[PATCH] frv: fix signal handling

The attached patch makes FRV signal handling work properly:

 (1) After do_notify_resume() has been called, the work flags must be checked
     again (there may be another signal to deliver or the process might require
     rescheduling for instance).

 (2) After the signal frame is set up on the userspace stack, ptrace() should
     be given an opportunity to single-step into the signal handler.

 (3) The error state from setting up a signal frame should be passed back up
     the call chain.

 (4) The segfault handler shouldn't be preemptively reset in the arch if we
     fail to deliver a SEGV signal: force_sig() will take care of that.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/frv/kernel/entry.S b/arch/frv/kernel/entry.S
index ad10ea595459c24787b928ac09bb96ff4c7a9da0..5f6548388b74a6d765a23f77e10aa6b793d9be22 100644 (file)
--- a/arch/frv/kernel/entry.S
+++ b/arch/frv/kernel/entry.S
@@ -1076,7 +1076,7 @@ __entry_work_notifysig:
        LEDS            0x6410
        ori.p           gr4,#0,gr8
        call            do_notify_resume
-       bra             __entry_return_direct
+       bra             __entry_resume_userspace
 
        # perform syscall entry tracing
 __syscall_trace_entry:

diff --git a/arch/frv/kernel/signal.c b/arch/frv/kernel/signal.c
index d4ccc0728dfe4b97ac7065f4b0fe344e72320873..89a1cf5c076af5949738c9c92273893907058e36 100644 (file)
--- a/arch/frv/kernel/signal.c
+++ b/arch/frv/kernel/signal.c
@@ -297,7 +297,8 @@ static inline void __user *get_sigframe(struct k_sigaction *ka,
 /*
  *
  */
-static void setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct pt_regs * regs)
+static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set,
+                      struct pt_regs *regs)
 {
        struct sigframe __user *frame;
        int rsig;
@@ -362,26 +363,30 @@ static void setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct p
 
        set_fs(USER_DS);
 
+       /* the tracer may want to single-step inside the handler */
+       if (test_thread_flag(TIF_SINGLESTEP))
+               ptrace_notify(SIGTRAP);
+
 #if DEBUG_SIG
        printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
-               sig, current->comm, current->pid, frame, regs->pc, frame->pretcode);
+              sig, current->comm, current->pid, frame, regs->pc,
+              frame->pretcode);
 #endif
 
-       return;
+       return 1;
 
 give_sigsegv:
-       if (sig == SIGSEGV)
-               ka->sa.sa_handler = SIG_DFL;
-
        force_sig(SIGSEGV, current);
+       return 0;
+
 } /* end setup_frame() */
 
 /*****************************************************************************/
 /*
  *
  */
-static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
-                          sigset_t *set, struct pt_regs * regs)
+static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+                         sigset_t *set, struct pt_regs * regs)
 {
        struct rt_sigframe __user *frame;
        int rsig;
@@ -457,17 +462,21 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 
        set_fs(USER_DS);
 
+       /* the tracer may want to single-step inside the handler */
+       if (test_thread_flag(TIF_SINGLESTEP))
+               ptrace_notify(SIGTRAP);
+
 #if DEBUG_SIG
        printk("SIG deliver %d (%s:%d): sp=%p pc=%lx ra=%p\n",
-               sig, current->comm, current->pid, frame, regs->pc, frame->pretcode);
+               sig, current->comm, current->pid, frame, regs->pc,
+              frame->pretcode);
 #endif
 
-       return;
+       return 1;
 
 give_sigsegv:
-       if (sig == SIGSEGV)
-               ka->sa.sa_handler = SIG_DFL;
        force_sig(SIGSEGV, current);
+       return 0;
 
 } /* end setup_rt_frame() */
 
@@ -475,10 +484,12 @@ give_sigsegv:
 /*
  * OK, we're invoking a handler
  */
-static void handle_signal(unsigned long sig, siginfo_t *info,
-                         struct k_sigaction *ka, sigset_t *oldset,
-                         struct pt_regs *regs)
+static int handle_signal(unsigned long sig, siginfo_t *info,
+                        struct k_sigaction *ka, sigset_t *oldset,
+                        struct pt_regs *regs)
 {
+       int ret;
+
        /* Are we from a system call? */
        if (in_syscall(regs)) {
                /* If so, check system call restarting.. */
@@ -493,6 +504,7 @@ static void handle_signal(unsigned long sig, siginfo_t *info,
                                regs->gr8 = -EINTR;
                                break;
                        }
+
                        /* fallthrough */
                case -ERESTARTNOINTR:
                        regs->gr8 = regs->orig_gr8;
@@ -502,16 +514,22 @@ static void handle_signal(unsigned long sig, siginfo_t *info,
 
        /* Set up the stack frame */
        if (ka->sa.sa_flags & SA_SIGINFO)
-               setup_rt_frame(sig, ka, info, oldset, regs);
+               ret = setup_rt_frame(sig, ka, info, oldset, regs);
        else
-               setup_frame(sig, ka, oldset, regs);
+               ret = setup_frame(sig, ka, oldset, regs);
+
+       if (ret) {
+               spin_lock_irq(&current->sighand->siglock);
+               sigorsets(&current->blocked, &current->blocked,
+                         &ka->sa.sa_mask);
+               if (!(ka->sa.sa_flags & SA_NODEFER))
+                       sigaddset(&current->blocked, sig);
+               recalc_sigpending();
+               spin_unlock_irq(&current->sighand->siglock);
+       }
+
+       return ret;
 
-       spin_lock_irq(&current->sighand->siglock);
-       sigorsets(&current->blocked, &current->blocked, &ka->sa.sa_mask);
-       if (!(ka->sa.sa_flags & SA_NODEFER))
-               sigaddset(&current->blocked, sig);
-       recalc_sigpending();
-       spin_unlock_irq(&current->sighand->siglock);
 } /* end handle_signal() */
 
 /*****************************************************************************/
@@ -542,12 +560,10 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
                oldset = &current->blocked;
 
        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
-       if (signr > 0) {
-               handle_signal(signr, &info, &ka, oldset, regs);
-               return 1;
-       }
+       if (signr > 0)
+               return handle_signal(signr, &info, &ka, oldset, regs);
 
- no_signal:
+no_signal:
        /* Did we come from a system call? */
        if (regs->syscallno >= 0) {
                /* Restart the system call - no handlers present */
@@ -565,6 +581,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
        }
 
        return 0;
+
 } /* end do_signal() */
 
 /*****************************************************************************/