This patch adds support in GAS to create generic GAS instructions
(a.k.a., the ginsn) for the x86 backend (AMD64 ABI only at this time).
Using this ginsn infrastructure, GAS can then synthesize CFI for
hand-written asm for x86_64.
A ginsn is a target-independent representation of the machine
instructions. One machine instruction may need one or more ginsn.
This patch also adds skeleton support for printing ginsn in the listing
output for debugging purposes.
Since the current use-case of ginsn is to synthesize CFI, the x86 target
needs to generate ginsns necessary for the following machine
instructions only:
- All change of flow instructions, including all conditional and
unconditional branches, call and return from functions.
- All register saves and unsaves to the stack.
- All instructions affecting the two registers that could potentially
be used as the base register for CFA tracking. For SCFI, the base
register for CFA tracking is limited to REG_SP and REG_FP only for
now.
The representation of ginsn is kept simple:
- GAS instruction has GINSN_NUM_SRC_OPNDS (defined to be 2 at this time)
number of source operands and one destination operand at this time.
- GAS instruction uses DWARF register numbers in its representation and
does not track register size.
- GAS instructions carry location information (file name and line
number).
- GAS instructions are ID's with a natural number in order of their
addtion to the list. This can be used as a proxy for the static
program order of the corresponding machine instructions.
Note that, GAS instruction (ginsn) format does not support
GINSN_TYPE_PUSH and GINSN_TYPE_POP. Some architectures, like aarch64,
do not have push and pop instructions, but rather STP/LDP/STR/LDR etc.
instructions. Further these instructions have a variety of addressing
modes, like offset, pre-indexing and post-indexing etc. Among other
things, one of differences in these addressing modes is _when_ the addr
register is updated with the result of the address calculation: before
or after the memory operation. To best support such needs, the generic
instructions like GINSN_TYPE_LOAD, GINSN_TYPE_STORE together with
GINSN_TYPE_ADD, and GINSN_TYPE_SUB may be used.
The functionality provided in ginsn.c and scfi.c is compiled in when a
target defines TARGET_USE_SCFI and TARGET_USE_GINSN. This can be
revisited later when there are other use-cases of creating ginsn's in
GAS, apart from the current use-case of synthesizing CFI for
hand-written asm.
Support is added only for System V AMD64 ABI for ELF at this time. If
the user enables SCFI with --32, GAS issues an error:
"Fatal error: SCFI is not supported for this ABI"
For synthesizing (DWARF) CFI, the SCFI machinery requires the programmer
to adhere to some pre-requisites for their asm:
- Hand-written asm block must begin with a .type foo, @function
It is highly recommended to, additionally, also ensure that:
- Hand-written asm block ends with a .size foo, .-foo
The SCFI machinery encodes some rules which align with the standard
calling convention specified by the ABI. Apart from the rules, the SCFI
machinery employs some heuristics. For example:
- The base register for CFA tracking may be either REG_SP or REG_FP.
- If the base register for CFA tracking is REG_SP, the precise amount of
stack usage (and hence, the value of REG_SP) must be known at all times.
- If using dynamic stack allocation, the function must switch to
FP-based CFA. This means using instructions like the following (in
AMD64) in prologue:
pushq %rbp
movq %rsp, %rbp
and analogous instructions in epilogue.
- Save and Restore of callee-saved registers must be symmetrical.
However, the SCFI machinery at this time only warns if any such
asymmetry is seen.
These heuristics/rules are architecture-independent and are meant to
employed for all architectures/ABIs using SCFI in the future.
gas/
* Makefile.am: Add new files.
* Makefile.in: Regenerated.
* as.c (defined): Handle documentation and listing option for
ginsns and SCFI.
* config/obj-elf.c (obj_elf_size): Invoke ginsn_data_end.
(obj_elf_type): Invoke ginsn_data_begin.
* config/tc-i386.c (x86_scfi_callee_saved_p): New function.
