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

[Daniil Kovalev via libcxx-commits]

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@@ -681,7 +681,18 @@ DEFINE_LIBUNWIND_FUNCTION(__libunwind_Registers_arm64_jumpto)
   // context struct, because it is allocated on the stack, and an exception
   // could clobber the de-allocated portion of the stack after sp has been
   // restored.
-  ldr    x16,     [x0, #0x0F8]
+
+  ldr    x16,     [x0, #0x0F8]  // load sp into scratch
+  ldr    lr,      [x0, #0x100]  // restore pc into lr
+
+#if __has_feature(ptrauth_calls) || defined(__PTRAUTH__)
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kovdan01 wrote:

Is this a correct check? It looks like that `#if __has_feature(ptrauth_returns)` (w/o check against `__PTRAUTH__`) is more suitable, isn't it? `__PTRAUTH__` just ensures that ptrauth intrinsics and header file are available, while here we want to ensure that RA is signed, don't we?

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