It was quite odd for the prior operand handling to have to clear this
flag for the actual operand handling to print nothing. Have the actual
operand handling determine whether the operand is actually present.
With this {d,q}_scalar_swap_mode become unused and hence also get dropped.
These are only used when VEX.L or EVEX.L'L have already been decoded,
and hence the "normal" length dependent name determination is quite
fine. Adjust a few enumerators to make clear that vex_len_table[] has
been consulted; be consistent and do so for all *f128 and *i128 insns
in one go.
Fold redundant case blocks and move the extra adjustments logic into
the single case block that actually needs it - there's no need to go
through the extra logic for all the other cases. Also utilize there that
vex.b cannot be set at this point, due to earlier logic. Reduce the
comment there, which was partly stale anyway.
Unlike the earlier ones these also need their operands adjusted. Replace
the (mis-described: there's nothing "scalar" here) {b,w}_scalar_mode by
a single new mode, with the actual unit width controlled by EVEX.W.
The operands don't allow disambiguating the insn in 64-bit mode, and
hence suffixes need to be emitted not just in AT&T mode. Achieve this
by re-using %LQ while dropping PCMPESTR_Fixup().
MOVBE_Fixup() is entirely redundant with the S macro already used on the
mnemonics, leading to double suffixes in suffix-always mode. Drop the
function.
Just like other insns with GPR operands, CRC32 with only register
operands should not get a suffix added unless in suffix-always mode.
Do away with CRC32_Fixup() altogether, using other more generic logic
instead.
Unlike for non-zero values passed to USED_REX(), where rex_used gets
updated only when the respective bit was actually set in the encoding,
zero getting passed in is not further guarded, yet such a (potentially
"empty") REX prefix takes effect only when there are registers numbered
4 and up.
There's only a very limited set of modes that this function gets invoked
with - avoid it being more generic than it needs to be. This may, down
the road, allow actually doing away with the function altogether.
This eliminates a first improperly used "USED_REX (0)".
Various of the test expectations get adjusted later in this and a
subsequent series, so in order to avoid having to adjust more instances
than necessary fold respective test ILP32 expectations with their main
64-bit counterparts where they're identical anyway.
When building gdbserver with AddressSanitizer, I get this annoying
little leak when gdbserver exits:
==307817==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 14 byte(s) in 1 object(s) allocated from:
#0 0x7f7fd4256459 in __interceptor_malloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
#1 0x563bef981b80 in xmalloc /home/simark/src/binutils-gdb/gdbserver/../gdb/alloc.c:60
#2 0x563befb53301 in xstrdup /home/simark/src/binutils-gdb/libiberty/xstrdup.c:34
#3 0x563bef9d742b in handle_query /home/simark/src/binutils-gdb/gdbserver/server.cc:2286
#4 0x563bef9ed0b7 in process_serial_event /home/simark/src/binutils-gdb/gdbserver/server.cc:4061
#5 0x563bef9f1d9e in handle_serial_event(int, void*) /home/simark/src/binutils-gdb/gdbserver/server.cc:4402
#6 0x563befb0ec65 in handle_file_event /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:548
#7 0x563befb0f49f in gdb_wait_for_event /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:673
#8 0x563befb0d4a1 in gdb_do_one_event() /home/simark/src/binutils-gdb/gdbsupport/event-loop.cc:215
#9 0x563bef9e721a in start_event_loop /home/simark/src/binutils-gdb/gdbserver/server.cc:3484
#10 0x563bef9eb90a in captured_main /home/simark/src/binutils-gdb/gdbserver/server.cc:3875
#11 0x563bef9ec2c7 in main /home/simark/src/binutils-gdb/gdbserver/server.cc:3961
#12 0x7f7fd3330001 in __libc_start_main (/usr/lib/libc.so.6+0x27001)
SUMMARY: AddressSanitizer: 14 byte(s) leaked in 1 allocation(s).
This is due to the handling of unknown qsupported features in
handle_query. The `qsupported` vector is built, containing all the
feature names received from GDB. As we iterate on them, when we
encounter unknown ones, we move them at the beginning of the vector, in
preparation of passing this vector of unknown features down to the
target (which may know about them).
When moving these unknown features to other slots in the vector, we
overwrite other pointers without freeing them, which therefore leak.
An easy fix would be to add a `free` when doing the move. However, I
think this is a good opportunity to sprinkle a bit of automatic memory
management in this code.
So, use a vector of std::string which owns all the entries. And use a
separate vector (that doesn't own the entries) for the unknown ones,
which is then passed to target_process_qsupported.
Given that the `c_str` method of std::string returns a `const char *`,
it follows that process_stratum_target::process_qsupported must accept a
`const char **` instead of a `char **`. And while at it, change the
pointer + size paramters to use an array_view instead.
gdbserver/ChangeLog:
* server.cc (handle_query): Use std::vector of
std::string for `qsupported` vector. Use separate
vector for unknowns.
* target.h (class process_stratum_target) <process_qsupported>:
Change parameters to array_view of const char *.
(target_process_qsupported): Remove `count` parameter.
* target.cc (process_stratum_target::process_qsupported): Change
parameters to array_view of const char *.
* linux-x86-low.cc (class x86_target) <process_qsupported>:
Likewise.
