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https://github.com/riscvarchive/riscv-zacas/releases/tag/v1.0
The Zacas extension introduce compare-and-swap instructions to operate
on 32-bit, 64-bit and 128-bit (RV64 only) data values.
It introduces three new instructions:
- amocas.w (32-bit CAS)
- amocas.d (64-bit CAS)
- amocas.q (128-bit CAS, RV64 only)
Like other AMOs in the A extension, Zacas instructions have '.aq',
'.rl' and '.aqrl' variations.
bfd/ChangeLog:
* elfxx-riscv.c (riscv_implicit_subsets): 'A' implied by 'Zacas'.
(riscv_supported_std_z_ext): Add 'Zacas' extension.
(riscv_multi_subset_supports, riscv_multi_subset_supports_ext):
Handle INSN_CLASS_ZACAS case.
gas/ChangeLog:
* NEWS: Updated.
* testsuite/gas/riscv/march-help.l: Updated.
* testsuite/gas/riscv/zacas-32.d: New test (RV32).
* testsuite/gas/riscv/zacas-fail-32.d: Likewise.
* testsuite/gas/riscv/zacas-64.d: New test (RV64).
* testsuite/gas/riscv/zacas-fail-64.d: Likewise.
* testsuite/gas/riscv/zacas.s: New test source.
* testsuite/gas/riscv/zacas-fail.s: Likewise.
* testsuite/gas/riscv/zacas-fail-32.l: New file.
* testsuite/gas/riscv/zacas-fail-64.l: Likewise.
include/ChangeLog:
* include/opcode/riscv.h (INSN_CLASS_ZACAS): New definition.
* include/opcode/riscv-opc.h (MATCH_AMOCAS_W, MASK_AMOCAS_W)
(MATCH_AMOCAS_D, MASK_AMOCAS_D, MATCH_AMOCAS_Q, MASK_AMOCAS_Q):
Likewise.
(amocas_w, amocas_d, amocas_q): Declare instructions.
opcodes/ChangeLog:
* riscv-opc.c (match_rs2_rd_even): New function.
(amocas_w, amocas_d, amocas_q, amocas_w.aq)
(amocas_d.aq, amocas_q.aq, amocas_w.rl, amocas_d.rl, amocas_q.rl)
(amocas_w.aqrl, amocas_d.aqrl, amocas_q.aqrl): Add instructions.
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opcodes/ChangeLog:
* i386-dis-evex-mod.h: Used MOD_EVEX_MAP4_F8_P_1/MOD_EVEX_MAP4_F8_P_3
instead of MOD_EVEX_MAP4_F8_P1/MOD_EVEX_MAP4_F8_P3.
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%ME is added specifically for movbe. Now with %NE, we can use
MOD table + %NE to indicate whether a {evex} prefix is needed.
opcodes/ChangeLog:
* i386-dis-evex-mod.h: Added movbe.
* i386-dis-evex.h: Let movbe go through the mod table.
* i386-dis.c (struct dis386): Removed %ME.
(putop): Removed case ME.
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CCMP and CTEST are two new sets of instructions for conditional CMP
and TEST, SCC and OSZC flags are given as suffixes of CCMP or CTEST
in the instruction mnemonic, e.g.:
ccmp<cc> { dfv=sf , cf , of } %eax, %ecx
also add
{evex} cmp/test %eax, %ecx
as an alias for ccmpt.
For the encoder part, add function check_Scc_OszcOperation to parse
'{ dfv=of , sf, sf, cf}', store scc in the lower 4 bits of base_opcode,
and adjust base_opcode to its normal meaning in install_template.
For the decoder part, add 'SC' and 'DF' macros to add scc and oszc flags
suffixes.
gas/ChangeLog:
* config/tc-i386.c (OSZC_CF): New.
(OSZC_ZF): Ditto.
(OSZC_SF): Ditto.
(OSZC_OF): Ditto.
(set_oszc_flags): Set oszc flags and report error for using the same oszc flags twice.
(check_Scc_OszcOperations): Handle SCC OSZC flags.
(install_template): Add scc and oszc_flags.
(build_apx_evex_prefix): Encode SCC and oszc flags bits.
(parse_insn): Handle check_Scc_OszcOperations.
* testsuite/gas/i386/x86-64-apx-evex-promoted-bad.d: Add ivalid test case.
* testsuite/gas/i386/x86-64-apx-evex-promoted-bad.s: Ditto.
* testsuite/gas/i386/x86-64.exp: Add test for ccmp and ctest.
* testsuite/gas/i386/x86-64-apx-ccmp-ctest-intel.d: New test.
* testsuite/gas/i386/x86-64-apx-ccmp-ctest-inval.l: Ditto.
* testsuite/gas/i386/x86-64-apx-ccmp-ctest-inval.s: Ditto.
* testsuite/gas/i386/x86-64-apx-ccmp-ctest.d: Ditto.
* testsuite/gas/i386/x86-64-apx-ccmp-ctest.s: Ditto.
opcodes/ChangeLog:
* i386-dis-evex-reg.h: Add ccmp and ctest.
