Similar to the previous patches, change get_frame_register_bytes to take
the "next frame" instead of "this frame".
Change-Id: Ie8f35042bfa6e93565fcefaee71b6b3903f0fe9f
Reviewed-By: John Baldwin <jhb@FreeBSD.org>
Similar to the previous patches, change put_frame_register_bytes to take
the "next frame" instead of "this frame".
Change-Id: I27bcb26573686d99b231230823cff8db6405a788
Reviewed-By: John Baldwin <jhb@FreeBSD.org>
Similar to the previous patches, change put_frame_register to take the
"next frame" instead of "this frame".
Change-Id: I062fd4663b8f54f0fc7bbf39c860b7341363821b
Reviewed-By: John Baldwin <jhb@FreeBSD.org>
Change put_frame_register to take an array_view instead of a raw
pointer.
Add an assertion to verify that the number of bytes we try to write
matches the length of the register.
Change-Id: Ib75a9c8a12b47e203097621643eaa2c1830591ae
Reviewed-By: John Baldwin <jhb@FreeBSD.org>
This moves the follow_static_link function to frame.c and exports it
for use elsewhere. The API is changed slightly to make it more
generically useful.
In commit 995a34b177 ("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 9b0ccb1eba ("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
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
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>
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 helps resolve some cyclic include problem later in the series.
The only language-related thing frame.h needs is enum language, and that
is in defs.h.
Doing so reveals that a bunch of files were relying on frame.h to
include language.h, so fix the fallouts here and there.
Change-Id: I178a7efec1953c2d088adb58483bade1f349b705
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, despite having a smart pointer for frame_infos, GDB may
attempt to use an invalidated frame_info_ptr, which would cause internal
errors to happen. One such example has been documented as PR
python/28856, that happened when printing frame arguments calls an
inferior function.
To avoid failures, the smart wrapper was changed to also cache the frame
id, so the pointer can be reinflated later. For this to work, the
frame-id stuff had to be moved to their own .h file, which is included
by frame-info.h.
Frame_id caching is done explicitly using the prepare_reinflate method.
Caching is done manually so that only the pointers that need to be saved
will be, and reinflating has to be done manually using the reinflate
method because the get method and the -> operator must not change
the internals of the class. Finally, attempting to reinflate when the
pointer is being invalidated causes the following assertion errors:
check_ptrace_stopped_lwp_gone: assertion `lp->stopped` failed.
get_frame_pc: Assertion `frame->next != NULL` failed.
As for performance concerns, my personal testing with `time make
chec-perf GDB_PERFTEST_MODE=run` showed an actual reduction of around
10% of time running.
This commit also adds a testcase that exercises the python/28856 bug with
7 different triggers, run, continue, step, backtrace, finish, up and down.
Some of them can seem to be testing the same thing twice, but since this
test relies on stale pointers, there is always a chance that GDB got lucky
when testing, so better to test extra.
Regression tested on x86_64, using both gcc and clang.
Approved-by: Tom Tomey <tom@tromey.com>
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>
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.
This commit was originally part of this patch series:
(v1): https://sourceware.org/pipermail/gdb-patches/2021-May/179357.html
(v2): https://sourceware.org/pipermail/gdb-patches/2021-June/180208.html
(v3): https://sourceware.org/pipermail/gdb-patches/2021-July/181028.html
However, that series is being held up in review, so I wanted to break
out some of the non-related fixes in order to get these merged.
This commit addresses two semi-related issues, both of which are
problems exposed by using 'set debug frame on'.
The first issue is in frame.c in get_prev_frame_always_1, and was
introduced by this commit:
commit a05a883fba
Date: Tue Jun 29 12:03:50 2021 -0400
gdb: introduce frame_debug_printf
This commit replaced fprint_frame with frame_info::to_string.
However, the former could handle taking a nullptr while the later, a
member function, obviously requires a non-nullptr in order to make the
function call. In one place we are not-guaranteed to have a
non-nullptr, and so, there is the possibility of triggering undefined
behaviour.
The second issue addressed in this commit has existed for a while in
GDB, and would cause this assertion:
gdb/frame.c:622: internal-error: frame_id get_frame_id(frame_info*): Assertion `fi->this_id.p != frame_id_status::COMPUTING' failed.
We attempt to get the frame_id for a frame while we are computing the
frame_id for that same frame.
What happens is that when GDB stops we create a frame_info object for
the sentinel frame (frame #-1) and then we attempt to unwind this
frame to create a frame_info object for frame #0.
In the test case used here to expose the issue we have created a
Python frame unwinder. In the Python unwinder we attemt to read the
program counter register.
Reading this register will initially create a lazy register value.
The frame-id stored in the lazy register value will be for the
sentinel frame (lazy register values hold the frame-id for the frame
from which the register will be unwound).
However, the Python unwinder does actually want to examine the value
of the program counter, and so the lazy register value is resolved
into a non-lazy value. This sends GDB into value_fetch_lazy_register
in value.c.
Now, inside this function, if 'set debug frame on' is in effect, then
we want to print something like:
frame=%d, regnum=%d(%s), ....
