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ARM: 7424/1: update die handler from x86 

Robustify ARM's die() handling with improvements from x86:

 - Fix for a deadlock (before panic in the case of panic_on_oops) if we
   oops under a spinlock which is also used from interrupt handler,
   since the old code was unconditionally enabling interrupts.

 - Usage of arch spinlock so lockdep etc doesn't get involved while
   we're trying to dump out oopses.

 - Deadlock prevention in the unlikely event that die() recurses.

The changes all touch the same few lines of code, so they're done
together in one patch.

Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Rabin Vincent 2012-06-15 10:23:32 +01:00 committed by Russell King
parent ffae894035
commit 02df19b422
1 changed files with 55 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
arch/arm/kernel/traps.c
View File

@ -233,9 +233,9 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
#define S_ISA " ARM"
#endif
static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
static int __die(const char *str, int err, struct pt_regs *regs)
{
struct task_struct *tsk = thread->task;
struct task_struct *tsk = current;
static int die_counter;
int ret;
@ -245,12 +245,12 @@ static int __die(const char *str, int err, struct thread_info *thread, struct pt
/* 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;
return 1;
print_modules();
__show_regs(regs);
printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
if (!user_mode(regs) || in_interrupt()) {
dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
@ -259,45 +259,77 @@ static int __die(const char *str, int err, struct thread_info *thread, struct pt
dump_instr(KERN_EMERG, regs);
}
return ret;
return 0;
}
static DEFINE_RAW_SPINLOCK(die_lock);
static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;
/*
* This function is protected against re-entrancy.
*/
void die(const char *str, struct pt_regs *regs, int err)
static unsigned long oops_begin(void)
{
struct thread_info *thread = current_thread_info();
int ret;
enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
int cpu;
unsigned long flags;
oops_enter();
raw_spin_lock_irq(&die_lock);
/* racy, but better than risking deadlock. */
raw_local_irq_save(flags);
cpu = smp_processor_id();
if (!arch_spin_trylock(&die_lock)) {
if (cpu == die_owner)
/* nested oops. should stop eventually */;
else
arch_spin_lock(&die_lock);
}
die_nest_count++;
die_owner = cpu;
console_verbose();
bust_spinlocks(1);
if (!user_mode(regs))
bug_type = report_bug(regs->ARM_pc, regs);
if (bug_type != BUG_TRAP_TYPE_NONE)
str = "Oops - BUG";
ret = __die(str, err, thread, regs);
return flags;
}
if (regs && kexec_should_crash(thread->task))
static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
{
if (regs && kexec_should_crash(current))
crash_kexec(regs);
bust_spinlocks(0);
die_owner = -1;
add_taint(TAINT_DIE);
raw_spin_unlock_irq(&die_lock);
die_nest_count--;
if (!die_nest_count)
/* Nest count reaches zero, release the lock. */
arch_spin_unlock(&die_lock);
raw_local_irq_restore(flags);
oops_exit();
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
if (ret != NOTIFY_STOP)
do_exit(SIGSEGV);
if (signr)
do_exit(signr);
}
/*
* This function is protected against re-entrancy.
*/
void die(const char *str, struct pt_regs *regs, int err)
{
enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
unsigned long flags = oops_begin();
int sig = SIGSEGV;
if (!user_mode(regs))
bug_type = report_bug(regs->ARM_pc, regs);
if (bug_type != BUG_TRAP_TYPE_NONE)
str = "Oops - BUG";
if (__die(str, err, regs))
sig = 0;
oops_end(flags, regs, sig);
}
void arm_notify_die(const char *str, struct pt_regs *regs,