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Commit b5943182 authored by Franck Bui-Huu's avatar Franck Bui-Huu Committed by Ralf Baechle
Browse files

[MIPS] get_wchan(): remove uses of mfinfo[64] 



This array was used to 'cache' some frame info about scheduler
functions to speed up get_wchan(). This array was 1Ko size and
was only used when CONFIG_KALLSYMS was set but declared for all
configs.

Rather than make the array statement conditional, this patches
removes this array and its uses. Indeed the common case doesn't
seem to use this array and get_wchan() is not a critical path
anyways.

It results in a smaller bss and a smaller/cleaner code:

   text    data     bss     dec     hex filename
2543808  254148  139296 2937252  2cd1a4 vmlinux-new-get-wchan
2544080  254148  143392 2941620  2ce2b4 vmlinux~old

Signed-off-by: default avatarFranck Bui-Huu <vagabon.xyz@gmail.com>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 29b376ff

arch/mips/kernel/process.c

+50 −82
Original line number Diff line number Diff line
@@ -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 {

/*

 *

 */

struct mips_frame_info {

	void		*func;

	unsigned long	func_size;

	int		frame_size;

	int		pc_offset;

} *schedule_frame, mfinfo[64];

static int mfinfo_num;

};



static inline int is_ra_save_ins(union mips_instruction *ip)

{
@@ -348,45 +350,30 @@ static int get_frame_info(struct mips_frame_info *info) 
	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)

		return 0;

	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 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)

	if (schedule_mfi.pc_offset < 0)

		return 0;



		for (i = mfinfo_num - 1; i >= 0; i--) {

			if (pc >= (unsigned long) mfinfo[i].func)

				break;

	return ((unsigned long *)t->reg29)[schedule_mfi.pc_offset];

}

		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;

}