Where 'frame=%d' will be the relative frame level of the frame for
which the register is being fetched, so, in this case we would expect
to see 'frame=0', i.e. we are reading a register as it would be in
frame #0. But, remember, the lazy register value actually holds the
frame-id for frame #-1 (the sentinel frame).
So, to get the frame_info for frame #0 we used to call:
frame = frame_find_by_id (VALUE_FRAME_ID (val));
Where VALUE_FRAME_ID is:
#define VALUE_FRAME_ID(val) (get_prev_frame_id_by_id (VALUE_NEXT_FRAME_ID (val)))
That is, we start with the frame-id for the next frame as obtained by
VALUE_NEXT_FRAME_ID, then call get_prev_frame_id_by_id to get the
frame-id of the previous frame.
The get_prev_frame_id_by_id function finds the frame_info for the
given frame-id (in this case frame #-1), calls get_prev_frame to get
the previous frame, and then calls get_frame_id.
The problem here is that calling get_frame_id requires that we know
the frame unwinder, so then have to try each frame unwinder in turn,
which would include the Python unwinder.... which is where we started,
and thus we have a loop!
To prevent this loop GDB has an assertion in place, which is what
actually triggers.
Solving the assertion failure is pretty easy, if we consider the code
in value_fetch_lazy_register and get_prev_frame_id_by_id then what we
do is:
1. Start with a frame_id taken from a value,
2. Lookup the corresponding frame,
3. Find the previous frame,
4. Get the frame_id for that frame, and
5. Lookup the corresponding frame
6. Print the frame's level
Notice that steps 3 and 5 give us the exact same result, step 4 is
just wasted effort. We could shorten this process such that we drop
steps 4 and 5, thus:
1. Start with a frame_id taken from a value,
2. Lookup the corresponding frame,
3. Find the previous frame,
6. Print the frame's level
This will give the exact same frame as a result, and this is what I
have done in this patch by removing the use of VALUE_FRAME_ID from
value_fetch_lazy_register.
Out of curiosity I looked to see how widely VALUE_FRAME_ID was used,
and saw it was only used in one other place in valops.c:value_assign,
where, once again, we take the result of VALUE_FRAME_ID and pass it to
frame_find_by_id, thus introducing a redundant frame_id lookup.
I don't think the value_assign case risks triggering the assertion
though, as we are unlikely to call value_assign while computing the
frame_id for a frame, however, we could make value_assign slightly
more efficient, with no real additional complexity, by removing the
use of VALUE_FRAME_ID.
So, in this commit, I completely remove VALUE_FRAME_ID, and replace it
with a use of VALUE_NEXT_FRAME_ID, followed by a direct call to
get_prev_frame_always, this should make no difference in either case,
and resolves the assertion issue from value.c.
As I said, this patch was originally part of another series, the
original test relied on the fixes in that original series. However, I
was able to create an alternative test for this issue by enabling
frame debug within an existing test script.
This commit probably fixes bug PR gdb/27938, though the bug doesn't
have a reproducer attached so it is not possible to know for sure.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27938
Introduce frame_debug_printf, to convert the "frame" debug messages to
the new system. Replace fprint_frame with a frame_info::to_string
method that returns a string, like what was done with
frame_id::to_string. This makes it easier to use with
frame_debug_printf.
gdb/ChangeLog:
* frame.h (frame_debug_printf): New.
* frame.c: Use frame_debug_printf throughout when printing frame
debug messages.
* amd64-windows-tdep.c: Likewise.
* value.c: Likewise.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/dw2-reg-undefined.exp: Update regexp.
Change-Id: I3c230b0814ea81c23af3e1aca1aac8d4ba91d726
gdb/ChangeLog:
* frame.h (frame_debug): Change type to bool.
* frame.c (frame_debug): Change type to bool.
(_initialize_frame): Adjust.
Change-Id: I27b5359a25ad53ac42618b5708a025c348a1eeda
Replace fprint_frame_id with a member function frame_id::to_string
that returns a std::string. Convert all of the previous users of
fprint_frame_id to use the new member function. This means that
instead of writing things like this:
fprintf_unfiltered (file, " id=");
fprint_frame_id (file, s->id.id);
We can write this:
fprintf_unfiltered (file, " id=%s", s->id.id.to_string ().c_str ());
There should be no user visible changes after this commit.
gdb/ChangeLog:
* dummy-frame.c (fprint_dummy_frames): Convert use of
fprint_frame_id to use frame_id::to_string.
* frame.c (fprint_field): Delete.
(fprint_frame_id): Moved to...
(frame_id::to_string): ...this, rewritten to return a string.
(fprint_frame): Convert use of fprint_frame_id to use
frame_id::to_string.
(compute_frame_id): Likewise.
(frame_id_p): Likewise.
(frame_id_eq): Likewise.
(frame_id_inner): Likewise.
* frame.h (struct frame_id) <to_string>: New member function.
(fprint_frame_id): Delete declaration.
* guile/scm-frame.c (frscm_print_frame_smob): Convert use of
fprint_frame_id to use frame_id::to_string.
* python/py-frame.c (frame_object_to_frame_info): Likewise.
