SFrames make the most sense when userland as a whole is built with them,
so add a --enable-default-sframe configure flag to facilitate distributors
and vendors doing that.
The primary motivation for a configure-time flag is that we don't support
SFrame for 32-bit x86 but some packaging uses the same flags (with some
added on top) for multilib builds (to support old binaries like games),
and simply adding `-Wa,--gsframe` to the standard build flags isn't an
option (*).
That aside, I believe it'll be helpful for testing and eventual adoption
in any case.
In summary, combined with the recent --gsframe=[yes|no] support (**):
* Configured with --enable-default-sframe and nothing is passed
=> SFrames (previously no SFrames)
* Configured with --enable-default-sframe and --gsframe=yes is passed
=> SFrames (no change from before)
* Configured with --enable-default-sframe and --gsframe=no is passed
=> No SFrames (no change from before)
* Configured with --enable-default-sframe and --gsframe is passed
=> SFrames (no change from before)
* Configured with --disable-default-sframe and nothing is passed
=> No SFrames (no change from before)
* Configured with --disable-default-sframe and --gsframe=yes is passed
=> SFrames (no change from before)
* Configured with --disable-default-sframe and --gsframe=no is passed
=> No SFrames (no change from before)
* Configured with --disable-default-sframe and --gsframe is passed
=> SFrames (no change from before)
I've introduced a sframe_as_bad macro on Indu's suggestion. A following
patch uses its sibling sframe_as_warn heavily and having symmetry plus
the macro as a form of documentation of intent seems useful.
(*) It gets added to multilib builds too and then we hit the
`.sframe not supported for target` error in gas/dw2gencfi.c.
(**) I've verbosely listed --gsframe=yes but it's the same as --gsframe.
gas/
PR gas/33126
* as.c (enum gen_sframe_option): Initialize if DEFAULT_SFRAME.
* config.in (DEFAULT_SFRAME): New.
* configure: Regenerate.
* configure.ac: Add --enable-default-sframe.
* doc/as.texi: Document --enable-default-sframe.
* dw2gencfi.c (cfi_finish): Don't warn if SFrames are enabled
by default but unavailable for this target.
* gen-sframe.h (sframe_as_bad): New macro.
over gas directive to emit .sframe section.
Fix PR gas/33175 sframe: --gsframe=no does not disable when
.cfi_sections directive with .sframe
--gsframe=no should also disable generation of SFrame section when
explicit CFI directive:
.cfi_sections .sframe
is specified in the input. This means we need to track whether SFrame
generation was explicitly disabled by the user. Introduce a new enum to
facilitate disambiguation between GEN_SFRAME_DEFAULT_NONE and
GEN_SFRAME_DISABLED.
While fixing the bug by adding the enum, keep the upcoming requirement
in mind: we will also need to disambiguate between
--enable-default-sframe and user-specified --gsframe/--gsframe=yes. The
intent is to not display SFrame related warnings or errors like:
as_bad (_(".sframe not supported for target"));
for unsupported targets if --enable-default-sframe is in effect.
This implies we need to have a four state enum (
GEN_SFRAME_DEFAULT_NONE, GEN_SFRAME_CONFIG_ENABLED,
GEN_SFRAME_DISABLED, GEN_SFRAME_ENABLED)
gas/
PR gas/33175
* dw2gencfi.c (cfi_finish): Check state of flag_gen_sframe to
determine whether any SFrame section is generated.
* as.h (enum gen_sframe_option): New definition.
* as.c (parse_args): Keep track of whether the flag is
explicitly enabled or disabled
gas/testsuite/
PR gas/33175
* gas/cfi-sframe/cfi-sframe-common-1.d: Remove redundant
--gsframe.
* gas/cfi-sframe/cfi-sframe.exp: Add new test.
* gas/cfi-sframe/cfi-sframe-common-1c.d: New test. No SFrame
section if explicit --gsframe=no.
* gas/cfi-sframe/cfi-sframe-common-1c.s: New test.
Process a new aarch64-specific CFI directive: .cfi_mte_tagged_frame
(LLVM uses this CFI directive already). The CFI directive, when
present for a function, indicates that the stack frame for the
function may modify the MTE tags of the stack space it uses. The
assembler emits char 'G' in the CIE augmentation string to indicate
the same.
ChangeLog:
* gas/config/tc-aarch64.c (s_aarch64_mte_tagged_frame): New
definition.
* gas/config/tc-aarch64.h (tc_fde_entry_extras): Add
memtag_frame_p.
(tc_cie_entry_extras): Likewise.
(tc_fde_entry_init_extra): Likewise.
(tc_cie_fde_equivalent_extra): Likewise.
(tc_cie_entry_init_extra): Likewise.
* gas/doc/c-aarch64.texi: Add documentation for
.cfi_mte_tagged_frame directive.
* gas/testsuite/gas/aarch64/mte_tagged_stack.d: New test.
* gas/testsuite/gas/aarch64/mte_tagged_stack.s: New test.
So far, SFrame sections were of type SHT_PROGBITS.
As per ELF specification, SHT_PROGBITS indicates that the section holds
information defined by the program, whose format and meaning are
determined solely by the program.
On the linker side, SHT_PROGBITS should be reserved for the simple "cat
contents after applying relocs" semantics.
Currently, the only way to know that a section contains SFrame stack
trace data is if consumer checks for section name. Such a check for
section name is not quite conformant to ELF principles.
Some of this was discussed here
https://sourceware.org/pipermail/binutils/2025-March/140181.html
With this change, the SFrame sections generated by gas, ld will have
section type set to SHT_GNU_SFRAME. The new section type is defined in
the SHT_LOOS/SHT_HIOS space. The SFrame parsing routine
_bfd_elf_parse_sframe () now admits sections only when the the section
type is SHT_GNU_SFRAME.
No special handling / validation is done at the moment for the case of
manual creation of SFrame sections via obj_elf_section (). Add function
level comments for now to add a note about this.
Although the default handling for (sh_type >= SHT_LOOS && sh_type <=
SHT_HIOS) is sufficient when SHT_GNU_SFRAME is in that range, it makes
sense to add it as a case of its own.
bfd/
* elf-sframe.c (_bfd_elf_parse_sframe): Check if section type is
SHT_GNU_SFRAME.
(_bfd_elf_set_section_sframe): Set SHT_GNU_SFRAME for output
SFrame section.
* elflink.c (obj_elf_section): Use section type for check
instead of section name.
* elfxx-x86.c: Set SHT_GNU_SFRAME for SFrame sections for
.plt* sections.
* elf.c (bfd_section_from_shdr): Add case for SHT_GNU_SFRAME.
binutils/
* readelf.c (get_os_specific_section_type_name): Add
SHT_GNU_SFRAME.
gas/
* NEWS: Announce emitted SFrame sections have SHT_GNU_SFRAME
set.
* config/obj-elf.c (obj_elf_attach_to_group): Add comments to
indicate no special handling for SFrame yet.
* dw2gencfi.c (cfi_finish): Set SHT_GNU_SFRAME for emitted
SFrame section.
ld/
* NEWS: Announce emitted SFrame sections have SHT_GNU_SFRAME
set.
gas/testsuite/
* gas/cfi-sframe/cfi-sframe.exp: Add new test.
* gas/cfi-sframe/cfi-sframe-common-1b.d: New test.
* gas/cfi-sframe/cfi-sframe-common-1b.s: New test.
include/
* elf/common.h (SHT_GNU_SFRAME): Add new section type for SFrame
stack trace information.
libsframe/doc/
* sframe-spec.texi: Add expected ELF section type.
SFrame is generated for ELF targets only. Guard the block with
support_sframe_p like others for consistency.
Also, in a later commit, we would like to do a:
elf_section_type (sframe_seg) = SHT_GNU_SFRAME;
This cannot be done for non-ELF targets, hence the need to guard with
some pre-processor conditional to enable it for only OBJ_ELF. Guarding
with support_sframe_p works for now, because those targets that support
SFrame define support_sframe_p:
- x86_64 and aarch64 define support_sframe_p when OBJ_ELF is defined
- s390x has no non-LEF target.
We continue to issue an error on targets where SFrame is not supported:
.sframe not supported for target
gas/
* dw2gencfi.c (cfi_finish): Guard with support_sframe_p.
(support_sframe_p): Remove stub to define to false for backends
not supporting SFrame.
This removes many unnecessary NULL casts. I'm also adding a few arg
casts in concat calls, to make the code consistent. Advice from quite
a few years ago was that it's better to use the exact type for args
corresponding to function ellipses, in case NULL is defined as plain
0. (I think that happened with some early 64-bit systems. Plain NULL
ought to be OK nowadays.)
