On 11/01/2018 11:56 AM, Sam Tebbs wrote: > Hi all, > > 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. > > Built on aarch64-linux-gnu and aarch64-none-elf, and tested on > aarch64-none-elf > with no regressions. This patch has been tested with the corresponding patch > that enables B-key support in GCC. > > OK for trunk? > > bfd/ > 2018-11-01 Sam Tebbs<sam.te...@arm.com> > > * elf-eh-frame.c (_bfd_elf_parse_eh_frame): Add check for 'B'. > > gas/ > 2018-11-01 Sam Tebbs<sam.te...@arm.com> > > * dw2gencfi.c (struct cie_entry): Add pauth_key field. > (alloc_fde_entry): Set pauth_key to AARCH64_PAUTH_KEY_A by default. > (output_cie): Output 'B' if pauth_key == AARCH64_PAUTH_KEY_B. > (select_cie_for_fde): Add check for pauth_key. Set cie's pauth_key to > fde's pauth_key. > (frch_cfi_data, cfa_save_data): Move to dwgencfi.h. > * config/tc-aarch64.c (dot_cfi_b_key_frame): Declare. > (md_pseudo_table): Add "cfi_b_key_frame". > * dw2gencfi.h (pointer_auth_key): Define. > (struct fde_entry): Add pauth_key field. > (frch_cfi_data, cfa_save_data): Move from dwgencfi.c. > > gas/doc/ > 2018-11-01 Sam Tebbs<sam.te...@arm.com> > > * c-aarch64.texi (.cfi_b_key_frame): Add documentation. > > gas/testsuite > 2018-11-01 Sam Tebbs<sam.te...@arm.com> > > * gas/aarch64/(pac_ab_key.d, pac_ab_key.s): New file. >
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