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Date: Thu, 14 Jan 2010 17:48:21 +0000
From: Russell King - ARM Linux <linux@....linux.org.uk>
To: Jason Wessel <jason.wessel@...driver.com>
Cc: linux-kernel@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net,
mingo@...e.hu, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 20/40] arm,kgdb: Add hook to catch an oops with debugger
On Thu, Jan 14, 2010 at 08:59:16AM -0600, Jason Wessel wrote:
> Add in a low level hook to catch calls to die() in the debugger.
>
> After the debugger is done, the standard system rules will be in play
> for the original exception.
>
> The kdb debugger wants a chance to catch these sorts of exceptions for
> analysis.
NAK. I have a similar patch which implements the hook properly - but
with one caveat. It needs a review to ensure that its safe to return
from die(). Until that's established, this patch can not be merged.
Please also ensure that the linux-arm-kernel list is copied with ARM
patches.
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index d65b2f5..5b66e51 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -73,8 +73,7 @@ extern unsigned int mem_fclk_21285;
struct pt_regs;
-void die(const char *msg, struct pt_regs *regs, int err)
- __attribute__((noreturn));
+void die(const char *msg, struct pt_regs *regs, int err);
struct siginfo;
void arm_notify_die(const char *str, struct pt_regs *regs, struct siginfo *info,
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index f838f36..29a0f4a 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -12,15 +12,17 @@
* 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
* kill the offending process.
*/
-#include <linux/module.h>
#include <linux/signal.h>
-#include <linux/spinlock.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
-#include <linux/delay.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
#include <linux/hardirq.h>
+#include <linux/kdebug.h>
+#include <linux/module.h>
+#include <linux/kexec.h>
+#include <linux/delay.h>
#include <linux/init.h>
-#include <linux/uaccess.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
@@ -224,14 +226,21 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
#define S_SMP ""
#endif
-static void __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
+static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
{
struct task_struct *tsk = thread->task;
static int die_counter;
+ int ret;
printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
str, err, ++die_counter);
sysfs_printk_last_file();
+
+ /* trap and error numbers are mostly meaningless on ARM */
+ ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
+ if (ret == NOTIFY_STOP)
+ return ret;
+
print_modules();
__show_regs(regs);
printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
@@ -243,6 +252,8 @@ static void __die(const char *str, int err, struct thread_info *thread, struct p
dump_backtrace(regs, tsk);
dump_instr(KERN_EMERG, regs);
}
+
+ return ret;
}
DEFINE_SPINLOCK(die_lock);
@@ -250,16 +261,21 @@ DEFINE_SPINLOCK(die_lock);
/*
* This function is protected against re-entrancy.
*/
-NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
+void die(const char *str, struct pt_regs *regs, int err)
{
struct thread_info *thread = current_thread_info();
+ int ret;
oops_enter();
spin_lock_irq(&die_lock);
console_verbose();
bust_spinlocks(1);
- __die(str, err, thread, regs);
+ ret = __die(str, err, thread, regs);
+
+ if (regs && kexec_should_crash(thread->task))
+ crash_kexec(regs);
+
bust_spinlocks(0);
add_taint(TAINT_DIE);
spin_unlock_irq(&die_lock);
@@ -267,11 +283,10 @@ NORET_TYPE void die(const char *str, struct pt_regs *regs, int err)
if (in_interrupt())
panic("Fatal exception in interrupt");
-
if (panic_on_oops)
panic("Fatal exception");
-
- do_exit(SIGSEGV);
+ if (ret != NOTIFY_STOP)
+ do_exit(SIGSEGV);
}
void arm_notify_die(const char *str, struct pt_regs *regs,
--
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