I noticed that Frame.older and Frame.newer don't document that they
return None at the ends of the stack. This patch updates the
documentation, and also fixes a somewhat related typo in a comment
that I noticed while digging into this.
Approved-By: Eli Zaretskii <eliz@gnu.org>
In commit 995a34b1772 ("Guard against frame.c destructors running before
frame-info.c's") the following problem was addressed.
The frame_info_ptr destructor:
...
~frame_info_ptr ()
{
frame_list.erase (frame_list.iterator_to (*this));
}
...
uses frame_list, which is a static member of class frame_info_ptr,
instantiated in frame-info.c:
...
intrusive_list<frame_info_ptr> frame_info_ptr::frame_list;
...
Then there's a static frame_info_pointer variable named selected_frame in
frame.c:
...
static frame_info_ptr selected_frame;
...
Because the destructor of selected_frame uses frame_list, its destructor needs
to be called before the destructor of frame_list.
But because they're in different compilation units, the initialization order and
consequently destruction order is not guarantueed.
The commit fixed this by handling the case that the destructor of frame_list
is called first, adding a check on is_linked ():
...
~frame_info_ptr ()
{
- frame_list.erase (frame_list.iterator_to (*this));
+ /* If this node has static storage, it may be deleted after
+ frame_list. Attempting to erase ourselves would then trigger
+ internal errors, so make sure we are still linked first. */
+ if (is_linked ())
+ frame_list.erase (frame_list.iterator_to (*this));
}
...
However, since then frame_list has been moved into frame.c, and
initialization/destruction order is guarantueed inside a compilation unit.
Revert aforementioned commit, and fix the destruction order problem by moving
frame_list before selected_frame.
Reverting the commit is another way of fixing the already fixed
Wdangling-pointer warning reported in PR build/30413, in a different way than
commit 9b0ccb1ebae ("Pass const frame_info_ptr reference for
skip_[language_]trampoline").
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Tested on x86_64-linux.
PR build/30413
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30413
A recent patch caused my system gcc (Fedora 36, so gcc 12.2.1) to warn
about sym_addr being possibly uninitialized in frame.c. It isn't, but
the compiler can't tell. So, this patch initializes the variable. I
also fixed a formatting buglet that I missed in review.
In the case where a Fortran program has a program name of "main" and
there is also a minimal symbol called main, such as with programs built
with GCC version 4.4.7 or below, the backtrace will erroneously stop at
the minimal symbol rather than the user specified main, e.g.:
(gdb) bt
#0 bar () at .../gdb/testsuite/gdb.fortran/backtrace.f90:17
#1 0x0000000000402556 in foo () at .../gdb/testsuite/gdb.fortran/backtrace.f90:21
#2 0x0000000000402575 in main () at .../gdb/testsuite/gdb.fortran/backtrace.f90:31
#3 0x00000000004025aa in main ()
(gdb)
This patch fixes this issue by increasing the precedence of the full
symbol when the language of the current frame is Fortran.
Newer versions of GCC transform the program name to "MAIN__" in this
case, avoiding the problem.
Co-Authored-By: Maciej W. Rozycki <macro@embecosm.com>
gdb 13.1 crashes while running the rust compiler's debugger tests.
The crash has a number of causes.
First, the rust compiler still uses the C++-like _Z mangling, but with
its own twist -- some hex digits added to the end of a symbol. So,
while gdb finds the correct name of "main":
(top-gdb) p name
$13 = 0x292e0c0 "rustc_gdb_1031745::main"
It isn't found in the minsyms, because C++ demangling yields:
[99] t 0x90c0 _ZN17rustc_gdb_10317454main17h5b5be7fe16a97225E section .text rustc_gdb_1031745::main::h5b5be7fe16a97225 zko06yobckx336v
This could perhaps be fixed. I also filed a new PR to suggest
preferring the linkage name of the main program.
Next, the rust compiler emits both a DW_TAG_subprogram and a
DW_TAG_namespace for "main". This happens because the file is named
"main.rs" -- i.e., the bug is specific to the source file name. The
crash also seems to require the nested function inside of 'main', at
least for me. The namespace always is generated, but perhaps this
changes the ordering in the DWARF.
When inside_main_func looks up the main symbol, it finds the namespace
symbol rather than the function. (I filed a bug about fixing gdb's
symbol tables -- long overdue.)
Meanwhile, as I think it's important to fix this crash sooner rather
than later, this patch changes inside_main_func to check that the
symbol that is found is LOC_BLOCK. This perhaps should have been done
in the first place, anyway.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30158
Tom de Vries reported [1] a regression in gdb.btrace/record_goto.exp
caused by 6d3717d4c4 ("gdb: call frame unwinders' dealloc_cache methods
through destroying the frame cache"). This issue is caught by ASan. On
a non-ASan build, it may or may not cause a crash or some other issue, I
haven't tried.
I managed to narrow it down to:
$ ./gdb -nx -q --data-directory=data-directory testsuite/outputs/gdb.btrace/record_goto/record_goto -ex "start" -ex "record btrace" -ex "next"
... and then doing repeatedly "record goto 19" and "record goto 27".
