zig

commit 843d91e75d166ac41d7c9b27b86b236f14865e31 (tree)
parent bea791b63992d57501c0f878408923806650069b
Author: Jakub Konka <kubkon@jakubkonka.com>
Date:   Thu, 21 Jan 2021 20:34:00 +0100

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>

Diffstat:
M
lib/std/debug.zig
 | 
18
++++++++++++++++++

1 file changed, 18 insertions(+), 0 deletions(-)
diff --git a/lib/std/debug.zig b/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;