* i386-dis-evex.h: Ditto.
* i386-dis.c (struct instr_info): add scc.
(struct dis386): Add new micro 'NE','SC' and'DF'.
(get_valid_dis386): Get scc value and move MAP4 invalid check to print_insn.
(putop): Handle %NE, %SC and %DF.
* i386-opc.h (SCC): New.
* i386-opc.tbl: Add ccmp/ctest and evex format for cmp/test.
* i386-mnem.h: Regenerated.
* i386-tbl.h: Ditto.
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In some cases we may want to use different options only for certain
assembly, so the .option directive is added to control the assembler
options.
.option can accept 4 parameters:
push
pop
Pushes or pops the current option stack. They limit the scope of
option changes so that they do not affect other parts of the assembly
file.
relax
norelax
Enables or disables relaxation.
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The "Output file must be distinct from input" test in gas/all/gas.exp
operates on none.s as output. Should the test fail it may happen that
GAS will delete the output file requested in which case none.s will be
removed. Since the test operates directly on the source tree it will be
clobbered as a result. It has actually been observed in the field in
the form of intermittent:
FAIL: gas/all/none
regressions in a parallel run of many configurations.
Prevent this from happening by copying none.s first to the test object
directory and operating on it instead. It does not prevent the file
from being removed should the test fail, but the source tree won't be
clobbered in that case.
A nice side effect is that syntactically different paths will now be
used in this test for the input and the output file each, so coverage
will extend to verifying that a file is checked against itself even if
referred to via different paths. Previously "$srcdir/$subdir/none.s"
was used for both paths and now "tmpdir/none.s" is referred to directly
and via a relative path from "$srcdir/$subdir" respectively.
I note that we have no previous use of the UNRESOLVED test result in the
GAS testsuite, but it seems the correct one should copying none.s fail,
as this is an unexpected situation that requires a human intervention
and the test proper has not been evaluated.
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Implement a helper to construct a relative path from $srcdir/$subdir,
where `gas_run' operates, to an arbitrary place in the filesystem, for
example a file in the test object directory.
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Implement a helper to construct a relative path between two locations in
the filesystem, for example to make a path from the source to the object
directory for the case where a tool has been set up to look at a given
path and there is a need to point it elsewhere, but an absolute path
will not work. The helper works on normalized paths internally, so the
result is correct even in the presence of symlinks as intermediate path
components.
So given "/path/to/src/gas/testsuite/gas/all" as the FROM argument and
then "/path/to/obj/gas/testsuite/tmpdir/none.s" as the TO argument the
helper will return "../../../../../obj/gas/testsuite/tmpdir/none.s" in
the absence of symlinks.
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When running test-case gdb.fortran/array-indices.exp on a system without
fortran compiler, I run into a duplicate:
...
Running /home/vries/gdb/src/gdb/testsuite/gdb.fortran/array-indices.exp ...
gdb compile failed, default_target_compile: Can't find gfortran.
UNTESTED: gdb.fortran/array-indices.exp: array-indices.exp
gdb compile failed, default_target_compile: Can't find gfortran.
UNTESTED: gdb.fortran/array-indices.exp: array-indices.exp
DUPLICATE: gdb.fortran/array-indices.exp: array-indices.exp
...
Fix this by adding a with_test_prefix at the toplevel.
Likewise in gdb.fortran/array-repeat.exp.
Tested on x86_64-linux.
Reviewed-By: Alexandra Petlanova Hajkova <ahajkova@redhat.com>
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PR 31898
* dwarf.c (display_debug_rnglists_list): Correct fetch of "end"
indexed address. Remove excess parens.
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Error/warning messages are only printed for the target that
successfully matched, which makes sense for warnings, but not so much
for errors where the errors cause no target to match. I noticed this
when looking at the pr20520 testcase again with objdump, which just
reports "file format not recognized" omitting the five "SHT_GROUP
section [index n] has no SHF_GROUP sections" messages. They are
omitted because multiple ELF targets match the object file. This is
going to be true for all ELF objects due to at least the proper ELF
target and the generic ELF target matching.
* format.c (print_and_clear_messages): Print messages if all
targets with messages have exactly the same set of messages.
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This changes tui_register_info::highlight to be private, renaming it
to m_highlight.
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This TUI code calls fflush on stdout, but I don't believe this is
useful in gdb.
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Clean up script gdb/features/feature_to_c.sh by:
- fixing shellcheck warnings,
- moving an embedded awk script out of the file, reducing the amount of
escaping in the awk script, making it more readable and maintainable, and
- adding emacs / vi settings for local tab size 2 (copied from ./ltmain.sh).
Tested on x86_64-linux.
Approved-by: Kevin Buettner <kevinb@redhat.com>
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Fix shellcheck warnings in script lib/dg-add-core-file-count.sh.
Tested on x86_64-linux.