Eventually, I get:
(gdb) record goto 27
=================================================================
==1527735==ERROR: AddressSanitizer: heap-use-after-free on address 0x6210003392a8 at pc 0x55e4c26eef86 bp 0x7ffd229f24e0 sp 0x7ffd229f24d8
READ of size 8 at 0x6210003392a8 thread T0
#0 0x55e4c26eef85 in bfcache_eq /home/simark/src/binutils-gdb/gdb/record-btrace.c:1639
#1 0x55e4c37cdeff in htab_find_slot_with_hash /home/simark/src/binutils-gdb/libiberty/hashtab.c:659
#2 0x55e4c37ce24a in htab_find_slot /home/simark/src/binutils-gdb/libiberty/hashtab.c:703
#3 0x55e4c26ef0c6 in bfcache_new /home/simark/src/binutils-gdb/gdb/record-btrace.c:1653
#4 0x55e4c26f1242 in record_btrace_frame_sniffer /home/simark/src/binutils-gdb/gdb/record-btrace.c:1820
#5 0x55e4c1b926a1 in frame_unwind_try_unwinder /home/simark/src/binutils-gdb/gdb/frame-unwind.c:136
#6 0x55e4c1b930d7 in frame_unwind_find_by_frame(frame_info_ptr, void**) /home/simark/src/binutils-gdb/gdb/frame-unwind.c:196
#7 0x55e4c1bb867f in get_frame_type(frame_info_ptr) /home/simark/src/binutils-gdb/gdb/frame.c:2925
#8 0x55e4c2ae6798 in print_frame_info(frame_print_options const&, frame_info_ptr, int, print_what, int, int) /home/simark/src/binutils-gdb/gdb/stack.c:1049
#9 0x55e4c2ade3e1 in print_stack_frame(frame_info_ptr, int, print_what, int) /home/simark/src/binutils-gdb/gdb/stack.c:367
#10 0x55e4c26fda03 in record_btrace_set_replay /home/simark/src/binutils-gdb/gdb/record-btrace.c:2779
#11 0x55e4c26fddc3 in record_btrace_target::goto_record(unsigned long) /home/simark/src/binutils-gdb/gdb/record-btrace.c:2843
#12 0x55e4c2de2bb2 in target_goto_record(unsigned long) /home/simark/src/binutils-gdb/gdb/target.c:4169
#13 0x55e4c275ed98 in record_goto(char const*) /home/simark/src/binutils-gdb/gdb/record.c:372
#14 0x55e4c275edba in cmd_record_goto /home/simark/src/binutils-gdb/gdb/record.c:383
0x6210003392a8 is located 424 bytes inside of 4064-byte region [0x621000339100,0x62100033a0e0)
freed by thread T0 here:
#0 0x7f6ca34a5b6f in __interceptor_free ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:123
#1 0x55e4c38a4c17 in rpl_free /home/simark/src/binutils-gdb/gnulib/import/free.c:44
#2 0x55e4c1bbd378 in xfree<void> /home/simark/src/binutils-gdb/gdb/../gdbsupport/gdb-xfree.h:37
#3 0x55e4c37d1b63 in call_freefun /home/simark/src/binutils-gdb/libiberty/obstack.c:103
#4 0x55e4c37d25a2 in _obstack_free /home/simark/src/binutils-gdb/libiberty/obstack.c:280
#5 0x55e4c1bad701 in reinit_frame_cache() /home/simark/src/binutils-gdb/gdb/frame.c:2112
#6 0x55e4c27705a3 in registers_changed_ptid(process_stratum_target*, ptid_t) /home/simark/src/binutils-gdb/gdb/regcache.c:564
#7 0x55e4c27708c7 in registers_changed_thread(thread_info*) /home/simark/src/binutils-gdb/gdb/regcache.c:573
#8 0x55e4c26fd922 in record_btrace_set_replay /home/simark/src/binutils-gdb/gdb/record-btrace.c:2772
#9 0x55e4c26fddc3 in record_btrace_target::goto_record(unsigned long) /home/simark/src/binutils-gdb/gdb/record-btrace.c:2843
#10 0x55e4c2de2bb2 in target_goto_record(unsigned long) /home/simark/src/binutils-gdb/gdb/target.c:4169
#11 0x55e4c275ed98 in record_goto(char const*) /home/simark/src/binutils-gdb/gdb/record.c:372
#12 0x55e4c275edba in cmd_record_goto /home/simark/src/binutils-gdb/gdb/record.c:383
previously allocated by thread T0 here:
#0 0x7f6ca34a5e8f in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
#1 0x55e4c0b55c60 in xmalloc /home/simark/src/binutils-gdb/gdb/alloc.c:57
#2 0x55e4c37d1a6d in call_chunkfun /home/simark/src/binutils-gdb/libiberty/obstack.c:94
#3 0x55e4c37d1c20 in _obstack_begin_worker /home/simark/src/binutils-gdb/libiberty/obstack.c:141
#4 0x55e4c37d1ed7 in _obstack_begin /home/simark/src/binutils-gdb/libiberty/obstack.c:164
#5 0x55e4c1bad728 in reinit_frame_cache() /home/simark/src/binutils-gdb/gdb/frame.c:2113
#6 0x55e4c27705a3 in registers_changed_ptid(process_stratum_target*, ptid_t) /home/simark/src/binutils-gdb/gdb/regcache.c:564
#7 0x55e4c27708c7 in registers_changed_thread(thread_info*) /home/simark/src/binutils-gdb/gdb/regcache.c:573
#8 0x55e4c26fd922 in record_btrace_set_replay /home/simark/src/binutils-gdb/gdb/record-btrace.c:2772
#9 0x55e4c26fddc3 in record_btrace_target::goto_record(unsigned long) /home/simark/src/binutils-gdb/gdb/record-btrace.c:2843
#10 0x55e4c2de2bb2 in target_goto_record(unsigned long) /home/simark/src/binutils-gdb/gdb/target.c:4169
#11 0x55e4c275ed98 in record_goto(char const*) /home/simark/src/binutils-gdb/gdb/record.c:372
#12 0x55e4c275edba in cmd_record_goto /home/simark/src/binutils-gdb/gdb/record.c:383
The problem is a stale entry in the bfcache hash table (in
record-btrace.c), left across a reinit_frame_cache. This entry points
to something that used to be allocated on the frame obstack, that has
since been wiped by reinit_frame_cache.