* python/py-unwind.c (unwind_infopy_str): Likewise.
(pyuw_this_id): Likewise.
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
If the remote target closes while we're reading registers/memory for
restoring the selected frame in scoped_restore_current_thread's dtor,
the corresponding TARGET_CLOSE_ERROR error is swallowed by the
scoped_restore_current_thread's dtor, because letting exceptions
escape from a dtor is bad. It isn't great to lose that errors like
that, though. I've been thinking about how to avoid it, and I came up
with this patch.
The idea here is to make scoped_restore_current_thread's dtor do as
little as possible, to avoid any work that might throw in the first
place. And to do that, instead of having the dtor call
restore_selected_frame, which re-finds the previously selected frame,
just record the frame_id/level of the desired selected frame, and have
get_selected_frame find the frame the next time it is called. In
effect, this implements most of Cagney's suggestion, here:
/* On demand, create the selected frame and then return it. If the
selected frame can not be created, this function prints then throws
an error. When MESSAGE is non-NULL, use it for the error message,
otherwize use a generic error message. */
/* FIXME: cagney/2002-11-28: At present, when there is no selected
frame, this function always returns the current (inner most) frame.
It should instead, when a thread has previously had its frame
selected (but not resumed) and the frame cache invalidated, find
and then return that thread's previously selected frame. */
extern struct frame_info *get_selected_frame (const char *message);
The only thing missing to fully implement that would be to make
reinit_frame_cache just clear selected_frame instead of calling
select_frame(NULL), and the call select_frame(NULL) explicitly in the
places where we really wanted reinit_frame_cache to go back to the
current frame too. That can done separately, though, I'm not
proposing to do that in this patch.
Note that this patch renames restore_selected_frame to
lookup_selected_frame, and adds a new restore_selected_frame function
that doesn't throw, to be paired with the also-new save_selected_frame
function.
There's a restore_selected_frame function in infrun.c that I think can
be replaced by the new one in frame.c.
Also done in this patch is make the get_selected_frame's parameter be
optional, so that we don't have to pass down nullptr explicitly all
over the place.
lookup_selected_frame should really move from thread.c to frame.c, but
I didn't do that here, just to avoid churn in the patch while it
collects comments. I did make it extern and declared it in frame.h
already, preparing for the move. I will do the move as a follow up
patch if people agree with this approach.
Incidentally, this patch alone would fix the crashes fixed by the
previous patches in the series, because with this,
scoped_restore_current_thread's constructor doesn't throw either.
gdb/ChangeLog:
* blockframe.c (block_innermost_frame): Use get_selected_frame.
* frame.c
(scoped_restore_selected_frame::scoped_restore_selected_frame):
Use save_selected_frame. Save language as well.
(scoped_restore_selected_frame::~scoped_restore_selected_frame):
Use restore_selected_frame, and restore language as well.
(selected_frame_id, selected_frame_level): New.
(selected_frame): Update comments.
(save_selected_frame, restore_selected_frame): New.
(get_selected_frame): Use lookup_selected_frame.
(get_selected_frame_if_set): Delete.
(select_frame): Record selected_frame_level and selected_frame_id.
* frame.h (scoped_restore_selected_frame) <m_level, m_lang>: New
fields.
(get_selected_frame): Make 'message' parameter optional.
(get_selected_frame_if_set): Delete declaration.
(select_frame): Update comments.
(save_selected_frame, restore_selected_frame)
(lookup_selected_frame): Declare.
* gdbthread.h (scoped_restore_current_thread) <m_lang>: New field.
* infrun.c (struct infcall_control_state) <selected_frame_level>:
New field.
(save_infcall_control_state): Use save_selected_frame.
(restore_selected_frame): Delete.
(restore_infcall_control_state): Use restore_selected_frame.
* stack.c (select_frame_command_core, frame_command_core): Use
get_selected_frame.
* thread.c (restore_selected_frame): Rename to ...
(lookup_selected_frame): ... this and make extern. Select the
current frame if the frame level is -1.
(scoped_restore_current_thread::restore): Also restore the
language.
(scoped_restore_current_thread::~scoped_restore_current_thread):
Don't try/catch.
(scoped_restore_current_thread::scoped_restore_current_thread):
Save the language as well. Use save_selected_frame.
Change-Id: I73fd1cfc40d8513c28e5596383b7ecd8bcfe700f
In the following patch, we'll need to easily differentiate the frame_id
of the outer frame (or the frame id of a frame inlined into the outer
frame) from a simply invalid frame id.
Currently, the frame id of the outer frame has `stack_status` set to
FID_STACK_INVALID plus special_addr_p set. A frame inlined into the
outer frame would also have `artificial_depth` set to greater than one.
That makes the job of differntiating the frame id of the outer frame (or a
frame inlined into the outer frame) cumbersome.
To make it easier, give the outer frame id its own frame_id_stack_status
enum value. outer_frame_id then becomes very similar to
sentinel_frame_id, another "special" frame id value.
In frame_id_p, we don't need a special case for the outer frame id, as
it's no long a special case of FID_STACK_INVALID. Same goes for
frame_id_eq.