Approved-by: Kevin Buettner <kevinb@redhat.com>
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In emacs, on gdb/contrib/cc-with-tweaks.sh, do:
- M-x whitespace-cleanup,
- M-x mark-whole-buffer and M-x indent-region, and
- and undo the unwanted changes in the header comment.
Only whitespace changes.
Tested on x86_64-linux.
Approved-by: Kevin Buettner <kevinb@redhat.com>
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Fix shellcheck warnings in script gdb/contrib/cc-with-tweaks.sh.
Tested on x86_64-linux.
Approved-by: Kevin Buettner <kevinb@redhat.com>
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Clean up script gdb/contrib/expect-read1.sh by:
- fixing shellcheck warnings,
- using mktemp (which takes TMPDIR into account) instead of a hardcoded
"/tmp/expect-read1.$$.so",
- adding comments, and
- adding emacs / vi settings for local tab size 2 (copied from ./ltmain.sh).
Tested on x86_64-linux.
Approved-by: Kevin Buettner <kevinb@redhat.com>
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Add -z isa-level-report=[none|all|needed|used] to the x86 ELF linker to
report needed and used x86-64 ISA levels.
bfd/
PR ld/31868
* elf-linker-x86.h (elf_x86_isa_level_report): New.
(elf_linker_x86_params): Add isa_level_report.
* elfxx-x86.c (report_isa_level): New.
(_bfd_x86_elf_link_setup_gnu_properties): Check
-z isa-level-report=[none|all|needed|used] to report needed and
used x86-64 ISA level.
ld/
PR ld/31868
* NEWS: Mention -z isa-level-report=[none|all|needed|used].
* ld.texi: Document -z isa-level-report=[none|all|needed|used].
* emulparams/elf32_x86_64.sh: Source x86-64-level-report.sh.
* emulparams/elf_i386.sh: Likewise.
* emulparams/elf_x86_64.sh: Likewise.
* emulparams/x86-64-level-report.sh: New file.
* testsuite/ld-i386/pr31868a.d: Likewise.
* testsuite/ld-i386/pr31868b.d: Likewise.
* testsuite/ld-i386/pr31868c.d: Likewise.
* testsuite/ld-x86-64/pr31868a-x32.d: Likewise.
* testsuite/ld-x86-64/pr31868a.d: Likewise.
* testsuite/ld-x86-64/pr31868a.l: Likewise.
* testsuite/ld-x86-64/pr31868a.s: Likewise.
* testsuite/ld-x86-64/pr31868b-x32.d: Likewise.
* testsuite/ld-x86-64/pr31868b.d: Likewise.
* testsuite/ld-x86-64/pr31868b.l: Likewise.
* testsuite/ld-x86-64/pr31868b.s: Likewise.
* testsuite/ld-x86-64/pr31868c-x32.d: Likewise.
* testsuite/ld-x86-64/pr31868c.d: Likewise.
* testsuite/ld-x86-64/pr31868c.l: Likewise.
* testsuite/ld-i386/i386.exp: Run PR ld/31868 tests.
* testsuite/ld-x86-64/x86-64.exp: Likewise.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
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* lexsup.c (elf_static_list_options): Align --no-error-execstack
help output.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
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This patch simplifies ada_lookup_encoded_symbol by having it return
its result, rather than returning void and having an out parameter.
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This introduces the new method language_defn::lookup_symbol_local, and
then changes lookup_symbol_local to use it. This removes an explicit
language check from this function, and makes it easier for other
languages to hook into this code.
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lookup_local_symbol checks whether 'function' is null before calling
block::inlined_p, but this is not necessary.
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This simplifies lookup_local_symbol a little, by having it check
whether the current block is the static or global block, instead of
first searching for the static block.
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This changes lookup_local_symbol to directly examine any attached
template symbols, rather than gating this lookup on the use of C++ or
Fortran. As mentioned in an earlier patch, these objects are not
necessarily C++-specific, and doing the search generically seems
better.
This also renames cp_lookup_symbol_imports_or_template now that the
"template" part has been removed.
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This moves search_symbol_list to symtab.c and exports it. It will be
useful in a later patch.
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This patch renames is_cplus_template_function to is_template_function.
There is nothing C++-specific about this code, and the code in the
DWARF reader that creates these objects is not C++-specific. In fact
this may already be used by Rust (though I didn't check).
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Since this commit:
commit 0ee6b1c511c0e2a6793568692d2e5418cd6bc10d
Date: Wed May 18 13:32:04 2022 -0700
Use aarch64_features to describe register features in target descriptions.
There has been an issue with how aarch64 target descriptions are
cached within gdbserver, and specifically, how this caching impacts
the in process agent (IPA).
The function initialize_tracepoint_ftlib (gdbserver/tracepoint.cc) is
part of the IPA, this function is a constructor function, i.e. is
called as part of the global initialisation process. We can't
guarantee the ordering of when this function is called vs when other
global state is initialised.
Now initialize_tracepoint_ftlib calls initialize_tracepoint, which
calls initialize_low_tracepoint, which for aarch64 calls
aarch64_linux_read_description.
