Auto merge of #22637 - gterzian:fix_mac_sampler, r=jdm

Fix frame-pointer stackwalking

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This seems to fix the problem, it's a check that is also done at https://dxr.mozilla.org/mozilla-central/rev/c2593a3058afdfeaac5c990e18794ee8257afe99/mozglue/misc/StackWalk.cpp#904

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- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #22604 (GitHub issue number if applicable)

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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components/background_hang_monitor/sampler_mac.rs

@@ -96,14 +96,22 @@ unsafe fn frame_pointer_stack_walk(regs: Registers) -> NativeStack {
     // --dev,
     // or --with-frame-pointer.
 
-    let stackaddr = libc::pthread_get_stackaddr_np(libc::pthread_self());
+    let pthread_t = libc::pthread_self();
+    let stackaddr = libc::pthread_get_stackaddr_np(pthread_t);
+    let stacksize = libc::pthread_get_stacksize_np(pthread_t);
     let mut native_stack = NativeStack::new();
     let pc = regs.instruction_ptr as *mut std::ffi::c_void;
     let stack = regs.stack_ptr as *mut std::ffi::c_void;
     let _ = native_stack.process_register(pc, stack);
     let mut current = regs.frame_ptr as *mut *mut std::ffi::c_void;
     while !current.is_null() {
         if (current as usize) < stackaddr as usize {
+            // Reached the end of the stack.
+            break;
+        }
+        if current as usize >= stackaddr.add(stacksize * 8) as usize {
+            // Reached the beginning of the stack.
+            // Assumining 64 bit mac(see the stacksize * 8).
             break;
         }
         let next = *current as *mut *mut std::ffi::c_void;
@@ -112,6 +120,9 @@ unsafe fn frame_pointer_stack_walk(regs: Registers) -> NativeStack {
         if let Err(()) = native_stack.process_register(*pc, *stack) {
             break;
         }
+        if (next <= current) || (next as usize & 3 != 0) {
+            break;
+        }
         current = next;
     }
     native_stack