gas: elf: binutils: add new section type SHT_GNU_SFRAME
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.
14 files changed
