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

arch/um/include/shared/as-layout.h

@@ -60,7 +60,8 @@ extern unsigned long host_task_size;
 
 extern int linux_main(int argc, char **argv);
 
-extern void (*sig_info[])(int, struct uml_pt_regs *);
+struct siginfo;
+extern void (*sig_info[])(int, struct siginfo *si, struct uml_pt_regs *);
 
 #endif
 

arch/um/include/shared/irq_user.h

@@ -20,7 +20,8 @@ struct irq_fd {
 
 enum { IRQ_READ, IRQ_WRITE };
 
-extern void sigio_handler(int sig, struct uml_pt_regs *regs);
+struct siginfo;
+extern void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 extern void free_irq_by_fd(int fd);
 extern void reactivate_fd(int fd, int irqnum);
 extern void deactivate_fd(int fd, int irqnum);

arch/um/include/shared/kern_util.h

@@ -9,6 +9,8 @@
 #include "sysdep/ptrace.h"
 #include "sysdep/faultinfo.h"
 
+struct siginfo;
+
 extern int uml_exitcode;
 
 extern int ncpus;
@@ -22,7 +24,7 @@ extern void free_stack(unsigned long stack, int order);
 
 extern int do_signal(void);
 extern void interrupt_end(void);
-extern void relay_signal(int sig, struct uml_pt_regs *regs);
+extern void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs);
 
 extern unsigned long segv(struct faultinfo fi, unsigned long ip,
 			  int is_user, struct uml_pt_regs *regs);
@@ -33,9 +35,8 @@ extern unsigned int do_IRQ(int irq, struct uml_pt_regs *regs);
 extern int smp_sigio_handler(void);
 extern void initial_thread_cb(void (*proc)(void *), void *arg);
 extern int is_syscall(unsigned long addr);
-extern void timer_handler(int sig, struct uml_pt_regs *regs);
 
-extern void timer_handler(int sig, struct uml_pt_regs *regs);
+extern void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 
 extern int start_uml(void);
 extern void paging_init(void);
@@ -59,9 +60,9 @@ extern unsigned long from_irq_stack(int nested);
 extern void syscall_trace(struct uml_pt_regs *regs, int entryexit);
 extern int singlestepping(void *t);
 
-extern void segv_handler(int sig, struct uml_pt_regs *regs);
-extern void bus_handler(int sig, struct uml_pt_regs *regs);
-extern void winch(int sig, struct uml_pt_regs *regs);
+extern void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
+extern void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs);
+extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
 extern void fatal_sigsegv(void) __attribute__ ((noreturn));
 
 

arch/um/kernel/irq.c

@@ -30,7 +30,7 @@ static struct irq_fd **last_irq_ptr = &active_fds;
 
 extern void free_irqs(void);
 
-void sigio_handler(int sig, struct uml_pt_regs *regs)
+void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
 	struct irq_fd *irq_fd;
 	int n;

arch/um/kernel/time.c

@@ -13,7 +13,7 @@
 #include "kern_util.h"
 #include "os.h"
 
-void timer_handler(int sig, struct uml_pt_regs *regs)
+void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
 	unsigned long flags;
 

arch/um/kernel/trap.c

@@ -172,7 +172,7 @@ void fatal_sigsegv(void)
 	os_dump_core();
 }
 
-void segv_handler(int sig, struct uml_pt_regs *regs)
+void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
 	struct faultinfo * fi = UPT_FAULTINFO(regs);
 
@@ -258,8 +258,11 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
 	return 0;
 }
 
-void relay_signal(int sig, struct uml_pt_regs *regs)
+void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs)
 {
+	struct faultinfo *fi;
+	struct siginfo clean_si;
+
 	if (!UPT_IS_USER(regs)) {
 		if (sig == SIGBUS)
 			printk(KERN_ERR "Bus error - the host /dev/shm or /tmp "
@@ -269,18 +272,40 @@ void relay_signal(int sig, struct uml_pt_regs *regs)
 
 	arch_examine_signal(sig, regs);
 
-	current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
-	force_sig(sig, current);
+	memset(&clean_si, 0, sizeof(clean_si));
+	clean_si.si_signo = si->si_signo;
+	clean_si.si_errno = si->si_errno;
+	clean_si.si_code = si->si_code;
+	switch (sig) {
+	case SIGILL:
+	case SIGFPE:
+	case SIGSEGV:
+	case SIGBUS:
+	case SIGTRAP:
+		fi = UPT_FAULTINFO(regs);
+		clean_si.si_addr = (void __user *) FAULT_ADDRESS(*fi);
+		current->thread.arch.faultinfo = *fi;
+#ifdef __ARCH_SI_TRAPNO
+		clean_si.si_trapno = si->si_trapno;
+#endif
+		break;
+	default:
+		printk(KERN_ERR "Attempted to relay unknown signal %d (si_code = %d)\n",
+			sig, si->si_code);
+	}
+
+	force_sig_info(sig, &clean_si, current);
 }
 
