if returning errno value directly from a syscall, we need to negate it.

[musl] / src / process / execve.c

#include <unistd.h>
#include "syscall.h"

int execve(const char *path, char *const argv[], char *const envp[])
{
        /* do we need to use environ if envp is null? */
        return syscall3(__NR_execve, (long)path, (long)argv, (long)envp);
}