From: German Gomez <german.go...@arm.com> Implement DW_CFA_AARCH64_negate_ra_state in accordance with the DWARF AARCH64 ABI [1].
Followup commits will use the value of this register to remove the PAC from return addresses. [1] https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst#44call-frame-instructions Signed-off-by: German Gomez <german.go...@arm.com> Signed-off-by: Steve Capper <steve.cap...@arm.com> --- libdw/cfi.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/libdw/cfi.c b/libdw/cfi.c index a7174405..743bfc07 100644 --- a/libdw/cfi.c +++ b/libdw/cfi.c @@ -125,6 +125,15 @@ execute_cfi (Dwarf_CFI *cache, fs->regs[regno].value = (r_value); \ } while (0) + /* The AARCH64 DWARF ABI states that register 34 (ra_sign_state) must + be initialized to 0. So do it before executing the CFI. */ + if (cache->e_machine == EM_AARCH64) + { + if (unlikely (! enough_registers (DW_AARCH64_RA_SIGN_STATE, &fs, &result))) + goto out; + fs->regs[DW_AARCH64_RA_SIGN_STATE].value = 0; + } + while (program < end) { uint8_t opcode = *program++; @@ -357,7 +366,10 @@ execute_cfi (Dwarf_CFI *cache, { /* Toggles the return address state, indicating whether the return address is encrypted or not on - aarch64. XXX not handled yet. */ + aarch64. */ + if (unlikely (! enough_registers (DW_AARCH64_RA_SIGN_STATE, &fs, &result))) + goto out; + fs->regs[DW_AARCH64_RA_SIGN_STATE].value ^= 0x1; } else { -- 2.43.0