Before the aforementioned, unwinder deallocation functions were called
by iterating on the frame chain, starting with the sentinel frame, like
so:
/* Tear down all frame caches. */
for (frame_info *fi = sentinel_frame; fi != NULL; fi = fi->prev)
{
if (fi->prologue_cache && fi->unwind->dealloc_cache)
fi->unwind->dealloc_cache (fi, fi->prologue_cache);
if (fi->base_cache && fi->base->unwind->dealloc_cache)
fi->base->unwind->dealloc_cache (fi, fi->base_cache);
}
After that patch, we relied on the fact that all frames are (supposedly)
in the frame_stash. A deletion function was added to the frame_stash
hash table, so that dealloc functions would be called when emptying the
frame stash. There is one case, however, where a frame_info is not in
the frame stash. That is when we create the frame_info for the current
frame (level 0, unwound from the sentinel frame), but don't compute its
frame id. The computation of the frame id for that frame (and only that
frame, AFAIK) is done lazily. And putting a frame_info in the frame stash
requires knowing its id. So a frame 0 whose frame id is not computed
yet is necessarily not in the frame stash.
When replaying with btrace, record_btrace_frame_sniffer insert entries
corresponding to frames in the "bfcache" hash table. It then relies on
record_btrace_frame_dealloc_cache being called for each frame to remove
all those entries when the frames get invalidated. If a frame reinit
happens while frame 0's id is not computed (and therefore that frame is
not in frame_stash), record_btrace_frame_dealloc_cache does not get
called for it, and it leaves a stale entry in bfcache. That then leads
to a use-after-free when that entry is accessed later, which ASan
catches.
The proposed solution is to explicitly call frame_info_del on frame 0,
if it exists, and if its frame id is not computed. If its frame id is
computed, it is expected that it will be in the frame stash, so it will
be "deleted" through that.
[1] https://inbox.sourceware.org/gdb-patches/20230130200249.131155-1-simon.marchi@efficios.com/T/#mcf1340ce2906a72ec7ed535ec0c97dba11c3d977
Reported-By: Tom de Vries <tdevries@suse.de>
Tested-By: Tom de Vries <tdevries@suse.de>
Change-Id: I2351882dd511f3bbc01e4152e9db13b69b3ba384
This removes deprecated_lval_hack and the VALUE_LVAL macro, replacing
all uses with a call to value::lval.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns many functions that are related to optimized-out or
availability-checking to be methods of value. The static function
value_entirely_covered_by_range_vector is also converted to be a
private method.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns the remaining value_contents functions -- value_contents,
value_contents_all, value_contents_for_printing, and
value_contents_for_printing_const -- into methods of value. It also
converts the static functions require_not_optimized_out and
require_available to be private methods.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This turns value_contents_raw, value_contents_writeable, and
value_contents_all_raw into methods on value. The remaining functions
will be changed later in the series; they were a bit trickier and so I
didn't include them in this patch.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
This changes the value_lazy and set_value_lazy functions to be methods
of value. Much of this patch was written by script.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
The test gdb.base/frame-view.exp fails like this on AArch64:
frame^M
#0 baz (z1=hahaha, /home/simark/src/binutils-gdb/gdb/value.c:4056: internal-error: value_fetch_lazy_register: Assertion `next_frame != NULL' failed.^M
A problem internal to GDB has been detected,^M
further debugging may prove unreliable.^M
FAIL: gdb.base/frame-view.exp: with_pretty_printer=true: frame (GDB internal error)
The sequence of events leading to this is the following:
- When we create the user frame (the "select-frame view" command), we
create a sentinel frame just for our user-created frame, in
create_new_frame. This sentinel frame has the same id as the regular
sentinel frame.
- When printing the frame, after doing the "select-frame view" command,
the argument's pretty printer is invoked, which does an inferior
function call (this is the point of the test). This clears the frame
cache, including the "real" sentinel frame, which sets the
sentinel_frame global to nullptr.
- Later in the frame-printing process (when printing the second
argument), the auto-reinflation mechanism re-creates the user frame
by calling create_new_frame again, creating its own special sentinel
frame again. However, note that the "real" sentinel frame, the
sentinel_frame global, is still nullptr. If the selected frame had
been a regular frame, we would have called get_current_frame at some
point during the reinflation, which would have re-created the "real"
sentinel frame. But it's not the case when reinflating a user frame.