The aarch64_linux_read_description function lives in
linux-aarch64-tdesc.cc and after the above commit, depends on a
std::unordered_map having been initialized.
Prior to the above commit aarch64_linux_read_description used a global
C style array, which obviously requires no runtime initialization.
The consequence of the above is that any inferior linked with the IPA
(for aarch64) will experience undefined behaviour (access to an
uninitialized std::unordered_map) during startup, which for me
manifests as a segfault.
I propose fixing this by moving the std::unordered_map into the
function body, but leaving it static. The map will now be initialized
the first time the function is called, which removes the undefiend
behaviour.
The same problem exists for the expedited_registers global, however
this global can just be made into a function local instead. The
expedited_registers variable is used to build a pointer list which is
then passed to init_target_desc, however init_target_desc copies the
values it is given so expedited_registers does not need to live longer
than its containing function.
On most of the AArch64 machines I have access too tracing is not
supported, and so the gdb.trace/*.exp tests that use the IPA just exit
early reporting unsupported. I've added a test which links an
inferior with the IPA and just starts the inferior. No tracing is
performed. This exposes the current issue even on hosts that don't
support tracing. After this patch the test passes.
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This commit builds on the previous series of commits to share the
target description caching code between GDB and gdbserver for
x86/Linux targets.
The objective of this commit is to move the four functions (2 each of)
i386_linux_read_description and amd64_linux_read_description into the
gdb/arch/ directory and combine them so we have just a single copy of
each. Then GDB, gdbserver, and the in-process-agent (IPA) will link
against these shared functions.
One curiosity with this patch is the function
x86_linux_post_init_tdesc. On the gdbserver side the two functions
amd64_linux_read_description and i386_linux_read_description have some
functionality that is not present on the GDB side, there is some
additional configuration that is performed as each target description
is created, to setup the expedited registers.
To support this I've added the function x86_linux_post_init_tdesc.
This function is called from the two *_linux_read_description
functions, but is implemented separately for GDB and gdbserver.
An alternative approach that avoids adding x86_linux_post_init_tdesc
would be to have x86_linux_tdesc_for_tid return a non-const target
description, then in x86_target::low_arch_setup we could inspect the
target description to figure out if it is 64-bit or not, and modify
the target description as needed. In the end I think that adding the
x86_linux_post_init_tdesc function is the simpler solution.
The contents of gdbserver/linux-x86-low.cc have moved to
gdb/arch/x86-linux-tdesc-features.c, and gdbserver/linux-x86-tdesc.h
has moved to gdb/arch/x86-linux-tdesc-features.h, this change leads to
some updates in the #includes in the gdbserver/ directory.
This commit also changes how target descriptions are cached.
Previously both GDB and gdbserver used static C-style arrays to act as
the tdesc cache. This was fine, except for two problems. Either the
C-style arrays would need to be placed in x86-linux-tdesc-features.c,
which would allow us to use the x86_linux_*_tdesc_count_1() functions
to size the arrays for us, or we'd need to hard code the array sizes
using separate #defines, which we'd then have to keep in sync with the
rest of the code in x86-linux-tdesc-features.c.
Given both of these problems I decided a better solution would be to
just switch to using a std::unordered_map to act as the cache. This
will resize automatically, and we can use the xcr0 value as the key.
At first inspection, using xcr0 might seem to be a problem; after all
the {i386,amd64}_create_target_description functions take more than
just the xcr0 value. However, this patch is only for x86/Linux
targets, and for x86/Linux all of the other flags passed to the tdesc
creation functions have constant values and so are irrelevant when we
consider tdesc caching.
For testing I've done the following:
- Built on x86-64 GNU/Linux for all targets, and just for the native
target,
- Build on i386 GNU/Linux for all targets, and just for the native
target,
- Build on a 64-bit, non-x86 GNU/Linux for all targets, just for the
native target, and for targets x86_64-*-linux and i386-*-linux.
Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
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This commit is part of a series which aims to share more of the target
description creation between GDB and gdbserver for x86/Linux.
After some refactoring earlier in this series the shared
x86_linux_tdesc_for_tid function was added into nat/x86-linux-tdesc.c.
However, this function still relies on amd64_linux_read_description
and i386_linux_read_description which are implemented separately for
both gdbserver and GDB. Given that at their core, all these functions
do is:
1. take an xcr0 value as input,
2. mask out some feature bits,
3. look for a cached pre-generated target description and return it
if found,
4. if no cached target description is found then call either
amd64_create_target_description or
i386_create_target_description to create a new target
description, which is then added to the cache. Return the newly
created target description.
The inner functions amd64_create_target_description and
i386_create_target_description are already shared between GDB and
gdbserver (in the gdb/arch/ directory), so the only thing that
the *_read_description functions really do is add the caching layer,
and it feels like this really could be shared.
However, we have a small problem.
Despite using the same {amd64,i386}_create_target_description
functions in both GDB and gdbserver to create the target descriptions,
on the gdbserver side we cache target descriptions based on a reduced
set of xcr0 feature bits.
