the
process. That testcase sometimes fails with the inferior crashing
with SIGTRAP after the detach because of the bug fixed by this patch,
when tested with the native target.
The problem is that target_detach removes breakpoints from the target
immediately, and that does not work with the native GNU/Linux target
(and probably no other native target) currently. The test wouldn't
fail with this issue when testing against gdbserver, because gdbserver
does allow accessing memory while the current thread is running, by
transparently pausing all threads temporarily, without GDB noticing.
Implementing that in gdbserver was a lot of work, so I'm not looking
forward right now to do the same in the native target. Instead, I
came up with a simpler solution -- push the breakpoints removal down
to the targets. The Linux target conveniently already pauses all
threads before detaching them, since PTRACE_DETACH only works with
stopped threads, so we move removing breakpoints to after that. Only
the remote and GNU/Linux targets support support async execution, so
no other target should really need this.
gdb/ChangeLog:
* linux-nat.c (linux_nat_target::detach): Remove breakpoints
here...
* remote.c (remote_target::remote_detach_1): ... and here ...
* target.c (target_detach): ... instead of here.
* target.h (target_ops::detach): Add comment.
Pedro Alves [Sun, 13 Dec 2020 01:35:05 +0000 (01:35 +0000)]
prepare_for_detach and ongoing displaced stepping
I noticed that "detach" while a program was running sometimes resulted
in the process crashing. I tracked it down to this change to
prepare_for_detach in commit 187b041e ("gdb: move displaced stepping
logic to gdbarch, allow starting concurrent displaced steps"):
/* Is any thread of this process displaced stepping? If not,
there's nothing else to do. */
- if (displaced->step_thread == nullptr)
+ if (displaced_step_in_progress (inf))
return;
The problem above is that the condition was inadvertently flipped. It
should have been:
if (!displaced_step_in_progress (inf))
So I fixed it, and wrote a testcase to exercise it. The testcase has
a number of threads constantly stepping over a breakpoint, and then
GDB detaches the process, while threads are running and stepping over
the breakpoint. And then I was surprised that my testcase would hang
-- GDB would get stuck in an infinite loop in prepare_for_detach,
here:
while (displaced_step_in_progress (inf))
{
...
What is going on is that since we now have two displaced stepping
buffers, as one displaced step finishes, GDB starts another, and
there's another one already in progress, and on and on, so the
displaced_step_in_progress condition never turns false. This happens
because we go via the whole handle_inferior_event, which tries to
start new step overs when one finishes. And also because while we
remove breakpoints from the target before prepare_for_detach is
called, handle_inferior_event ends up calling insert_breakpoints via
e.g. keep_going.
Thinking through all this, I came to the conclusion that going through
the whole handle_inferior_event isn't ideal. A _lot_ is done by that
function, e.g., some thread may get a signal which is passed to the
inferior, and gdb decides to try to get over the signal handler, which
reinstalls breakpoints. Or some process may exit. We can end up
reporting these events via normal_stop while detaching, maybe end up
running some breakpoint commands, or maybe even something runs an
inferior function call. Etc. All this after the user has already
declared they don't want to debug the process anymore, by asking to
detach.
I came to the conclusion that it's better to do the minimal amount of
work possible, in a more controlled fashion, without going through
handle_inferior_event. So in the new approach implemented by this
patch, if there are threads of the inferior that we're detaching in
the middle of a displaced step, stop them, and cancel the displaced
step. This is basically what stop_all_threads already does, via
wait_one and (the now factored out) handle_one, so I'm reusing those.
gdb/ChangeLog:
* infrun.c (struct wait_one_event): Move higher up.
(prepare_for_detach): Abort in-progress displaced steps instead of
letting them complete.
(handle_one): If the inferior is detaching, don't add the thread
back to the global step-over chain.
(restart_threads): Don't restart threads if detaching.
(handle_signal_stop): Remove inferior::detaching reference.
Pedro Alves [Mon, 11 Jan 2021 18:52:12 +0000 (18:52 +0000)]
prepare_for_detach: don't release scoped_restore at the end
After detaching from a process, the inf->detaching flag is
inadvertently left set to true. If you afterwards reuse the same
inferior to start a new process, GDB will mishave...
The problem is that prepare_for_detach discards the scoped_restore at
the end, while the intention is for the flag to be set only for the
duration of prepare_for_detach.
This was already a bug in the original commit that added
prepare_for_detach, commit 24291992dac3 ("PR gdb/11321"), by yours
truly. Back then, we still used cleanups, and the function called
discard_cleanups instead of do_cleanups, by mistake.
gdb/ChangeLog:
* infrun.c (prepare_for_detach): Don't release scoped_restore
before returning.