- Deep down the stack, something wants to fill in the unwind stop
reason for frame 0, which requires trying to unwind frame 1. This
leads us to trying to unwind the PC of frame 1:
#0 gdbarch_unwind_pc (gdbarch=0xffff8d010080, next_frame=...) at /home/simark/src/binutils-gdb/gdb/gdbarch.c:2955
#1 0x000000000134569c in dwarf2_tailcall_sniffer_first (this_frame=..., tailcall_cachep=0xffff773fcae0, entry_cfa_sp_offsetp=0xfffff7f7d450)
at /home/simark/src/binutils-gdb/gdb/dwarf2/frame-tailcall.c:390
#2 0x0000000001355d84 in dwarf2_frame_cache (this_frame=..., this_cache=0xffff773fc928) at /home/simark/src/binutils-gdb/gdb/dwarf2/frame.c:1089
#3 0x00000000013562b0 in dwarf2_frame_unwind_stop_reason (this_frame=..., this_cache=0xffff773fc928) at /home/simark/src/binutils-gdb/gdb/dwarf2/frame.c:1101
#4 0x0000000001990f64 in get_prev_frame_always_1 (this_frame=...) at /home/simark/src/binutils-gdb/gdb/frame.c:2281
#5 0x0000000001993034 in get_prev_frame_always (this_frame=...) at /home/simark/src/binutils-gdb/gdb/frame.c:2376
#6 0x000000000199b814 in get_frame_unwind_stop_reason (frame=...) at /home/simark/src/binutils-gdb/gdb/frame.c:3051
#7 0x0000000001359cd8 in dwarf2_frame_cfa (this_frame=...) at /home/simark/src/binutils-gdb/gdb/dwarf2/frame.c:1356
#8 0x000000000132122c in dwarf_expr_context::execute_stack_op (this=0xfffff7f80170, op_ptr=0xffff8d8883ee "\217\002", op_end=0xffff8d8883ee "\217\002")
at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:2110
#9 0x0000000001317b30 in dwarf_expr_context::eval (this=0xfffff7f80170, addr=0xffff8d8883ed "\234\217\002", len=1) at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:1239
#10 0x000000000131d68c in dwarf_expr_context::execute_stack_op (this=0xfffff7f80170, op_ptr=0xffff8d88840e "", op_end=0xffff8d88840e "") at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:1811
#11 0x0000000001317b30 in dwarf_expr_context::eval (this=0xfffff7f80170, addr=0xffff8d88840c "\221p", len=2) at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:1239
#12 0x0000000001314c3c in dwarf_expr_context::evaluate (this=0xfffff7f80170, addr=0xffff8d88840c "\221p", len=2, as_lval=true, per_cu=0xffff90b03700, frame=..., addr_info=0x0,
type=0xffff8f6c8400, subobj_type=0xffff8f6c8400, subobj_offset=0) at /home/simark/src/binutils-gdb/gdb/dwarf2/expr.c:1078
#13 0x000000000149f9e0 in dwarf2_evaluate_loc_desc_full (type=0xffff8f6c8400, frame=..., data=0xffff8d88840c "\221p", size=2, per_cu=0xffff90b03700, per_objfile=0xffff9070b980,
subobj_type=0xffff8f6c8400, subobj_byte_offset=0, as_lval=true) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1513
#14 0x00000000014a0100 in dwarf2_evaluate_loc_desc (type=0xffff8f6c8400, frame=..., data=0xffff8d88840c "\221p", size=2, per_cu=0xffff90b03700, per_objfile=0xffff9070b980, as_lval=true)
at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:1557
#15 0x00000000014aa584 in locexpr_read_variable (symbol=0xffff8f6cd770, frame=...) at /home/simark/src/binutils-gdb/gdb/dwarf2/loc.c:3052
- AArch64 defines a special "prev register" function,
aarch64_dwarf2_prev_register, to handle unwinding the PC. This
function does
frame_unwind_register_unsigned (this_frame, AARCH64_LR_REGNUM);
- frame_unwind_register_unsigned ultimately creates a lazy register
value, saving the frame id of this_frame->next. this_frame is the
user-created frame, to this_frame->next is the special sentinel frame
we created for it. So the saved ID is the sentinel frame ID.
- When time comes to un-lazify the value, value_fetch_lazy_register
calls frame_find_by_id, to find the frame with the ID we saved.
- frame_find_by_id sees it's the sentinel frame ID, so returns the
sentinel_frame global, which is, if you remember, nullptr.
- We hit the `gdb_assert (next_frame != NULL)` assertion in
value_fetch_lazy_register.
The issues I see here are:
- The ID of the sentinel frame created for the user-created frame is
not distinguishable from the ID of the regular sentinel frame. So
there's no way frame_find_by_id could find the right frame, in
value_fetch_lazy_register.
- Even if they had distinguishable IDs, sentinel frames created for
user frames are not registered anywhere, so there's no easy way
frame_find_by_id could find it.
This patch addresses these two issues:
- Give sentinel frames created for user frames their own distinct IDs
- Register sentinel frames in the frame cache, so they can be found
with frame_find_by_id.
I initially had this split in two patches, but I then found that it was
easier to explain as a single patch.
Rergarding the first part of the change: with this patch, the sentinel
frames created for user frames (in create_new_frame) still have
stack_status == FID_STACK_SENTINEL, but their code_addr and stack_addr
fields are now filled with the addresses used to create the user frame.
This ensures this sentinel frame ID is different from the "target"
sentinel frame ID, as well as any other "user" sentinel frame ID. If
the user tries to create the same frame, with the same addresses,
multiple times, create_sentinel_frame just reuses the existing frame.