Change-Id: I97f133825faa6d7abbf83a58504eb0ba77462812
The addition of an anchor for the "frame apply" command was causing
the HTML documentation to include files named both "frame-apply.html"
and "Frame-Apply.html", which collide on case-insensitive file
systems. This patch removes the redundant anchor and adjusts the two
xrefs to it.
2020-07-13 Paul Carroll <pcarroll@codesourcery.com>
PR gdb/25716
gdb/doc/
* gdb.texinfo (Frame Apply): Remove anchor for 'frame
apply' and adjust xrefs to it.
When testing on a remote host, source files from build are copied to
an arbitrary location on host. Tests that try to pattern-match host
pathnames against directory prefixes on build don't generally work.
2020-07-13 Sandra Loosemore <sandra@codesourcery.com>
gdb/testsuite/
* gdb.base/info_sources.exp: Skip directory match tests on
remote hosts.
When encoding a 32-bit offset, there is no need to sign-extend it to 64
bits since only the lower 32 bits are used.
* config/tc-i386.c (offset_in_range): Remove 32-bit sign
extension.
gdb.arch/i386-sse.exp fails to run with clang, because of:
gdb compile failed, /gdbtest/src/gdb/testsuite/gdb.arch/i386-sse.c:56:40: warning:
passing 'int *' to parameter of type 'unsigned int *' converts between
pointers to integer types with different sign [-Wpointer-sign]
if (!x86_cpuid (1, NULL, NULL, NULL, &edx))
^~~~
/gdbtest/src/gdb/testsuite/../nat/x86-cpuid.h:35:41: note: passing
argument to parameter '__edx' here
unsigned int *__ecx, unsigned int *__edx)
^
1 warning generated.
Fix it by declaring edx unsigned.
gdb/testsuite/ChangeLog:
* gdb.arch/i386-sse.c (have_sse) <edx>: Make unsigned.
Clang fails to compile a number of files with the following warning:
indirection of non-volatile null pointer will be deleted, not trap
[-Wnull-dereference]. This commit qualifies the relevant pointers
with 'volatile'.
gdb/testsuite/ChangeLog:
* gdb.base/bigcore.c (main): Use a volatile pointer when
attempting to trigger a SIGSEGV.
* gdb.base/gcore-relro-pie.c (break_here): Likewise.
* gdb.base/gcore-tls-pie.c (break_here): Likewise.
* gdb.base/savedregs.c (thrower): Likewise.
* gdb.mi/mi-syn-frame.c (bar): Likewise.
Clang fails to compile gdb.base/vla-datatypes.c with the following
error: fields must have a constant size: 'variable length array in
structure' extension will never be supported. This commit factors
the affected tests out into a new testcase, vla-struct-fields.{exp,c},
which is skipped when the testcase is compiled using clang,
gdb/testsuite/ChangeLog:
* gdb.base/vla-datatypes.c (vla_factory): Factor out sections
defining and using VLA structure fields into...
* gdb.base/vla-struct-fields.c: New file.
* gdb.base/vla-datatypes.exp: Factor out VLA structure field
tests into...
* gdb.base/vla-struct-fields.exp: New file.
Tests just having "xfail: x86_64-*-cygwin" aren't good, since
presumably if a test fails on x86_64-cygwin then it also fails on
x86_64-*-pe* and x86_64-*-mingw*.
binutils/
* testsuite/lib/binutils-common.exp (is_pecoff_format): Accept
optional machine-os arg.
ld/
* testsuite/ld-scripts/default-script1.d: Don't skip, xfail
using is_pecoff_format.
* testsuite/ld-scripts/default-script2.d: Likewise.
* testsuite/ld-scripts/default-script3.d: Likewise.
* testsuite/ld-scripts/default-script4.d: Likewise.
* testsuite/ld-scripts/pr20302.d: Remove x86_64-*-cygwin from notarget.
* testsuite/ld-scripts/provide-6.d: Remove x86_64-*-cygwin from xfail.
* testsuite/ld-scripts/provide-8.d: Likewise.
git commit af2b318648 introduced a number of XPASSes. This removes
them. (It also introduces a FAIL on ft32-elf but the comment in the
.d file didn't adequately explain why the failure should be expected.)
* testsuite/gas/elf/dwarf2-7.d: Remove most xfails.
* testsuite/gas/elf/dwarf2-12.d: Likewise.
* testsuite/gas/elf/dwarf2-13.d: Likewise.
* testsuite/gas/elf/dwarf2-14.d: Likewise.
When running test-case gdb.base/morestack.exp without the gold linker
installed, we run into:
...
Running src/gdb/testsuite/gdb.base/morestack.exp ...
gdb compile failed, collect2: fatal error: cannot find 'ld'
compilation terminated.
FAIL: gdb.base/morestack.exp: continue
=== gdb Summary ===
nr of expected passes 1
nr of unexpected failures 1
nr of untested testcases 1
...
The test-case needs the gold linker to run correctly (as explained in commit
b8d38ee425 "testsuite: Fix false FAIL for gdb.base/morestack.exp"), but
only prefers it, and doesn't require it.
Fix this by requiring the gold linker in the test-case. Furthermore, silence
the compilation error by introducing a caching proc have_fuse_ld_gold and
using it in this and other test-cases that use -fuse-ld=gold.
Tested on x86_64-linux.
gdb/testsuite/ChangeLog:
2020-07-13 Tom de Vries <tdevries@suse.de>
* lib/gdb.exp (have_fuse_ld_gold): New caching proc.