(ginsn_prefix_66H_p): Likewise.
(ginsn_dw2_regnum): Likewise.
(x86_ginsn_addsub_reg_mem): Likewise.
(x86_ginsn_addsub_mem_reg): Likewise.
(x86_ginsn_alu_imm): Likewise.
(x86_ginsn_move): Likewise.
(x86_ginsn_lea): Likewise.
(x86_ginsn_jump): Likewise.
(x86_ginsn_jump_cond): Likewise.
(x86_ginsn_enter): Likewise.
(x86_ginsn_safe_to_skip): Likewise.
(x86_ginsn_unhandled): Likewise.
(x86_ginsn_new): New functionality to generate ginsns.
(md_assemble): Invoke x86_ginsn_new.
(s_insn): Likewise.
(i386_target_format): Add hard error for usage of SCFI with non AMD64 ABIs.
* config/tc-i386.h (TARGET_USE_GINSN): New definition.
(TARGET_USE_SCFI): Likewise.
(SCFI_MAX_REG_ID): Likewise.
(REG_FP): Likewise.
(REG_SP): Likewise.
(SCFI_INIT_CFA_OFFSET): Likewise.
(SCFI_CALLEE_SAVED_REG_P): Likewise.
(x86_scfi_callee_saved_p): Likewise.
* gas/listing.h (LISTING_GINSN_SCFI): New define for ginsn and
SCFI.
* gas/read.c (read_a_source_file): Close SCFI processing at end
of file read.
* gas/scfidw2gen.c (scfi_process_cfi_label): Add implementation.
(scfi_process_cfi_signal_frame): Likewise.
* subsegs.h (struct frch_ginsn_data): New forward declaration.
(struct frchain): New member for ginsn data.
* gas/subsegs.c (subseg_set_rest): Initialize the new member.
* symbols.c (colon): Invoke ginsn_frob_label to convey
user-defined labels to ginsn infrastructure.
* ginsn.c: New file.
* ginsn.h: New file.
* scfi.c: New file.
* scfi.h: New file.
When the command line option --scfi=experimenta is passed to the GNU
assembler, it will synthesize DWARF call frame information (CFI) for the
input assembly.
The option --scfi=experimental will also ignore most of the existing
.cfi_* directives, if already contained in the provided input file.
Only the following CFI directives will not be ignored:
- .cfi_sections,
- .cfi_label,
- .cfi_signal_frame
To use SCFI, a target will need to:
- define TARGET_USE_SCFI and TARGET_USE_GINSN, and other necessary
definitions,
- provide means to help GAS understand the target specific instruction
semantics by creating ginsns.
The upcoming support for SCFI is inteded to be experimental, hence the
option --scfi=experimental. The --scfi= may see more options like
--scfi=[all,none] added in future, once the SCFI support in GAS is
mature and robust. The offering may also see for example, an
--scfi=inline option for dealing with inline asm may be added in the
future. In --scfi=inline option, the GNU assembler may consume (and not
ignore) the compiler generated CFI for the code surrounding the inline
asm.
Also document the option.
gas/
* as.c (show_usage): Add support for --scfi=experimental.
(parse_args): Likewise.
* as.h (enum synth_cfi_type): Define new type.
* doc/as.texi: Document the new option.
Adds two new external authors to etc/update-copyright.py to cover
bfd/ax_tls.m4, and adds gprofng to dirs handled automatically, then
updates copyright messages as follows:
1) Update cgen/utils.scm emitted copyrights.
2) Run "etc/update-copyright.py --this-year" with an extra external
author I haven't committed, 'Kalray SA.', to cover gas testsuite
files (which should have their copyright message removed).
3) Build with --enable-maintainer-mode --enable-cgen-maint=yes.
4) Check out */po/*.pot which we don't update frequently.
Yet again with the removal of gasp about 20 years ago this extra level
of indirection isn't necessary anymore either. Drop macro.c's local
variable and make as.c's global.
