Commit 63077519 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
Browse files

[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: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 1bdfd0d9

arch/mips/kernel/process.c

+77 −81
Original line number Diff line number Diff line
@@ -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 || info->frame_offset == -1) {

	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;

			}

	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;

	}

	} while (found);

	mips_frame_info_initialized = 1;

#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;

}

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