* gdb.base/gcore-tls-pie.exp: Use have_fuse_ld_gold.
* gdb.base/gold-gdb-index.exp: Same.
* gdb.base/morestack.exp: Same.
Getting the bounds of an array (or string) type is a common operation,
and is currently done through its index type:
my_array_type->index_type ()->bounds ()
I think it would make sense to let the `type::bounds` methods work for
arrays and strings, as a shorthand for this. It's natural that when
asking for the bounds of an array, we get the bounds of the range type
used as its index type. In a way, it's equivalent as the now-removed
TYPE_ARRAY_{LOWER,UPPER}_BOUND_IS_UNDEFINED and
TYPE_ARRAY_{LOWER,UPPER}_BOUND_VALUE, except it returns the
`range_bounds` object. The caller is then responsible for getting the
property it needs in it.
I updated all the spots I could find that could take advantage of this.
Note that this also makes `type::bit_stride` work on array types, since
`type::bit_stride` uses `type::bounds`. `my_array_type->bit_stride ()`
now returns the bit stride of the array's index type. So some spots
are also changed to take advantage of this.
gdb/ChangeLog:
* gdbtypes.h (struct type) <bounds>: Handle array and string
types.
* ada-lang.c (assign_aggregate): Use type::bounds on
array/string type.
* c-typeprint.c (c_type_print_varspec_suffix): Likewise.
* c-varobj.c (c_number_of_children): Likewise.
(c_describe_child): Likewise.
* eval.c (evaluate_subexp_for_sizeof): Likewise.
* f-typeprint.c (f_type_print_varspec_suffix): Likewise.
(f_type_print_base): Likewise.
* f-valprint.c (f77_array_offset_tbl): Likewise.
(f77_get_upperbound): Likewise.
(f77_print_array_1): Likewise.
* guile/scm-type.c (gdbscm_type_range): Likewise.
* m2-typeprint.c (m2_array): Likewise.
(m2_is_long_set_of_type): Likewise.
* m2-valprint.c (get_long_set_bounds): Likewise.
* p-typeprint.c (pascal_type_print_varspec_prefix): Likewise.
* python/py-type.c (typy_range): Likewise.
* rust-lang.c (rust_internal_print_type): Likewise.
* type-stack.c (type_stack::follow_types): Likewise.
* valarith.c (value_subscripted_rvalue): Likewise.
* valops.c (value_cast): Likewise.
Change-Id: I5c0c08930bffe42fd69cb4bfcece28944dd88d1f
Remove it and update all callers to use the equivalent accessor methods.
A subsequent patch will make type::bit_stride work for array types
(effectively replacing this macro), but I wanted to keep this patch a
simple mechanical change.
gdb/ChangeLog:
* gdbtypes.c (TYPE_ARRAY_BIT_STRIDE): Remove. Update all
callers to use the equivalent accessor methods.
Change-Id: I09e14bd45075f98567adce8a0b93edea7722f812
Remove the macro and add a `bit_stride` method to `struct range_bounds`,
which does the byte -> bit conversion if needed.
Add a convenience `bit_stride` method to `struct type` as well. I don't
really understand why the bit/byte stride is stored in the data
structure for bounds. Maybe it was just put there because
`range_bounds` was already a data structure specific to TYPE_CODE_RANGE
types? If the stride is indeed not related to the bounds, then I find
it more logical to do `my_range_type->bit_stride ()` than
`my_range_type->bounds ()->bit_stride ()`, hence the convenience
function on `struct type`.
gdb/ChangeLog:
* gdbtypes.h (struct range_bounds) <bit_stride>: New method.
(struct type) <bit_stride>: New method.
(TYPE_BIT_STRIDE): Remove.
* gdbtypes.c (update_static_array_size): Use type::bit_stride.
Change-Id: I6ecc1cfefdc20711fa8f188a94a05c1e116c9922
Remove the macros, use the various equivalent getters instead.
gdb/ChangeLog:
* gdbtypes.h (TYPE_ARRAY_LOWER_BOUND_VALUE,
TYPE_ARRAY_UPPER_BOUND_VALUE): Remove. Update all
callers to use the equivalent accessor methods instead.
Change-Id: I7f96d988f872170e7a2f58095832710e62b85cfd
Remove the macros, use the various equivalent getters instead.
gdb/ChangeLog:
* gdbtypes.h (TYPE_ARRAY_UPPER_BOUND_IS_UNDEFINED,
TYPE_ARRAY_LOWER_BOUND_IS_UNDEFINED): Remove. Update all
callers to use the equivalent accessor methods instead.
Change-Id: Ifb4c36f440b82533bde5d15a5cbb2fc91f467292
Remove the macros, use the getters of `struct dynamic_prop` instead.
gdb/ChangeLog:
* gdbtypes.h (TYPE_LOW_BOUND_KIND,
TYPE_HIGH_BOUND_KIND): Remove. Update all callers
to use dynamic_prop::kind.
Change-Id: Icb1fc761f675bfac934209f8102392504d905c44
Remove the macros, use the getters of `struct dynamic_prop` instead.
gdb/ChangeLog:
* gdbtypes.h (TYPE_LOW_BOUND_UNDEFINED,
TYPE_HIGH_BOUND_UNDEFINED): Remove. Update all callers
to get the bound property's kind and check against
PROP_UNDEFINED.
