Sam Tebbs
3a67e1a6b4
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.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.