From: "H. Peter Anvin" <hpa@xxxxxxxxx> Date: Wed, 24 May 2006 11:00:59 -0700 (PDT) > I'm having an issue with klibc on sparc64 (i.e. a 64-bit userspace > binary), which doesn't appear on sparc32: > > If I leave the signal restorer function as NULL, I get a SIGSEGV on > attempting to return from the signal handler. > > If I generate a system call stub for rt_sigreturn, and pass that in as > the restorer, then the process will loop forever on signal handler > return. > > A lot of architectures have ugly corners in this area (i386, for > example, needs to drop one word from the stack before calling the > sigreturn system call.) However, I simply don't understand the SPARC > architecture well enough to understand if/what I'm supposed to do > here, or if this is simply a bug. GLIBC is the source of all knowledge :-) libc/sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c In there you'll see that you have to set the sa_restorer to NULL and pass in the "stub" address minus 8, as the 4th argument to rt_sigation system call. The "stub" is simply: stub: mov __NR_rt_sigreturn ta 0x6d on sparc64. So: sys_rt_sigation(signr, &action, &old_action, &stub - 0x8, _NSIG/8); Hope this helps. - To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
