3 files changed, 48 insertions, 0 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 182c6a39d5a2..ab38322111c4 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1383,6 +1383,12 @@ and is between 256 and 4096 characters. It is defined in the file
                         autoconfiguration.
                         Ranges are in pairs (memory base and size).
 
+        print-fatal-signals=
+                        [KNL] debug: print fatal signals
+                        print-fatal-signals=1: print segfault info to
+                        the kernel console.
+                        default: off.
+
         profile=        [KNL] Enable kernel profiling via /proc/profile
                         Format: [schedule,]<number>
                         Param: "schedule" - profile schedule points.
diff --git a/kernel/signal.c b/kernel/signal.c
index f9405609774e..39d122753bac 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -718,6 +718,37 @@ out_set:
 #define LEGACY_QUEUE(sigptr, sig) \
         (((sig) < SIGRTMIN) && sigismember(&(sigptr)->signal, (sig)))
 
+int print_fatal_signals;
+
+static void print_fatal_signal(struct pt_regs *regs, int signr)
+{
+        printk("%s/%d: potentially unexpected fatal signal %d.\n",
+                current->comm, current->pid, signr);
+
+#ifdef __i386__
+        printk("code at %08lx: ", regs->eip);
+        {
+                int i;
+                for (i = 0; i < 16; i++) {
+                        unsigned char insn;
+
+                        __get_user(insn, (unsigned char *)(regs->eip + i));
+                        printk("%02x ", insn);
+                }
+        }
+#endif
+        printk("\n");
+        show_regs(regs);
+}
+
+static int __init setup_print_fatal_signals(char *str)
+{
+        get_option (&str, &print_fatal_signals);
+
+        return 1;
+}
+
+__setup("print-fatal-signals=", setup_print_fatal_signals);
 
 static int
 specific_send_sig_info(int sig, struct siginfo *info, struct task_struct *t)
@@ -1855,6 +1886,8 @@ relock:
                  * Anything else is fatal, maybe with a core dump.
                  */
                 current->flags |= PF_SIGNALED;
+                if ((signr != SIGKILL) && print_fatal_signals)
+                        print_fatal_signal(regs, signr);
                 if (sig_kernel_coredump(signr)) {
                         /*
                          * If it was able to dump core, this kills all
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index ccaebbbd75ae..2cce2286bdcd 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -61,6 +61,7 @@ extern int proc_nr_files(ctl_table *table, int write, struct file *filp,
 
 /* External variables not in a header file. */
 extern int C_A_D;
+extern int print_fatal_signals;
 extern int sysctl_overcommit_memory;
 extern int sysctl_overcommit_ratio;
 extern int sysctl_panic_on_oom;
@@ -340,6 +341,14 @@ static ctl_table kern_table[] = {
                 .proc_handler   = &proc_dointvec,
         },
 #endif
+        {
+                .ctl_name       = CTL_UNNUMBERED,
+                .procname       = "print-fatal-signals",
+                .data           = &print_fatal_signals,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = &proc_dointvec,
+        },
 #ifdef __sparc__
         {
                 .ctl_name       = KERN_SPARC_REBOOT,