What this means is that, in theory, different xcr0 values can map to
the same cache entry, which could result in the wrong target
description being used.
However, I'm not sure if this can actually happen in reality. Within
gdbserver we already split the target description cache based on i386,
amd64, and x32. I suspect within a given gdbserver session we'll only
see at most one target description for each of these.
The cache conflicting problem is caused by xcr0_to_tdesc_idx, which
maps an xcr0 value to a enum x86_linux_tdesc value, and there are only
7 usable values in enum x86_linux_tdesc.
In contrast, on the GDB side there are 64, 32, and 16 cache slots for
i386, amd64, and x32 respectively.
On the GDB side it is much more important to cache things correctly as
a single GDB session might connect to multiple different remote
targets, each of which might have slightly different x86
architectures.
And so, if we want to merge the target description caching between GDB
and gdbserver, then we need to first update gdbserver so that it
caches in the same way as GDB, that is, it needs to adopt a mechanism
that allows for the same number of cache slots of each of i386, amd64,
and x32. In this way, when the caching is shared, GDB's behaviour
will not change.
Unfortunately it's a little more complex than that due to the in
process agent (IPA).
When the IPA is in use, gdbserver sends a target description index to
the IPA, and the IPA uses this to find the correct target description
to use, the IPA having first generated every possible target
description.
Interestingly, there is certainly a bug here which results from only
having 7 values in enum x86_linux_tdesc. As multiple possible target
descriptions in gdbserver map to the same enum x86_linux_tdesc value,
then, when the enum x86_linux_tdesc value is sent to the IPA there is
no way for gdbserver to know that the IPA will select the correct
target description. This bug will get fixed by this commit.
** START OF AN ASIDE **
Back in the day I suspect this approach of sending a target
description index made perfect sense. However since this commit:
commit a8806230241d201f808d856eaae4d44088117b0c
Date: Thu Dec 7 17:07:01 2017 +0000
Initialize target description early in IPA
I think that passing an index was probably a bad idea.
We used to pass the index, and then use that index to lookup which
target description to instantiate and use, the target description was
not generated until the index arrived.
However, the above commit fixed an issue where we can't call malloc()
within (certain parts of) the IPA (apparently), so instead we now
pre-compute _every_ possible target description within the IPA. The
index is only used to lookup which of the (many) pre-computed target
descriptions to use.
It would (I think) have been easier all around if the IPA just
self-inspected, figured out its own xcr0 value, and used that to
create the one target description that is required. So long as the
xcr0 to target description code is shared (at compile time) with
gdbserver, then we can be sure that the IPA will derive the same
target description as gdbserver, and we would avoid all this index
passing business, which has made this commit so very, very painful.
I did look at how a process might derive its own xcr0 value, but I
don't believe this is actually that simple, so for now I've just
doubled down on the index passing approach.
While reviewing earlier iterations of this patch there has been
discussion about the possibility of removing the IPA from GDB. That
would certainly make all of the code touched in this patch much
simpler, but I don't really want to do that as part of this series.
** END OF AN ASIDE **
Currently then for x86/linux, gdbserver sends a number between 0 and 7
to the IPA, and the IPA uses this to create a target description.
However, I am proposing that gdbserver should now create one of (up
to) 64 different target descriptions for i386, so this 0 to 7 index
isn't going to be good enough any more (amd64 and x32 have slightly
fewer possible target descriptions, but still more than 8, so the
problem is the same).
For a while I wondered if I was going to have to try and find some
backward compatible solution for this mess. But after seeing how
lightly the IPA is actually documented, I wonder if it is not the case
that there is a tight coupling between a version of gdbserver and a
version of the IPA? At least I'm hoping so, and that's what I've
assumed in this commit.
In this commit I have thrown out the old IPA target description index
numbering scheme, and switched to a completely new numbering scheme.
Instead of the index that is passed being arbitrary, the index is
instead calculated from the set of xcr0 features that are present on
the target. Within the IPA we can then reverse this logic to recreate
the xcr0 value based on the index, and from the xcr0 value we can
choose the correct target description.
With the gdbserver to IPA numbering scheme issue resolved I have then
update the gdbserver versions of amd64_linux_read_description and
i386_linux_read_description so that they cache target descriptions
using the same set of xcr0 features as GDB itself.
After this gdbserver should now always come up with the same target
description as GDB does on any x86/Linux target.
This commit does not introduce any new code sharing between GDB and
gdbserver as previous commits in this series have done. Instead this
commit is all about bringing GDB and gdbserver into alignment
functionally so that the next commit(s) can merge the GDB and
gdbserver versions of these functions.
Notes On The Implementation
---------------------------
Previously, within gdbserver, target descriptions were cached within
arrays. These arrays were sized based on enum x86_linux_tdesc and
xcr0_to_tdesc_idx returned the array (cache) index.
Now we need different array lengths for each of i386, amd64, and x32.
And the index to use within each array is calculated based on which
xcr0 bits are set and valid for a particular target type.