Pedro Alves [Mon, 11 Jan 2021 11:42:38 +0000 (11:42 +0000)]
gdbserver: spurious SIGTRAP w/ detach while step-over in progress
A following patch will add a new testcase that has two processes, each
with a number of threads constantly tripping a breakpoint and stepping
over it, because the breakpoint has a condition that evals false.
Then GDB detaches from one of the processes, while both processes are
running. And then the testcase sends a SIGUSR1 to the other process.
When run against gdbserver, that would occasionaly fail like this:
Thread 2.5 "detach-step-ove" received signal SIGTRAP, Trace/breakpoint trap.
[Switching to Thread 208303.208305]
0x000055555555522a in thread_func (arg=0x0) at /home/pedro/gdb/binutils-gdb/src/gdb/testsuite/gdb.threads/detach-step-over.c:54
54 counter++; /* Set breakpoint here. */
What happened was that GDBserver is doing a step-over for process A
when a detach request for process B arrives. And that generates a
spurious SIGTRAP report for process A, as seen above.
The GDBserver logs reveal what happened:
- GDB manages to detach while a step over is in progress. That reaches
linux_process_target::complete_ongoing_step_over(), which does:
/* Passing NULL_PTID as filter indicates we want all events to
be left pending. Eventually this returns when there are no
unwaited-for children left. */
ret = wait_for_event_filtered (minus_one_ptid, null_ptid, &wstat,
__WALL);
As the comment say, this leaves all events pending, _including_ the
just finished step SIGTRAP. We never discard that SIGTRAP. So
GDBserver reports the SIGTRAP to GDB. GDB can't explain the
SIGTRAP, so it reports it to the user.
The GDBserver log looks like this. The LWP of interest is 208305:
Need step over [LWP 208305]? yes, found breakpoint at 0x555555555227
proceed_all_lwps: found thread 208305 needing a step-over
Starting step-over on LWP 208305. Stopping all threads
208305 starts a step-over.
>>>> entering void linux_process_target::stop_all_lwps(int, lwp_info*)
stop_all_lwps (stop-and-suspend, except=LWP 208303.208305)
Sending sigstop to lwp 208303
Sending sigstop to lwp 207755
wait_for_sigstop: pulling events
LWFE: waitpid(-1, ...) returned 207755, ERRNO-OK
LLW: waitpid 207755 received Stopped (signal) (stopped)
pc is 0x7f7e045593bf
Expected stop.
LLW: SIGSTOP caught for LWP 207755.207755 while stopping threads.
LWFE: waitpid(-1, ...) returned 208303, ERRNO-OK
LLW: waitpid 208303 received Stopped (signal) (stopped)
pc is 0x7ffff7e743bf
Expected stop.
LLW: SIGSTOP caught for LWP 208303.208303 while stopping threads.
LWFE: waitpid(-1, ...) returned 0, ERRNO-OK
leader_pid=208303, leader_lp!=NULL=1, num_lwps=11, zombie=0
leader_pid=207755, leader_lp!=NULL=1, num_lwps=11, zombie=0
LLW: exit (no unwaited-for LWP)
stop_all_lwps done, setting stopping_threads back to !stopping
<<<< exiting void linux_process_target::stop_all_lwps(int, lwp_info*)
Done stopping all threads for step-over.
pc is 0x555555555227
Writing 8b to 0x555555555227 in process 208305
Could not findsigchld_handler
fast tracepoint jump at 0x555555555227 in list (uninserting).
pending reinsert at 0x555555555227
step from pc 0x555555555227
Resuming lwp 208305 (step, signal 0, stop expected)
<<<< exiting ptid_t linux_process_target::wait_1(ptid_t, target_waitstatus*, target_wait_flags)
handling possible serial event
getpkt ("D;32b8b"); [no ack sent]
The detach request arrives.
sigchld_handler
Tracing is already off, ignoring
detach: step over in progress, finish it first
GDBserver realizes a step over for 208305 was in progress, let's it
finish.
LWFE: waitpid(-1, ...) returned 208305, ERRNO-OK
LLW: waitpid 208305 received Stopped (signal) (stopped)
pc is 0x555555555227
Expected stop.