While doing the conversion, switch the variable to "bool".
Again with the removal of gasp about 20 years ago the extra level of
indirection isn't necessary anymore. Drop macro.c's local variable and
use the global flag directly.
This removes a leftover from i960 support; with that nothing is left
which would set macro_strip_at to non-zero, so the variable is converted
to a #define (retaining the logic in case a new user would appear) and
macro_init()'s respective parameter is dropped.
With the removal of gasp (about 20 years ago) the need for this kind-
of-hook has disappeared. Go a step beyond merely moving the to be called
function: Inline its contents right at the sole call site.
This fixes a bug in .include and .incbin where given an absolute path
the -I dirs would be searched for the path.
* read.c (include_dir_count, include_dir_maxlen): Make them size_t.
(search_and_open): New function.
(s_incbin, s_include): Use search_and_open.
(init_include_dir): New function.
(add_include_dir): Don't set initial "." dir here.
* read.h (include_dir_count, include_dir_maxlen): Update.
(init_include_dir, search_and_open): Declare.
* as.c (gas_early_init): Call init_include_dir.
* config/tc-rx.c (rx_include): Avoid warning by using size_t.
* config/tc-tic54x.c (tic54x_set_default_include): Simplify and
use notes for include path.
(tic54x_mlib): Use search_and_open.
Fix another case of oss-fuzz tripping over gas static state,
ie. starting over testing another input file with rubbish left
uncleared in bss. size_end_sym pointed at garbage.
* ehopt.c (get_cie_info): Delete forward declaration.
(struct frame_data): Move to file scope.
(frame): New static, packaged..
(check_eh_frame): ..eh_frame_data and debug_frame_data.
(eh_begin): New function.
* as.c (gas_init): Call eh_begin.
* as.h (eh_begin): Declare.
While commit b0c295e1b8 ("add --enable-default-compressed-debug-
sections-algorithm configure option") adjusted flag_compress_debug's
initializer, it didn't alter the default used when the command line
option was specified with an (optional!) argument. This rendered help
text inconsistent with actual behavior in certain configurations.
As to help text - the default reported there clearly shouldn't be
affected by a possible earlier --compress-debug-sections= option, so
flag_compress_debug can't be used when emitting usage information.
I don't see much point in cluttering the source with the PROGRESS
macros, which of course do nothing at all with the definitions in
progress.h. progress.h is unchanged apart from the copyright comment
since commit d4d4c53c68 in 1994.
binutils/
* ar.c: Don't include progress.h, or invoke PROGRESS macros.
* nm.c: Likewise.
* objcopy.c: Likewise.
* objdump.c: Likewise.
gas/
* as.h: Don't include progress.h.
* as.c: Don't invoke PROGRESS macros.
* write.c: Likewise.
include/
* progress.h: Delete.
ld/
* ldmain.c: Don't include progress.h, or invoke PROGRESS macros.
Rename gas_late_init to plain gas_init, to reinforce the idea that
this is where the bulk of gas initialisation belongs. Also reorder
some initialisation.
* as.c (gas_init): Rename from gas_late_init. Open output
file and arrange for dump_statistics to be called here rather
than in main. Create .gasversion. local symbol earlier,
because we can.
The newer update-copyright.py fixes file encoding too, removing cr/lf
on binutils/bfdtest2.c and ld/testsuite/ld-cygwin/exe-export.exp, and
embedded cr in binutils/testsuite/binutils-all/ar.exp string match.
When --gsframe is specified, the assembler will generate a .sframe
section from the CFI directives in the assembly.
ChangeLog:
* gas/as.c (parse_args): Parse args and set flag_gen_sframe.
* gas/as.h: Introduce skeleton for --gsframe.
* gas/doc/as.texi: document --gsframe.
bfd/ChangeLog:
* bfd-in.h (bfd_hash_set_default_size): Add COMPRESS_UNKNOWN
enum value.
