CRIS: Add config for pausing a seg-faulting process

Put it on a wait queue, so we can attach gdb to the process
to debug it instead of just killing it.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>

2 files changed, 16 insertions, 3 deletions

diff --git a/arch/cris/Kconfig.debug b/arch/cris/Kconfig.debug
index 0a1d62a23614..0b9a630dc812 100644
--- a/arch/cris/Kconfig.debug
+++ b/arch/cris/Kconfig.debug
@@ -32,4 +32,10 @@ config DEBUG_NMI_OOPS
           If the system locks up without any debug information you can say Y
           here to make it possible to dump an OOPS with an external NMI.
 
+config NO_SEGFAULT_TERMINATION
+        bool "Keep segfaulting processes"
+        help
+          Place segfaulting user mode processes on a wait queue instead of
+          delivering a terminating SIGSEGV to allow debugging with gdb.
+
 endmenu
diff --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index a2b4c0b8f0fd..7705cd7cef36 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c
@@ -7,6 +7,7 @@
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
+#include <linux/wait.h>
 #include <asm/uaccess.h>
 
 extern int find_fixup_code(struct pt_regs *);
@@ -190,14 +191,20 @@ do_page_fault(unsigned long address, struct pt_regs *regs,
         /* User mode accesses just cause a SIGSEGV */
 
         if (user_mode(regs)) {
+                printk(KERN_NOTICE "%s (pid %d) segfaults for page "
+                        "address %08lx at pc %08lx\n",
+                        tsk->comm, tsk->pid,
+                        address, instruction_pointer(regs));
+#ifdef CONFIG_NO_SEGFAULT_TERMINATION
+                DECLARE_WAIT_QUEUE_HEAD(wq);
+                wait_event_interruptible(wq, 0 == 1);
+#else
                 info.si_signo = SIGSEGV;
                 info.si_errno = 0;
                 /* info.si_code has been set above */
                 info.si_addr = (void *)address;
                 force_sig_info(SIGSEGV, &info, tsk);
-                printk(KERN_NOTICE "%s (pid %d) segfaults for page "
-                       "address %08lx at pc %08lx\n",
-                       tsk->comm, tsk->pid, address, instruction_pointer(regs));
+#endif
                 return;
         }