LLW: step LWP 208303.208305, 0, 0 (discard delayed SIGSTOP)
pending reinsert at 0x555555555227
step from pc 0x555555555227
Resuming lwp 208305 (step, signal 0, stop not expected)
LWFE: waitpid(-1, ...) returned 0, ERRNO-OK
leader_pid=208303, leader_lp!=NULL=1, num_lwps=11, zombie=0
leader_pid=207755, leader_lp!=NULL=1, num_lwps=11, zombie=0
sigsuspend'ing
LWFE: waitpid(-1, ...) returned 208305, ERRNO-OK
LLW: waitpid 208305 received Trace/breakpoint trap (stopped)
pc is 0x55555555522a
CSBB: LWP 208303.208305 stopped by trace
LWFE: waitpid(-1, ...) returned 0, ERRNO-OK
leader_pid=208303, leader_lp!=NULL=1, num_lwps=11, zombie=0
leader_pid=207755, leader_lp!=NULL=1, num_lwps=11, zombie=0
LLW: exit (no unwaited-for LWP)
Finished step over.
The step-over for 208305 finishes.
Writing cc to 0x555555555227 in process 208305
Could not find fast tracepoint jump at 0x555555555227 in list (reinserting).
>>>> entering void linux_process_target::stop_all_lwps(int, lwp_info*)
stop_all_lwps (stop, except=none)
wait_for_sigstop: pulling events
The detach proceeds (snipped).
...
proceed_one_lwp: lwp 208305
LWP 208305 has pending status, leaving stopped
Later on, 208305 has a pending status (the step SIGTRAP from the
step-over), so GDBserver starts the process of reporting it.
Pedro Alves [Wed, 6 Jan 2021 02:19:38 +0000 (02:19 +0000)]
Fix a couple vStopped pending ack bugs
A following patch will add a testcase that has two processes with
threads stepping over a breakpoint continuously, and then detaches
from one of the processes while threads are running. The other
process continues stepping over its breakpoint. And then the testcase
sends a SIGUSR1, expecting that GDB reports it. That would sometimes
hang against gdbserver, due to the bugs fixed here. Both bugs are
related, in that they're about remote protocol asynchronous Stop
notifications. There's a bug in GDB, and another in GDBserver.
The GDB bug:
- when we detach from a process, the remote target discards any
pending RSP notification related to that process, including the
in-flight, yet-unacked notification. Discarding the in-flight
notification is the problem. Until the in-flight notification is
acked with a vStopped packet, the server won't send another %Stop
notification. As a result, the debug session gets messed up. In
the new testcase's case, GDB would hang inside stop_all_threads,
waiting for a stop for one of the process'es threads, which never
arrived -- its stop reply was permanently stuck in the stop reply
queue, waiting for a vStopped packet that never arrived.
In summary:
1. GDBserver sends stop notification about thread X, the remote
target receives it and stores it
2. At the same time, GDB detaches thread X's inferior
3. The remote target discards the received stop notification
4. GDBserver waits forever for the ack
The GDBserver bug:
GDBserver has the opposite bug. It also discards notifications for
the process being detached. If that discards the head of the
notification queue, when gdb sends an ack, it ends up acking the
_next_ notification. Meaning, gdb loses one notification. In the
testcase, this results in a similar hang in stop_all_threads.
So we have two very similar bugs in GDB and GDBserver, both resulting
in a similar symptom. That's why I'm fixing them both at the same
time.
gdb/ChangeLog:
* remote.c (remote_notif_stop_ack): Don't error out on
TARGET_WAITKIND_IGNORE; instead, just ignore the notification.
(remote_target::discard_pending_stop_replies): Don't delete
in-flight notification; instead, clear its contents.
gdbserver/ChangeLog:
* server.cc (discard_queued_stop_replies): Don't ever discard the
notification at the head of the list.