So in the end, FID_STACK_OUTER isn't even used (except in
fprint_frame_id). But that's expected: all the times we wanted to
identify an outer frame was to differentiate it from an otherwise
invalid frame. Since their frame_id_stack_status value is different
now, that is done naturally.
gdb/ChangeLog:
* frame.h (enum frame_id_stack_status) <FID_STACK_OUTER>: New.
* frame.c (fprint_frame_id): Handle FID_STACK_OUTER.
(outer_frame_id): Use FID_STACK_OUTER instead of
FID_STACK_INVALID.
(frame_id_p): Don't check for outer_frame_id.
Change-Id: I654e7f936349debc4f04f7f684b15e71a0c37619
Change instances of int variables and return values used as boolean
values to use the bool type.
Shorten the comments of a few functions, because I think they go a bit
too much in implementation details, which appear out of date anyway.
Make other misc changes to the functions that are already being changed,
such as using nullptr instead of NULL, dropping `struct` keywords and
declaring variables when first used.
gdb/ChangeLog:
* frame.h (frame_id_p): Return bool.
(frame_id_artificial_p): Return bool.
(frame_id_eq): Return bool.
(has_stack_frames): Return bool.
(get_selected_frame): Fix typo in comment.
(get_frame_pc_if_available): Return bool.
(get_frame_address_in_block_if_available): Return bool.
(get_frame_func_if_available): Return bool.
(read_frame_register_unsigned): Return bool.
(get_frame_register_bytes): Return bool.
(safe_frame_unwind_memory): Return bool.
(deprecated_frame_register_read): Return bool.
(frame_unwinder_is): Return bool.
* frame.c (struct frame_info) <prev_arch::p>: Change type to
bool.
<this_id::p>: Likewise.
<prev_p>: Likewise.
(frame_stash_add): Return bool.
(get_frame_id): Use bool.
(frame_id_build_special) Use bool.
(frame_id_build_unavailable_stack): Use bool.
(frame_id_build): Use bool.
(frame_id_p): Return bool, use true/false instead of 1/0.
(frame_id_artificial_p): Likewise.
(frame_id_eq): Likewise.
(frame_id_inner): Likewise.
(get_frame_func_if_available): Likewise.
(read_frame_register_unsigned): Likewise.
(deprecated_frame_register_read): Likewise.
(get_frame_register_bytes): Likewise.
(has_stack_frames): Likewise.
(inside_main_func): Likewise.
(inside_entry_func): Likewise.
(get_frame_pc_if_available): Likewise.
(get_frame_address_in_block_if_available): Likewise.
(frame_unwinder_is): Likewise.
(safe_frame_unwind_memory): Likewise.
(frame_unwind_arch): Likewise.
Change-Id: I6121fa56739b688be79d73d087d76b268ba5a46a
This fixes yet another bug exposed by ASAN + multi-target.exp
Running an Asan-enabled GDB against gdb.multi/multi-target.exp exposed
yet another latent GDB bug. See here for the full log:
https://sourceware.org/pipermail/gdb-patches/2020-July/170761.html
As Simon described, the problem is:
- We create a new frame_info object in restore_selected_frame (by
calling find_relative_frame)
- The frame is allocated on the frame_cache_obstack
- In frame_unwind_try_unwinder, we try to find an unwinder for that
frame
- While trying unwinders, memory read fails because the remote target
closes, because of "monitor exit"
- That calls reinit_frame_cache (as shown above), which resets
frame_cache_obstack
- When handling the exception in frame_unwind_try_unwinder, we try to
set some things on the frame_info object (like *this_cache, which
in fact tries to write into frame_info::prologue_cache), but the
frame_info object is no more, it went away with the obstack.
Fix this by maintaining a frame cache generation counter. Then in
exception handling code paths, don't touch frame objects if the
generation is not the same as it was on entry.
This commit generalizes the gdb.server/server-kill.exp testcase and
reuses it to test the scenario in question. The new tests fail
without the GDB fix.
gdb/ChangeLog:
* frame-unwind.c (frame_unwind_try_unwinder): On exception, don't
touch THIS_CACHE/THIS_FRAME if the frame cache was cleared
meanwhile.
* frame.c (frame_cache_generation, get_frame_cache_generation):
New.
(reinit_frame_cache): Increment FRAME_CACHE_GENERATION.
(get_prev_frame_if_no_cycle): On exception, don't touch
PREV_FRAME/THIS_FRAME if the frame cache was cleared meanwhile.
* frame.h (get_frame_cache_generation): Declare.
gdb/testsuite/ChangeLog:
* gdb.server/server-kill.exp (prepare): New, factored out from the
top level.
(kill_server): New.
(test_tstatus, test_unwind_nosyms, test_unwind_syms): New.
(top level) : Call test_tstatus, test_unwind_nosyms, test_unwind_syms.
This started with me running into the bug described in python/22748,
in summary, if the frame sniffing code accessed any registers within
an inline frame then GDB would crash with this error:
gdb/frame.c:579: internal-error: frame_id get_frame_id(frame_info*): Assertion `fi->level == 0' failed.