(struct compressed_type_tuple): New.
* bfd-in2.h (bfd_hash_set_default_size): Regenerate.
(struct compressed_type_tuple): Likewise.
* libbfd.c (ARRAY_SIZE): New macro.
(bfd_get_compression_algorithm): New function.
(bfd_get_compression_algorithm_name): Likewise.
gas/ChangeLog:
* as.c: Do not special-case, use the new functions.
ld/ChangeLog:
* emultempl/elf.em: Do not special-case, use the new functions.
* lexsup.c (elf_static_list_options): Likewise.
PR29397 PR29563: Add new configure option --with-zstd which defaults to
auto. If pkgconfig/libzstd.pc is found, define HAVE_ZSTD and support
zstd compressed debug sections for most tools.
* bfd: for addr2line, objdump --dwarf, gdb, etc
* gas: support --compress-debug-sections=zstd
* ld: support ELFCOMPRESS_ZSTD input and --compress-debug-sections=zstd
* objcopy: support ELFCOMPRESS_ZSTD input for
--decompress-debug-sections and --compress-debug-sections=zstd
* gdb: support ELFCOMPRESS_ZSTD input. The bfd change references zstd
symbols, so gdb has to link against -lzstd in this patch.
If zstd is not supported, ELFCOMPRESS_ZSTD input triggers an error. We
can avoid HAVE_ZSTD if binutils-gdb imports zstd/ like zlib/, but this
is too heavyweight, so don't do it for now.
```
% ld/ld-new a.o
ld/ld-new: a.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
...
% ld/ld-new a.o --compress-debug-sections=zstd
ld/ld-new: --compress-debug-sections=zstd: ld is not built with zstd support
% binutils/objcopy --compress-debug-sections=zstd a.o b.o
binutils/objcopy: --compress-debug-sections=zstd: binutils is not built with zstd support
% binutils/objcopy b.o --decompress-debug-sections
binutils/objcopy: zstd.o: section .debug_abbrev is compressed with zstd, but BFD is not built with zstd support
...
```
Currently md_end is typically used for some final actions rather than
freeing memory like other *_end functions. Rename it to md_finish,
and rename target implementation. The renaming of target functions
makes it possible to find them all with "grep md_finish",
eg. md_mips_end is renamed to mips_md_finish, not md_mips_finish.
This patch leaves a number of md_end functions unchanged, those that
either do nothing or deallocate memory, and calls them late.
The idea here is that target maintainers implement md_end functions to
tidy memory, if anyone cares. Freeing persistent memory in gas is
not at all important, except that it can hide more important memory
leaks, those that happen once per some frequent gas operation, amongst
these unimportant memory leaks.
* as.c (main): Rename md_end to md_finish.
* config/tc-alpha.c, * config/tc-alpha.h,
* config/tc-arc.c, * config/tc-arc.h,
* config/tc-arm.c, * config/tc-arm.h,
* config/tc-csky.c, * config/tc-csky.h,
* config/tc-ia64.c, * config/tc-ia64.h,
* config/tc-mcore.c, * config/tc-mcore.h,
* config/tc-mips.c, * config/tc-mips.h,
* config/tc-mmix.c, * config/tc-mmix.h,
* config/tc-msp430.c, * config/tc-msp430.h,
* config/tc-nds32.c, * config/tc-nds32.h,
* config/tc-ppc.c, * config/tc-ppc.h,
* config/tc-pru.c, * config/tc-pru.h,
* config/tc-riscv.c, * config/tc-riscv.h,
* config/tc-s390.c, * config/tc-s390.h,
* config/tc-sparc.c, * config/tc-sparc.h,
* config/tc-tic4x.c, * config/tc-tic4x.h,
* config/tc-tic6x.c, * config/tc-tic6x.h,
* config/tc-v850.c, * config/tc-v850.h,
* config/tc-xtensa.c, * config/tc-xtensa.h,
* config/tc-z80.c, * config/tc-z80.h: Similarly.