Attaching to the hung GDB shows that GDB is busy in an infinite loop
in stop_all_threads:
(top-gdb) bt
#0 stop_all_threads () at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:4755
#1 0x000055555597b424 in stop_waiting (ecs=0x7fffffffd930) at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:7738
#2 0x0000555555976fba in handle_signal_stop (ecs=0x7fffffffd930) at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:5868
#3 0x0000555555975f6a in handle_inferior_event (ecs=0x7fffffffd930) at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:5527
#4 0x0000555555971da4 in fetch_inferior_event () at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:3910
#5 0x00005555559540b2 in inferior_event_handler (event_type=INF_REG_EVENT) at /home/pedro/gdb/binutils-gdb/src/gdb/inf-loop.c:42
#6 0x000055555597e825 in infrun_async_inferior_event_handler (data=0x0) at /home/pedro/gdb/binutils-gdb/src/gdb/infrun.c:9162
#7 0x0000555555687d1d in check_async_event_handlers () at /home/pedro/gdb/binutils-gdb/src/gdb/async-event.c:328
#8 0x0000555555e48284 in gdb_do_one_event () at /home/pedro/gdb/binutils-gdb/src/gdbsupport/event-loop.cc:216
#9 0x00005555559e7512 in start_event_loop () at /home/pedro/gdb/binutils-gdb/src/gdb/main.c:347
#10 0x00005555559e765d in captured_command_loop () at /home/pedro/gdb/binutils-gdb/src/gdb/main.c:407
#11 0x00005555559e8f80 in captured_main (data=0x7fffffffdb70) at /home/pedro/gdb/binutils-gdb/src/gdb/main.c:1239
#12 0x00005555559e8ff2 in gdb_main (args=0x7fffffffdb70) at /home/pedro/gdb/binutils-gdb/src/gdb/main.c:1254
#13 0x0000555555627c86 in main (argc=12, argv=0x7fffffffdc88) at /home/pedro/gdb/binutils-gdb/src/gdb/gdb.c:32
The problem is that the remote sends stops for all the threads:
But then wait_one never consumes them, always hitting this path:
4473 if (nfds == 0)
4474 {
4475 /* No waitable targets left. All must be stopped. */
4476 return {NULL, minus_one_ptid, {TARGET_WAITKIND_NO_RESUMED}};
4477 }
Resulting in GDB constanly calling target_stop to stop threads, but
the remote target never reporting back the stops to infrun.
That TARGET_WAITKIND_NO_RESUMED path shown above is always taken
because here, in wait_one too, just above:
The problem is that attaching installs an inferior continuation,
called when the target reports the initial attach stop, here, in
inf-loop.c:inferior_event_handler:
/* Do all continuations associated with the whole inferior (not
a particular thread). */
if (inferior_ptid != null_ptid)
do_all_inferior_continuations (0);
However, currently in non-stop mode, inferior_ptid is still null_ptid
when we get here.
If you try to do "set debug infrun 1" to debug the problem, however,
then the attach completes correctly, with GDB reporting a stop for
each thread.
The bug is that we're missing a switch_to_thread/context_switch call
when handling the initial stop, here:
Note how the STOP_QUIETLY / STOP_QUIETLY_REMOTE case above that does
call context_switch.
And the reason "set debug infrun 1" "fixes" it, is that the debug path
has a switch_to_thread call.
This patch fixes it by moving the main context_switch call earlier.
It also removes the:
if (ecs->ptid != inferior_ptid)
check at the same time because:
#1 - that is half of what context_switch already does
#2 - deprecated_context_hook is only used in Insight, and all it does
is set an int. It won't care if we call it when the current
thread hasn't actually changed.
A testcase exercising this will be added in a following patch.
gdb/ChangeLog:
PR gdb/27055
* infrun.c (handle_signal_stop): Move main context_switch call
earlier, before STOP_QUIETLY_NO_SIGSTOP.
Lancelot SIX [Wed, 6 Jan 2021 20:58:04 +0000 (20:58 +0000)]
Inferior without argument prints detail of current inferior.
This patch makes the inferior command display information about the
current inferior when called with no argument. This behavior is similar
to the one of the thread command.
Before patch:
(gdb) info inferior
Num Description Connection Executable
* 1 process 19221 1 (native) /home/lsix/tmp/a.out
2 process 19239 1 (native) /home/lsix/tmp/a.out
(gdb) inferior 2
[Switching to inferior 2 [process 19239] (/home/lsix/tmp/a.out)]
[Switching to thread 2.1 (process 19239)]
#0 0x0000000000401146 in main ()
(gdb) inferior
Argument required (expression to compute).
After patch:
(gdb) info inferior
Num Description Connection Executable
* 1 process 18699 1 (native) /home/lsix/tmp/a.out
2 process 18705 1 (native) /home/lsix/tmp/a.out
(gdb) inferior 2
[Switching to inferior 2 [process 18705] (/home/lsix/tmp/a.out)]
[Switching to thread 2.1 (process 18705)]
#0 0x0000000000401146 in main ()
(gdb) inferior
[Current inferior is 2 [process 18705] (/home/lsix/tmp/a.out)]
gdb/doc/ChangeLog:
* gdb.texinfo (Inferiors Connections and Programs): Document the
inferior command when used without argument.
gdb/ChangeLog:
* NEWS: Add entry for the behavior change of the inferior command.
* inferior.c (inferior_command): When no argument is given to the
inferior command, display info about the currently selected
inferior.
gdb/testsuite/ChangeLog:
* gdb.base/inferior-noarg.c: New test.
* gdb.base/inferior-noarg.exp: New test.