Change-Id: I6a7641ac1aa3fa7fca0c21f00556f185f2e2d68c
Remove the macros, use the getters of `struct dynamic_prop` instead.
gdb/ChangeLog:
* gdbtypes.h (TYPE_LOW_BOUND, TYPE_HIGH_BOUND): Remove. Update
all callers to use type::range_bounds followed by
dynamic_prop::{low,high}.
Change-Id: I31beeed65d94d81ac4f999244a8b859e2ee961d1
Add setters, to ensure that the kind and value of the property are
always kept in sync (a caller can't forget one or the other). Add
getters, such that we can assert that when a caller accesses a data bit
of the property, the property is indeed of the corresponding kind.
Note that because of the way `struct dynamic_prop` is allocated
currently, we can't make the `m_kind` and `m_data` fields private. That
would make the type non-default-constructible, and we would have to call
the constructor when allocating them. However, I still prefixed them
with `m_` to indicate that they should not be accessed from outside the
class (and also to be able to use the name `kind` for the method).
gdb/ChangeLog:
* gdbtypes.h (struct dynamic_prop) <kind, set_undefined,
const_val, set_const_val, baton, set_locexpr, set_loclist,
set_addr_offset, variant_parts, set_variant_parts,
original_type, set_original_type>: New methods.
<kind>: Rename to...
<m_kind>: ... this. Update all users to use the new methods
instead.
<data>: Rename to...
<m_data>: ... this. Update all users to use the new methods
instead.
Change-Id: Ib72a8eb440dfeb1a5421d0933334230d7f2478f9
The next patch adds getters to the `dynamic_prop` structure. These
getters validate that the accessed data matches the property kind (for
example, to access the `const_val` field, the property must be of kind
`PROP_CONST`). It found one instance where we are accessing the
`const_val` data of a property that has the undefined kind.
This happens in function `get_discrete_bounds`, and is exposed by test
gdb.base/ptype.exp, amongst others. Without this patch, we would get:
$ ./gdb -q -nx --data-directory=data-directory testsuite/outputs/gdb.base/ptype/ptype -ex "ptype t_char_array"
Reading symbols from testsuite/outputs/gdb.base/ptype/ptype...
type = char [
/home/smarchi/src/binutils-gdb/gdb/gdbtypes.h:526: internal-error: LONGEST dynamic_prop::const_val() const: Assertion `m_kind == PROP_CONST' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
The `get_discrete_bounds` function returns the bounds of a type (not
only range types). For range types, it naturally uses the bound
properties that are intrinsic to the range type. It accesses these
properties using TYPE_LOW_BOUND and TYPE_HIGH_BOUND, which assume the
properties are defined and have constant values. This is sometimes not
the case, and the passed range type (as in the example above) has an
undefined high/upper bound.
Given its current interface (returning two LONGEST values for low and
high), `get_discrete_bounds` can't really work if the range type's
bounds are not both defined and both constant values.
This patch changes the function to return -1 (failure to get the bounds)
if any of the range type's bounds is not a constant value. It is
sufficient to fix the issue and it seems to keep the callers happy, at
least according to the testsuite.
A bit in `get_array_bounds` could be removed, since
`get_discrete_bounds` no longer returns 1 if a bound is undefined.
gdb/ChangeLog:
* gdbtypes.c (get_discrete_bounds): Return failure if
the range type's bounds are not both defined and constant
values.
(get_array_bounds): Update comment. Remove undefined bound check.
Change-Id: I047a3beee2c1e275f888cfc4778228339922bde9
Remove it in favor of using type::bounds directly.
gdb/ChangeLog:
* gdbtypes.h (TYPE_RANGE_DATA): Remove. Update callers to use
the type::bounds method directly.
Change-Id: Id4fab22af0a94cbf505f78b01b3ee5b3d682fba2
Add the `bounds` and `set_bounds` methods on `struct type`, in order to
remove the `TYPE_RANGE_DATA` macro. In this patch, the
`TYPE_RANGE_DATA` macro is changed to use `type::bounds`, so all the
call sites that are used to set a range type's bounds are changed to use
`type::set_bounds`. The next patch will remove `TYPE_RANGE_DATA`
completely.
gdb/ChangeLog:
* gdbtypes.h (struct type) <bounds, set_bounds>: New methods.
(TYPE_RANGE_DATA): Use type::bounds. Change all uses that
are used to set the range type's bounds to use set_bounds.
Change-Id: I62e15506239b98404e62bbea8120db184ed87847
I noticed that the modules test was failing. Some choice use of `nm`
revealed `TWENTY_THREE` was not in the final binary. Fix by taking a
pointer to the global, forcing the linker to keep the symbol in.
gdb/testsuite/ChangeLog
2020-07-11 Daniel Xu <dxu@dxuuu.xyz>
PR rust/26121
* gdb.rust/modules.rs: Prevent linker from discarding test
symbol.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
It was deemed better to explicitly mention in help and doc that build IDs
are used for comparison, and that symbols are loaded when asking to
load the exec-file.
This is V2, fixing 2 typos and replacing 'If the user asks to load'
by 'If the user confirms loading', as suggested by Pedro.
gdb/ChangeLog
2020-07-11 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* exec.c (_initialize_exec): Update exec-file-mismatch help.
gdb/doc/ChangeLog
2020-07-11 Philippe Waroquiers <philippe.waroquiers@skynet.be>
* gdb.texinfo (Attach): Update exec-file-mismatch doc.
