[aadwarf64]] Add DW_CFA_AARCH64_set_ra_state stack frame operation #346
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The DW_CFA_AARCH64_set_ra_state operation updates the RA_SIGN_STATE pseudo register with the current signing state. If the signing state includes signing is DW_AARCH64_RA_SIGNED_SP_PC, then it also provides the offset to the signing instruction so that the PC value used in the signing can be calculated. The DW_CFA_AARCH64_negate_ra_state_with_pc operation has been marked as deprecated. This is because it has been found that it is not suitable for describing all cases where the PC was used to sign the return address (see ARM-software#327) The contents of the RA_SIGN_STATE pseudo register is also changed from being described in terms of a set of bits to being a series of defined values. Previously the state of the RA_SIGN_STATE pseudo register was changed implicitly by the DW_CFA_AARCH64_negate_ra_state and DW_CFA_AARCH64_set_ra_state operations. This meant that the actual encoding was actually internal to any implementation. Now with the introduction of the DW_CFA_AARCH64_set_ra_state operation the encoding has been made externally visible. So the opportunity has been taken now to change the encoding to a simpler form.
bgergely0
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Aug 26, 2025
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| | | | - Deprecated | | ||
| | | | DW_CFA_AARCH64_negate_ra_state. | |
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I believe this should be DW_CFA_AARCH64_negate_ra_state_with_pc.
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Thanks for spotting that. I'll fix it.
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The DW_CFA_AARCH64_set_ra_state operation updates the RA_SIGN_STATE pseudo register with the current signing state. If the signing state includes signing is DW_AARCH64_RA_SIGNED_SP_PC, then it also provides the offset to the signing instruction so that the PC value used in the signing can be calculated.
The DW_CFA_AARCH64_negate_ra_state_with_pc operation has been marked as deprecated. This is because it has been found that it is not suitable for describing all cases where the PC was used to sign the return address (see #327)
The contents of the RA_SIGN_STATE pseudo register is also changed from being described in terms of a set of bits to being a series of defined values.
Previously the state of the RA_SIGN_STATE pseudo register was changed implicitly by the DW_CFA_AARCH64_negate_ra_state and DW_CFA_AARCH64_set_ra_state operations. This meant that the actual encoding was actually internal to any implementation.
Now with the introduction of the DW_CFA_AARCH64_set_ra_state operation the encoding has been made externally visible. So the opportunity has been taken now to change the encoding to a simpler form.