On Thu, Jan 23, 2025 at 11:07:21PM +0100, Christophe Leroy wrote: [...] > To add a bit more to the confusion, a task can be flagged with > TIF_NOERROR by calling force_successful_syscall_return(), in which case > even if gpr[3] contains a negative between -MAX_ERRNO and -1 the syscall > will be handled as successfull hence CCR[SO] won't be set. But it seems > this is not handled by syscall_set_return_value(). So what will happen > with time() when approaching year 2036 for instance ?
syscall_set_return_value() takes both "int error" and "long val" arguments. It doesn't and shouldn't take TIF_NOERROR into account. With my patch applied, when it's called by PTRACE_SET_SYSCALL_INFO from do_syscall_trace_leave(), it will properly update gpr[3] and ccr regardless of TIF_NOERROR. If tracer wants to set an error status for a syscall that cannot return an error, it's up to the tracer to face the consequences. Tracers can do it now via PTRACE_SETREGS* anyway. -- ldv
