Commit `843d91e75d`

Jakub Konka <kubkon@jakubkonka.com>

2021-01-21 20:34:00

Bring back stack trace printing on ARM Darwin

This temporary patch fixes a segfault caused by miscompilation by the LLD when generating stubs for initialization of thread local storage. We effectively bypass TLS in the default panic handler so that no segfault is generated and the stack trace is correctly reported back to the user. Note that, this is linked directly to a bigger issue with LLD ziglang/zig#7527 and when resolved, we only need to remove the `comptime` code path introduced with this patch to use the default panic handler that relies on TLS. Co-authored-by: Andrew Kelley <andrew@ziglang.org>

master

1 parent bea791b

Changed files (1)

lib

std

debug.zig

@@ -250,6 +250,24 @@ pub fn panicExtra(trace: ?*const builtin.StackTrace, first_trace_addr: ?usize, c
         resetSegfaultHandler();
     }
 
+    if (comptime std.Target.current.isDarwin() and std.Target.current.cpu.arch == .aarch64)
+        nosuspend {
+            // As a workaround for not having threadlocal variable support in LLD for this target,
+            // we have a simpler panic implementation that does not use threadlocal variables.
+            // TODO https://github.com/ziglang/zig/issues/7527
+            const stderr = io.getStdErr().writer();
+            if (@atomicRmw(u8, &panicking, .Add, 1, .SeqCst) == 0) {
+                stderr.print("panic: " ++ format ++ "\n", args) catch os.abort();
+                if (trace) |t| {
+                    dumpStackTrace(t.*);
+                }
+                dumpCurrentStackTrace(first_trace_addr);
+            } else {
+                stderr.print("Panicked during a panic. Aborting.\n", .{}) catch os.abort();
+            }
+            os.abort();
+        };
+
     nosuspend switch (panic_stage) {
         0 => {
             panic_stage = 1;

Commit 843d91e75d

Commit `843d91e75d`