[clang] [clang] Add arm64e ABI-defined key assignments to ptrauth.h. (PR #93901)

[Ahmed Bougacha via cfe-commits]

https://github.com/ahmedbougacha created https://github.com/llvm/llvm-project/pull/93901

These are currently gated by __APPLE__; we can figure out a way to define these on ELF targets as well, and maybe have them be defined by clang itself, depending on ABI modes.

>From fc8f76b404b25951dc10ecaaa760b4b4c3d4f858 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed at bougacha.org>
Date: Thu, 30 May 2024 17:07:04 -0700
Subject: [PATCH] [clang] Add arm64e ABI-defined key assignments to ptrauth.h.

These are currently gated by __APPLE__; we can figure out a way to
define these on ELF targets as well, and maybe have them be defined
by clang itself, depending on ABI modes.
---
 clang/lib/Headers/ptrauth.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/clang/lib/Headers/ptrauth.h b/clang/lib/Headers/ptrauth.h
index 56c3c3636c9bc..036665d75a91b 100644
--- a/clang/lib/Headers/ptrauth.h
+++ b/clang/lib/Headers/ptrauth.h
@@ -15,6 +15,29 @@ typedef enum {
   ptrauth_key_asib = 1,
   ptrauth_key_asda = 2,
   ptrauth_key_asdb = 3,
+
+#ifdef __APPLE__
+  /* A process-independent key which can be used to sign code pointers.
+     Signing and authenticating with this key is a no-op in processes
+     which disable ABI pointer authentication. */
+  ptrauth_key_process_independent_code = ptrauth_key_asia,
+
+  /* A process-specific key which can be used to sign code pointers.
+     Signing and authenticating with this key is enforced even in processes
+     which disable ABI pointer authentication. */
+  ptrauth_key_process_dependent_code = ptrauth_key_asib,
+
+  /* A process-independent key which can be used to sign data pointers.
+     Signing and authenticating with this key is a no-op in processes
+     which disable ABI pointer authentication. */
+  ptrauth_key_process_independent_data = ptrauth_key_asda,
+
+  /* A process-specific key which can be used to sign data pointers.
+     Signing and authenticating with this key is a no-op in processes
+     which disable ABI pointer authentication. */
+  ptrauth_key_process_dependent_data = ptrauth_key_asdb,
+#endif /* __APPLE__ */
+
 } ptrauth_key;
 
 /* An integer type of the appropriate size for a discriminator argument. */