Some DW_CFA_* and DW_OP_* take wider than byte, but non-LEB128 operands.
Having to hand-encode such when needing to resort to .cfi_escape isn't
very helpful.
These are data generating directives not overly different from e.g.
.byte and .long. Whatever (directly) results from should also be
represented in the listing, if one was requested. It's just that the
output data is generated much later than the parsing of the directive
arguments.
Ignoring return values often isn't a good idea. The Sparc assembler in
particular would report an internal error if an expression with
relocation specifier is used with .cfi_escape, when the same works fine
with .byte. Propagate the relocation indicator up from
do_parse_cons_expression(), and eventually into emit_expr_with_reloc().
dot_cfi_fde_data(), only retaining the expression's X_add_number, would
require further work. Simply report the lack of support there. While
there, also check that what we were dealt is actually a constant.
CFI_escape is most commonly used to include DWARF expressions in the
unwind information. One may also use CFI_escape to add OS-specific CFI
opcodes. Up until now, SFrame generation process would skip generating
SFrame FDE at the mere sight of a CFI_escape opcode.
Fine tune the handling of CFI_escape for SFrame generation by explicitly
checking for few "harmless" (in context of SFrame generation)
CFI_escape DWARF info:
- DW_CFA_expression affecting registers of no significance to SFrame
stack trace info
- DW_CFA_value_offset affecting registers of no significance to SFrame
stack trace info
Expose the current cfi_escape_data structure in dw2gencfi.c to the
relevant header file to allow SFrame generation APIs to use it too.
Valid unwind info may be split across multiple .cfi_escape directives.
Conversely, it is also allowed to simply put multiple DWARF expressions
and/or operations in a single .cfi_escape directive. Handling all of
these cases correctly will need parsing/processing that is not deemed
worth the effort in context of SFrame generation; We continue to skip
generating SFrame FDE for these cases and warn the user.
In future, SFrame stack trace format may support non-SP/FP as base
register (albeit in limited form). Add an explicit check in
sframe_xlate_do_escape_expr (to test against the current CFA register)
to ensure the functionality continues to work.
Use differentiated warning text in sframe_xlate_do_val_offset to avoid
confusion to the user as the same function is used for handling
.cfi_val_offset and .cfi_escape DW_CFA_val_offset,...
Also, add a common test with DWARF reg 12 which is non SP / FP on x86_64
and aarch64 (and s390x too).
gas/
* gas/dw2gencfi.c (struct cfi_escape_data): Move from ...
* gas/dw2gencfi.h (struct cfi_escape_data): ... to.
* gas/gen-sframe.c (sframe_xlate_do_val_offset): Include string
for .cfi_escape conditionally.
(sframe_xlate_do_escape_expr): New definition.
(sframe_xlate_do_escape_val_offset): Likewise.
(sframe_xlate_do_cfi_escape): Likewise.
(sframe_do_cfi_insn): Handle CFI_escape explicitly.
gas/testsuite/
* gas/cfi-sframe/cfi-sframe.exp: Add new tests.
* gas/cfi-sframe/cfi-sframe-common-9.d: New test.
* gas/cfi-sframe/cfi-sframe-common-9.s: New test.
* gas/cfi-sframe/cfi-sframe-x86_64-empty-1.d: New test.
* gas/cfi-sframe/cfi-sframe-x86_64-empty-1.s: New test.
* gas/cfi-sframe/cfi-sframe-x86_64-empty-2.d: New test.
* gas/cfi-sframe/cfi-sframe-x86_64-empty-2.s: New test.
* gas/cfi-sframe/cfi-sframe-x86_64-empty-3.d: New test.
* gas/cfi-sframe/cfi-sframe-x86_64-empty-3.s: New test.
This patch adds a new CFI directive (cfi_negate_ra_state_with_pc) which
set an additional bit in the RA state to inform that RA was signed with
SP but also PC as an additional diversifier.
RA state | Description
0b00 | Return address not signed (default if no cfi_negate_ra_state*)
0b01 | Return address signed with SP (cfi_negate_ra_state)
0b10 | Invalid state
0b11 | Return address signed with SP+PC (cfi_negate_ra_state_with_pc)
Approved-by: Indu Bhagat <indu.bhagat@oracle.com>
Approved-by: Jan Beulich <jbeulich@suse.com>
Some of these could have remained as malloc'd memory, but that would
require quite a bit of code to traverse frch_cfi_data for example, and
would rely on matching cfi directives (ie. valid input). Just put
them on the notes obstack instead.
