## Host environment - Operating system: Ubuntu 26.04 - OS/kernel version: `Linux 7.0.0-31-generic x86_64` - Architecture: x86_64 - QEMU flavor: qemu-sparc64 - QEMU version: 11.1.0 - QEMU command line: `qemu-sparc64 qemu-sparc64-repro.elf` ## Description of problem When running the affected binary under QEMU 11.1.0, it will sometimes crash due to what appears to be random register corruption. I suspect it has to do with signal handling because it only tends to manifest in test cases that involve signals, e.g. for cancelation. See below for some sample failures. I have run the binary in a loop on a SPARC T5-2 for an hour with no failures; on the other hand, the failures appear in <10s when run under QEMU in a loop. So while I have not dug deeper than this, I'd say odds are good that this is a QEMU bug. The binary is built from Zig's standard library module tests for `sparc64-linux-none` at commit `d26018b0f46f14adac17f021782270e13ede5a92`. ## Steps to reproduce 1. Build QEMU 11.1.0 2. `wget https://files.alexrp.com/qemu-sparc64-repro.elf` 3. `while qemu-sparc64 qemu-sparc64-repro.elf; do :; done` ## Additional information ``` Bus error at address 0x65 lib/std/Io.zig:1822:37: 0x127fc9d in waitTimeout (test) defer mutex.lockUncancelable(io); ^ qemu: uncaught target signal 6 (Aborted) - core dumped ``` ``` thread 237665 panic: switch on corrupt value error return context: lib/std/Io/Threaded.zig:1365:27: 0x1268498 in start (test) .canceling => return error.Canceled, // new status is `.canceled` ^ lib/std/Io/Threaded.zig:988:85: 0x1267ed8 in futexWaitInner (test) const syscall: Syscall = if (uncancelable) .{ .thread = null } else try .start(); ^ lib/std/Io/Threaded.zig:939:9: 0x12c9778 in futexWait (test) return Thread.futexWaitInner(ptr, expect, false, timeout_ns); ^ lib/std/Io/Threaded.zig:2517:5: 0x12c9660 in futexWait (test) return Thread.futexWait(ptr, expected, timeout_ns); ^ lib/std/Io.zig:1686:5: 0x1280450 in futexWaitTimeout__anon_20282 (test) return io.vtable.futexWait(io.userdata, @ptrCast(ptr), expected_int, timeout); ^ lib/std/Io.zig:1845:17: 0x127fcbc in waitTimeout (test) return err; ^ lib/std/Io/Semaphore.zig:42:28: 0x1322cb4 in waitTimeout (test) while (s.permits == 0) try s.cond.waitTimeout(io, &s.mutex, deadline); ^ lib/std/Io/Semaphore.zig:25:31: 0x1322a14 in wait (test) error.Canceled => |e| return e, ^ lib/std/Io/RwLock.zig:79:17: 0x1322828 in lock (test) return error.Canceled; ^ lib/std/Io/RwLock.zig:359:13: 0x1322274 in lockUnlock (test) try rl.lock(io); ^ lib/std/Io.zig:1845:17: 0x127fcbc in waitTimeout (test) return err; ^ lib/std/Io/Semaphore.zig:42:28: 0x1322cb4 in waitTimeout (test) while (s.permits == 0) try s.cond.waitTimeout(io, &s.mutex, deadline); ^ stack trace: lib/std/Io/Semaphore.zig:23:5: 0x1322a24 in wait (test) s.waitTimeout(io, .none) catch |err| switch (err) { ^ lib/std/Io/RwLock.zig:71:26: 0x132272c in lock (test) rl.semaphore.wait(io) catch |err| switch (err) { ^ lib/std/Io/RwLock.zig:359:24: 0x1322204 in lockUnlock (test) try rl.lock(io); ^ lib/std/Io.zig:2570:13: 0x1322090 in start (test) result_casted.* = @call(.auto, function, args_casted.*); ^ lib/std/Io/Threaded.zig:742:20: 0x12cf854 in start (test) future.func(future.contextPointer(), future.resultPointer()); ^ lib/std/Io/Threaded.zig:1800:29: 0x12ccddc in worker (test) runnable.startFn(runnable, &thread, t); ^ lib/std/Thread.zig:422:13: 0x12ccb58 in callFn__anon_25098 (test) @call(.auto, f, args); ^ lib/std/Thread.zig:1451:30: 0x12cc8b8 in entryFn (test) return callFn(f, self.fn_args); ^ lib/std/os/linux/sparc64.zig:247:5: 0x12cca84 in clone (test) asm volatile ( ^ qemu: uncaught target signal 6 (Aborted) - core dumped ``` ``` thread 240190 panic: switch on corrupt value error return context: lib/std/Io.zig:1845:17: 0x127fcbc in waitTimeout (test) return err; ^ lib/std/Io/Semaphore.zig:42:28: 0x1322cb4 in waitTimeout (test) while (s.permits == 0) try s.cond.waitTimeout(io, &s.mutex, deadline); ^ stack trace: lib/std/Io/Semaphore.zig:23:5: 0x1322a24 in wait (test) s.waitTimeout(io, .none) catch |err| switch (err) { ^ lib/std/Io/RwLock.zig:71:26: 0x132272c in lock (test) rl.semaphore.wait(io) catch |err| switch (err) { ^ lib/std/Io/RwLock.zig:359:24: 0x1322204 in lockUnlock (test) try rl.lock(io); ^ lib/std/Io.zig:2570:13: 0x1322090 in start (test) result_casted.* = @call(.auto, function, args_casted.*); ^ lib/std/Io/Threaded.zig:742:20: 0x12cf854 in start (test) future.func(future.contextPointer(), future.resultPointer()); ^ lib/std/Io/Threaded.zig:1800:29: 0x12ccddc in worker (test) runnable.startFn(runnable, &thread, t); ^ lib/std/Thread.zig:422:13: 0x12ccb58 in callFn__anon_25098 (test) @call(.auto, f, args); ^ lib/std/Thread.zig:1451:30: 0x12cc8b8 in entryFn (test) return callFn(f, self.fn_args); ^ lib/std/os/linux/sparc64.zig:247:5: 0x12cca84 in clone (test) asm volatile ( ^ qemu: uncaught target signal 6 (Aborted) - core dumped ```