I really wanted to avoid having fixed array sizes, or having the set
of relevant xcr0 bits encoded in multiple places.
The solution I came up with was to create a single data structure
which would contain a list of xcr0 bits along with flags to indicate
which of the i386, amd64, and x32 targets the bit is relevant for. By
making the table constexpr, and adding some constexpr helper
functions, it is possible to calculate the sizes for the cache arrays
at compile time, as well as the bit masks needed to each target type.
During review it was pointed out[1] that possibly the failure to check
the SSE and X87 bits for amd64/x32 targets might be an error, however,
if this is the case then this is an issue that existed long before
this patch. I'd really like to keep this patch focused on reworking
the existing code and try to avoid changing how target descriptions
are actually created, mostly out of fear that I'll break something.
[1] https://inbox.sourceware.org/gdb-patches/MN2PR11MB4566070607318EE7E669A5E28E1B2@MN2PR11MB4566.namprd11.prod.outlook.com
Approved-By: John Baldwin <jhb@FreeBSD.org>
Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
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This commit is part of a series to share more of the x86 target
description creation code between GDB and gdbserver.
Unlike previous commits which were mostly refactoring, this commit is
the first that makes a real change, though that change should mostly
be for gdbserver; I've largely adopted the "GDB" way of doing things
for gdbserver, and this fixes a real gdbserver bug.
On a x86-64 Linux target, running the test:
gdb.server/connect-with-no-symbol-file.exp
results in two core files being created. Both of these core files are
from the inferior process, created after gdbserver has detached.
In this test a gdbserver process is started and then, after gdbserver
has started, but before GDB attaches, we either delete the inferior
executable, or change its permissions so it can't be read. Only after
doing this do we attempt to connect with GDB.
As GDB connects to gdbserver, gdbserver attempts to figure out the
target description so that it can send the description to GDB, this
involves a call to x86_linux_read_description.
In x86_linux_read_description one of the first things we do is try to
figure out if the process is 32-bit or 64-bit. To do this we look up
the executable via the thread-id, and then attempt to read the
architecture size from the executable. This isn't going to work if
the executable has been deleted, or is no longer readable.
And so, as we can't read the executable, we default to an i386 target
and use an i386 target description.
A consequence of using an i386 target description is that addresses
are assumed to be 32-bits. Here's an example session that shows the
problems this causes. This is run on an x86-64 machine, and the test
binary (xx.x) is a standard 64-bit x86-64 binary:
shell_1$ gdbserver --once localhost :54321 /tmp/xx.x
shell_2$ gdb -q
(gdb) set sysroot
(gdb) shell chmod 000 /tmp/xx.x
(gdb) target remote :54321
Remote debugging using :54321
warning: /tmp/xx.x: Permission denied.
0xf7fd3110 in ?? ()
(gdb) show architecture
The target architecture is set to "auto" (currently "i386").
(gdb) p/x $pc
$1 = 0xf7fd3110
(gdb) info proc mappings
process 2412639
Mapped address spaces:
Start Addr End Addr Size Offset Perms objfile
0x400000 0x401000 0x1000 0x0 r--p /tmp/xx.x
0x401000 0x402000 0x1000 0x1000 r-xp /tmp/xx.x
0x402000 0x403000 0x1000 0x2000 r--p /tmp/xx.x
0x403000 0x405000 0x2000 0x2000 rw-p /tmp/xx.x
0xf7fcb000 0xf7fcf000 0x4000 0x0 r--p [vvar]
0xf7fcf000 0xf7fd1000 0x2000 0x0 r-xp [vdso]
0xf7fd1000 0xf7fd3000 0x2000 0x0 r--p /usr/lib64/ld-2.30.so
0xf7fd3000 0xf7ff3000 0x20000 0x2000 r-xp /usr/lib64/ld-2.30.so
0xf7ff3000 0xf7ffb000 0x8000 0x22000 r--p /usr/lib64/ld-2.30.so
0xf7ffc000 0xf7ffe000 0x2000 0x2a000 rw-p /usr/lib64/ld-2.30.so
0xf7ffe000 0xf7fff000 0x1000 0x0 rw-p
0xfffda000 0xfffff000 0x25000 0x0 rw-p [stack]
0xff600000 0xff601000 0x1000 0x0 r-xp [vsyscall]
(gdb) info inferiors
Num Description Connection Executable
* 1 process 2412639 1 (remote :54321)
(gdb) shell cat /proc/2412639/maps
00400000-00401000 r--p 00000000 fd:03 45907133 /tmp/xx.x
00401000-00402000 r-xp 00001000 fd:03 45907133 /tmp/xx.x
00402000-00403000 r--p 00002000 fd:03 45907133 /tmp/xx.x
00403000-00405000 rw-p 00002000 fd:03 45907133 /tmp/xx.x
7ffff7fcb000-7ffff7fcf000 r--p 00000000 00:00 0 [vvar]
7ffff7fcf000-7ffff7fd1000 r-xp 00000000 00:00 0 [vdso]
7ffff7fd1000-7ffff7fd3000 r--p 00000000 fd:00 143904 /usr/lib64/ld-2.30.so
7ffff7fd3000-7ffff7ff3000 r-xp 00002000 fd:00 143904 /usr/lib64/ld-2.30.so
7ffff7ff3000-7ffff7ffb000 r--p 00022000 fd:00 143904 /usr/lib64/ld-2.30.so
7ffff7ffc000-7ffff7ffe000 rw-p 0002a000 fd:00 143904 /usr/lib64/ld-2.30.so
7ffff7ffe000-7ffff7fff000 rw-p 00000000 00:00 0
7ffffffda000-7ffffffff000 rw-p 00000000 00:00 0 [stack]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
(gdb)
Notice the difference between the mappings reported via GDB and those
reported directly from the kernel via /proc/PID/maps, the addresses of
every mapping is clamped to 32-bits for GDB, while the kernel reports
real 64-bit addresses.