* dw2gencfi.c (alloc_fde_entry): Use notes_calloc.
(alloc_cfi_insn_data): Likewise.
(cfi_end_fde): Don't free frch_cfi_data.
(cfi_add_label): Use notes_strdup.
(cfi_add_CFA_remember_state): Use notes_alloc.
(cfi_add_CFA_restore_state): Don't free.
(dot_cfi_escape): Use notes_alloc.
(cfi_finish): Free cies after each pass, not before. Clear
out static vars too.
While originally this was in preparation of a subsequent change making
SUPPORT_FRAME_LINKONCE potentially dependent on a global variable, the
construct appears unlikely to have been correct in the first place: The
variable would have been passed reliably uninitialized when
SUPPORT_FRAME_LINKONCE is build-time true.
While there correct indentation of the parameters passed to
get_cfi_seg().
scfidw2gen will use this for processing the .cfi_sections directive.
gas/
* dw2gencfi.c (dot_cfi_sections): Not static anymore.
* dw2gencfi.h (dot_cfi_sections): Mark as extern.
Move the following three defines to the header file, so the SCFI
machinery can use them:
- tc_cfi_frame_initial_instructions
- tc_cfi_startproc
- tc_cfi_endproc
gas/
* dw2gencfi.c: Move from ...
* dw2gencfi.h: ... to here.
The code in dw2gencfi.c was checking variable cfi_sections and
all_cfi_sections seemingly randomly. Accessing all_cfi_sections seems
to the correct variable to access.
The data in cfi_sections has already been propagated to all_cfi_sections
once cfi_dot_startproc () has been called.
gas/
* dw2gencfi.c (dot_cfi_startproc): Use all_cfi_sections
instead.
(dot_cfi_endproc): Likewise.
(dot_cfi_fde_data): Likewise.
cfi_sections_set is best set to true in cfi_dot_startproc (). Setting
it to true again in other APIs (dot_cfi_endproc, dot_cfi_fde_data, and
cfi_finish) is unnecessary. Also, move setting the global var
all_cfi_sections into cfi_set_sections ().
gas/
* dw2gencfi.c (cfi_set_sections): Set cfi_sections_set and
cfi_sections here.
(dot_cfi_startproc): Remove unnecessarily setting
cfi_set_sections to true.
(dot_cfi_endproc): Likewise.
(dot_cfi_fde_data): Likewise.
(cfi_finish): Likewise.
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.
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.
Currently supported for x86_64 and aarch64 only.
[PS: Currently, the compiler has not been adapted to generate
".cfi_sections" with ".sframe" in it. The newly added command line
option of --gsframe provides an easy way to try out .sframe support
in the toolchain.]
gas interprets the CFI directives to generate DWARF-based .eh_frame
info. These internal DWARF structures are now consumed by
gen-sframe.[ch] sub-system to, in turn, create the SFrame unwind
information. These internal DWARF structures are read-only for the
purpose of SFrame unwind info generation.
SFrame unwind info generation does not impact .eh_frame unwind info
generation. Both .eh_frame and .sframe can co-exist in an ELF file,
if so desired by the user.
Recall that SFrame unwind information only contains the minimal
necessary information to generate backtraces and does not provide
information to recover all callee-saved registers. The reason being
that callee-saved registers other than FP are not needed for stack
unwinding, and hence are not included in the .sframe section.
Consequently, gen-sframe.[ch] only needs to interpret a subset of
DWARF opcodes in gas. More details follow.
[Set 1, Interpreted] The following opcodes are interpreted:
- DW_CFA_advance_loc
- DW_CFA_def_cfa
- DW_CFA_def_cfa_register
- DW_CFA_def_cfa_offset
- DW_CFA_offset
- DW_CFA_remember_state
- DW_CFA_restore_state
- DW_CFA_restore
[Set 2, Bypassed] The following opcodes are acknowledged but are not
necessary for generating SFrame unwind info:
- DW_CFA_undefined
- DW_CFA_same_value
Anything else apart from the two above-mentioned sets is skipped
altogether. This means that any function containing a CFI directive not
in Set 1 or Set 2 above, will not have any SFrame unwind information
generated for them. Holes in instructions covered by FREs of a single
FDE are not representable in the SFrame unwind format.