Simon Marchi [Tue, 2 Feb 2021 15:40:53 +0000 (10:40 -0500)]
gdb/testsuite: add test for .debug_{rng,loc}lists section without offset array
It is possible for the tables in the .debug_{rng,loc}lists sections to
not have an array of offsets. In that case, the offset_entry_count
field of the header is 0. The forms DW_FORM_{rng,loc}listx (reference
by index) can't be used with that table. Instead, the
DW_FORM_sec_offset form, which references a {rng,loc}list by direct
offset in the section, must be used. From what I saw, this is what GCC
currently produces.
Add tests for this case. I didn't see any bug related to this, I just
think that it would be nice to have coverage for this. A new
`-with-offset-array` option is added to the `table` procs, used when
generating {rng,loc}lists, to decide whether to generate the offset
array.
gdb/testsuite/ChangeLog:
* lib/dwarf.exp (rnglists): Add -no-offset-array option to
table proc.
* gdb.dwarf2/rnglists-sec-offset.exp: Add test for
.debug_rnglists table without offset array.
* gdb.dwarf2/loclists-sec-offset.exp: Add test for
.debug_loclists table without offset array.
Simon Marchi [Tue, 2 Feb 2021 15:40:52 +0000 (10:40 -0500)]
gdb/dwarf: make read_{loc,rng}list_index return sect_offset
I think it's wrong that read_loclist_index and read_rnglist_index return
a CORE_ADDR. A CORE_ADDR is an address in the program. These functions
return offset in sections (.debug_loclists and .debug_rnglists). I
think sect_offset is more appropriate.
I'm wondering if struct attribute should have a "set_sect_offset"
method, that takes a sect_offset parameter, or if it's better to be
left as a simple "unsigned".
gdb/ChangeLog:
* dwarf2/read.c (read_loclist_index, read_rnglist_index): Return
a sect_offset.
(read_attribute_reprocess): Adjust.
Simon Marchi [Tue, 2 Feb 2021 15:41:59 +0000 (10:41 -0500)]
gdb/dwarf: split dwarf2_cu::ranges_base in two
Consider the test case added in this patch. It defines a compilation
unit with a DW_AT_rnglists_base attribute (used for attributes of form
DW_FORM_rnglistx), but also uses DW_AT_ranges of form
DW_FORM_sec_offset:
The DW_AT_rnglists_base does not play a role in reading the DW_AT_ranges of
form DW_FORM_sec_offset, but it should also not do any harm.
This case is currently not handled correctly by GDB. This is not
something that a compiler is likely to emit, but in my opinion there's
no reason why GDB should fail reading it.
The problem is that in partial_die_info::read and a few other places
where the same logic is replicated, the cu->ranges_base value,
containing the DW_AT_rnglists_base value, is wrongfully added to the
DW_AT_ranges value.
It is quite messy how to decide whether cu->ranges_base should be added
to the attribute's value or not. But to summarize, the only time we
want to add it is when the attribute comes from a pre-DWARF 5 split unit
file (a .dwo) [1]. In this case, the DW_AT_ranges attribute from the
split unit file will have form DW_FORM_sec_offset, pointing somewhere in
the linked file's .debug_ranges section. *But* it's not a "true"
DW_FORM_sec_offset, in that it's an offset relative to the beginning of
that CU's contribution in the section, not relative to the beginning of
the section. So in that case, and only that case, do we want to add the
ranges base value, which we found from the DW_AT_GNU_ranges_base
attribute on the skeleton unit.
Almost all instances of the DW_AT_ranges attribute will be found in the
split unit (on DW_TAG_subprogram, for example), and therefore need to
have the ranges base added. However, the DW_TAG_compile_unit DIE in the
skeleton may also have a DW_AT_ranges attribute. For that one, the
ranges base must not be added. Once the DIEs have been loaded in GDB,
however, the distinction between what's coming from the skeleton and
what's coming from the split unit is not clear. It is all merged in one
big happy tree. So how do we know if a given attribute comes from the
split unit or not?
We use the fact that in pre-DWARF 5 split DWARF, DW_AT_ranges is found
on the skeleton's DW_TAG_compile_unit (in the linked file) and never in
the split unit's DW_TAG_compile_unit. This is why you have this in
partial_die_info::read:
int need_ranges_base = (tag != DW_TAG_compile_unit
&& attr.form != DW_FORM_rnglistx);
However, with the corner case described above (where we have a
DW_AT_rnglists_base attribute and a DW_AT_ranges attribute of form
DW_FORM_sec_offset) the condition gets it wrong when it encounters an
attribute like DW_TAG_subprogram with a DW_AT_ranges attribute of
DW_FORM_sec_offset form: it thinks that it is necessary to add the base,
when it reality it is not.
