[PARISC] Fix show_stack() when we can't kmalloc

show_stack() was calling kzalloc() to allocate a struct pt_regs.
This meant that *really* early stack dumps would cause a null pointer
dereference.  x86_64 allocates its pt_regs on the stack, so do the same.

Kyle actually committed this exact patch to CVS on
Wed Jul 26 14:32:39 2006 UTC, and never moved it across to git.
Bad Kyle.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

1 files changed, 10 insertions, 9 deletions

diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index fa0811295acc..949722540864 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -187,18 +187,19 @@ void show_stack(struct task_struct *task, unsigned long *s)
 
         if (!task) {
                 unsigned long sp;
-                struct pt_regs *r;
 
 HERE:
                 asm volatile ("copy %%r30, %0" : "=r"(sp));
-                r = kzalloc(sizeof(struct pt_regs), GFP_KERNEL);
-                if (!r)
-                        return;
-                r->iaoq[0] = (unsigned long)&&HERE;
-                r->gr[2] = (unsigned long)__builtin_return_address(0);
-                r->gr[30] = sp;
-                unwind_frame_init(&info, current, r);
-                kfree(r);
+                {
+                        struct pt_regs r;
+
+                        memset(&r, 0, sizeof(struct pt_regs));
+                        r.iaoq[0] = (unsigned long)&&HERE;
+                        r.gr[2] = (unsigned long)__builtin_return_address(0);
+                        r.gr[30] = sp;
+
+                        unwind_frame_init(&info, current, &r);
+                }
         } else {
                 unwind_frame_init_from_blocked_task(&info, task);
         }