Running the testsuite against an Asan-enabled build of GDB makes
gdb.base/multi-target.exp expose this bug.
scoped_restore_current_thread's ctor calls get_frame_id to record the
selected frame's ID to restore later. If the frame ID hasn't been
computed yet, it will be computed on the spot, and that will usually
require accessing the target's memory and registers. If the remote
connection closes, while we're computing the frame ID, the remote
target exits its inferiors, unpushes itself, and throws a
TARGET_CLOSE_ERROR error. Exiting the inferiors deletes the
inferior's threads.
scoped_restore_current_thread increments the current thread's refcount
to prevent the thread from being deleted from under its feet.
However, the code that does that isn't considering the case of the
thread being deleted from within get_frame_id. It only increments the
refcount _after_ get_frame_id returns. So if the current thread is
indeed deleted, the
tp->incref ();
statement references a stale TP pointer.
Incrementing the refcounts earlier fixes it.
We should probably also let the TARGET_CLOSE_ERROR error propagate in
this case. That alone would fix it, though it seems better to tweak
the refcount handling too. And to avoid having to manually decref
before throwing, convert to use gdb::ref_ptr.
Unfortunately, we can't define inferior_ref in inferior.h and then use
it in scoped_restore_current_thread, because
scoped_restore_current_thread is defined before inferior is
(inferior.h includes gdbthread.h). To break that dependency, we would
have to move scoped_restore_current_thread to its own header. I'm not
doing that here.
gdb/ChangeLog:
* gdbthread.h (inferior_ref): Define.
(scoped_restore_current_thread) <m_thread>: Now a thread_info_ref.
(scoped_restore_current_thread) <m_inf>: Now an inferior_ref.
* thread.c
(scoped_restore_current_thread::restore):
Adjust to gdb::ref_ptr.
(scoped_restore_current_thread::~scoped_restore_current_thread):
Remove manual decref handling.
(scoped_restore_current_thread::scoped_restore_current_thread):
Adjust to use
inferior_ref::new_reference/thread_info_ref::new_reference.
Incref the thread before calling get_frame_id instead of after.
Let TARGET_CLOSE_ERROR propagate.
Running the testsuite against an Asan-enabled build of GDB makes
gdb.base/multi-target.exp expose this bug.
scoped_restore_current_thread's ctor calls get_frame_id to record the
selected frame's ID to restore later. If the frame ID hasn't been
computed yet, it will be computed on the spot, and that will usually
require accessing the target's memory and registers, which requires
remote accesses. If the remote connection closes while we're
computing the frame ID, the remote target exits its inferiors,
unpushes itself, and throws a TARGET_CLOSE_ERROR error.
If that happens, GDB can currently crash, here:
> ==18555==ERROR: AddressSanitizer: heap-use-after-free on address 0x621004670aa8 at pc 0x0000007ab125 bp 0x7ffdecaecd20 sp 0x7ffdecaecd10
> READ of size 4 at 0x621004670aa8 thread T0
> #0 0x7ab124 in dwarf2_frame_this_id src/binutils-gdb/gdb/dwarf2/frame.c:1228
> #1 0x983ec5 in compute_frame_id src/binutils-gdb/gdb/frame.c:550
> #2 0x9841ee in get_frame_id(frame_info*) src/binutils-gdb/gdb/frame.c:582
> #3 0x1093faa in scoped_restore_current_thread::scoped_restore_current_thread() src/binutils-gdb/gdb/thread.c:1462
> #4 0xaee5ba in fetch_inferior_event(void*) src/binutils-gdb/gdb/infrun.c:3968
> #5 0xaa990b in inferior_event_handler(inferior_event_type, void*) src/binutils-gdb/gdb/inf-loop.c:43
> #6 0xea61b6 in remote_async_serial_handler src/binutils-gdb/gdb/remote.c:14161
> #7 0xefca8a in run_async_handler_and_reschedule src/binutils-gdb/gdb/ser-base.c:137
> #8 0xefcd23 in fd_event src/binutils-gdb/gdb/ser-base.c:188
> #9 0x15a7416 in handle_file_event src/binutils-gdb/gdbsupport/event-loop.cc:548
> #10 0x15a7c36 in gdb_wait_for_event src/binutils-gdb/gdbsupport/event-loop.cc:673
> #11 0x15a5dbb in gdb_do_one_event() src/binutils-gdb/gdbsupport/event-loop.cc:215
> #12 0xbfe62d in start_event_loop src/binutils-gdb/gdb/main.c:356
> #13 0xbfe935 in captured_command_loop src/binutils-gdb/gdb/main.c:416
> #14 0xc01d39 in captured_main src/binutils-gdb/gdb/main.c:1253
> #15 0xc01dc9 in gdb_main(captured_main_args*) src/binutils-gdb/gdb/main.c:1268
