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-rw-r--r--Documentation/kernel-parameters.txt5
-rw-r--r--arch/i386/kernel/traps.c3
-rw-r--r--arch/i386/mm/fault.c39
-rw-r--r--include/linux/kernel.h3
-rw-r--r--kernel/panic.c97
5 files changed, 130 insertions, 17 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 880be3a..7b7382d 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1126,6 +1126,11 @@ running once the system is up.
pas16= [HW,SCSI]
See header of drivers/scsi/pas16.c.
+ pause_on_oops=
+ Halt all CPUs after the first oops has been printed for
+ the specified number of seconds. This is to be used if
+ your oopses keep scrolling off the screen.
+
pcbit= [HW,ISDN]
pcd. [PARIDE]
diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 1b7ad41..de5386b 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -352,6 +352,8 @@ void die(const char * str, struct pt_regs * regs, long err)
static int die_counter;
unsigned long flags;
+ oops_enter();
+
if (die.lock_owner != raw_smp_processor_id()) {
console_verbose();
spin_lock_irqsave(&die.lock, flags);
@@ -404,6 +406,7 @@ void die(const char * str, struct pt_regs * regs, long err)
ssleep(5);
panic("Fatal exception");
}
+ oops_exit();
do_exit(SIGSEGV);
}
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 47a3b72..7f0fcf2 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -509,24 +509,31 @@ no_context:
bust_spinlocks(1);
-#ifdef CONFIG_X86_PAE
- if (error_code & 16) {
- pte_t *pte = lookup_address(address);
-
- if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
- printk(KERN_CRIT "kernel tried to execute NX-protected page - exploit attempt? (uid: %d)\n", current->uid);
+ if (oops_may_print()) {
+ #ifdef CONFIG_X86_PAE
+ if (error_code & 16) {
+ pte_t *pte = lookup_address(address);
+
+ if (pte && pte_present(*pte) && !pte_exec_kernel(*pte))
+ printk(KERN_CRIT "kernel tried to execute "
+ "NX-protected page - exploit attempt? "
+ "(uid: %d)\n", current->uid);
+ }
+ #endif
+ if (address < PAGE_SIZE)
+ printk(KERN_ALERT "BUG: unable to handle kernel NULL "
+ "pointer dereference");
+ else
+ printk(KERN_ALERT "BUG: unable to handle kernel paging"
+ " request");
+ printk(" at virtual address %08lx\n",address);
+ printk(KERN_ALERT " printing eip:\n");
+ printk("%08lx\n", regs->eip);
}
-#endif
- if (address < PAGE_SIZE)
- printk(KERN_ALERT "BUG: unable to handle kernel NULL pointer dereference");
- else
- printk(KERN_ALERT "BUG: unable to handle kernel paging request");
- printk(" at virtual address %08lx\n",address);
- printk(KERN_ALERT " printing eip:\n");
- printk("%08lx\n", regs->eip);
page = read_cr3();
page = ((unsigned long *) __va(page))[address >> 22];
- printk(KERN_ALERT "*pde = %08lx\n", page);
+ if (oops_may_print())
+ printk(KERN_ALERT "*pde = %08lx\n", page);
/*
* We must not directly access the pte in the highpte
* case, the page table might be allocated in highmem.
@@ -534,7 +541,7 @@ no_context:
* it's allocated already.
*/
#ifndef CONFIG_HIGHPTE
- if (page & 1) {
+ if ((page & 1) && oops_may_print()) {
page &= PAGE_MASK;
address &= 0x003ff000;
page = ((unsigned long *) __va(page))[address >> PAGE_SHIFT];
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 3b507bf..bb6e7dd 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -91,6 +91,9 @@ extern struct notifier_block *panic_notifier_list;
extern long (*panic_blink)(long time);
NORET_TYPE void panic(const char * fmt, ...)
__attribute__ ((NORET_AND format (printf, 1, 2)));
+extern void oops_enter(void);
+extern void oops_exit(void);
+extern int oops_may_print(void);
fastcall NORET_TYPE void do_exit(long error_code)
ATTRIB_NORET;
NORET_TYPE void complete_and_exit(struct completion *, long)
diff --git a/kernel/panic.c b/kernel/panic.c
index 126dc43..acd95ad 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -20,10 +20,13 @@
#include <linux/nmi.h>
#include <linux/kexec.h>
-int panic_timeout;
int panic_on_oops;
int tainted;
+static int pause_on_oops;
+static int pause_on_oops_flag;
+static DEFINE_SPINLOCK(pause_on_oops_lock);
+int panic_timeout;
EXPORT_SYMBOL(panic_timeout);
struct notifier_block *panic_notifier_list;
@@ -174,3 +177,95 @@ void add_taint(unsigned flag)
tainted |= flag;
}
EXPORT_SYMBOL(add_taint);
+
+static int __init pause_on_oops_setup(char *str)
+{
+ pause_on_oops = simple_strtoul(str, NULL, 0);
+ return 1;
+}
+__setup("pause_on_oops=", pause_on_oops_setup);
+
+static void spin_msec(int msecs)
+{
+ int i;
+
+ for (i = 0; i < msecs; i++) {
+ touch_nmi_watchdog();
+ mdelay(1);
+ }
+}
+
+/*
+ * It just happens that oops_enter() and oops_exit() are identically
+ * implemented...
+ */
+static void do_oops_enter_exit(void)
+{
+ unsigned long flags;
+ static int spin_counter;
+
+ if (!pause_on_oops)
+ return;
+
+ spin_lock_irqsave(&pause_on_oops_lock, flags);
+ if (pause_on_oops_flag == 0) {
+ /* This CPU may now print the oops message */
+ pause_on_oops_flag = 1;
+ } else {
+ /* We need to stall this CPU */
+ if (!spin_counter) {
+ /* This CPU gets to do the counting */
+ spin_counter = pause_on_oops;
+ do {
+ spin_unlock(&pause_on_oops_lock);
+ spin_msec(MSEC_PER_SEC);
+ spin_lock(&pause_on_oops_lock);
+ } while (--spin_counter);
+ pause_on_oops_flag = 0;
+ } else {
+ /* This CPU waits for a different one */
+ while (spin_counter) {
+ spin_unlock(&pause_on_oops_lock);
+ spin_msec(1);
+ spin_lock(&pause_on_oops_lock);
+ }
+ }
+ }
+ spin_unlock_irqrestore(&pause_on_oops_lock, flags);
+}
+
+/*
+ * Return true if the calling CPU is allowed to print oops-related info. This
+ * is a bit racy..
+ */
+int oops_may_print(void)
+{
+ return pause_on_oops_flag == 0;
+}
+
+/*
+ * Called when the architecture enters its oops handler, before it prints
+ * anything. If this is the first CPU to oops, and it's oopsing the first time
+ * then let it proceed.
+ *
+ * This is all enabled by the pause_on_oops kernel boot option. We do all this
+ * to ensure that oopses don't scroll off the screen. It has the side-effect
+ * of preventing later-oopsing CPUs from mucking up the display, too.
+ *
+ * It turns out that the CPU which is allowed to print ends up pausing for the
+ * right duration, whereas all the other CPUs pause for twice as long: once in
+ * oops_enter(), once in oops_exit().
+ */
+void oops_enter(void)
+{
+ do_oops_enter_exit();
+}
+
+/*
+ * Called when the architecture exits its oops handler, after printing
+ * everything.
+ */
+void oops_exit(void)
+{
+ do_oops_enter_exit();
+}
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