-void bus_handler(int sig, struct uml_pt_regs *regs)
+void bus_handler(int sig, struct siginfo *si, struct uml_pt_regs *regs)
 {
 	if (current->thread.fault_catcher != NULL)
 		UML_LONGJMP(current->thread.fault_catcher, 1);
-	else relay_signal(sig, regs);
+	else
+		relay_signal(sig, si, regs);
 }
 
-void winch(int sig, struct uml_pt_regs *regs)
+void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
 {
 	do_IRQ(WINCH_IRQ, regs);
 }

arch/um/os-Linux/internal.h

-void alarm_handler(int, mcontext_t *);
+void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc);

arch/um/os-Linux/signal.c

@@ -13,8 +13,9 @@
 #include "kern_util.h"
 #include "os.h"
 #include "sysdep/mcontext.h"
+#include "internal.h"
 
-void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
+void (*sig_info[NSIG])(int, siginfo_t *, struct uml_pt_regs *) = {
 	[SIGTRAP]	= relay_signal,
 	[SIGFPE]	= relay_signal,
 	[SIGILL]	= relay_signal,
@@ -24,7 +25,7 @@ void (*sig_info[NSIG])(int, struct uml_pt_regs *) = {
 	[SIGIO]		= sigio_handler,
 	[SIGVTALRM]	= timer_handler };
 
-static void sig_handler_common(int sig, mcontext_t *mc)
+static void sig_handler_common(int sig, siginfo_t *si, mcontext_t *mc)
 {
 	struct uml_pt_regs r;
 	int save_errno = errno;
@@ -40,7 +41,7 @@ static void sig_handler_common(int sig, mcontext_t *mc)
 	if ((sig != SIGIO) && (sig != SIGWINCH) && (sig != SIGVTALRM))
 		unblock_signals();
 
-	(*sig_info[sig])(sig, &r);
+	(*sig_info[sig])(sig, si, &r);
 
 	errno = save_errno;
 }
@@ -60,7 +61,7 @@ static void sig_handler_common(int sig, mcontext_t *mc)
 static int signals_enabled;
 static unsigned int signals_pending;
 
-void sig_handler(int sig, mcontext_t *mc)
+void sig_handler(int sig, siginfo_t *si, mcontext_t *mc)
 {
 	int enabled;
 
@@ -72,7 +73,7 @@ void sig_handler(int sig, mcontext_t *mc)
 
 	block_signals();
 
-	sig_handler_common(sig, mc);
+	sig_handler_common(sig, si, mc);
 
 	set_signals(enabled);
 }
@@ -85,10 +86,10 @@ static void real_alarm_handler(mcontext_t *mc)
 		get_regs_from_mc(&regs, mc);
 	regs.is_user = 0;
 	unblock_signals();
-	timer_handler(SIGVTALRM, &regs);
+	timer_handler(SIGVTALRM, NULL, &regs);
 }
 
-void alarm_handler(int sig, mcontext_t *mc)
+void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
 {
 	int enabled;
 
@@ -119,7 +120,7 @@ void set_sigstack(void *sig_stack, int size)
 		panic("enabling signal stack failed, errno = %d\n", errno);
 }
 
-static void (*handlers[_NSIG])(int sig, mcontext_t *mc) = {
+static void (*handlers[_NSIG])(int sig, siginfo_t *si, mcontext_t *mc) = {
 	[SIGSEGV] = sig_handler,
 	[SIGBUS] = sig_handler,
 	[SIGILL] = sig_handler,
@@ -132,7 +133,7 @@ static void (*handlers[_NSIG])(int sig, mcontext_t *mc) = {
 };
 
 
-static void hard_handler(int sig, siginfo_t *info, void *p)
+static void hard_handler(int sig, siginfo_t *si, void *p)
 {
 	struct ucontext *uc = p;
 	mcontext_t *mc = &uc->uc_mcontext;
@@ -161,7 +162,7 @@ static void hard_handler(int sig, siginfo_t *info, void *p)
 		while ((sig = ffs(pending)) != 0){
 			sig--;
 			pending &= ~(1 << sig);
-			(*handlers[sig])(sig, mc);
+			(*handlers[sig])(sig, si, mc);
 		}
 
 		/*
@@ -273,9 +274,12 @@ void unblock_signals(void)
 		 * Deal with SIGIO first because the alarm handler might
 		 * schedule, leaving the pending SIGIO stranded until we come
 		 * back here.
+		 *
+		 * SIGIO's handler doesn't use siginfo or mcontext,
+		 * so they can be NULL.
 		 */
 		if (save_pending & SIGIO_MASK)
-			sig_handler_common(SIGIO, NULL);
+			sig_handler_common(SIGIO, NULL, NULL);
 
 		if (save_pending & SIGVTALRM_MASK)
 			real_alarm_handler(NULL);

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:

arch/um/os-Linux/time.c

@@ -87,7 +87,7 @@ static int after_sleep_interval(struct timespec *ts)
 
 static void deliver_alarm(void)
 {
-	alarm_handler(SIGVTALRM, NULL);
+	alarm_handler(SIGVTALRM, NULL, NULL);
 }
 
 static unsigned long long sleep_time(unsigned long long nsecs)