core: strip the PAC out of IP during backtrace on AArch64 macOS

Apple's libunwind for AArch64 returns the Instruction Pointer with the
Pointer Authentication Codes (bits 47-63) even though Tarantool is compiled
for arm64 (not arm64e) architecture, so we have to strip them out [1].
Although there is the ptrauth_strip macro for this purpose, it works only
if compilation target is arm64e (not arm64) [2].

1. https://developer.apple.com/documentation/security/preparing_your_app_to_work_with_pointer_authentication#3042105
2. https://github.com/dotnet/runtime/issues/42955#issuecomment-886910180

Closes #8074
Closes tarantool/tarantool-qa#308
Closes tarantool/tarantool-qa#309

NO_DOC=bugfix

(cherry picked from commit 88990e2f)

changelogs/unreleased/gh-8074-fix-backtraces-on-m1-macs.md

+## bugfix/core
+
+* Fixed the collection of fiber backtraces on the M1/M2 macOS platform
+  (gh-8074).

src/lib/core/backtrace.c

@@ -75,6 +75,13 @@ collect_current_stack(struct backtrace *bt, void *stack)
 				  "status: %d", rc);
 			return stack;
 		}
+#ifdef __aarch64__
+		/*
+		 * Apple's libunwind for AArch64 returns the IP with the Pointer
+		 * Authentication Codes (bits 47-63). Strip them out.
+		 */
+		ip &= 0x7fffffffffffull;
+#endif /* __aarch64__ */
 		append_frame(bt, (void *)ip);
 		rc = unw_step(&unw_cur);
 		if (rc <= 0) {

test/app-luatest/fiber_parent_backtrace_test.lua

@@ -4,8 +4,6 @@ local t = require('luatest')
 local g = t.group()
 
 g.before_all(function()
-    t.skip_if(jit.arch == 'arm64' and jit.os == 'OSX',
-              'Disabled on macOS/M1 due to tarantool/tarantool-qa#309')
     g.dflt = server:new({alias = 'dflt'})
     g.dflt:start()
     g.dflt:exec(function()

test/app/fiber.skipcond

@@ -4,8 +4,4 @@ import platform
 if platform.system() == 'OpenBSD':
     self.skip = 1
 
-# Disabled on macOS/M1 due to fail tarantool/tarantool-qa#308.
-if platform.machine() == 'arm64' and platform.system() == 'Darwin':
-    self.skip = 1
-
 # vim: set ft=python: