[aadwarf64] Add DWARF support for unwinding with FEAT_PAuth_LR enabled #245
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This introduces DWARF support to enable unwinders to authenticate return addresses signed using FEAT_PAuth_LR, where the value of PC is used as an extra diversifier. To achieve that, this proposes the following changes to the aadwarf64 document: * Expanding usage of the `RA_SIGN_STATE` pseudo-register, allocating it's bit[1] to indicate wether the value of PC has been used for return address signing. * Introducing a new vendor call frame instruction, `DW_CFA_AARCH64_negate_ra_state_with_pc`, which negates both bit[0] and bit[1] of `RA_SIGN_STATE` and instructs the unwinder to capture the current code location to be used when authenticating the return address. Co-authored-by: Oliver Stannard <oliver.stannard@arm.com>
DanielKristofKiss
approved these changes
Feb 26, 2024
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This introduces DWARF support to enable unwinders to authenticate return
addresses signed using FEAT_PAuth_LR, where the value of PC is used as
an extra diversifier.
To achieve that, this proposes the following changes to the aadwarf64
document:
RA_SIGN_STATEpseudo-register, allocatingit's bit[1] to indicate wether the value of PC has been used for
return address signing.
DW_CFA_AARCH64_negate_ra_state_with_pc, which negates both bit[0]and bit[1] of
RA_SIGN_STATEand instructs the unwinder to capturethe current code location to be used when authenticating the return
address.
Co-authored-by: Oliver Stannard oliver.stannard@arm.com