[Blackfin] arch: fix bug - when we crash, current is not valid
Sometimes when we crash, current is not valid, (has been written
over), so the existing code causes a invalid read during exception
context - which is a unrecoverable double fault. This fixes this.
Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
diff --git a/arch/blackfin/kernel/traps.c b/arch/blackfin/kernel/traps.c
index e8e8f73..7557d0d 100644
--- a/arch/blackfin/kernel/traps.c
+++ b/arch/blackfin/kernel/traps.c
@@ -655,21 +655,30 @@
else if (context & 0x8000)
printk(KERN_NOTICE "Kernel process context\n");
- if (current->pid && current->mm) {
+ /* Because we are crashing, and pointers could be bad, we check things
+ * pretty closely before we use them
+ */
+ if (!((unsigned long)current & 0x3) && current->pid) {
printk(KERN_NOTICE "CURRENT PROCESS:\n");
- printk(KERN_NOTICE "COMM=%s PID=%d\n",
- current->comm, current->pid);
+ if (current->comm >= (char *)FIXED_CODE_START)
+ printk(KERN_NOTICE "COMM=%s PID=%d\n",
+ current->comm, current->pid);
+ else
+ printk(KERN_NOTICE "COMM= invalid\n");
- printk(KERN_NOTICE "TEXT = 0x%p-0x%p DATA = 0x%p-0x%p\n"
- KERN_NOTICE "BSS = 0x%p-0x%p USER-STACK = 0x%p\n"
- KERN_NOTICE "\n",
- (void *)current->mm->start_code,
- (void *)current->mm->end_code,
- (void *)current->mm->start_data,
- (void *)current->mm->end_data,
- (void *)current->mm->end_data,
- (void *)current->mm->brk,
- (void *)current->mm->start_stack);
+ if (!((unsigned long)current->mm & 0x3) && (unsigned long)current->mm >= FIXED_CODE_START)
+ printk(KERN_NOTICE "TEXT = 0x%p-0x%p DATA = 0x%p-0x%p\n"
+ KERN_NOTICE " BSS = 0x%p-0x%p USER-STACK = 0x%p\n"
+ KERN_NOTICE "\n",
+ (void *)current->mm->start_code,
+ (void *)current->mm->end_code,
+ (void *)current->mm->start_data,
+ (void *)current->mm->end_data,
+ (void *)current->mm->end_data,
+ (void *)current->mm->brk,
+ (void *)current->mm->start_stack);
+ else
+ printk(KERN_NOTICE "invalid mm\n");
} else
printk(KERN_NOTICE "\n" KERN_NOTICE
"No Valid process in current context\n");