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>

4 files changed, 26 insertions, 17 deletions

diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h
index 2c3c3ec..0dc2c9f 100644
--- a/arch/um/os-Linux/internal.h
+++ b/arch/um/os-Linux/internal.h
@@ -1 +1 @@
-void alarm_handler(int, mcontext_t *);
+void alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc);
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 2d22f1f..6366ce9 100644
--- a/arch/um/os-Linux/signal.c
+++ b/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);
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 2687f1f..d93bb40 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/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:
diff --git a/arch/um/os-Linux/time.c b/arch/um/os-Linux/time.c
index 910499d..f602385 100644
--- a/arch/um/os-Linux/time.c
+++ b/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)