11 files changed, 66 insertions, 23 deletions

diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
index a021681d21f8..8bdb4b6af0ff 100644
--- a/arch/i386/kernel/crash.c
+++ b/arch/i386/kernel/crash.c
@@ -100,12 +100,31 @@ static void crash_get_current_regs(struct pt_regs *regs)
         regs->eip = (unsigned long)current_text_addr();
 }
 
-static void crash_save_self(void)
+/* CPU does not save ss and esp on stack if execution is already
+ * running in kernel mode at the time of NMI occurrence. This code
+ * fixes it.
+ */
+static void crash_setup_regs(struct pt_regs *newregs, struct pt_regs *oldregs)
+{
+        memcpy(newregs, oldregs, sizeof(*newregs));
+        newregs->esp = (unsigned long)&(oldregs->esp);
+        __asm__ __volatile__("xorl %eax, %eax;");
+        __asm__ __volatile__ ("movw %%ss, %%ax;" :"=a"(newregs->xss));
+}
+
+/* We may have saved_regs from where the error came from
+ * or it is NULL if via a direct panic().
+ */
+static void crash_save_self(struct pt_regs *saved_regs)
 {
         struct pt_regs regs;
         int cpu;
         cpu = smp_processor_id();
-        crash_get_current_regs(&regs);
+
+        if (saved_regs)
+                crash_setup_regs(&regs, saved_regs);
+        else
+                crash_get_current_regs(&regs);
         crash_save_this_cpu(&regs, cpu);
 }
 
@@ -124,15 +143,8 @@ static int crash_nmi_callback(struct pt_regs *regs, int cpu)
                 return 1;
         local_irq_disable();
 
-        /* CPU does not save ss and esp on stack if execution is already
-         * running in kernel mode at the time of NMI occurrence. This code
-         * fixes it.
-         */
         if (!user_mode(regs)) {
-                memcpy(&fixed_regs, regs, sizeof(*regs));
-                fixed_regs.esp = (unsigned long)&(regs->esp);
-                __asm__ __volatile__("xorl %eax, %eax;");
-                __asm__ __volatile__ ("movw %%ss, %%ax;" :"=a"(fixed_regs.xss));
+                crash_setup_regs(&fixed_regs, regs);
                 regs = &fixed_regs;
         }
         crash_save_this_cpu(regs, cpu);
@@ -184,7 +196,7 @@ static void nmi_shootdown_cpus(void)
 }
 #endif
 
-void machine_crash_shutdown(void)
+void machine_crash_shutdown(struct pt_regs *regs)
 {
         /* This function is only called after the system
          * has paniced or is otherwise in a critical state.
@@ -204,5 +216,5 @@ void machine_crash_shutdown(void)
 #if defined(CONFIG_X86_IO_APIC)
         disable_IO_APIC();
 #endif
-        crash_save_self();
+        crash_save_self(regs);
 }
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 207ea8ba7169..e458463ebc05 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -27,6 +27,7 @@
 #include <linux/ptrace.h>
 #include <linux/utsname.h>
 #include <linux/kprobes.h>
+#include <linux/kexec.h>
 
 #ifdef CONFIG_EISA
 #include <linux/ioport.h>
@@ -294,6 +295,9 @@ bug:
         printk("Kernel BUG\n");
 }
 
+/* This is gone through when something in the kernel
+ * has done something bad and is about to be terminated.
+*/
 void die(const char * str, struct pt_regs * regs, long err)
 {
         static struct {
@@ -341,6 +345,10 @@ void die(const char * str, struct pt_regs * regs, long err)
         bust_spinlocks(0);
         die.lock_owner = -1;
         spin_unlock_irq(&die.lock);
+
+        if (kexec_should_crash(current))
+                crash_kexec(regs);
+
         if (in_interrupt())
                 panic("Fatal exception in interrupt");
 
@@ -570,6 +578,15 @@ void die_nmi (struct pt_regs *regs, const char *msg)
         console_silent();
         spin_unlock(&nmi_print_lock);
         bust_spinlocks(0);
+
+        /* If we are in kernel we are probably nested up pretty bad
+         * and might aswell get out now while we still can.
+        */
+        if (!user_mode(regs)) {
+                current->thread.trap_no = 2;
+                crash_kexec(regs);
+        }
+
         do_exit(SIGSEGV);
 }
 
diff --git a/arch/ppc/kernel/machine_kexec.c b/arch/ppc/kernel/machine_kexec.c
index 435ad9ea0a83..b82535357d6d 100644
--- a/arch/ppc/kernel/machine_kexec.c
+++ b/arch/ppc/kernel/machine_kexec.c
@@ -34,7 +34,7 @@ void machine_shutdown(void)
         }
 }
 