So we won't end up with multiple user sentinels with the same ID.
Regular "target" sentinel frames remain with code_addr and stack_addr
unset.
The concrete changes for that part are:
- Remove the sentinel_frame_id constant, since there isn't one
"sentinel frame ID" now. Add the frame_id_build_sentinel function
for building sentinel frame IDs and a is_sentinel_frame_id function
to check if a frame id represents a sentinel frame.
- Replace the sentinel_frame_id check in frame_find_by_id with a
comparison to `frame_id_build_sentinel (0, 0)`. The sentinel_frame
global is meant to contain a reference to the "target" sentinel, so
the one with addresses (0, 0).
- Add stack and code address parameters to create_sentinel_frame, to be
able to create the various types of sentinel frames.
- Adjust get_current_frame to create the regular "target" sentinel.
- Adjust create_new_frame to create a sentinel with the ID specific to
the created user frame.
- Adjust sentinel_frame_prev_register to get the sentinel frame ID from
the frame_info object, since there isn't a single "sentinel frame ID"
now.
- Change get_next_frame_sentinel_okay to check for a
sentinel-frame-id-like frame ID, rather than for sentinel_frame
specifically, since this function could be called with another
sentinel frame (and we would want the assert to catch it).
The rest of the change is about registering the sentinel frame in the
frame cache:
- Change frame_stash_add's assertion to allow sentinel frame levels
(-1).
- Make create_sentinel_frame add the frame to the frame cache.
- Change the "sentinel_frame != NULL" check in reinit_frame_cache for a
check that the frame stash is not empty. The idea is that if we only
have some user-created frames in the cache when reinit_frame_cache is
called, we probably want to emit the frames invalid annotation. The
goal of that check is to avoid unnecessary repeated annotations, I
suppose, so the "frame cache not empty" check should achieve that.
After this change, I think we could theoritically get rid of the
sentienl_frame global. That sentinel frame could always be found by
looking up `frame_id_build_sentinel (0, 0)` in the frame cache.
However, I left the global there to avoid slowing the typical case down
for nothing. I however, noted in its comment that it is an
optimization.
With this fix applied, the gdb.base/frame-view.exp now passes for me on
AArch64. value_of_register_lazy now saves the special sentinel frame ID
in the value, and value_fetch_lazy_register is able to find that
sentinel frame after the frame cache reinit and after the user-created
frame was reinflated.
Tested-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com>
Tested-By: Luis Machado <luis.machado@arm.com>
Change-Id: I8b77b3448822c8aab3e1c3dda76ec434eb62704f
Currently, some frame resources are deallocated by iterating on the
frame chain (starting from the sentinel), calling dealloc_cache. The
problem is that user-created frames are not part of that chain, so we
never call dealloc_cache for them.
I propose to make it so the dealloc_cache callbacks are called when the
frames are removed from the frame_stash hash table, by registering a
deletion function to the hash table. This happens when
frame_stash_invalidate is called by reinit_frame_cache. This way, all
frames registered in the cache will get their unwinder's dealloc_cache
callbacks called.
Note that at the moment, the sentinel frames are not registered in the
cache, so we won't call dealloc_cache for them. However, it's just a
theoritical problem, because the sentinel frame unwinder does not
provide this callback. Also, a subsequent patch will change things so
that sentinel frames are registered to the cache.
I moved the obstack_free / obstack_init pair below the
frame_stash_invalidate call in reinit_frame_cache, because I assumed
that some dealloc_cache would need to access some data on that obstack,
so it would be better to free it after clearing the hash table.
Change-Id: If4f9b38266b458c4e2f7eb43e933090177c22190
This is the second step of making frame_info_ptr automatic, reinflate on
demand whenever trying to obtain the wrapper frame_info pointer, either
through the get method or operator->. Make the reinflate method
private, it is used as a convenience method in those two.
Add an "is_null" method, because it is often needed to know whether the
frame_info_ptr wraps an frame_info or is empty.
Make m_ptr mutable, so that it's possible to reinflate const
frame_info_ptr objects. Whether m_ptr is nullptr or not does not change
the logical state of the object, because we re-create it on demand. I
believe this is the right use case for mutable.
Change-Id: Icb0552d0035e227f81eb3c121d8a9bb2f9d25794
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
This is the first step of making frame_info_ptr automatic. Remove the
frame_info_ptr::prepare_reinflate method, move that code to the
constructor.
Change-Id: I85cdae3ab1c043c70e2702e7fb38e9a4a8a675d8
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
This patch teaches frame_info_ptr to reinflate user-created frames
(frames created through create_new_frame, with the "select-frame view"
command).
Before this patch, frame_info_ptr doesn't support reinflating
user-created frames, because it currently reinflates by getting the
current target frame (for frame 0) or frame_find_by_id (for other
frames). To reinflate a user-created frame, we need to call
create_new_frame, to make it lookup an existing user-created frame, or
otherwise create one.
So, in prepare_reinflate, get the frame id even if the frame has level
0, if it is user-created. In reinflate, if the saved frame id is user
create it, call create_new_frame.
