Fix wchan implementation, based on earlier by from Atsushi Nemoto.

Signed-off-by: Thiemo Seufer <ths@networkno.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 77 insertions, 58 deletions

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index e4f2f8011387..f99efce556ea 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -211,22 +211,48 @@ long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
         return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 }
 
-struct mips_frame_info {
+static struct mips_frame_info {
+        void *func;
+        int omit_fp;    /* compiled without fno-omit-frame-pointer */
         int frame_offset;
         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 },
 };
-static struct mips_frame_info schedule_frame;
-static struct mips_frame_info schedule_timeout_frame;
-static struct mips_frame_info sleep_on_frame;
-static struct mips_frame_info sleep_on_timeout_frame;
-static struct mips_frame_info wait_for_completion_frame;
+
 static int mips_frame_info_initialized;
-static int __init get_frame_info(struct mips_frame_info *info, void *func)
+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 = -1;
+        info->frame_offset = info->omit_fp ? 0 : -1;
         for (i = 0; i < 128; i++, ip++) {
                 /* if jal, jalr, jr, stop. */
                 if (ip->j_format.opcode == jal_op ||
@@ -247,14 +273,16 @@ static int __init get_frame_info(struct mips_frame_info *info, void *func)
                         /* sw / sd $ra, offset($sp) */
                         if (ip->i_format.rt == 31) {
                                 if (info->pc_offset != -1)
-                                        break;
+                                        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)
-                                        break;
+                                        continue;
+//#endif
                                 info->frame_offset =
                                         ip->i_format.simmediate / sizeof(long);
                         }
@@ -272,13 +300,25 @@ static int __init get_frame_info(struct mips_frame_info *info, void *func)
 
 static int __init frame_info_init(void)
 {
-        mips_frame_info_initialized =
-                !get_frame_info(&schedule_frame, schedule) &&
-                !get_frame_info(&schedule_timeout_frame, schedule_timeout) &&
-                !get_frame_info(&sleep_on_frame, sleep_on) &&
-                !get_frame_info(&sleep_on_timeout_frame, sleep_on_timeout) &&
-                !get_frame_info(&wait_for_completion_frame, wait_for_completion);
-
+        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;
         return 0;
 }
 
@@ -303,60 +343,39 @@ unsigned long thread_saved_pc(struct task_struct *tsk)
 /* 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;
 
         if (!p || p == current || p->state == TASK_RUNNING)
                 return 0;
 
-        if (!mips_frame_info_initialized)
+        stack_page = (unsigned long)p->thread_info;
+        if (!stack_page || !mips_frame_info_initialized)
                 return 0;
+
         pc = thread_saved_pc(p);
         if (!in_sched_functions(pc))
-                goto out;
-
-        if (pc >= (unsigned long) sleep_on_timeout)
-                goto schedule_timeout_caller;
-        if (pc >= (unsigned long) sleep_on)
-                goto schedule_caller;
-        if (pc >= (unsigned long) interruptible_sleep_on_timeout)
-                goto schedule_timeout_caller;
-        if (pc >= (unsigned long)interruptible_sleep_on)
-                goto schedule_caller;
-        if (pc >= (unsigned long)wait_for_completion)
-                goto schedule_caller;
-        goto schedule_timeout_caller;
-
-schedule_caller:
-        frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
-        if (pc >= (unsigned long) sleep_on)
-                pc = ((unsigned long *)frame)[sleep_on_frame.pc_offset];
-        else
-                pc = ((unsigned long *)frame)[wait_for_completion_frame.pc_offset];
-        goto out;
+                return pc;
 
-schedule_timeout_caller:
-        /*
-         * The schedule_timeout frame
-         */
         frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
+        do {
+                int i;
 
-        /*
-         * frame now points to sleep_on_timeout's frame
-         */
-        pc    = ((unsigned long *)frame)[schedule_timeout_frame.pc_offset];
+                if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
+                        return 0;
 
-        if (in_sched_functions(pc)) {
-                /* schedule_timeout called by [interruptible_]sleep_on_timeout */
-                frame = ((unsigned long *)frame)[schedule_timeout_frame.frame_offset];
-                pc    = ((unsigned long *)frame)[sleep_on_timeout_frame.pc_offset];
-        }
-
-out:
+                for (i = ARRAY_SIZE(mfinfo) - 1; i >= 0; i--) {
+                        if (pc >= (unsigned long) mfinfo[i].func)
+                                break;
+                }
+                if (i < 0)
+                        break;
 
-#ifdef CONFIG_64BIT
-        if (current->thread.mflags & MF_32BIT_REGS) /* Kludge for 32-bit ps  */
-                pc &= 0xffffffffUL;
-#endif
+                if (mfinfo[i].omit_fp)
+                        break;
+                pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
+                frame = ((unsigned long *)frame)[mfinfo[i].frame_offset];
+        } while (in_sched_functions(pc));
 
         return pc;
 }