> #16 0x414ddd in main src/binutils-gdb/gdb/gdb.c:32
> #17 0x7f590110b82f in __libc_start_main ../csu/libc-start.c:291
> #18 0x414bd8 in _start (build/binutils-gdb/gdb/gdb+0x414bd8)
What happens is that above, we're in dwarf2_frame_this_id, just after
the dwarf2_frame_cache call. The "cache" variable that the
dwarf2_frame_cache function returned is already stale. It's been
released here, from within the dwarf2_frame_cache:
(top-gdb) bt
#0 reinit_frame_cache () at src/gdb/frame.c:1855
#1 0x00000000014ff7b0 in switch_to_no_thread () at src/gdb/thread.c:1301
#2 0x0000000000f66d3e in switch_to_inferior_no_thread (inf=0x615000338180) at src/gdb/inferior.c:626
#3 0x00000000012f3826 in remote_unpush_target (target=0x6170000c5900) at src/gdb/remote.c:5521
#4 0x00000000013097e0 in remote_target::readchar (this=0x6170000c5900, timeout=2) at src/gdb/remote.c:9137
#5 0x000000000130be4d in remote_target::getpkt_or_notif_sane_1 (this=0x6170000c5900, buf=0x6170000c5918, forever=0, expecting_notif=0, is_notif=0x0) at src/gdb/remote.c:9683
#6 0x000000000130c8ab in remote_target::getpkt_sane (this=0x6170000c5900, buf=0x6170000c5918, forever=0) at src/gdb/remote.c:9790
#7 0x000000000130bc0d in remote_target::getpkt (this=0x6170000c5900, buf=0x6170000c5918, forever=0) at src/gdb/remote.c:9623
#8 0x000000000130838e in remote_target::remote_read_bytes_1 (this=0x6170000c5900, memaddr=0x7fffffffcdc0, myaddr=0x6080000ad3bc "", len_units=64, unit_size=1, xfered_len_units=0x7fff6a29b9a0) at src/gdb/remote.c:8860
#9 0x0000000001308bd2 in remote_target::remote_read_bytes (this=0x6170000c5900, memaddr=0x7fffffffcdc0, myaddr=0x6080000ad3bc "", len=64, unit_size=1, xfered_len=0x7fff6a29b9a0) at src/gdb/remote.c:8987
#10 0x0000000001311ed1 in remote_target::xfer_partial (this=0x6170000c5900, object=TARGET_OBJECT_MEMORY, annex=0x0, readbuf=0x6080000ad3bc "", writebuf=0x0, offset=140737488342464, len=64, xfered_len=0x7fff6a29b9a0) at src/gdb/remote.c:10988
#11 0x00000000014ba969 in raw_memory_xfer_partial (ops=0x6170000c5900, readbuf=0x6080000ad3bc "", writebuf=0x0, memaddr=140737488342464, len=64, xfered_len=0x7fff6a29b9a0) at src/gdb/target.c:918
#12 0x00000000014bb720 in target_xfer_partial (ops=0x6170000c5900, object=TARGET_OBJECT_RAW_MEMORY, annex=0x0, readbuf=0x6080000ad3bc "", writebuf=0x0, offset=140737488342464, len=64, xfered_len=0x7fff6a29b9a0) at src/gdb/target.c:1148
#13 0x00000000014bc3b5 in target_read_partial (ops=0x6170000c5900, object=TARGET_OBJECT_RAW_MEMORY, annex=0x0, buf=0x6080000ad3bc "", offset=140737488342464, len=64, xfered_len=0x7fff6a29b9a0) at src/gdb/target.c:1380
#14 0x00000000014bc593 in target_read (ops=0x6170000c5900, object=TARGET_OBJECT_RAW_MEMORY, annex=0x0, buf=0x6080000ad3bc "", offset=140737488342464, len=64) at src/gdb/target.c:1419
#15 0x00000000014bbd4d in target_read_raw_memory (memaddr=0x7fffffffcdc0, myaddr=0x6080000ad3bc "", len=64) at src/gdb/target.c:1252
#16 0x0000000000bf27df in dcache_read_line (dcache=0x6060001eddc0, db=0x6080000ad3a0) at src/gdb/dcache.c:336
#17 0x0000000000bf2b72 in dcache_peek_byte (dcache=0x6060001eddc0, addr=0x7fffffffcdd8, ptr=0x6020001231b0 "") at src/gdb/dcache.c:403
#18 0x0000000000bf3103 in dcache_read_memory_partial (ops=0x6170000c5900, dcache=0x6060001eddc0, memaddr=0x7fffffffcdd8, myaddr=0x6020001231b0 "", len=8, xfered_len=0x7fff6a29bf20) at src/gdb/dcache.c:484
#19 0x00000000014bafe9 in memory_xfer_partial_1 (ops=0x6170000c5900, object=TARGET_OBJECT_STACK_MEMORY, readbuf=0x6020001231b0 "", writebuf=0x0, memaddr=140737488342488, len=8, xfered_len=0x7fff6a29bf20) at src/gdb/target.c:1034
#20 0x00000000014bb212 in memory_xfer_partial (ops=0x6170000c5900, object=TARGET_OBJECT_STACK_MEMORY, readbuf=0x6020001231b0 "", writebuf=0x0, memaddr=140737488342488, len=8, xfered_len=0x7fff6a29bf20) at src/gdb/target.c:1076
#21 0x00000000014bb6b3 in target_xfer_partial (ops=0x6170000c5900, object=TARGET_OBJECT_STACK_MEMORY, annex=0x0, readbuf=0x6020001231b0 "", writebuf=0x0, offset=140737488342488, len=8, xfered_len=0x7fff6a29bf20) at src/gdb/target.c:1133
#22 0x000000000164564d in read_value_memory (val=0x60f000029440, bit_offset=0, stack=1, memaddr=0x7fffffffcdd8, buffer=0x6020001231b0 "", length=8) at src/gdb/valops.c:956