In order to test this, I initially enhanced the gdb.base/frame-view.exp
test added by the previous patch by setting a pretty-printer for the
type of the function parameters, in which we do an inferior call. This
causes print_frame_args to not reinflate its frame (which is a
user-created one) properly. On one machine (my Arch Linux one), it
properly catches the bug, as the frame is not correctly restored after
printing the first parameter, so it messes up the second parameter:
frame
#0 baz (z1=hahaha, z2=<error reading variable: frame address is not available.>) at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:40
40 return z1.m + z2.n;
(gdb) FAIL: gdb.base/frame-view.exp: with_pretty_printer=true: frame
frame
#0 baz (z1=hahaha, z2=<error reading variable: frame address is not available.>) at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:40
40 return z1.m + z2.n;
(gdb) FAIL: gdb.base/frame-view.exp: with_pretty_printer=true: frame again
However, on another machine (my Ubuntu 22.04 one), it just passes fine,
without the appropriate fix. I then thought about writing a selftest
for that, it's more reliable. I left the gdb.base/frame-view.exp pretty
printer test there, it's already written, and we never know, it might
catch some unrelated issue some day.
Change-Id: I5849baf77991fc67a15bfce4b5e865a97265b386
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
I would like to improve frame_info_ptr to automatically grab the
information needed to reinflate a frame, and automatically reinflate it
as needed. One thing that is in the way is the fact that some frames
can be created out of thin air by the create_new_frame function. These
frames are not the fruit of unwinding from the target's current frame.
These frames are created by the "select-frame view" command.
These frames are not correctly handled by the frame save/restore
functions, save_selected_frame, restore_selected_frame and
lookup_selected_frame. This can be observed here, using the test
included in this patch:
$ ./gdb --data-directory=data-directory -nx -q testsuite/outputs/gdb.base/frame-view/frame-view
Reading symbols from testsuite/outputs/gdb.base/frame-view/frame-view...
(gdb) break thread_func
Breakpoint 1 at 0x11a2: file /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c, line 42.
(gdb) run
Starting program: /home/simark/build/binutils-gdb/gdb/testsuite/outputs/gdb.base/frame-view/frame-view
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/../lib/libthread_db.so.1".
[New Thread 0x7ffff7cc46c0 (LWP 4171134)]
[Switching to Thread 0x7ffff7cc46c0 (LWP 4171134)]
Thread 2 "frame-view" hit Breakpoint 1, thread_func (p=0x0) at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:42
42 foo (11);
(gdb) info frame
Stack level 0, frame at 0x7ffff7cc3ee0:
rip = 0x5555555551a2 in thread_func (/home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:42); saved rip = 0x7ffff7d4e8fd
called by frame at 0x7ffff7cc3f80
source language c.
Arglist at 0x7ffff7cc3ed0, args: p=0x0
Locals at 0x7ffff7cc3ed0, Previous frame's sp is 0x7ffff7cc3ee0
Saved registers:
rbp at 0x7ffff7cc3ed0, rip at 0x7ffff7cc3ed8
(gdb) thread 1
[Switching to thread 1 (Thread 0x7ffff7cc5740 (LWP 4171122))]
#0 0x00007ffff7d4b4b6 in ?? () from /usr/lib/libc.so.6
Here, we create a custom frame for thread 1 (using the stack from thread
2, for convenience):
(gdb) select-frame view 0x7ffff7cc3f80 0x5555555551a2
The first calls to "frame" looks good:
(gdb) frame
#0 thread_func (p=0x7ffff7d4e630) at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:42
42 foo (11);
But not the second one:
(gdb) frame
#0 0x00007ffff7d4b4b6 in ?? () from /usr/lib/libc.so.6
This second "frame" command shows the current target frame instead of
the user-created frame.
It's not totally clear how the "select-frame view" feature is expected
to behave, especially since it's not tested. I heard accounts that it
used to be possible to select a frame like this and do "up" and "down"
to navigate the backtrace starting from that frame. The fact that
create_new_frame calls frame_unwind_find_by_frame to install the right
unwinder suggest that it used to be possible. But that doesn't work
today:
(gdb) select-frame view 0x7ffff7cc3f80 0x5555555551a2
(gdb) up
Initial frame selected; you cannot go up.
(gdb) down
Bottom (innermost) frame selected; you cannot go down.
and "backtrace" always shows the actual thread's backtrace, it ignores
the user-created frame:
(gdb) bt
#0 0x00007ffff7d4b4b6 in ?? () from /usr/lib/libc.so.6
#1 0x00007ffff7d50403 in ?? () from /usr/lib/libc.so.6
#2 0x000055555555521a in main () at /home/simark/src/binutils-gdb/gdb/testsuite/gdb.base/frame-view.c:56
I don't want to address all the `select-frame view` issues , but I think
we can agree that the "frame" command changing the selected frame, as
shown above, is a bug. I would expect that command to show the
currently selected frame and not change it.
This happens because of the scoped_restore_selected_frame object in
print_frame_args. The frame information is saved in the constructor
(the backtrace below), and restored in the destructor.
