1 files changed, 50 insertions, 82 deletions

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index b160ea30de0..2613a0dd4b8 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -273,13 +273,15 @@ long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
 
-static struct mips_frame_info {
-        void *func;
-        unsigned long func_size;
-        int frame_size;
-        int pc_offset;
-} *schedule_frame, mfinfo[64];
-static int mfinfo_num;
+/*
+ *
+ */
+struct mips_frame_info {
+        void            *func;
+        unsigned long   func_size;
+        int             frame_size;
+        int             pc_offset;
+};
 
 static inline int is_ra_save_ins(union mips_instruction *ip)
 {
@@ -348,45 +350,30 @@ err:
         return -1;
 }
 
+static struct mips_frame_info schedule_mfi __read_mostly;
+
 static int __init frame_info_init(void)
 {
-        int i;
+        unsigned long size = 0;
 #ifdef CONFIG_KALLSYMS
+        unsigned long ofs;
         char *modname;
         char namebuf[KSYM_NAME_LEN + 1];
-        unsigned long start, size, ofs;
-        extern char __sched_text_start[], __sched_text_end[];
-        extern char __lock_text_start[], __lock_text_end[];
-
-        start = (unsigned long)__sched_text_start;
-        for (i = 0; i < ARRAY_SIZE(mfinfo); i++) {
-                if (start == (unsigned long)schedule)
-                        schedule_frame = &mfinfo[i];
-                if (!kallsyms_lookup(start, &size, &ofs, &modname, namebuf))
-                        break;
-                mfinfo[i].func = (void *)(start + ofs);
-                mfinfo[i].func_size = size;
-                start += size - ofs;
-                if (start >= (unsigned long)__lock_text_end)
-                        break;
-                if (start == (unsigned long)__sched_text_end)
-                        start = (unsigned long)__lock_text_start;
-        }
-#else
-        mfinfo[0].func = schedule;
-        schedule_frame = &mfinfo[0];
+
+        kallsyms_lookup((unsigned long)schedule, &size, &ofs, &modname, namebuf);
 #endif
-        for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
-                get_frame_info(mfinfo + i);
+        schedule_mfi.func = schedule;
+        schedule_mfi.func_size = size;
+
+        get_frame_info(&schedule_mfi);
 
         /*
          * Without schedule() frame info, result given by
          * thread_saved_pc() and get_wchan() are not reliable.
          */
-        if (schedule_frame->pc_offset < 0)
+        if (schedule_mfi.pc_offset < 0)
                 printk("Can't analyze schedule() prologue at %p\n", schedule);
 
-        mfinfo_num = i;
         return 0;
 }
 
@@ -402,58 +389,11 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
         /* New born processes are a special case */
         if (t->reg31 == (unsigned long) ret_from_fork)
                 return t->reg31;
-
-        if (!schedule_frame || schedule_frame->pc_offset < 0)
+        if (schedule_mfi.pc_offset < 0)
                 return 0;
-        return ((unsigned long *)t->reg29)[schedule_frame->pc_offset];
+        return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];
 }
 
-/* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
-unsigned long get_wchan(struct task_struct *p)
-{
-        unsigned long stack_page;
-        unsigned long pc;
-#ifdef CONFIG_KALLSYMS
-        unsigned long frame;
-#endif
-
-        if (!p || p == current || p->state == TASK_RUNNING)
-                return 0;
-
-        stack_page = (unsigned long)task_stack_page(p);
-        if (!stack_page || !mfinfo_num)
-                return 0;
-
-        pc = thread_saved_pc(p);
-#ifdef CONFIG_KALLSYMS
-        if (!in_sched_functions(pc))
-                return pc;
-
-        frame = p->thread.reg29 + schedule_frame->frame_size;
-        do {
-                int i;
-
-                if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
-                        return 0;
-
-                for (i = mfinfo_num - 1; i >= 0; i--) {
-                        if (pc >= (unsigned long) mfinfo[i].func)
-                                break;
-                }
-                if (i < 0)
-                        break;
-
-                if (mfinfo[i].pc_offset < 0)
-                        break;
-                pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
-                if (!mfinfo[i].frame_size)
-                        break;
-                frame += mfinfo[i].frame_size;
-        } while (in_sched_functions(pc));
-#endif
-
-        return pc;
-}
 
 #ifdef CONFIG_KALLSYMS
 /* used by show_backtrace() */
@@ -504,3 +444,31 @@ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
         return __kernel_text_address(pc) ? pc : 0;
 }
 #endif
+
+/*
+ * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
+ */
+unsigned long get_wchan(struct task_struct *task)
+{
+        unsigned long pc = 0;
+#ifdef CONFIG_KALLSYMS
+        unsigned long sp;
+#endif
+
+        if (!task || task == current || task->state == TASK_RUNNING)
+                goto out;
+        if (!task_stack_page(task))
+                goto out;
+
+        pc = thread_saved_pc(task);
+
+#ifdef CONFIG_KALLSYMS
+        sp = task->thread.reg29 + schedule_mfi.frame_size;
+
+        while (in_sched_functions(pc))
+                pc = unwind_stack(task, &sp, pc, 0);
+#endif
+
+out:
+        return pc;
+}