[MIPS] Rewrite get_wchan and its helper functions using kallsyms_lookup.

    
Implement get_wchan() and frame_info_init() using kallsyms_lookup().
This fixes problem with static sched/lock functions and mfinfo[]
maintenance issue.  If CONFIG_KALLSYMS was disabled, get_wchan() just
returns thread_saved_pc() value.
    
Also unwind stackframe based on "addiu sp,-imm" analysis instead of
frame pointer.  This fixes problem with functions compiled without
-fomit-frame-pointer.
    
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 77 insertions, 81 deletions

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 5232fc752935..092679c2dca9 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -25,6 +25,7 @@
 #include <linux/a.out.h>
 #include <linux/init.h>
 #include <linux/completion.h>
+#include <linux/kallsyms.h>
 
 #include <asm/abi.h>
 #include <asm/bootinfo.h>
@@ -272,46 +273,19 @@ long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 
 static struct mips_frame_info {
         void *func;
-        int omit_fp;    /* compiled without fno-omit-frame-pointer */
-        int frame_offset;
+        unsigned long func_size;
+        int frame_size;
         int pc_offset;
-} schedule_frame, mfinfo[] = {
-        { schedule, 0 },        /* must be first */
-        /* arch/mips/kernel/semaphore.c */
-        { __down, 1 },
-        { __down_interruptible, 1 },
-        /* kernel/sched.c */
-#ifdef CONFIG_PREEMPT
-        { preempt_schedule, 0 },
-#endif
-        { wait_for_completion, 0 },
-        { interruptible_sleep_on, 0 },
-        { interruptible_sleep_on_timeout, 0 },
-        { sleep_on, 0 },
-        { sleep_on_timeout, 0 },
-        { yield, 0 },
-        { io_schedule, 0 },
-        { io_schedule_timeout, 0 },
-#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
-        { __preempt_spin_lock, 0 },
-        { __preempt_write_lock, 0 },
-#endif
-        /* kernel/timer.c */
-        { schedule_timeout, 1 },
-/*      { nanosleep_restart, 1 }, */
-        /* lib/rwsem-spinlock.c */
-        { __down_read, 1 },
-        { __down_write, 1 },
-};
+} *schedule_frame, mfinfo[64];
+static int mfinfo_num;
 
-static int mips_frame_info_initialized;
 static int __init get_frame_info(struct mips_frame_info *info)
 {
         int i;
         void *func = info->func;
         union mips_instruction *ip = (union mips_instruction *)func;
         info->pc_offset = -1;
-        info->frame_offset = info->omit_fp ? 0 : -1;
+        info->frame_size = 0;
         for (i = 0; i < 128; i++, ip++) {
                 /* if jal, jalr, jr, stop. */
                 if (ip->j_format.opcode == jal_op ||
@@ -320,6 +294,23 @@ static int __init get_frame_info(struct mips_frame_info *info)
                       ip->r_format.func == jr_op)))
                         break;
 
+                if (info->func_size && i >= info->func_size / 4)
+                        break;
+                if (
+#ifdef CONFIG_32BIT
+                    ip->i_format.opcode == addiu_op &&
+#endif
+#ifdef CONFIG_64BIT
+                    ip->i_format.opcode == daddiu_op &&
+#endif
+                    ip->i_format.rs == 29 &&
+                    ip->i_format.rt == 29) {
+                        /* addiu/daddiu sp,sp,-imm */
+                        if (info->frame_size)
+                                continue;
+                        info->frame_size = - ip->i_format.simmediate;
+                }
+
                 if (
 #ifdef CONFIG_32BIT
                     ip->i_format.opcode == sw_op &&
@@ -327,31 +318,20 @@ static int __init get_frame_info(struct mips_frame_info *info)
 #ifdef CONFIG_64BIT
                     ip->i_format.opcode == sd_op &&
 #endif
-                    ip->i_format.rs == 29)
-                {
+                    ip->i_format.rs == 29 &&
+                    ip->i_format.rt == 31) {
                         /* sw / sd $ra, offset($sp) */
-                        if (ip->i_format.rt == 31) {
-                                if (info->pc_offset != -1)
-                                        continue;
-                                info->pc_offset =
-                                        ip->i_format.simmediate / sizeof(long);
-                        }
-                        /* sw / sd $s8, offset($sp) */
-                        if (ip->i_format.rt == 30) {
-//#if 0 /* gcc 3.4 does aggressive optimization... */
-                                if (info->frame_offset != -1)
-                                        continue;
-//#endif
-                                info->frame_offset =
-                                        ip->i_format.simmediate / sizeof(long);
-                        }
+                        if (info->pc_offset != -1)
+                                continue;
+                        info->pc_offset =
+                                ip->i_format.simmediate / sizeof(long);
                 }
         }
-        if (info->pc_offset == -1 || info->frame_offset == -1) {
-                printk("Can't analyze prologue code at %p\n", func);
+        if (info->pc_offset == -1 || info->frame_size == 0) {
+                if (func == schedule)
+                        printk("Can't analyze prologue code at %p\n", func);
                 info->pc_offset = -1;
-                info->frame_offset = -1;
-                return -1;
+                info->frame_size = 0;
         }
 
         return 0;
@@ -359,25 +339,36 @@ static int __init get_frame_info(struct mips_frame_info *info)
 
 static int __init frame_info_init(void)
 {
-        int i, found;
-        for (i = 0; i < ARRAY_SIZE(mfinfo); i++)
-                if (get_frame_info(&mfinfo[i]))
-                        return -1;
-        schedule_frame = mfinfo[0];
-        /* bubble sort */
-        do {
-                struct mips_frame_info tmp;
-                found = 0;
-                for (i = 1; i < ARRAY_SIZE(mfinfo); i++) {
-                        if (mfinfo[i-1].func > mfinfo[i].func) {
-                                tmp = mfinfo[i];
-                                mfinfo[i] = mfinfo[i-1];
-                                mfinfo[i-1] = tmp;
-                                found = 1;
-                        }
-                }
-        } while (found);
-        mips_frame_info_initialized = 1;
+        int i;
+#ifdef CONFIG_KALLSYMS
+        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];
+#endif
+        for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++)
+                get_frame_info(&mfinfo[i]);
+
+        mfinfo_num = i;
         return 0;
 }
 
@@ -394,47 +385,52 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
         if (t->reg31 == (unsigned long) ret_from_fork)
                 return t->reg31;
 
-        if (schedule_frame.pc_offset < 0)
+        if (!schedule_frame || schedule_frame->pc_offset < 0)
                 return 0;
-        return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
+        return ((unsigned long *)t->reg29)[schedule_frame->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 frame, pc;
+        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 || !mips_frame_info_initialized)
+        if (!stack_page || !mfinfo_num)
                 return 0;
 
         pc = thread_saved_pc(p);
+#ifdef CONFIG_KALLSYMS
         if (!in_sched_functions(pc))
                 return pc;
 
-        frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
+        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 = ARRAY_SIZE(mfinfo) - 1; i >= 0; i--) {
+                for (i = mfinfo_num - 1; i >= 0; i--) {
                         if (pc >= (unsigned long) mfinfo[i].func)
                                 break;
                 }
                 if (i < 0)
                         break;
 
-                if (mfinfo[i].omit_fp)
-                        break;
                 pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
-                frame = ((unsigned long *)frame)[mfinfo[i].frame_offset];
+                if (!mfinfo[i].frame_size)
+                        break;
+                frame += mfinfo[i].frame_size;
         } while (in_sched_functions(pc));
+#endif
 
         return pc;
 }