Notice also that the $pc value is a 32-bit value. It appears to be
within one of the mappings reported by GDB, but is outside any of the
mappings reported from the kernel.
And this is where the problem arises. When gdbserver detaches from
the inferior we pass the inferior the address from which it should
resume. Due to the 32/64 bit confusion we tell the inferior to resume
from the 32-bit $pc value, which is not within any valid mapping, and
so, as soon as the inferior resumes, it segfaults.
If we look at how GDB (not gdbserver) figures out its target
description then we see an interesting difference. GDB doesn't try to
read the executable. Instead GDB uses ptrace to query the thread's
state, and uses this to figure out the if the thread is 32 or 64 bit.
If we update gdbserver to do it the "GDB" way then the above problem
is resolved, gdbserver now sees the process as 64-bit, and when we
detach from the inferior we give it the correct 64-bit address, and
the inferior no longer segfaults.
Now, I could just update the gdbserver code, but better, I think, to
share one copy of the code between GDB and gdbserver in gdb/nat/.
That is what this commit does.
The cores of x86_linux_read_description from gdbserver and
x86_linux_nat_target::read_description from GDB are moved into a new
file gdb/nat/x86-linux-tdesc.c and combined into a single function
x86_linux_tdesc_for_tid which is called from each location.
This new function does things mostly the GDB way, some changes are
needed to allow for the sharing; we now take some pointers for where
the shared code can cache the xcr0 and xsave layout values.
Another thing to note about this commit is how the functions
i386_linux_read_description and amd64_linux_read_description are
handled. For now I've left these function as implemented separately
in GDB and gdbserver. I've moved the declarations of these functions
into gdb/arch/{i386,amd64}-linux-tdesc.h, but the implementations are
left where they are.
A later commit in this series will make these functions shared too,
but doing this is not trivial, so I've left that for a separate
commit. Merging the declarations as I've done here ensures that
everyone implements the function to the same API, and once these
functions are shared (in a later commit) we'll want a shared
declaration anyway.
Reviewed-By: Felix Willgerodt <felix.willgerodt@intel.com>
Acked-By: John Baldwin <jhb@FreeBSD.org>
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Currently, in i386_linux_core_read_description, if GDB fails to
extract an xcr0 value from the core file, then we will have a default
zero value for the xcr0 variable, we still call the
i386_linux_read_description function, which checks for this zero value
and returns nullptr.
Back in i386_linux_core_read_description we spot the nullptr return
value from i386_linux_read_description and call
i386_linux_read_description again, but this time passing a default
value for xcr0.
In the next commit I plan to rework i386_linux_read_description, and
in so doing I will remove the check for xcr0 == 0, this is inline with
how the amd64 code is written.
However, this means that the 'xcr0 == 0' check needs to move up the
stack to i386_linux_core_read_description, again, this brings the i386
code into line with the amd64 code.
This is just a refactor in preparation for the next commit, there
should be no user visible changes after this commit.
Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
Approved-By: John Baldwin <jhb@FreeBSD.org>
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This patch is part of a series that has the aim sharing the x86 Linux
target description creation code between GDB and gdbserver.
Within GDB part of this process involves reading the cs and ds state
from the 'struct user_regs_struct' using a ptrace call.
This isn't done by gdbserver, which is part of the motivation for this
whole series; the approach gdbserver takes is inferior to the approach
GDB takes (gdbserver relies on reading the file being debugged, and
extracting similar information from the file headers).
This commit moves the reading of cs and ds, which is used to figure
out if a thread is 32-bit or 64-bit (or in x32 mode), into the gdb/nat
directory so that the code can be shared with gdbserver, but at this
point I'm not actually using the code in gdbserver, that will come
later.
As such there should be no user visible changes after this commit, GDB
continues to do things as it did before (reading cs/ds), while
gdbserver continues to use its own approach (which doesn't require
reading cs/ds).
Approved-By: John Baldwin <jhb@FreeBSD.org>
Reviewed-By: Felix Willgerodt <felix.willgerodt@intel.com>
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In a later commit I want to access have_ptrace_getregset from a .c
file in the nat/ directory. To achieve this I need access to the
declaration of have_ptrace_getregset.
