Strip PAC

Author: jeremy-rifkin

src/unwind/unwind_with_libunwind.cpp

@@ -26,6 +26,13 @@ namespace detail {
             unw_word_t pc;
             unw_word_t sp;
             unw_get_reg(&cursor, UNW_REG_IP, &pc);
+            #if defined(__APPLE__) && (defined(__arm64__) || defined(__aarch64__))
+            // Apple's unw_get_reg(UNW_REG_IP) may return pointer-authenticated addresses with PAC
+            // signature bits in the upper bytes
+            uintptr_t stripped = static_cast<uintptr_t>(pc);
+            __asm__ volatile("xpaci %0" : "+r"(stripped));
+            pc = static_cast<unw_word_t>(stripped);
+            #endif
             unw_get_reg(&cursor, UNW_REG_SP, &sp);
             if(skip) {
                 skip--;
@@ -53,6 +60,13 @@ namespace detail {
             unw_word_t sp;
             // thread and signal-safe https://www.nongnu.org/libunwind/man/unw_get_reg(3).html
             unw_get_reg(&cursor, UNW_REG_IP, &pc);
+            #if defined(__APPLE__) && (defined(__arm64__) || defined(__aarch64__))
+            {
+                uintptr_t stripped = static_cast<uintptr_t>(pc);
+                __asm__ volatile("xpaci %0" : "+r"(stripped));
+                pc = static_cast<unw_word_t>(stripped);
+            }
+            #endif
             unw_get_reg(&cursor, UNW_REG_SP, &sp);
             if(skip) {
                 skip--;