The problem boils down to failing to differentiate these cases:
- a DW_AT_ranges attribute of form DW_FORM_sec_offset in a
pre-DWARF 5 split unit (in which case we need to add the base)
- a DW_AT_ranges attribute of form DW_FORM_sec_offset in a DWARF 5
non-split unit (in which case we must not add the base)
What makes it unnecessarily complex is that the cu->ranges_base field is
overloaded, used to hold the pre-DWARF 5, non-standard
DW_AT_GNU_ranges_base and the DWARF 5 DW_AT_rnglists_base. In reality,
these two are called "bases" but are not the same thing. The result is
that we need twisted conditions to try to determine whether or not we
should add the base to the attribute's value.
To fix it, split the field in two distinct fields. I renamed everything
related to the "old" ranges base to "gnu_ranges_base", to make it clear
that it's about the non-standard, pre-DWARF 5 thing. And everything
related to the DWARF 5 thing gets renamed "rnglists". I think it
becomes much easier to reason this way.
The issue described above gets fixed by the fact that the
DW_AT_rnglists_base value does not end up in cu->gnu_ranges_base, so
cu->gnu_ranges_base stays 0. The condition to determine whether
gnu_ranges_base should be added can therefore be simplified back to:
tag != DW_TAG_compile_unit
... as it was before rnglistx support was added.
Extend the gdb.dwarf2/rnglists-sec-offset.exp to cover this case. I
also extended the test case for loclists similarly, just to see if there
would be some similar problem. There wasn't, but I think it's not a bad
idea to test that case for loclists as well, so I left it in the patch.
* gdb.dwarf2/rnglists-sec-offset.exp: Add test for DW_AT_ranges
of DW_FORM_sec_offset form plus DW_AT_rnglists_base attribute.
* gdb.dwarf2/loclists-sec-offset.exp: Add test for
DW_AT_location of DW_FORM_sec_offset plus DW_AT_loclists_base
attribute
Simon Marchi [Tue, 2 Feb 2021 15:40:52 +0000 (10:40 -0500)]
gdb/testsuite: DWARF assembler: add context parameters to _location
The _location proc is used to assemble a location description. It needs
to know some contextual information:
- size of an address
- size of an offset (into another DWARF section)
- DWARF version
It currently get all this directly from global variables holding the
compilation unit information. This is fine because as of now, all
location descriptions are generated in the context of creating a
compilation unit. However, a subsequent patch will generate location
descriptions while generating a .debug_loclists section. _location
should therefore no longer rely on the current compilation unit's
properties.
Change it to accept these values as parameters instead of accessing the
values for the CU.
Simon Marchi [Tue, 2 Feb 2021 15:40:52 +0000 (10:40 -0500)]
gdb/testsuite: add .debug_rnglists tests
Add tests for the various issues fixed in the previous patches.
Add a new "rnglists" procedure to the DWARF assembler, to allow
generating .debug_rnglists sections. A trivial change is required to
support the DWARF 5 CU header layout.
gdb/testsuite/ChangeLog:
PR gdb/26813
* lib/dwarf.exp (_handle_DW_FORM): Handle DW_FORM_rnglistx.
(cu): Generate header for DWARF 5.
(rnglists): New proc.
* gdb.dwarf2/rnglists-multiple-cus.exp: New.
* gdb.dwarf2/rnglists-sec-offset.exp: New.
Simon Marchi [Tue, 2 Feb 2021 15:40:51 +0000 (10:40 -0500)]
gdb/dwarf: read correct rnglist/loclist header in read_{rng,loc}list_index
When loading the binary from PR 26813 in GDB, we get:
DW_FORM_rnglistx index pointing outside of .debug_rnglists offset array [in module /home/simark/build/binutils-gdb/gdb/MagicPurse]
... and the symbols fail to load.
In read_rnglist_index and read_loclist_index, we read the header
(documented in sections 7.28 and 7.29 of DWARF 5) of the CU's
contribution to the .debug_rnglists / .debug_loclists sections to
validate that the index we want to read makes sense. However, we always
read the header at the beginning of the section, rather than the header
for the contribution from which we want to read the index.
To illustrate, here's what the binary from PR 26813 contains. There are
two compile units:
The layout of the .debug_rnglists is the following:
[0x00, 0x0B]: header for CU 1's contribution
[0x0C, 0x0F]: list of offsets for CU 1 (1 element)
[0x10, 0x78]: range lists data for CU 1
[0x79, 0x84]: header for CU 2's contribution
[0x85, 0xB4]: list of offsets for CU 2 (12 elements)
[0xB5, 0xBD7]: range lists data for CU 2
The DW_AT_rnglists_base attrbute points to the beginning of the list of
offsets for that CU, relative to the start of the .debug_rnglists
section. That's right after the header for that contribution.
