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async/coro: make coroutines unwindable by zeroing the initial stack region, preventing random unwinding behavior and SIGSEGV during _Unwind_Backtrace.

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Tarry Singh 2025-03-10 16:25:45 +00:00
parent f63c673f45
commit 6fc1148206
1 changed files with 7 additions and 0 deletions
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7
async/coro_base.zig
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@ -60,6 +60,13 @@ pub const Coro = packed struct {
return Error.StackTooSmall; return Error.StackTooSmall;
} }
const register_space = stack[stack.len - register_bytes ..]; const register_space = stack[stack.len - register_bytes ..];
// Zero out the register space so that the initial stack swap
// of new coroutines doesn't poison ebp.
//
// A better solution would be to prepare the initial stack so that the
// stack is valid up to the caller.
@memset(register_space, 0);
const jump_ptr: *Func = @ptrCast(@alignCast(&register_space[arch_info.jump_idx * 8])); const jump_ptr: *Func = @ptrCast(@alignCast(&register_space[arch_info.jump_idx * 8]));
jump_ptr.* = func; jump_ptr.* = func;
return .{ .stack_pointer = register_space.ptr }; return .{ .stack_pointer = register_space.ptr };