As few examples, following opcodes are not processed for .sframe
generation, and are skipped:
- .cfi_personality*
- .cfi_*lsda
- .cfi_escape
- .cfi_negate_ra_state
- ...
Not processing .cfi_escape, .cfi_negate_ra_state will cause SFrame
unwind information to be absent for SFrame FDEs that contain these CFI
directives, hence affecting the asynchronicity.
x86-64 and aarch64 backends need to have a few new definitions and
functions for .sframe generation. These provide gas with architecture
specific information like the SP/FP/RA register numbers and an
SFrame-specific ABI marker.
Lastly, the patch also implements an optimization for size, where
specific fragments containing SFrame FRE start address and SFrame FDE
function are fixed up. This is similar to other similar optimizations
in gas, where fragments are sized and fixed up when the associated
symbols can be resolved. This optimization is controlled by a #define
SFRAME_FRE_TYPE_SELECTION_OPT and should be easy to turn off if needed.
The optimization is on by default for both x86_64 and aarch64.
ChangeLog:
* gas/Makefile.am: Include gen-sframe.c and sframe-opt.c.
* gas/Makefile.in: Regenerated.
* gas/as.h (enum _relax_state): Add new state rs_sframe.
(sframe_estimate_size_before_relax): New function.
(sframe_relax_frag): Likewise.
(sframe_convert_frag): Likewise.
* gas/config/tc-aarch64.c (aarch64_support_sframe_p): New
definition.
(aarch64_sframe_ra_tracking_p): Likewise.
(aarch64_sframe_cfa_ra_offset): Likewise.
(aarch64_sframe_get_abi_arch): Likewise.
(md_begin): Set values of sp/fp/ra registers.
* gas/config/tc-aarch64.h (aarch64_support_sframe_p): New
declaration.
(support_sframe_p): Likewise.
(SFRAME_CFA_SP_REG): Likewise.
(SFRAME_CFA_FP_REG): Likewise.
(SFRAME_CFA_RA_REG): Likewise.
(aarch64_sframe_ra_tracking_p): Likewise.
(sframe_ra_tracking_p): Likewise.
(aarch64_sframe_cfa_ra_offset): Likewise.
(sframe_cfa_ra_offset): Likewise.
(aarch64_sframe_get_abi_arch): Likewise.
(sframe_get_abi_arch): Likewise.
* gas/config/tc-i386.c (x86_support_sframe_p): New definition.
(x86_sframe_ra_tracking_p): Likewise.
(x86_sframe_cfa_ra_offset): Likewise.
(x86_sframe_get_abi_arch): Likewise.
* gas/config/tc-i386.h (x86_support_sframe_p): New declaration.
(support_sframe_p): Likewise.
(SFRAME_CFA_SP_REG): Likewise.
(SFRAME_CFA_FP_REG): Likewise.
(x86_sframe_ra_tracking_p): Likewise.
(sframe_ra_tracking_p): Likewise.
(x86_sframe_cfa_ra_offset): Likewise.
(sframe_cfa_ra_offset): Likewise.
(x86_sframe_get_abi_arch): Likewise.
(sframe_get_abi_arch): Likewise.
* gas/config/tc-xtensa.c (unrelaxed_frag_max_size): Add case for
rs_sframe.
* gas/doc/as.texi: Add .sframe to the documentation for
.cfi_sections.
* gas/dw2gencfi.c (cfi_finish): Create a .sframe section.
* gas/dw2gencfi.h (CFI_EMIT_sframe): New definition.
* gas/write.c (cvt_frag_to_fill): Handle rs_sframe.
(relax_segment): Likewise.
* gas/gen-sframe.c: New file.
* gas/gen-sframe.h: New file.
* gas/sframe-opt.c: New file.
This patch is based on MULTIPLE_FRAME_SECTIONS and EH_FRAME_LINKONCE,
it allows backend to enable this feature and use '--gc-sections' simply.
* gas/dw2gencfi.h (TARGET_MULTIPLE_EH_FRAME_SECTIONS): New.
(MULTIPLE_FRAME_SECTIONS): Add TARGET_MULTIPLE_EH_FRAME_SECTIONS.
* gas/dw2gencfi.c (EH_FRAME_LINKONCE): Add TARGET_MULTIPLE_EH_FRAME_SECTIONS.
(is_now_linkonce_segment): Likewise.
(get_cfi_seg): Create relocation info between .eh_frame.* and .text.* section.