#0 save_selected_frame (frame_id=0x7ffdc0020ad0, frame_level=0x7ffdc0020af0) at /home/simark/src/binutils-gdb/gdb/frame.c:1682
#1 0x00005631390242f0 in scoped_restore_selected_frame::scoped_restore_selected_frame (this=0x7ffdc0020ad0) at /home/simark/src/binutils-gdb/gdb/frame.c:324
#2 0x000056313993581e in print_frame_args (fp_opts=..., func=0x62100023bde0, frame=..., num=-1, stream=0x60b000000300) at /home/simark/src/binutils-gdb/gdb/stack.c:755
#3 0x000056313993ad49 in print_frame (fp_opts=..., frame=..., print_level=1, print_what=SRC_AND_LOC, print_args=1, sal=...) at /home/simark/src/binutils-gdb/gdb/stack.c:1401
#4 0x000056313993835d in print_frame_info (fp_opts=..., frame=..., print_level=1, print_what=SRC_AND_LOC, print_args=1, set_current_sal=1) at /home/simark/src/binutils-gdb/gdb/stack.c:1126
#5 0x0000563139932e0b in print_stack_frame (frame=..., print_level=1, print_what=SRC_AND_LOC, set_current_sal=1) at /home/simark/src/binutils-gdb/gdb/stack.c:368
#6 0x0000563139932bbe in print_stack_frame_to_uiout (uiout=0x611000016840, frame=..., print_level=1, print_what=SRC_AND_LOC, set_current_sal=1) at /home/simark/src/binutils-gdb/gdb/stack.c:346
#7 0x0000563139b0641e in print_selected_thread_frame (uiout=0x611000016840, selection=...) at /home/simark/src/binutils-gdb/gdb/thread.c:1993
#8 0x0000563139940b7f in frame_command_core (fi=..., ignored=true) at /home/simark/src/binutils-gdb/gdb/stack.c:1871
#9 0x000056313994db9e in frame_command_helper<frame_command_core>::base_command (arg=0x0, from_tty=1) at /home/simark/src/binutils-gdb/gdb/stack.c:1976
Since the user-created frame has level 0 (identified by the saved level
-1), lookup_selected_frame just reselects the target's current frame,
and the user-created frame is lost.
My goal here is to fix this particular problem.
Currently, select_frame does not set selected_frame_id and
selected_frame_level for frames with level 0. It leaves them at
null_frame_id / -1, indicating to restore_selected_frame to use the
target's current frame. User-created frames also have level 0, so add a
special case them such that select_frame saves their selected id and
level.
save_selected_frame does not need any change.
Change the assertion in restore_selected_frame that checks `frame_level
!= 0` to account for the fact that we can restore user-created frames,
which have level 0.
Finally, change lookup_selected_frame to make it able to re-create
user-created frame_info objects from selected_frame_level and
selected_frame_id.
Add a minimal test case for the case described above, that is the
"select-frame view" command followed by the "frame" command twice. In
order to have a known stack frame to switch to, the test spawns a second
thread, and tells the first thread to use the other thread's top frame.
Change-Id: Ifc77848dc465fbd21324b9d44670833e09fe98c7
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
The subsequent patches will need to call create_new_frame with an
existing frame_id representing a user created frame. They could call
the existing create_new_frame, passing both addresses, but it seems
nicer to have a version of the function that takes a frame_id directly.
Change-Id: If31025314fec0c3e644703e4391a5ef8079e1a32
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
A subsequent patch makes it possible for frame_info_ptr to reinflate
user-created frames. If two frame_info_ptr objects wrapping the same
user-created frame_info need to do reinflation, we want them to end up
pointing to the same frame_info instance, and not create two separate
frame_infos. Otherwise, GDB gets confused down the line, as the state
kept in one frame_info object starts differing from the other
frame_info.
Achieve this by making create_new_frame place the user-created frames in
the frame stash. This way, when the second frame_info_ptr does
reinflation, it will find the existing frame_info object, created by the
other frame_info_ptr, in the frame stash.
To make the frame stash differentiate between regular and user-created
frame infos which would otherwise be equal, change frame_addr_hash and
frame_id::operator== to account for frame_id::user_created_p.
I made create_new_frame look up existing frames in the stash, and only
create one if it doesn't find one. The goal is to avoid the
"select-frame view"/"info frame view"/"frame view" commands from
overriding existing entries into the stash, should the user specify the
same frame more than once. This will also help in the subsequent patch
that makes frame_info_ptr capable of reinflating user-created frames.
It will be able to just call create_new_frame and it will do the right
thing.
Change-Id: I14ba5799012056c007b4992ecb5c7adafd0c2404
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
Later in this series, we'll need to differentiate frame ids for regular
frames (obtained from the target state and unwinding from it) vs frame
ids for user-created frames (created with create_new_frame). Add the
frame_id::user_created_p field to indicate a frame is user-created, and
set it in create_new_frame.
The field is otherwise not used yet, so not changes in behavior are
expected.
Change-Id: I60de3ce581ed01bf0fddb30dff9bd932840120c3
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
A patch later in this series will make frame_info_ptr access some
fields internal to frame_info, which we don't want to expose outside of
frame.c. Move the frame_info_ptr class to frame.h, and the definitions
to frame.c. Remove frame-info.c and frame-info.h.
Change-Id: Ic5949759e6262ea0da6123858702d48fe5673fea
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
Instead of using `select_frame (nullptr)` to invalidate the selected
frame, introduce a function to do that. There is no change in behavior,
but it makes the intent a bit clearer. It also allows adding an assert
in select_frame that fi is not nullptr, so it avoids passing nullptr by
mistake.
Change-Id: I61643f46bc8eca428334513ebdaadab63997bdd0
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
I don't see any particular reason why the implementations of the
frame_info_ptr object are in the header file. It only seems to add some
complexity. Since we can't include frame.h in frame-info.h, we have to
add declarations of functions defined in frame.c, in frame-info.h. By
moving the implementations to a new frame-info.c, we can avoid that.