The problem is that, when in the Python unwinder I write this:
pending_frame.read_register ("register-name")
This is translated internally into a call to `value_of_register',
which in turn becomes a call to `value_of_register_lazy'.
Usually this isn't a problem, `value_of_register_lazy' requires the
next frame (more inner) to have a valid frame_id, which will be the
case (if we're sniffing frame #1, then frame #0 will have had its
frame-id figured out).
Unfortunately if frame #0 is inline within frame #1, then the frame-id
for frame #0 can't be computed until we have the frame-id for #1. As
a result we can't create a lazy register for frame #1 when frame #0 is
inline.
Initially I proposed a solution inline with that proposed in bugzilla,
changing value_of_register to avoid creating a lazy register value.
However, when this was discussed on the mailing list I got this reply:
https://sourceware.org/pipermail/gdb-patches/2020-June/169633.html
Which led me to look at these two patches:
[1] https://sourceware.org/pipermail/gdb-patches/2020-April/167612.html
[2] https://sourceware.org/pipermail/gdb-patches/2020-April/167930.html
When I considered patches [1] and [2] I saw that all of the issues
being addressed here were related, and that there was a single
solution that could address all of these issues.
First I wrote the new test gdb.opt/inline-frame-tailcall.exp, which
shows that [1] and [2] regress the inline tail-call unwinder, the
reason for this is that these two patches replace a call to
gdbarch_unwind_pc with a call to get_frame_register, however, this is
not correct. The previous call to gdbarch_unwind_pc takes THIS_FRAME
and returns the $pc value in the previous frame. In contrast
get_frame_register takes THIS_FRAME and returns the value of the $pc
in THIS_FRAME; these calls are not equivalent.
The reason these patches appear (or do) fix the regressions listed in
[1] is that the tail call sniffer depends on identifying the address
of a caller and a callee, GDB then looks for a tail-call sequence that
takes us from the caller address to the callee, if such a series is
found then tail-call frames are added.
The bug that was being hit, and which was address in patch [1] is that
in order to find the address of the caller, GDB ended up creating a
lazy register value for an inline frame with to frame-id. The
solution in patch [1] is to instead take the address of the callee and
treat this as the address of the caller. Getting the address of the
callee works, but we then end up looking for a tail-call series from
the callee to the callee, which obviously doesn't return any sane
results, so we don't insert any tail call frames.
The original patch [1] did cause some breakage, so patch [2] undid
patch [1] in all cases except those where we had an inline frame with
no frame-id. It just so happens that there were no tests that fitted
this description _and_ which required tail-call frames to be
successfully spotted, as a result patch [2] appeared to work.
The new test inline-frame-tailcall.exp, exposes the flaw in patch [2].
This commit undoes patch [1] and [2], and replaces them with a new
solution, which is also different to the solution proposed in the
python/22748 bug report.
In this solution I propose that we introduce some special case logic
to value_of_register_lazy. To understand what this logic is we must
first look at how inline frames unwind registers, this is very simple,
they do this:
static struct value *
inline_frame_prev_register (struct frame_info *this_frame,
void **this_cache, int regnum)
{
return get_frame_register_value (this_frame, regnum);
}
And remember:
struct value *
get_frame_register_value (struct frame_info *frame, int regnum)
{
return frame_unwind_register_value (frame->next, regnum);
}
So in all cases, unwinding a register in an inline frame just asks the
next frame to unwind the register, this makes sense, as an inline
frame doesn't really exist, when we unwind a register in an inline
frame, we're really just asking the next frame for the value of the
register in the previous, non-inline frame.
So, if we assume that we only get into the missing frame-id situation
when we try to unwind a register from an inline frame during the frame
sniffing process, then we can change value_of_register_lazy to not
create lazy register values for an inline frame.
Imagine this stack setup, where #1 is inline within #2.
#3 -> #2 -> #1 -> #0
\______/
inline
Now when trying to figure out the frame-id for #1, we need to compute
the frame-id for #2. If the frame sniffer for #2 causes a lazy
register read in #2, either due to a Python Unwinder, or for the
tail-call sniffer, then we call value_of_register_lazy passing in
frame #2.
In value_of_register_lazy, we grab the next frame, which is #1, and we
used to then ask for the frame-id of #1, which was not computed, and
this was our bug.
Now, I propose we spot that #1 is an inline frame, and so lookup the
next frame of #1, which is #0. As #0 is not inline it will have a
valid frame-id, and so we create a lazy register value using #0 as the
next-frame-id. This will give us the exact same result we had
previously (thanks to the code we inspected above).
Encoding into value_of_register_lazy the knowledge that reading an
inline frame register will always just forward to the next frame
feels.... not ideal, but this seems like the cleanest solution to this
recursive frame-id computation/sniffing issue that appears to crop
up.
The following two commits are fully reverted with this commit, these
correspond to patches [1] and [2] respectively:
commit 5939967b35
Date: Tue Apr 14 17:26:22 2020 -0300
Fix inline frame unwinding breakage
commit 991a3e2e99
Date: Sat Apr 25 00:32:44 2020 -0300
Fix remaining inline/tailcall unwinding breakage for x86_64
gdb/ChangeLog:
PR python/22748
* dwarf2/frame-tailcall.c (dwarf2_tailcall_sniffer_first): Remove
special handling for inline frames.