Currently have_ptrace_getregset is declared (and defined) twice, once
in GDB and once in gdbserver.
This commit moves the declaration into nat/linux-nat.h, but leaves the
two definitions where they are. Now, in my later commit, I can pull
in the declaration from nat/linux-nat.h.
There should be no user visible changes after this commit.
Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
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The have_ptrace_getfpxregs global tracks whether GDB or gdbserver is
running on a kernel that supports the GETFPXREGS ptrace request.
Currently this global is declared twice (once in GDB and once in
gdbserver), I think it makes sense to move this global into the nat/
directory, and have a single declaration and definition.
While moving this variable I have converted it to a tribool, as that
was what it really was, if even used the same numbering as the tribool
enum (-1, 0, 1). Where have_ptrace_getfpxregs was used I have updated
in the obvious way.
However, while making this change I noticed what I think is a bug in
x86_linux_nat_target::read_description and x86_linux_read_description,
both of these functions can be called multiple times, but in both
cases we only end up calling i386_linux_read_description the first
time through in the event that PTRACE_GETFPXREGS is not supported.
This is because initially have_ptrace_getfpxregs will be
TRIBOOL_UNKNOWN, but after the ptrace call fails we set
have_ptrace_getfpxregs to TRIBOOL_FALSE. The next time we attempt to
read the target description we'll skip the ptrace call, and so skip
the call to i386_linux_read_description.
I've not tried to address this preexisting bug in this commit, this is
purely a refactor, there should be no user visible changes after this
commit. In later commits I'll merge the gdbserver and GDB code
together into the nat/ directory, and after that I'll try to address
this bug.
Reviewed-By: Felix Willgerodt <felix.willgerodt@intel.com>
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This commit is part of a series that aims to share more of the x86
target description reading/generation code between GDB and gdbserver.
There are a huge number of similarities between the code in
gdbserver's x86_linux_read_description function and GDB's
x86_linux_nat_target::read_description function, and it is this
similarity that I plan, in a later commit, to share between GDB and
gdbserver.
However, one thing that is different in x86_linux_read_description is
the code inside the '!use_xml' block. This is the code that handles
the case where gdbserver is not allowed to send an XML target
description back to GDB. In this case gdbserver uses some predefined,
fixed, target descriptions.
First, it's worth noting that I suspect this code is not tested any
more. I couldn't find anything in the testsuite that tries to disable
XML target description support. And the idea of having a single
"fixed" target description really doesn't work well when we think
about all the various x86 extensions that exist. Part of me would
like to rip out the no-xml support in gdbserver (at least for x86),
and if a GDB connects that doesn't support XML target descriptions,
gdbserver can just give an error and drop the connection. GDB has
supported XML target descriptions for 16 years now, I think it would
be reasonable for our shipped gdbserver to drop support for the old
way of doing things.
Anyway.... this commit doesn't do that.
What I did notice was that, over time, the '!use_xml' block appears to
have "drifted" within the x86_linux_read_description function; it's
now not the first check we do. Instead we make some ptrace calls and
return a target description generated based on the result of these
ptrace calls. Surely it only makes sense to generate variable target
descriptions if we can send these back to GDB?
So in this commit I propose to move the '!use_xml' block earlier in
the x86_linux_read_description function.
The benefit of this is that this leaves the later half of
x86_linux_read_description much more similar to the GDB function
x86_linux_nat_target::read_description and sets us up for potentially
sharing code between GDB and gdbserver in a later commit.
Approved-By: John Baldwin <jhb@FreeBSD.org>
Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
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Share the definition of I386_LINUX_XSAVE_XCR0_OFFSET between GDB and
gdbserver.
This commit moves the definition into gdbsupport/x86-xstate.h, which
allows the #define to be shared.
There should be no user visible changes after this commit.
Approved-By: Felix Willgerodt <felix.willgerodt@intel.com>
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This adds an overload of gdbpy_call_method that accepts a gdbpy_ref<>.
This is just a small convenience.
Reviewed-By: Tom de Vries <tdevries@suse.de>
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This changes gdbpy_call_method to return a gdbpy_ref<>. This is
slightly safer because it makes it simpler to correctly handle
reference counts.
Reviewed-By: Tom de Vries <tdevries@suse.de>
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Starting with gcc commit 80048aa13a6 ("debug/111409 - don't generate COMDAT
macro sections for split DWARF"), available from release gcc 14.1 onwards, gcc
produces a usable dwarf-5 32-bit .debug_macro.dwo section.
Add a test-case excercising this.
Tested on x86_64-linux.
Tested test-case using a current gcc trunk build, and gcc 14.
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Test-case gdb.base/watchpoint-running.exp reports the following kfail:
...
KFAIL: $exp: all-stop: software: watchpoint hit (timeout) (PRMS: gdb/111111)
...
but the referenced gdb PR doesn't exist.
Fix this by using an actual PR.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31833
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generating two read-only segments.
PR 30907
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