Change-Id: I435c828f81b8a3392c43ef018af31effddf6be9c
Reviewed-By: Bruno Larsen <blarsen@redhat.com>
Reviewed-By: Tom Tromey <tom@tromey.com>
Currently, every internal_error call must be passed __FILE__/__LINE__
explicitly, like:
internal_error (__FILE__, __LINE__, "foo %d", var);
The need to pass in explicit __FILE__/__LINE__ is there probably
because the function predates widespread and portable variadic macros
availability. We can use variadic macros nowadays, and in fact, we
already use them in several places, including the related
gdb_assert_not_reached.
So this patch renames the internal_error function to something else,
and then reimplements internal_error as a variadic macro that expands
__FILE__/__LINE__ itself.
The result is that we now should call internal_error like so:
internal_error ("foo %d", var);
Likewise for internal_warning.
The patch adjusts all calls sites. 99% of the adjustments were done
with a perl/sed script.
The non-mechanical changes are in gdbsupport/errors.h,
gdbsupport/gdb_assert.h, and gdb/gdbarch.py.
Approved-By: Simon Marchi <simon.marchi@efficios.com>
Change-Id: Ia6f372c11550ca876829e8fd85048f4502bdcf06
This changes GDB to use frame_info_ptr instead of frame_info *
The substitution was done with multiple sequential `sed` commands:
sed 's/^struct frame_info;/class frame_info_ptr;/'
sed 's/struct frame_info \*/frame_info_ptr /g' - which left some
issues in a few files, that were manually fixed.
sed 's/\<frame_info \*/frame_info_ptr /g'
sed 's/frame_info_ptr $/frame_info_ptr/g' - used to remove whitespace
problems.
The changed files were then manually checked and some 'sed' changes
undone, some constructors and some gets were added, according to what
made sense, and what Tromey originally did
Co-Authored-By: Bruno Larsen <blarsen@redhat.com>
Approved-by: Tom Tomey <tom@tromey.com>
This adds frame_info_ptr, a smart pointer class. Every instance of
the class is kept on an intrusive list. When reinit_frame_cache is
called, the list is traversed and all the pointers are invalidated.
This should help catch the typical GDB bug of keeping a frame_info
pointer alive where a frame ID was needed instead.
Co-Authored-By: Bruno Larsen <blarsen@redhat.com>
Approved-by: Tom Tomey <tom@tromey.com>
This replaces frame_id_eq with operator== and operator!=. I wrote
this for a version of this series that I later abandoned; but since it
simplifies the code, I left this patch in.
Approved-by: Tom Tomey <tom@tromey.com>
When debugging a certain class of GDB bug, I often end up wanting to
know what GDB thinks the frame-id is in a particular frame. It's
not too hard to pull this from some debug output, but I thought it
might be nice if there was a maintenance command that could tell us.
This commit adds 'maint print frame-id' which prints the frame-id of
the currently selected frame. You can also pass a frame level number
to find the frame-id for a specific frame.
There's a new test too.
Now that filtered and unfiltered output can be treated identically, we
can unify the printf family of functions. This is done under the name
"gdb_printf". Most of this patch was written by script.
Add a getter and a setter for a symbol's line. Remove the corresponding macro
and adjust all callers.
Change-Id: I229f2b8fcf938c07975f641361313a8761fad9a5
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
Change a few relatively obvious spots using value contents to propagate
the use array_view a bit more.
Change-Id: I5338a60986f06d5969fec803d04f8423c9288a15
I think it would make sense for extract_integer, extract_signed_integer
and extract_unsigned_integer to take an array_view. This way, when we
extract an integer, we can validate that we don't overflow the buffer
passed by the caller (e.g. ask to extract a 4-byte integer but pass a
2-byte buffer).
- Change extract_integer to take an array_view
- Add overloads of extract_signed_integer and extract_unsigned_integer
that take array_views. Keep the existing versions so we don't
need to change all callers, but make them call the array_view
versions.
This shortens some places like:
result = extract_unsigned_integer (value_contents (result_val).data (),
TYPE_LENGTH (value_type (result_val)),
byte_order);
into
result = extract_unsigned_integer (value_contents (result_val), byte_order);
value_contents returns an array view that is of length
`TYPE_LENGTH (value_type (result_val))` already, so the length is
implicitly communicated through the array view.
Change-Id: Ic1c1f98c88d5c17a8486393af316f982604d6c95
There's a common pattern to call add_basic_prefix_cmd and
add_show_prefix_cmd to add matching set and show commands. Add the
add_setshow_prefix_cmd function to factor that out and use it at a few
places.
Change-Id: I6e9e90a30e9efb7b255bf839cac27b85d7069cfd
The bug fixed by this [1] patch was caused by an out-of-bounds access to
a value's content. The code gets the value's content (just a pointer)
and then indexes it with a non-sensical index.
This made me think of changing functions that return value contents to
return array_views instead of a plain pointer. This has the advantage
that when GDB is built with _GLIBCXX_DEBUG, accesses to the array_view
are checked, making bugs more apparent / easier to find.
This patch changes the return types of these functions, and updates
callers to call .data() on the result, meaning it's not changing
anything in practice. Additional work will be needed (which can be done
little by little) to make callers propagate the use of array_view and
reap the benefits.
[1] https://sourceware.org/pipermail/gdb-patches/2021-September/182306.html
Change-Id: I5151f888f169e1c36abe2cbc57620110673816f3