When we try to read the DW_AT_ranges attribute for CU 2,
read_rnglist_index reads the header for CU 1 instead of the one for CU
2. Since there's only one element in CU 1's offset list, it believes
(wrongfully) that the index 0xB is out of range.
Fix it by reading the header just before where DW_AT_rnglists_base
points to. With this patch, I am able to load GDB built with clang-11
and -gdwarf-5 in itself, with and without -readnow.
gdb/ChangeLog:
PR gdb/26813
* dwarf2/read.c (read_loclists_rnglists_header): Add
header_offset parameter and use it.
(read_loclist_index): Read header of the current contribution,
not the one at the beginning of the section.
(read_rnglist_index): Likewise.
Simon Marchi [Tue, 2 Feb 2021 15:40:51 +0000 (10:40 -0500)]
gdb/dwarf: few fixes for handling DW_FORM_{rng,loc}listx
We hit an assertion when loading the binary from PR 26813. When fixing
it, execution goes a up bit further but then hits another assert, and
another, and another. With these fours fixes, I am able to load the
binary and get to the prompt. An error is shown (index pointing outside
of the section), because the DW_FORM_rnglistx attribute is not read
correctly, but that one is taken care of by the next patch.
The four fixes are:
- attribute::form_requires_reprocessing needs to handle forms
DW_FORM_rnglistx and DW_FORM_loclistx, because set_unsigned_reprocess
is called for them in read_attribute_value.
- read_attribute_reprocess must call set_unsigned for them, not
set_address. The parameter of set_address is a CORE_ADDR, meaning
it's for program addresses. Post-reprocess, DW_FORM_rnglistx and
DW_FORM_loclistx are offsets into their respective sections
(.debug_rnglists and .debug_loclists). set_unsigned is the current
attribute value setter that fits the best. But perhaps we should have
a setter that takes a sect_offset?
- read_attribute_process must call as_unsigned_reprocess instead of
as_unsigned to get the pre-reprocess value, otherwise we hit the
assert inside as_unsigned that makes sure the attribute doesn't need
reprocessing.
- attribute::set_unsigned needs to clear the requires_reprocessing flag,
otherwise it stays set when reprocessing DW_FORM_rnglistx and
DW_FORM_loclistx attributes.
There's another assert that we hit once the next patch is applied, but
since it's in the same vein as the changes in this patch, I included it
in this patch:
- attribute::form_is_unsigned must handle form DW_FORM_loclistx,
otherwise we hit the assert when trying to call set_unsigned for an
attribute of this form. DW_FORM_rnglistx is already handled.
gdb/ChangeLog:
PR gdb/26813
* dwarf2/attribute.h (struct attribute) <set_unsigned>: Clear
requires_reprocessing flag.
* dwarf2/attribute.c (attribute::form_is_unsigned): Handle
DW_FORM_loclistx.
(attribute::form_requires_reprocessing): Handle DW_FORM_rnglistx
and DW_FORM_loclistx.
* dwarf2/read.c (read_attribute_reprocess): Use set_unsigned
instead of set_address for DW_FORM_loclistx and
DW_FORM_rnglistx.
Simon Marchi [Tue, 2 Feb 2021 15:40:51 +0000 (10:40 -0500)]
gdb/dwarf: remove unnecessary check in read_{rng,loc}list_index
In read_rnglist_index and read_loclist_index, we check that both the
start and end of the offset that we read from the offset table are
within the section. I think it's unecessary to do both: if the end of
the offset is within the section, then surely the start of the offset is
within it.
Remove the check for the start of the offset in both functions.
gdb/ChangeLog:
* dwarf2/read.c (read_loclist_index): Remove bound check for
start of offset.
(read_rnglist_index): Likewise.
Simon Marchi [Tue, 2 Feb 2021 15:40:51 +0000 (10:40 -0500)]
gdb/dwarf: add missing bound check to read_loclist_index
read_rnglist_index has a bound check to make sure that we don't go past
the end of the section while reading the offset, but read_loclist_index
doesn't. Add it to read_loclist_index.
gdb/ChangeLog:
* dwarf2/read.c (read_loclist_index): Add bound check for the end
of the offset.
