um: pass siginfo to guest process

UML guest processes now get correct siginfo_t for SIGTRAP, SIGFPE,
SIGILL and SIGBUS. Specifically, si_addr and si_code are now correct
where previously they were si_addr = NULL and si_code = 128.

Signed-off-by: Martin Pärtel <martin.partel@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/os-Linux/skas/process.c

@@ -346,6 +346,7 @@ void userspace(struct uml_pt_regs *regs)
 	int err, status, op, pid = userspace_pid[0];
 	/* To prevent races if using_sysemu changes under us.*/
 	int local_using_sysemu;
+	siginfo_t si;
 
 	/* Handle any immediate reschedules or signals */
 	interrupt_end();
@@ -407,13 +408,17 @@ void userspace(struct uml_pt_regs *regs)
 
 		if (WIFSTOPPED(status)) {
 			int sig = WSTOPSIG(status);
+
+			ptrace(PTRACE_GETSIGINFO, pid, 0, &si);
+
 			switch (sig) {
 			case SIGSEGV:
 				if (PTRACE_FULL_FAULTINFO ||
 				    !ptrace_faultinfo) {
 					get_skas_faultinfo(pid,
 							   &regs->faultinfo);
-					(*sig_info[SIGSEGV])(SIGSEGV, regs);
+					(*sig_info[SIGSEGV])(SIGSEGV, &si,
+							     regs);
 				}
 				else handle_segv(pid, regs);
 				break;
@@ -421,14 +426,14 @@ void userspace(struct uml_pt_regs *regs)
 			        handle_trap(pid, regs, local_using_sysemu);
 				break;
 			case SIGTRAP:
-				relay_signal(SIGTRAP, regs);
+				relay_signal(SIGTRAP, &si, regs);
 				break;
 			case SIGVTALRM:
 				now = os_nsecs();
 				if (now < nsecs)
 					break;
 				block_signals();
-				(*sig_info[sig])(sig, regs);
+				(*sig_info[sig])(sig, &si, regs);
 				unblock_signals();
 				nsecs = timer.it_value.tv_sec *
 					UM_NSEC_PER_SEC +
@@ -442,7 +447,7 @@ void userspace(struct uml_pt_regs *regs)
 			case SIGFPE:
 			case SIGWINCH:
 				block_signals();
-				(*sig_info[sig])(sig, regs);
+				(*sig_info[sig])(sig, &si, regs);
 				unblock_signals();
 				break;
 			default: