[binutils-gdb] sframe.h: add support for .cfi_b_key_frame

[Indu Bhagat]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=41eed6e1878d93753ff82913d4577616c4778fa7

commit 41eed6e1878d93753ff82913d4577616c4778fa7
Author: Indu Bhagat <indu.bhagat@oracle.com>
Date:   Thu Dec 22 09:57:02 2022 -0800

    sframe.h: add support for .cfi_b_key_frame
    
    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.

Diff:
---
 include/sframe.h | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/include/sframe.h b/include/sframe.h
index b2bd41a724e..77071c99d90 100644
--- a/include/sframe.h
+++ b/include/sframe.h
@@ -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