[compiler-rt] [libcxxabi] [libunwind] [runtimes][PAC] Harden unwinding when possible (#138571) (PR #143230)

[Anatoly Trosinenko via llvm-commits]

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@@ -30,6 +30,50 @@ EXCEPTION_DISPOSITION _GCC_specific_handler(PEXCEPTION_RECORD, void *, PCONTEXT,
                                             _Unwind_Personality_Fn);
 #endif
 
+#if __has_feature(ptrauth_qualifier)
+#include <ptrauth.h>
+#endif
+
+#if defined(__APPLE__) && __has_feature(ptrauth_qualifier)
+#if __has_feature(ptrauth_restricted_intptr_qualifier)
+#define __ptrauth_gcc_personality_intptr(key, addressDiscriminated,            \
+                                              discriminator)                   \
+  __ptrauth_restricted_intptr(key, addressDiscriminated, discriminator)
+#else
+#define __ptrauth_gcc_personality_intptr(key, addressDiscriminated,            \
+                                              discriminator)                   \
+  __ptrauth(key, addressDiscriminated, discriminator)
+#endif
+#else
+#define __ptrauth_gcc_personality_intptr(...)
+#endif
+
+// The actual value of the discriminators listed below is not important.
+// The derivation of the constants is only being included for the purpose
+// of maintaining a record of how they were originally produced.
+
+// ptrauth_string_discriminator("__gcc_personality_v0'funcStart") == 0xDFEB
+#define __ptrauth_gcc_personality_func_start \
+  __ptrauth_gcc_personality_intptr(ptrauth_key_function_pointer, 1, 0xDFEB)
+
+// ptrauth_string_discriminator("__gcc_personality_v0'start") == 0x52DC
+#define __ptrauth_gcc_start \
+  __ptrauth_gcc_personality_intptr(ptrauth_key_function_pointer, 1, 0x52DC)
+
+// ptrauth_string_discriminator("__gcc_personality_v0'length") == 0xFFF7
+#define __ptrauth_gcc_length \
+  __ptrauth_gcc_personality_intptr(ptrauth_key_function_pointer, 1, 0xFFF7)
+
+// ptrauth_string_discriminator("__gcc_personality_v0'landingPadOffset") == 0x6498
+#define __ptrauth_gcc_personality_lpoffset \
+  __ptrauth_gcc_personality_intptr(ptrauth_key_function_pointer, 1, 0x6498)
+
+// ptrauth_string_discriminator("__gcc_personality_v0'landingPad")
+#define __ptrauth_personality_lpad_disc 0xA134
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atrosinenko wrote:

Another possibly unintentional difference: `__ptrauth_personality` prefix.

https://github.com/llvm/llvm-project/pull/143230