* bfd/elf-bfd.h (elf_backend_can_make_multiple_eh_frame): New.
* bfd/elfxx-target.h (elf_backend_can_make_multiple_eh_frame): Likewise.
* bfd/elflink.c (_bfd_elf_default_action_discarded): Add checking for
elf_backend_can_make_multiple_eh_frame.
Use notes obstack for dwcfi_hash entries, and free table. Freeing the
table makes memory checkers complain more about "definitely lost"
memory as we've moved some from the "still reachable" category.
That will be fixed with a later patch.
* dw2gencfi.c (get_debugseg_name): Allocate on notes obstack.
(alloc_debugseg_item): Likewise.
(dwcfi_hash_find_or_make): Adjust failure path free.
(cfi_finish): Delete dwfci_hash.
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.
Let's make sure what we allow in the CIE initial instructions and what
select_cie_for_fde compares for a match is always in sync. Also
correct the previous patch that allowed DW_CFA_GNU_window_save to be
part of the CIE initial instructions, which was likely a mistake.
PR 27723
* dw2gencfi.c (initial_cie_insn): New function, extracted from..
(select_cie_for_fde): ..here. Simplify.
This patch implements the .cfi_negate_ra_state to be consistent with
LLVM (https://reviews.llvm.org/D50136). The relevant DWARF code DW_CFA_AARCH64_negate_ra_state
is multiplexed on top of DW_CFA_GNU_window_save, as per
https://gcc.gnu.org/ml/gcc-patches/2017-08/msg00753.html
I believe this is the simplest patch implementing this and is needed to
allow users to build, for example, the Linux kernel with Armv8.3-A
pointer authentication support with Clang while using gas as the
assembler, which is a common usecase.
gas/
2019-12-06 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
* dw2gencfi.c (cfi_pseudo_table): Add cfi_negate_ra_state.
* testsuite/gas/aarch64/pac_negate_ra_state.s: New file.
* testsuite/gas/aarch64/pac_negate_ra_state.d: Likewise.
In version 1 of DWARF CIE format, the return register column is just a
single byte. For targets with large numbers of DWARF registers, any
use of a register with a high number for the return column
will (currently) silently overflow giving incorrect DWARF.
This commit adds an error when the overflow occurs.
gas/ChangeLog:
* dw2gencfi.c (output_cie): Error on return column overflow.
* testsuite/gas/riscv/cie-rtn-col-1.d: New file.
* testsuite/gas/riscv/cie-rtn-col-3.d: New file.
* testsuite/gas/riscv/cie-rtn-col.s: New file.
Change-Id: I1809f739ba7771737ec012807f0260e1a3ed5e64
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
If we happen to get the fixed and variable parts of the advance_loc
in different frags, bad things happen when subtracting one from a
fr_fix of zero.
PR 25125
* dw2gencfi.c (output_cfi_insn): Don't allow DW_CFA_advance_loc4
to be placed in a different frag to the rs_cfa.
These can be generated when multiple cfi directives are emitted for an
instruction and the insn frag is closed off between directives, as
happens when listings are enabled. No doubt the advance_loc of zero
could be avoided by backtracking over frags in dw2gencfi.c before
calling cfi_add_advance_loc, but that seems like more work than
cleaning up afterwards as this patch does.
Noticed when looking at the testcase in PR25125.
PR 25125
* dw2gencfi.c (output_cfi_insn): Don't output DW_CFA_advance_loc+0.
* ehopt.c (eh_frame_estimate_size_before_relax): Return -1 for
an advance_loc of zero.
(eh_frame_relax_frag): Translate fr_subtype of 7 to size -1.
(eh_frame_convert_frag): Handle fr_subtype of 7. Abort on
unexpected fr_subtype.
PR 24538
gas * macro.c (get_any_string): Increase size of buffer used to hold
decimal value of expression result.
* dw2gencfi.c (get_debugseg_name): Handle an empty name.
* dwarf2dbg.c (get_filenum): Catch integer wraparound when
extending allocate file array.
(dwarf2_directive_filename): Add extra checks of the computed file
number.
* config/tc-arm.c (arm_tc_equal_in_insn): Insert copy of name into
warning hash table.
(s_arm_eabi_attribute): Check for obj_elf_vendor_attribute
returning -1.
* config/tc-i386.c (i386_output_nops): Catch an attempt to
generate nops of negative lengths.
* as.h (MAX_LITTLENUMS): Move definition to here from...