* findvar.c (value_of_register_lazy): Skip inline frames when
creating lazy register values.
* frame.c (frame_id_computed_p): Delete definition.
* frame.h (frame_id_computed_p): Delete declaration.
gdb/testsuite/ChangeLog:
PR python/22748
* gdb.opt/inline-frame-tailcall.c: New file.
* gdb.opt/inline-frame-tailcall.exp: New file.
* gdb.python/py-unwind-inline.c: New file.
* gdb.python/py-unwind-inline.exp: New file.
* gdb.python/py-unwind-inline.py: New file.
Commit 5939967b35 fixed inline
frame unwinding breakage for some targets (aarch64, riscv, s390...)
but regressed a few amd64 testcases related to tailcalls.
Given the following example situation...
Frame #-1 - sentinel frame
Frame # 0 - inline frame
Frame # 1 - normal frame
... suppose we're at level #1 and call into dwarf2_tailcall_sniffer_first.
We'll attempt to fetch PC, which used to be done via the gdbarch_unwind_pc call
(before 5939967b35), but now it is being handled
by the get_frame_register function.
gdbarch_unwind_pc will attempt to use frame #1's cache to retrieve information
about the PC. Here's where different architectures behave differently.
x86_64 will find a dwarf rule to retrieve PC from memory, at a CFA + offset
location. So the PC value is readily available and there is no need to
create a lazy value.
For aarch64 (and others), GCC doesn't emit an explicit location for PC, so we
eventually will find that PC is DWARF2_FRAME_REG_UNSPECIFIED. This is known
and is handled by GDB by assuming GCC really meant DWARF2_FRAME_REG_SAME_VALUE.
This means we'll attempt to fetch the register value from frame #0, via a call
to frame_unwind_got_register, which will trigger the creation of a lazy value
that requires a valid frame id for frame #0.
We don't have a valid id for frame #0 yet, so we assert.
Given the above, the following patch attempts to handle the situation without
being too hacky. We verify if the next frame is an inline frame and if its
frame id has been computed already. If it hasn't been computed yet, then we
use the safer get_frame_register function, otherwise we use the regular
gdbarch_unwind_pc hook.
gdb/ChangeLog:
2020-04-27 Luis Machado <luis.machado@linaro.org>
* dwarf2/frame-tailcall.c (dwarf2_tailcall_sniffer_first): Handle
problematic inline frame unwinding situation.
* frame.c (frame_id_computed_p): New function.
* frame.h (frame_id_computed_p): New prototype.
This changes struct frame_arg to be self-managing and then fixes the
various users.
Tested by the buildbot.
gdb/ChangeLog
2019-08-07 Tom Tromey <tromey@adacore.com>
* stack.c (print_frame_arg, read_frame_local, read_frame_arg)
(print_frame_args): Update.
* python/py-framefilter.c (py_print_single_arg, enumerate_args):
Update.
* mi/mi-cmd-stack.c (list_arg_or_local): Update.
* frame.h (struct frame_arg): Add initializers.
<error>: Now a unique_xmalloc_ptr.
Armv8.3-a Pointer Authentication causes the function return address to be
obfuscated on entry to some functions. GDB must unmask the link register in
order to produce a backtrace.
The following patch adds markers of [PAC] to the bracktrace, to indicate
which addresses needed unmasking. This includes the backtrace when using MI.
For example, consider the following backtrace:
(gdb) bt
0 0x0000000000400490 in puts@plt ()
1 0x00000000004005dc in foo ("hello") at cbreak-lib.c:6
2 0x0000000000400604 [PAC] in bar () at cbreak-lib.c:12
3 0x0000000000400620 [PAC] in main2 () at cbreak.c:17
4 0x00000000004005b4 in main () at cbreak-3.c:10
The functions in cbreak-lib use pointer auth, which masks the return address
to the previous function, causing the addresses of bar (in the library) and main2
(in the main binary) to require unmasking in order to unwind the backtrace.
An extra bool is added alongside the prev_pc in the frame structure. At the
point at which the link register is unmasked, the AArch64 port calls into frame
to sets the bool. This is the most efficient way of doing it.
The marker is also added to the python frame printer, which is always printed if
set. The marker is not explicitly exposed to the python code.
I expect this will potentially cause issues with some tests in the testsuite
when Armv8.3 pointer authentication is used. This should be fixed up in the
the future once real hardware is available for full testsuite testing.
gdb/ChangeLog:
* NEWS: Expand the Pointer Authentication entry.
* aarch64-tdep.c (aarch64_frame_unmask_address): Rename from this.
(aarch64_frame_unmask_lr): ... to this.
(aarch64_prologue_prev_register, aarch64_dwarf2_prev_register):
Call aarch64_frame_unmask_lr.
* frame.c (struct frame_info): Add "masked" variable.
(frame_set_previous_pc_masked) (frame_get_pc_masked): New functions.