-void machine_crash_shutdown(void)
+void machine_crash_shutdown(struct pt_regs *regs)
 {
         if (ppc_md.machine_crash_shutdown) {
                 ppc_md.machine_crash_shutdown();
diff --git a/arch/ppc64/kernel/machine_kexec.c b/arch/ppc64/kernel/machine_kexec.c
index 217965d60a45..06b25b59c8a8 100644
--- a/arch/ppc64/kernel/machine_kexec.c
+++ b/arch/ppc64/kernel/machine_kexec.c
@@ -34,7 +34,7 @@ note_buf_t crash_notes[NR_CPUS];
  * and if what it will achieve. Letting it be now to compile the code
  * in generic kexec environment
  */
-void machine_crash_shutdown(void)
+void machine_crash_shutdown(struct pt_regs *regs)
 {
         /* do nothing right now */
         /* smp_relase_cpus() if we want smp on panic kernel */
diff --git a/arch/s390/kernel/crash.c b/arch/s390/kernel/crash.c
index db38283c1f27..7bd169c58b0c 100644
--- a/arch/s390/kernel/crash.c
+++ b/arch/s390/kernel/crash.c
@@ -12,6 +12,6 @@
 
 note_buf_t crash_notes[NR_CPUS];
 
-void machine_crash_shutdown(void)
+void machine_crash_shutdown(struct pt_regs *regs)
 {
 }
diff --git a/arch/x86_64/kernel/crash.c b/arch/x86_64/kernel/crash.c
index 6183bcb85257..d7fa4248501c 100644
--- a/arch/x86_64/kernel/crash.c
+++ b/arch/x86_64/kernel/crash.c
@@ -22,7 +22,7 @@
 
 note_buf_t crash_notes[NR_CPUS];
 
-void machine_crash_shutdown(void)
+void machine_crash_shutdown(struct pt_regs *regs)
 {
         /* This function is only called after the system
          * has paniced or is otherwise in a critical state.
diff --git a/drivers/char/sysrq.c b/drivers/char/sysrq.c
index 53b2c8fab00e..af79805b5576 100644
--- a/drivers/char/sysrq.c
+++ b/drivers/char/sysrq.c
@@ -100,7 +100,7 @@ static struct sysrq_key_op sysrq_unraw_op = {
 static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
                                 struct tty_struct *tty)
 {
-        crash_kexec();
+        crash_kexec(pt_regs);
 }
 static struct sysrq_key_op sysrq_crashdump_op = {
         .handler        = sysrq_handle_crashdump,
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 0653a27c3d72..7383173a3a9c 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -99,7 +99,8 @@ extern asmlinkage long compat_sys_kexec_load(unsigned long entry,
         unsigned long flags);
 #endif
 extern struct page *kimage_alloc_control_pages(struct kimage *image, unsigned int order);
-extern void crash_kexec(void);
+extern void crash_kexec(struct pt_regs *);
+int kexec_should_crash(struct task_struct *);
 extern struct kimage *kexec_image;
 
 #define KEXEC_ON_CRASH  0x00000001
@@ -123,6 +124,9 @@ extern struct kimage *kexec_image;
 extern struct resource crashk_res;
 
 #else /* !CONFIG_KEXEC */
-static inline void crash_kexec(void) { }
+struct pt_regs;
+struct task_struct;
+static inline void crash_kexec(struct pt_regs *regs) { }
+static inline int kexec_should_crash(struct task_struct *p) { return 0; }
 #endif /* CONFIG_KEXEC */
 #endif /* LINUX_KEXEC_H */
diff --git a/include/linux/reboot.h b/include/linux/reboot.h
index c5a05e16edb2..2d4dd23168dd 100644
--- a/include/linux/reboot.h
+++ b/include/linux/reboot.h
@@ -52,7 +52,8 @@ extern void machine_halt(void);
 extern void machine_power_off(void);
 
 extern void machine_shutdown(void);
-extern void machine_crash_shutdown(void);
+struct pt_regs;
+extern void machine_crash_shutdown(struct pt_regs *);
 
 #endif
 
diff --git a/kernel/kexec.c b/kernel/kexec.c
index a0411b3bd54a..277f22afe74b 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -18,6 +18,8 @@
 #include <linux/reboot.h>
 #include <linux/syscalls.h>
 #include <linux/ioport.h>
+#include <linux/hardirq.h>
+
 #include <asm/page.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
@@ -32,6 +34,13 @@ struct resource crashk_res = {
         .flags = IORESOURCE_BUSY | IORESOURCE_MEM
 };
 
+int kexec_should_crash(struct task_struct *p)
+{
+        if (in_interrupt() || !p->pid || p->pid == 1 || panic_on_oops)
+                return 1;
+        return 0;
+}
+
 /*
  * When kexec transitions to the new kernel there is a one-to-one
  * mapping between physical and virtual addresses.  On processors
@@ -1010,7 +1019,7 @@ asmlinkage long compat_sys_kexec_load(unsigned long entry,
 }
 #endif
 
-void crash_kexec(void)
+void crash_kexec(struct pt_regs *regs)
 {
         struct kimage *image;
         int locked;
@@ -1028,7 +1037,7 @@ void crash_kexec(void)
         if (!locked) {
                 image = xchg(&kexec_crash_image, NULL);
                 if (image) {
-                        machine_crash_shutdown();
+                        machine_crash_shutdown(regs);
                         machine_kexec(image);
                 }
                 xchg(&kexec_lock, 0);
diff --git a/kernel/panic.c b/kernel/panic.c
index 66f43d33cd80..74ba5f3e46c7 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -83,7 +83,7 @@ NORET_TYPE void panic(const char * fmt, ...)
          * everything else.
          * Do we want to call this before we try to display a message?
          */
-        crash_kexec();
+        crash_kexec(NULL);
 
 #ifdef CONFIG_SMP
         /*