* output-file.c (output_file_close): Call md_end.
So that the notes obstack can be used for persistent storage in
parse_args.
* as.c (parse_args): Use notes_alloc and notes_strdup.
(free_notes): New function.
(main): Init notes obstack, and arrange to be freed on exit.
* read.c (read_begin): Don't init notes obstack.
(read_end): Free cond_obstack.
* subsegs.c (subsegs_end): Don't free cond_obstack or notes.
itbl_files seems to be debug code. Get rid of it.
* as.c (struct itbl_file_list): Delete.
(itbl_files): Delete.
(parse_args): Don't keep itbl_files list.
This is mostly a tidy with the aim of being able to free
out_file_name, but it does fix a possible attempt to unlink the output
file twice (not that that matters).
* as.h (keep_it): New global.
* as.c (keep_it): Delete.
(close_output_file): Delete, merged into..
* output-file.c (output_file_close): ..here. Delete parameter.
* output-file.h (output_file_close): Update prototype.
The result of running etc/update-copyright.py --this-year, fixing all
the files whose mode is changed by the script, plus a build with
--enable-maintainer-mode --enable-cgen-maint=yes, then checking
out */po/*.pot which we don't update frequently.
The copy of cgen was with commit d1dd5fcc38ead reverted as that commit
breaks building of bfp opcodes files.
* as.c (parse_args): Add support for --multibyte-handling.
* as.h (multibyte_handling): Declare.
* app.c (scan_for_multibyte_characters): New function.
(do_scrub_chars): Call the new function if multibyte warning is
enabled.
* input-scrub,c (input_scrub_next_buffer): Call the multibyte
scanning function if multibyte warnings are enabled.
* symbols.c (struct symbol_flags): Add multibyte_warned bit.
(symbol_init): Call the multibyte scanning function if multibyte
symbol warnings are enabled.
(S_SET_SEGMENT): Likewise.
* NEWS: Mention the new feature.
* doc/as.texi: Document the new feature.
* testsuite/gas/all/multibyte.s: New test source file.
* testsuite/gas/all/multibyte1.d: New test driver file.
* testsuite/gas/all/multibyte1.l: New test expected output.
* testsuite/gas/all/multibyte2.d: New test driver file.
* testsuite/gas/all/multibyte2.l: New test expected output.
* testsuite/gas/all/gas.exp: Run the new tests.
parse_args uses getopt_long_only so it can handle long options both
with double and single dash. But this means that some single dash
options like -gdwarf-1 don't generate an error (unlike --gdwarf-1).
This is especially confusing since there is also --gdwarf2, but no
--gdwarf4 (it is --gdwarf-4). When giving -gdwarf4 the option is
silently interpreted as -g (which set dwarf_version to 2). This causes
some confusion for people who don't expect this and suddenly get
DWARF2 instead of DWARF4 as they might expect.
So make it so that the -gdwarf<unknown> creates an error, just like
--gdwarf<unknown> would.
PR 25612
* as.c (dwarf_level): Define.
(show_usage): Add --gdwarf-3, --gdwarf-4 and --gdwarf-5.
(parse_args): Add support for the new options.
as.h (dwarf_level): Prototype.
* dwarf2dbg.c (DWARF2_VERSION): Use dwarf_level as default version
value.
* config/tc-ia64.h (DWARF2_VERISION): Update definition.
(DWARF2_LINE_VERSION): Remove definition.
* doc/as.texi: Document the new options.
The flag controlling the default DWARF CIE version to produce now
starts with the value -1. This can be modified with the command line
flag as before, but after command line flag processing, in
md_after_parse_args targets can, if the global still has the value -1,
override this value. This gives a target specific default.
If a CIE version is not select either by command line flag, or a
target specific default, then some new code in dwarf2_init now select
a global default. This remains as version 1 to match previous
behaviour.
