CRISv32: handle multiple signals

Al Viro noted that CRIS fails to handle multiple signals.

This fixes the problem for CRISv32 by making it use a C work_pending
handling loop similar to the ARM implementation in 0a267fa6a15d41c
("ARM: 7472/1: pull all work_pending logics into C function").

This also happens to fixes the warnings which currently trigger on
CRISv32 due to do_signal() being called with interrupts disabled.

Test case (should die of the SIGSEGV which gets raised when setting up
the stack for SIGALRM, but instead reaches and executes the _exit(1)):

  #include <unistd.h>
  #include <signal.h>
  #include <sys/time.h>
  #include <err.h>

  static void handler(int sig) { }

  int main(int argc, char *argv[])
  {
  	int ret;
  	struct itimerval t1 = { .it_value = {1} };
  	stack_t ss = {
  		.ss_sp = NULL,
  		.ss_size = SIGSTKSZ,
  	};
  	struct sigaction action = {
  		.sa_handler = handler,
  		.sa_flags = SA_ONSTACK,
  	};

  	ret = sigaltstack(&ss, NULL);
  	if (ret < 0)
  		err(1, "sigaltstack");

  	sigaction(SIGALRM, &action, NULL);
   	setitimer(ITIMER_REAL, &t1, NULL);

  	pause();

  	_exit(1);

  	return 0;
  }

Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Link: http://lkml.kernel.org/r/20121208074429.GC4939@ZenIV.linux.org.uk
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Jesper Nilsson <jespern@axis.com>

2 files changed, 26 insertions, 32 deletions

diff --git a/arch/cris/arch-v32/kernel/entry.S b/arch/cris/arch-v32/kernel/entry.S
index 1ea29b7f263c..026a0b21b8f0 100644
--- a/arch/cris/arch-v32/kernel/entry.S
+++ b/arch/cris/arch-v32/kernel/entry.S
@@ -281,43 +281,14 @@ _syscall_exit_work:
         .type   _work_pending,@function
 _work_pending:
         addoq   +TI_flags, $r0, $acr
-        move.d  [$acr], $r10
-        btstq   TIF_NEED_RESCHED, $r10  ; Need resched?
-        bpl     _work_notifysig         ; No, must be signal/notify.
-        nop
-        .size   _work_pending, . - _work_pending
-
-        .type   _work_resched,@function
-_work_resched:
-        move.d  $r9, $r1                ; Preserve R9.
-        jsr     schedule
-        nop
-        move.d  $r1, $r9
-        di
-
-        addoq   +TI_flags, $r0, $acr
-        move.d  [$acr], $r1
-        and.d   _TIF_WORK_MASK, $r1     ; Ignore sycall trace counter.
-        beq     _Rexit
-        nop
-        btstq   TIF_NEED_RESCHED, $r1
-        bmi     _work_resched           ; current->work.need_resched.
-        nop
-        .size   _work_resched, . - _work_resched
-
-        .type   _work_notifysig,@function
-_work_notifysig:
-        ;; Deal with pending signals and notify-resume requests.
-
-        addoq   +TI_flags, $r0, $acr
         move.d  [$acr], $r12            ; The thread_info_flags parameter.
         move.d  $sp, $r11               ; The regs param.
-        jsr     do_notify_resume
-        move.d  $r9, $r10               ; do_notify_resume syscall/irq param.
+        jsr     do_work_pending
+        move.d  $r9, $r10               ; The syscall/irq param.
 
         ba _Rexit
         nop
-        .size   _work_notifysig, . - _work_notifysig
+        .size   _work_pending, . - _work_pending
 
         ;; We get here as a sidetrack when we've entered a syscall with the
         ;; trace-bit set. We need to call do_syscall_trace and then continue
diff --git a/arch/cris/kernel/ptrace.c b/arch/cris/kernel/ptrace.c
index 58d44ee1a71f..fd3427e563c5 100644
--- a/arch/cris/kernel/ptrace.c
+++ b/arch/cris/kernel/ptrace.c
@@ -42,3 +42,26 @@ void do_notify_resume(int canrestart, struct pt_regs *regs,
                 tracehook_notify_resume(regs);
         }
 }
+
+void do_work_pending(int syscall, struct pt_regs *regs,
+                     unsigned int thread_flags)
+{
+        do {
+                if (likely(thread_flags & _TIF_NEED_RESCHED)) {
+                        schedule();
+                } else {
+                        if (unlikely(!user_mode(regs)))
+                                return;
+                        local_irq_enable();
+                        if (thread_flags & _TIF_SIGPENDING) {
+                                do_signal(syscall, regs);
+                                syscall = 0;
+                        } else {
+                                clear_thread_flag(TIF_NOTIFY_RESUME);
+                                tracehook_notify_resume(regs);
+                        }
+                }
+                local_irq_disable();
+                thread_flags = current_thread_info()->flags;
+        } while (thread_flags & _TIF_WORK_MASK);
+}