(fprint_frame): Check for masked pc.
* frame.h (frame_set_previous_pc_masked) (frame_get_pc_masked): New
declarations.
* python/py-framefilter.c (py_print_frame): Check for masked pc.
* stack.c (print_frame): Check for masked pc.
gdb/doc/ChangeLog:
* gdb.texinfo (AArch64 Pointer Authentication): New subsection.
New settings allow to better control what frame information is printed.
'set print frame-info' allows to override the default frame information
printed when a GDB command prints a frame.
The backtrace command has a new option -frame-info to override
this global setting.
It is now possible to have very short frame information by using the
new 'set print frame-arguments presence' and
'set print frame-info short-location'.
Combined with 'set print address off', a backtrace will only show
the essential information to see the function call chain, e.g.:
(gdb) set print address off
(gdb) set print frame-arguments presence
(gdb) set print frame-info short-location
(gdb) bt
#0 break_me ()
#1 call_me (...)
#2 main ()
(gdb)
This is handy in particular for big backtraces with functions having
many arguments.
Python frame filter printing logic has been updated to respect the new
setting in non MI mode.
Also, the default frame information printed was inconsistent when
backtrace was printing the frame information itself, or when the python
frame filtering code was printing the frame information.
This patch changes the default of python frame filtering to have a
consistent behaviour regarding printed frame-information, whatever
the presence/activity/matches of python filters.
2019-07-29 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* frame.h (enum print_what): New value 'SHORT_LOCATION', update
comments.
(print_frame_info_auto, print_frame_info_source_line,
print_frame_info_location, print_frame_info_source_and_location,
print_frame_info_location_and_address, print_frame_info_short_location):
New declarations.
(struct frame_print_options): New member print_frame_info.
* extension.h (enum ext_lang_frame_args): New value CLI_PRESENCE.
* stack.h (get_user_print_what_frame_info): New declaration.
(frame_show_address): New declaration.
* stack.c (print_frame_arguments_choices): New value 'presence'.
(print_frame_info_auto, print_frame_info_source_line,
print_frame_info_location, print_frame_info_source_and_location,
print_frame_info_location_and_address, print_frame_info_short_location,
print_frame_info_choices, print_frame_info_print_what): New definitions.
(print_frame_args): Only print dots for args if print frame-arguments
is 'presence'.
(frame_print_option_defs): New element for "frame-info".
(get_user_print_what_frame_info): New function.
(frame_show_address): Make non static. Move comment to stack.h.
(print_frame_info_to_print_what): New function.
(print_frame_info): Update comment. Use fp_opts.print_frame_info
to decide what to print.
(backtrace_command_1): Handle the new print_frame_arguments_presence
value.
(_initialize_stack): Call add_setshow_enum_cmd for frame-info.
* python/py-framefilter.c (py_print_args): Handle CLI_PRESENCE.
(py_print_frame): In non-mi mode, use LOCATION as default for
print_what, similarly to frame information printed directly by
backtrace command. Handle frame-info user option in non MI mode.
This adds support for comand options to the "backtrace" command. We'll get:
(gdb) bt -
-entry-values -hide -past-main
-frame-arguments -no-filters -raw-frame-arguments
-full -past-entry
~~~~
(gdb) help backtrace
Print backtrace of all stack frames, or innermost COUNT frames.
Usage: backtrace [OPTION]... [QUALIFIER]... [COUNT | -COUNT]
Options:
-entry-values no|only|preferred|if-needed|both|compact|default
Set printing of function arguments at function entry
GDB can sometimes determine the values of function arguments at entry,
in addition to their current values. This option tells GDB whether
to print the current value, the value at entry (marked as val@entry),
or both. Note that one or both of these values may be <optimized out>.
-frame-arguments all|scalars|none
Set printing of non-scalar frame arguments
-raw-frame-arguments [on|off]
Set whether to print frame arguments in raw form.
If set, frame arguments are printed in raw form, bypassing any
pretty-printers for that value.
-past-main [on|off]
Set whether backtraces should continue past "main".
Normally the caller of "main" is not of interest, so GDB will terminate
the backtrace at "main". Set this if you need to see the rest
of the stack trace.
-past-entry [on|off]
Set whether backtraces should continue past the entry point of a program.
Normally there are no callers beyond the entry point of a program, so GDB
will terminate the backtrace there. Set this if you need to see
the rest of the stack trace.
-full
Print values of local variables.
-no-filters
Prohibit frame filters from executing on a backtrace.
-hide
Causes Python frame filter elided frames to not be printed.
For backward compatibility, the following qualifiers are supported:
full - same as -full option.
no-filters - same as -no-filters option.
hide - same as -hide.
With a negative COUNT, print outermost -COUNT frames.
~~~~
Implementation wise, this:
- Moves relevant options/settings globals to structures.
- Tweaks a number of functions to pass down references to such structures.
- Adds option_def structures describing the options/settings.
- Makes backtrace_command parse the options, with gdb::option::process_options.
- Tweaks "backtrace"'s help to describe the new options.
- Adds testcases.
Note that backtrace is a PROCESS_OPTIONS_UNKNOWN_IS_OPERAND command,
because of the "-COUNT" argument.
