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sframe.h: add support for .cfi_b_key_frame

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ARM 8.3 provides five separate keys that can be used to authenticate
pointers. There are two key for executable (instruction) pointers. The
enum pointer_auth_key in gas/config/tc-aarch64.h currently holds two keys:
  enum pointer_auth_key {
    AARCH64_PAUTH_KEY_A,
    AARCH64_PAUTH_KEY_B
  };

Analogous to the above, in SFrame format V1, a bit is reserved in the SFrame
FDE to indicate which key is used for signing the frame's return addresses:
  - SFRAME_AARCH64_PAUTH_KEY_A has a value of 0
  - SFRAME_AARCH64_PAUTH_KEY_B has a value of 1

Note that the information in this bit will always be used along with the
mangled_ra_p bit, the latter indicates whether the return addresses are
mangled/contain PAC auth bits.

include/ChangeLog:

	* sframe.h (SFRAME_AARCH64_PAUTH_KEY_A): New definition.
	(SFRAME_AARCH64_PAUTH_KEY_B): Likewise.
	(SFRAME_V1_FUNC_INFO): Adjust to accommodate pauth_key.
	(SFRAME_V1_FUNC_PAUTH_KEY): New macro.
	(SFRAME_V1_FUNC_INFO_UPDATE_PAUTH_KEY): Likewise.
This commit is contained in:
Indu Bhagat 2022-12-22 09:57:02 -08:00
parent a5ce326cfe
commit 41eed6e187
1 changed files with 19 additions and 6 deletions
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25
include/sframe.h
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@ -165,6 +165,10 @@ typedef struct sframe_header
#define SFRAME_V1_HDR_SIZE(sframe_hdr) \
((sizeof (sframe_header) + (sframe_hdr).sfh_auxhdr_len))
/* Two possible keys for executable (instruction) pointers signing. */
#define SFRAME_AARCH64_PAUTH_KEY_A 0 /* Key A. */
#define SFRAME_AARCH64_PAUTH_KEY_B 1 /* Key B. */
typedef struct sframe_func_desc_entry
{
/* Function start address. Encoded as a signed offset, relative to the
@ -181,21 +185,30 @@ typedef struct sframe_func_desc_entry
function.
- 4-bits: Identify the FRE type used for the function.
- 1-bit: Identify the FDE type of the function - mask or inc.
- 3-bits: Unused.
--------------------------------------------
| Unused | FDE type | FRE type |
--------------------------------------------
8 5 4 0 */
- 1-bit: PAC authorization A/B key (aarch64).
- 2-bits: Unused.
------------------------------------------------------------------------
| Unused | PAC auth A/B key (aarch64) | FDE type | FRE type |
| | Unused (amd64) | | |
------------------------------------------------------------------------
8 6 5 4 0 */
uint8_t sfde_func_info;
} ATTRIBUTE_PACKED sframe_func_desc_entry;
/* Macros to compose and decompose function info in FDE. */
/* Note: Set PAC auth key to SFRAME_AARCH64_PAUTH_KEY_A by default. */
#define SFRAME_V1_FUNC_INFO(fde_type, fre_enc_type) \
((((fde_type) & 0x1) << 4) | ((fre_enc_type) & 0xf))
(((SFRAME_AARCH64_PAUTH_KEY_A & 0x1) << 5) | \
(((fde_type) & 0x1) << 4) | ((fre_enc_type) & 0xf))
#define SFRAME_V1_FUNC_FRE_TYPE(data) ((data) & 0xf)
#define SFRAME_V1_FUNC_FDE_TYPE(data) (((data) >> 4) & 0x1)
#define SFRAME_V1_FUNC_PAUTH_KEY(data) (((data) >> 5) & 0x1)
/* Set the pauth key as indicated. */
#define SFRAME_V1_FUNC_INFO_UPDATE_PAUTH_KEY(pauth_key, fde_info) \
((((pauth_key) & 0x1) << 5) | ((fde_info) & 0xdf))
/* Size of stack frame offsets in an SFrame Frame Row Entry. A single
SFrame FRE has all offsets of the same size. Offset size may vary