#23 0x0000000001680fff in value_fetch_lazy_memory (val=0x60f000029440) at src/gdb/value.c:3764
#24 0x0000000001681efd in value_fetch_lazy (val=0x60f000029440) at src/gdb/value.c:3910
#25 0x0000000001676143 in value_optimized_out (value=0x60f000029440) at src/gdb/value.c:1411
#26 0x0000000000e0fcb8 in frame_register_unwind (next_frame=0x6210066bfde0, regnum=16, optimizedp=0x7fff6a29c200, unavailablep=0x7fff6a29c240, lvalp=0x7fff6a29c2c0, addrp=0x7fff6a29c300, realnump=0x7fff6a29c280, bufferp=0x7fff6a29c3a0 "@\304)j\377\177") at src/gdb/frame.c:1144
#27 0x0000000000e10418 in frame_unwind_register (next_frame=0x6210066bfde0, regnum=16, buf=0x7fff6a29c3a0 "@\304)j\377\177") at src/gdb/frame.c:1196
#28 0x0000000000f00431 in i386_unwind_pc (gdbarch=0x6210043d0110, next_frame=0x6210066bfde0) at src/gdb/i386-tdep.c:1969
#29 0x0000000000e39724 in gdbarch_unwind_pc (gdbarch=0x6210043d0110, next_frame=0x6210066bfde0) at src/gdb/gdbarch.c:3056
#30 0x0000000000c2ea90 in dwarf2_tailcall_sniffer_first (this_frame=0x6210066bfde0, tailcall_cachep=0x6210066bfee0, entry_cfa_sp_offsetp=0x0) at src/gdb/dwarf2/frame-tailcall.c:423
#31 0x0000000000c36bdb in dwarf2_frame_cache (this_frame=0x6210066bfde0, this_cache=0x6210066bfdf8) at src/gdb/dwarf2/frame.c:1198
#32 0x0000000000c36eb3 in dwarf2_frame_this_id (this_frame=0x6210066bfde0, this_cache=0x6210066bfdf8, this_id=0x6210066bfe40) at src/gdb/dwarf2/frame.c:1226
Note that remote_target::readchar in frame #4 throws
TARGET_CLOSE_ERROR after the remote_unpush_target in frame #3 returns.
The problem is that the TARGET_CLOSE_ERROR is swallowed by
value_optimized_out in frame #25.
If we fix that one, then we run into dwarf2_tailcall_sniffer_first
swallowing the exception in frame #30 too.
The attached patch fixes it by making those spots swallow fewer kinds
of errors.
gdb/ChangeLog:
* frame-tailcall.c (dwarf2_tailcall_sniffer_first): Only swallow
NO_ENTRY_VALUE_ERROR / MEMORY_ERROR / OPTIMIZED_OUT_ERROR /
NOT_AVAILABLE_ERROR.
* value.c (value_optimized_out): Only swallow MEMORY_ERROR /
OPTIMIZED_OUT_ERROR / NOT_AVAILABLE_ERROR.
When interrupting a program in non-stop, the program gets interrupted
correctly, but GDB busy loops (the event loop is always woken up).
Here is how to reproduce it:
1. Start GDB: ./gdb -nx --data-directory=data-directory -ex "set non-stop 1" --args /bin/sleep 60
2. Run the program with "run"
3. Interrupt with ^C.
4. Look into htop, see GDB taking 100% CPU
Debugging `handle_file_event`, we see that the event source that wakes
up the event loop is the linux-nat one:
(top-gdb) p file_ptr.proc
$5 = (handler_func *) 0xb9cccd <handle_target_event(int, gdb_client_data)>
^^^^^^^^^^^^^^^^^^^
|
\-- the linux-nat callback
Debugging fetch_inferior_event and do_target_wait, we see that we
don't actually call `wait` on the linux-nat target, because
inferior_matches returns false:
auto inferior_matches = [&wait_ptid] (inferior *inf)
{
return (inf->process_target () != NULL
&& (threads_are_executing (inf->process_target ())
|| threads_are_resumed_pending_p (inf))
&& ptid_t (inf->pid).matches (wait_ptid));
};
because `threads_are_executing` is false.
What happens is:
1. User types ctrl-c, that writes in the linux-nat pipe, waking up
the event source.
2. linux-nat's wait gets called, the SIGINT event is returned, but
before returning, it marks the pipe again, in order for wait to
get called again:
/* If we requested any event, and something came out, assume there
may be more. If we requested a specific lwp or process, also
assume there may be more. */
if (target_is_async_p ()
&& ((ourstatus->kind != TARGET_WAITKIND_IGNORE
&& ourstatus->kind != TARGET_WAITKIND_NO_RESUMED)
|| ptid != minus_one_ptid))
async_file_mark ();
3. The SIGINT event is handled, the program is stopped, the stop
notification is printed.
4. The event loop is woken up again because of the `async_file_mark`
of step 2.
5. Because `inferior_matches` returns false, we never call
linux-nat's wait, so the pipe stays readable.
6. Goto 4.
Pedro says:
This commit fixes it by letting do_target_wait call target_wait even
if threads_are_executing is false. This will normally result in the
target returning TARGET_WAITKIND_NO_RESUMED, and _not_ marking its
event source again. This results in infrun only calling into the
target only once (i.e., breaking the busy loop).