This RISC-V has a target specific default of version provided, this
make the return column uleb128, which means we can use all DWARF
registers include CSRs.
I chose to switch to version 3 rather than version 4 as this is most
similar to the global default (version 1). Switching to version 4
adds additional columns to the CIE header.
gas/ChangeLog:
* as.c (flag_dwarf_cie_version): Change initial value to -1, and
update comment.
* config/tc-riscv.c (riscv_after_parse_args): Set
flag_dwarf_cie_version if it has not already been set.
* dwarf2dbg.c (dwarf2_init): Initialise flag_dwarf_cie_version if
needed.
* testsuite/gas/riscv/default-cie-version.d: New file.
* testsuite/gas/riscv/default-cie-version.s: New file.
ld/ChangeLog:
* testsuite/ld-elf/eh5.d: Accept version 3 DWARF CIE.
Change-Id: Ibbfe8f0979fba480bf0a359978b09d2b3055555e
Add a flag to control the version of CIE that is generated. By
default gas produces CIE version 1, and this continues to be the
default after this patch.
However, a user can now provide --gdwarf-cie-version=NUMBER to switch
to either version 3 or version 4 of CIE, version 2 was never released,
and so causes an error as does any number less than 1 or greater than
4.
Producing version 4 CIE requires two new fields to be added to the
CIE, an address size field, and an segment selector field. For a flat
address space the DWARF specification indicates that the segment
selector should be 0, and the address size fields just contains the
address size in bytes. For now we support 4 or 8 byte addresses, and
the segment selector is always produced as 0. At some future time we
might need to allow targets to override this.
gas/ChangeLog:
* as.c (parse_args): Parse --gdwarf-cie-version option.
(flag_dwarf_cie_version): New variable.
* as.h (flag_dwarf_cie_version): Declare.
* dw2gencfi.c (output_cie): Switch from DW_CIE_VERSION to
flag_dwarf_cie_version.
* doc/as.texi (Overview): Document --gdwarf-cie-version.
* NEWS: Likewise.
* testsuite/gas/cfi/cfi.exp: Add new tests.
* testsuite/gas/cfi/cie-version-0.d: New file.
* testsuite/gas/cfi/cie-version-1.d: New file.
* testsuite/gas/cfi/cie-version-2.d: New file.
* testsuite/gas/cfi/cie-version-3.d: New file.
* testsuite/gas/cfi/cie-version-4.d: New file.
* testsuite/gas/cfi/cie-version.s: New file.
include/ChangeLog:
* dwarf2.h (DW_CIE_VERSION): Delete.
Change-Id: I9de19461aeb8332b5a57bbfe802953d0725a7ae8
This patch performs a run-time test that a shared libbfd.so has been
compiled with the same size bfd_vma as that of apps using the library.
On a 32-bit host it is easily possible to have one libbfd.so compiled
to support 64-bit targets (or configured with --enable-64-bit-bfd)
while another only supports 32-bit targets. The two libraries will
have differently sized bfd_vma types, and if the wrong one is loaded
all sorts of weird behaviour might be seen.
bfd/
PR 23534
* init.c (BFD_INIT_MAGIC): Define.
(bfd_init): Return BFD_INIT_MAGIC.
bfd-in2.h: Regenerate.
binutils/
PR 23534
* addr2line.c (main): Exit with fatal error if bfd_init
returns an unexpected value.
* ar.c (main): Likewise.
* dlltool.c (identify_dll_for_implib): Likewise.
* nm.c (main): Likewise.
* objcopy.c (main): Likewise.
* objdump.c (main): Likewise.
* size.c (main): Likewise.
* strings.c (main): Likewise.
* windmc.c (main): Likewise.
* windres.c (main): Likewise.
gas/
PR 23534
* as.c (main): Exit with fatal error if bfd_init returns an
unexpected value.
ld/
PR 23534
* ldmain.c (main): Exit with fatal error if bfd_init returns
an unexpected value.