Simon Marchi [Tue, 2 Feb 2021 15:40:50 +0000 (10:40 -0500)]
gdb/dwarf: fix bound check in read_rnglist_index
I think this check in read_rnglist_index is wrong:
/* Validate that reading won't go beyond the end of the section. */
if (start_offset + cu->header.offset_size > rnglist_base + section->size)
error (_("Reading DW_FORM_rnglistx index beyond end of"
".debug_rnglists section [in module %s]"),
objfile_name (objfile));
The addition `rnglist_base + section->size` doesn't make sense.
rnglist_base is an offset into `section`, so it doesn't make sense to
add it to `section`'s size. `start_offset` also is an offset into
`section`, so we should just compare it to just `section->size`.
Simon Marchi [Tue, 2 Feb 2021 15:40:50 +0000 (10:40 -0500)]
gdb/dwarf: change read_loclist_index complaints into errors
Unlike read_rnglists_index, read_loclist_index uses complaints when it
detects an inconsistency (a DW_FORM_loclistx value without a
.debug_loclists section or an offset outside of the section). I really
think they should be errors, since there's no point in continuing if
this situation happens, we will likely segfault or read garbage.
gdb/ChangeLog:
* dwarf2/read.c (read_loclist_index): Change complaints into
errors.
Alan Modra [Tue, 2 Feb 2021 04:35:14 +0000 (15:05 +1030)]
PR27311, ld.bfd (symbol from plugin): undefined reference
A default versioned symbol definition in a shared library is
overridden by an unversioned definition in a regular object file, and
thus should not be reason to make an as-needed library needed.
bfd/
PR 27311
* elflink.c (_bfd_elf_add_default_symbol): Add override parameter.
Use when handling default versioned symbol. Rename existing
override variable to nondef_override and use for non-default
versioned symbol.
(elf_link_add_object_symbols): Adjust call to suit. Don't
pull in as-needed libraries when override is set.
ld/
* testsuite/ld-plugin/pr27311.d,
* testsuite/ld-plugin/pr27311.ver,
* testsuite/ld-plugin/pr27311a.c,
* testsuite/ld-plugin/pr27311b.c,
* testsuite/ld-plugin/pr27311c.c: New testcase.
* testsuite/ld-plugin/lto.exp: Run it. Correct PR14918 and
PR12982 entries.
Tom de Vries [Tue, 2 Feb 2021 07:37:45 +0000 (08:37 +0100)]
[gdb/symtab] Fix assert in write_one_signatured_type
When running test-case gdb.dwarf2/fission-reread.exp with target board
cc-with-gdb-index, we run into an abort during the generation of the gdb-index
by cc-with-tweaks.sh:
...
build/gdb/testsuite/cache/gdb.sh: line 1: 27275 Aborted (core dumped)
...
This can be reproduced on the command line like this:
...
$ gdb -batch ./outputs/gdb.dwarf2/fission-reread/fission-reread \
-ex 'save gdb-index ./outputs/gdb.dwarf2/fission-reread'
warning: Could not find DWO TU fission-reread.dwo(0x9022f1ceac7e8b19) \
referenced by TU at offset 0x0 [in module fission-reread]
warning: Could not find DWO CU fission-reread.dwo(0x807060504030201) \
referenced by CU at offset 0x561 [in module fission-reread]
Aborted (core dumped)
...
The abort is a segfault due to a using a nullptr psymtab in
write_one_signatured_type.
The problem is that we're trying to write index entries for the type unit
with signature:
...
(gdb) p /x entry->signature
$2 = 0x9022f1ceac7e8b19
...
which is a skeleton type unit:
...
Contents of the .debug_types section:
Compilation Unit @ offset 0x0:
Length: 0x4a (32-bit)
Version: 4
Abbrev Offset: 0x165
Pointer Size: 4
Signature: 0x9022f1ceac7e8b19
Type Offset: 0x0
<0><17>: Abbrev Number: 2 (DW_TAG_type_unit)
<18> DW_AT_comp_dir : /tmp/src/gdb/testsuite
<2f> DW_AT_GNU_dwo_name: fission-reread.dwo
<42> DW_AT_GNU_pubnames: 0x0
<46> DW_AT_GNU_pubtypes: 0x0
<4a> DW_AT_GNU_addr_base: 0x0
...
referring to a .dwo file, but as the warnings show, the .dwo file is not
found.
Fix this by skipping the type unit in write_one_signatured_type if
psymtab == nullptr.
Tested on x86_64-linux.
gdb/ChangeLog:
2021-02-02 Tom de Vries <tdevries@suse.de>
PR symtab/24620
* dwarf2/index-write.c (write_one_signatured_type): Skip if
psymtab == nullptr.
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