Note that the busy loop bug didn't trigger in all-stop mode because
all-stop handles this by unregistering the target from the event loop
as soon as it was all stopped -- see
inf-loop.c:inferior_event_handler's INF_EXEC_COMPLETE handling. If we
remove that non-stop check from inferior_event_handler, and replace
the target_has_execution check for threads_are_executing instead, it
also fixes the issue for non-stop. I considered that as the final
solution, but decided that the solution proposed here instead is just
simpler and more future-proof design. With the
TARGET_WAITKIND_NO_RESUMED handling fixes done in the previous
patches, I think it should be possible to always keep the target
registered in the event loop, meaning we could eliminate the
target_async(0) call from inferior_event_handler as well as most of
the target_async(1) calls in the target backends. That would allow in
the future e.g., the remote target reporting asynchronous
notifications even if all threads are stopped. I haven't attempted
that, though.
gdb/ChangeLog:
yyyy-mm-dd Simon Marchi <simon.marchi@polymtl.ca>
Pedro Alves <pedro@palves.net>
PR gdb/26199
* infrun.c (threads_are_resumed_pending_p): Delete.
(do_target_wait): Remove threads_are_executing and
threads_are_resumed_pending_p checks from the inferior_matches
lambda. Update comments.
This adds a testcase that covers the scenarios described in the
previous two commits.
gdb/testsuite/ChangeLog:
PR gdb/26199
* gdb.multi/multi-target.c (exit_thread): New.
(thread_start): Break loop if EXIT_THREAD.
* gdb.multi/multi-target.exp (test_no_unwaited_for): New proc.
(top level) Call test_no_resumed.
Let's consider the same use case as in the previous commit:
Say you have two inferiors 1 and 2, each connected to a different
target, A and B.
Now say you set inferior 2 running, with "continue &".
Now you select a thread of inferior 1, say thread 1.2, and continue in
the foreground. All other threads of inferior 1 are left stopped.
Thread 1.2 exits, and thus target A has no other resumed thread, so it
reports TARGET_WAITKIND_NO_RESUMED.
At this point, because the threads of inferior 2 are still executing
the TARGET_WAITKIND_NO_RESUMED event is ignored.
Now, the user types Ctrl-C. Because GDB had previously put inferior 1
in the foreground, the kernel sends the SIGINT to that inferior.
However, no thread in that inferior is executing right now, so ptrace
never intercepts the SIGINT -- it is never dequeued by any thread.
The result is that GDB's CLI is stuck. There's no way to get back the
prompt (unless inferior 2 happens to report some event).
The fix in this commit is to make handle_no_resumed give the terminal
to some other inferior that still has threads executing so that a
subsequent Ctrl-C reaches that target first (and then GDB intercepts
the SIGINT). This is a bit hacky, but seems like the best we can do
with the current design.
I think that putting all native inferiors in their own session would
help fixing this in a clean way, since with that a Ctrl-C on GDB's
terminal will _always_ reach GDB first, and then GDB can decide how to
pause the inferior. But that's a much larger change.
The testcase added by the following patch needs this fix.
gdb/ChangeLog:
PR gdb/26199
* infrun.c (handle_no_resumed): Transfer terminal to inferior with
executing threads.
handle_no_resumed is currently not considering multiple targets.
Say you have two inferiors 1 and 2, each connected to a different
target, A and B.
Now say you set inferior 2 running, with "continue &".
Now you select a thread of inferior 1, say thread 1.2, and continue in
the foreground. All other threads of inferior 1 are left stopped.
Thread 1.2 exits, and thus target A has no other resumed thread, so it
reports TARGET_WAITKIND_NO_RESUMED.
At this point, if both inferiors were running in the same target,
handle_no_resumed would realize that threads of inferior 2 are still
executing, so the TARGET_WAITKIND_NO_RESUMED event should be ignored.
But because handle_no_resumed only walks the threads of the current
target, it misses noticing that threads of inferior 2 are still
executing. The fix is just to walk over all threads of all targets.
A testcase covering the use case above will be added in a following
patch. It can't be added yet because it depends on yet another fix to
handle_no_resumed not included here.
gdb/ChangeLog:
PR gdb/26199
* infrun.c (handle_no_resumed): Handle multiple targets.
If we hit the synchronous execution command case described by
handle_no_resumed, and handle_no_resumed determines that the event
should be ignored, because it found a thread that is executing, we end
up in prepare_to_wait.
There, if the current target is not registered in the event loop right
now, we call mark_infrun_async_event_handler. With that event handler
marked, the event loop calls again into fetch_inferior_event, which
calls target_wait, which returns TARGET_WAITKIND_NO_RESUMED, and we
end up in handle_no_resumed, again ignoring the event and marking
infrun_async_event_handler. The result is that GDB is now always
keeping the CPU 100% busy in this loop, even though it continues to be
able to react to input and to real target events, because we still go
through the event-loop.
The problem is that marking of the infrun_async_event_handler in
prepare_to_wait. That is there to handle targets that don't support
asynchronous execution. So the correct predicate is whether async
execution is supported, not whether the target is async right now.
gdb/ChangeLog:
PR gdb/26199
* infrun.c (prepare_to_wait): Check target_can_async_p instead of
target_is_async_p.
