parisc: Stop unwinding at start of stack

Check stack pointer if we are reaching the stack end and stop unwinding
if we do. This fixes early backtraces and avoids showing unrealistic
call stacks.

Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/kernel/unwind.c b/arch/parisc/kernel/unwind.c
index 48dc7d4d20bba5e6fdb8669ae6d03b3ed3cb27c4..caab39dfa95d606564af62d3fd565eef6fc41757 100644 (file)
--- a/arch/parisc/kernel/unwind.c
+++ b/arch/parisc/kernel/unwind.c
@@ -14,6 +14,7 @@
 #include <linux/slab.h>
 #include <linux/kallsyms.h>
 #include <linux/sort.h>
+#include <linux/sched.h>
 
 #include <linux/uaccess.h>
 #include <asm/assembly.h>
@@ -279,6 +280,17 @@ static void unwind_frame_regs(struct unwind_frame_info *info)
 
                        info->prev_sp = sp - 64;
                        info->prev_ip = 0;
+
+                       /* The stack is at the end inside the thread_union
+                        * struct. If we reach data, we have reached the
+                        * beginning of the stack and should stop unwinding. */
+                       if (info->prev_sp >= (unsigned long) task_thread_info(info->t) &&
+                           info->prev_sp < ((unsigned long) task_thread_info(info->t)
+                                               + THREAD_SZ_ALGN)) {
+                               info->prev_sp = 0;
+                               break;
+                       }
+
                        if (get_user(tmp, (unsigned long *)(info->prev_sp - RP_OFFSET))) 
                                break;
                        info->prev_ip = tmp;