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Fix Windows exception callback argument passing #1256

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Merged
Weiteng Chen (CvvT) merged 2 commits into from
Sep 2, 2026
Merged

Fix Windows exception callback argument passing #1256

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134cb6a
Fix Windows exception callback argument
CvvT Sep 2, 2026
84ff82b
update comment
CvvT Sep 2, 2026
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5 changes: 4 additions & 1 deletion litebox_platform_windows_userland/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -157,6 +157,10 @@ unsafe extern "system" fn vectored_exception_handler(
context.Rip = exception_callback as *const () as usize as u64;
context.Rsp = rsp as u64;
context.Rbp = tls.host_bp.get() as u64;
// `host_sp` points at the slot where `run_thread_arch` saved its
// `ThreadContext` argument. Set it to `rcx` (i.e., the first argument) so
// that [`exception_handler`] can access it.
context.Rcx = unsafe { tls.host_sp.get().cast::<usize>().read() } as u64;
context.Rdx = exception_record_ptr as u64;
}

Expand Down Expand Up @@ -602,7 +606,6 @@ exception_callback:
// Handle the exception. The stack and frame pointers are already restored,
// and the guest context is up to date. rcx contains a pointer to the
// guest pt_regs, and rdx contains a pointer to the exception record.
mov rcx, QWORD PTR [rsp] // thread_ctx
call {exception_handler}
jmp .Ldone

Expand Down