* config/atof-ieee.c: ...here.
* config/tc-aarch64.c: ...here.
* config/tc-arc.c: ...here.
* config/tc-arm.c: ...here.
* config/tc-epiphany.c: ...here.
* config/tc-i386.c: ...here.
* config/tc-ia64.c: ...here. (And correct the value).
* config/tc-m32c.c: ...here.
* config/tc-m32r.c: ...here.
* config/tc-metag.c: ...here.
* config/tc-microblaze.c: ...here.
* config/tc-nds32.c: ...here.
* config/tc-or1k.c: ...here.
* config/tc-score.c: ...here.
* config/tc-score7.c: ...here.
* config/tc-tic4x.c: ...here.
* config/tc-tilegx.c: ...here.
* config/tc-tilepro.c: ...here.
* config/tc-visium.c: ...here.
* config/tc-sh.c (md_assemble): Add check for an instruction with
no opcodes.
* config/tc-mips.c (mips_lookup_insn): Add check for very short
instruction name.
* config/tc-tic54x.c: Use unsigned chars to access is_end_of_line
array.
(tic54x_start_line_hook): Check for an empty line.
(next_line_shows_parallel): Do not walk off the end of the string.
(tic54x_macro_start): Check for too much macro nesting.
(tic54x_start_label): Add label_start parameter. Use this
parameter to check the first character of the label.
* config/tc-tic54x.h (TC_START_LABEL_WITHOUT_COLON): Pass
line_start variable to tic54x_start_label.
PR 24538
opcodes * ia64-opc.c (ia64_find_matching_opcode): Check for reaching the
end of the table prematurely.
Armv8.3-A has another key used in pointer authentication called the
B-key (other than the A-key that is already supported). In order for
stack unwinders to work it is necessary to be able to identify frames
that have been signed with the B-key rather than the A-key and it was
felt that keeping this as an augmentation character in the CIE was the
best bet. The DWARF extensions for ARM therefore propose to add a new
augmentation character 'B' to the CIE augmentation string and the
corresponding cfi directive ".cfi_b_key_frame". I've made the relevant
changes to GAS and LD to add support for B-key unwinding, which required
modifying LD to check for 'B' in the augmentation string, adding the
".cfi_b_key_frame" directive to GAS and adding a "pauth_key" field to
GAS's fde_entry and cie_entry structs.
The pointer authentication instructions will behave as NOPs on
architectures that don't support them, and so a check for the
architecture being assembled for is not necessary since there will be no
behavioural difference between augmentation strings with and without the
'B' character on such architectures.
2018-12-05 Sam Tebbs <sam.tebbs@arm.com>
bfd/
* elf-eh-frame.c (_bfd_elf_parse_eh_frame): Add check for 'B'.
gas/
* dw2gencfi.c (struct cie_entry): Add tc_cie_entry_extras invocation.
(alloc_fde_entry): Add tc_fde_entry_init_extra invocation.
(output_cie): Add tc_output_cie_extra invocation.
(select_cie_for_fde): Add tc_cie_fde_equivalent_extra and
tc_cie_entry_init_extra invocation.
(frch_cfi_data, cfa_save_data): Move to dwgencfi.h.
* config/tc-aarch64.c (s_aarch64_cfi_b_key_frame): Declare.
(md_pseudo_table): Add "cfi_b_key_frame".
* config/tc-aarch64.h (tc_fde_entry_extras, tc_cie_entry_extras,
tc_fde_entry_init_extra, tc_output_cie_extra,
tc_cie_fde_equivalent_extra, tc_cie_entry_init_extra): Define.
* dw2gencfi.h (struct fde_entry): Add tc_fde_entry_extras invocation.
(pointer_auth_key): Define.
(frch_cfi_data, cfa_save_data): Move from dwgencfi.c.
* doc/c-aarch64.texi (.cfi_b_key_frame): Add documentation.
* testsuite/gas/aarch64/(pac_ab_key.d, pac_ab_key.s): New file.
Add asserts that reloc size matches encoding size, and tidy.
* dw2gencfi.c (encoding_size): Return unsigned int.
(emit_expr_encoded): Assert size matches reloc bitsize.
(output_fde): Use unsigned for offset_size and addr_size. Set
addr_size earlier and use in place of constant 4 and uses of
DWARF2_FDE_RELOC_SIZE. Assert it matches reloc bitsize.
