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>

10 files changed, 71 insertions, 34 deletions

diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
index 896e16602176..86daa5461815 100644
--- a/arch/um/include/shared/as-layout.h
+++ b/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
 
diff --git a/arch/um/include/shared/irq_user.h b/arch/um/include/shared/irq_user.h
index c6c784df2673..2b6d703925b5 100644
--- a/arch/um/include/shared/irq_user.h
+++ b/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);
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index 00965d06d2ca..af6b6dc868ba 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/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));
 
 
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
index 00506c3d5d6e..9883026f0730 100644
--- a/arch/um/kernel/irq.c
+++ b/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;
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index d1a23fb3190d..5f76d4ba151c 100644
--- a/arch/um/kernel/time.c
+++ b/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;
 
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 3be60765c0e2..0353b98ae35a 100644
--- a/arch/um/kernel/trap.c
+++ b/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);
 }
diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h
index 2c3c3ecd8c01..0dc2c9f135f6 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 2d22f1fcd8e2..6366ce904b9b 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 2687f1f3a709..d93bb40499f7 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 910499d76a67..f60238559af3 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)