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>

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index e4f2f80..f99efce 100644 (file)
--- 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;
 }