The COUNT/-COUNT argument is currently parsed as an expression. I
considered whether it would be prudent here to require "--", but
concluded that the risk of causing a significant breakage here is much
lower compared to "print", since printing the expression is not the
whole point of the "backtrace" command. Seems OK to me to require
typing "backtrace -past-main -- -p" if the user truly wants to refer
to the negative of a backtrace count stored in an inferior variable
called "p".
gdb/ChangeLog:
2019-06-13 Pedro Alves <palves@redhat.com>
* frame.c: Include "cli/cli-option.h.
(user_set_backtrace_options): New.
(backtrace_past_main, backtrace_past_entry, backtrace_limit):
Delete.
(get_prev_frame): Adjust.
(boolean_option_def, uinteger_option_def)
(set_backtrace_option_defs): New.
(_initialize_frame): Adjust and use
gdb::option::add_setshow_cmds_for_options to install "set
backtrace past-main" and "set backtrace past-entry".
* frame.h: Include "cli/cli-option.h".
(struct frame_print_options): Forward declare.
(print_frame_arguments_all, print_frame_arguments_scalars)
(print_frame_arguments_none): Declare.
(print_entry_values): Delete declaration.
(struct frame_print_options, user_frame_print_options): New.
(struct set_backtrace_options): New.
(set_backtrace_option_defs, user_set_backtrace_options): Declare.
* mi/mi-cmd-stack.c (mi_cmd_stack_list_frames)
(mi_cmd_stack_list_locals, mi_cmd_stack_list_args)
(mi_cmd_stack_list_variables): Pass down USER_FRAME_PRINT_OPTIONS.
(list_args_or_locals): Add frame_print_options parameter.
(mi_cmd_stack_info_frame): Pass down USER_FRAME_PRINT_OPTIONS.
* python/py-framefilter.c (enumerate_args): Pass down
USER_FRAME_PRINT_OPTIONS.
* stack.c: Include "cli/cli-option.h".
(print_frame_arguments_all, print_frame_arguments_scalars)
(print_frame_arguments_none): Declare.
(print_raw_frame_arguments, print_entry_values): Delete.
(user_frame_print_options): New.
(boolean_option_def, enum_option_def, frame_print_option_defs):
New.
(struct backtrace_cmd_options): New.
(bt_flag_option_def): New.
(backtrace_command_option_defs): New.
(print_stack_frame): Pass down USER_FRAME_PRINT_OPTIONS.
(print_frame_arg, read_frame_arg, print_frame_args)
(print_frame_info, print_frame): Add frame_print_options parameter
and use it.
(info_frame_command_core): Pass down USER_FRAME_PRINT_OPTIONS.
(backtrace_command_1): Add frame_print_options and
backtrace_cmd_options parameters and use them.
(make_backtrace_options_def_group): New.
(backtrace_command): Process command options with
gdb::option::process_options.
(backtrace_command_completer): New.
(_initialize_stack): Extend "backtrace"'s help to mention
supported options. Install completer for "backtrace".
Install some settings commands with add_setshow_cmds_for_options.
gdb/testsuite/ChangeLog:
2019-06-13 Pedro Alves <palves@redhat.com>
* gdb.base/options.exp (test-backtrace): New.
(top level): Call it.
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
I am currently working with these functions, and though this renaming
could help to reason about the code. Some functions take a frame and
will return the value associated to that frame, others will return the
value associated to the previous frame. Those usually conveniently
contain "unwind" in their name, but naming the variable next_frame
instead of frame helps remembering which frame we are dealing with.
I also included a little typo fix at the top of frame.h.
gdb/ChangeLog:
* frame.c (frame_register_unwind): Change parameter name.
(frame_unwind_register): Likewise.
(frame_unwind_register_value): Likewise.
(frame_unwind_register_signed): Likewise.
(frame_unwind_register_unsigned): Likewise.
* frame.h (frame_register_unwind): Likewise.
(frame_unwind_register): Likewise.
(frame_unwind_register_value): Likewise.
(frame_unwind_register_signed): Likewise.
(frame_unwind_register_unsigned): Likewise.
(frame_unwind_arch): Likewise.
PR gdb/23203 reports 'bt full' causing the currently selected frame to
change, this issue is fixed in this commit.
Add a new class scoped_restore_selected_frame that saves and restores
the selected frame. Make use of this in print_frame_local_vars to
restore the selected frame on exit.
gdb/ChangeLog:
PR gdb/23203
* frame.c
(scoped_restore_selected_frame::scoped_restore_selected_frame):
Define.
(scoped_restore_selected_frame::~scoped_restore_selected_frame):
Define.
* frame.h (class scoped_restore_selected_frame): New class.
* stack.c (print_frame_local_vars): Remove catching and rethrowing
of any exception, use scoped_restore_selected_frame to restore the
frame instead.
gdb/testsuite/ChangeLog:
PR gdb/23203
* gdb.base/bt-selected-frame.c: New file.
* gdb.base/bt-selected-frame.exp: New file.
* lib/gdb.exp (get_current_frame_number): New function.
