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Commit f66686f7 authored by Atsushi Nemoto's avatar Atsushi Nemoto Committed by Ralf Baechle
Browse files

[MIPS] dump_stack() based on prologue code analysis 



Instead of dump all possible address in the stack, unwind the stack frame
based on prologue code analysis, as like as get_wchan() does.  While the
code analysis might fail for some reason, there is a new kernel option
"raw_show_trace" to disable this feature.

Signed-off-by: default avatarAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 79495d87

arch/mips/kernel/process.c

+55 −11
Original line number Diff line number Diff line
@@ -281,7 +281,7 @@ static struct mips_frame_info { 
} *schedule_frame, mfinfo[64];

static int mfinfo_num;



static int __init get_frame_info(struct mips_frame_info *info)

static int get_frame_info(struct mips_frame_info *info)

{

	int i;

	void *func = info->func;
@@ -329,14 +329,12 @@ static int __init get_frame_info(struct mips_frame_info *info) 
				ip->i_format.simmediate / sizeof(long);

		}

	}

	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_size = 0;

	}



	if (info->frame_size && info->pc_offset >= 0) /* nested */

		return 0;

	if (info->pc_offset < 0) /* leaf */

		return 1;

	/* prologue seems boggus... */

	return -1;

}



static int __init frame_info_init(void)
@@ -367,8 +365,15 @@ static int __init frame_info_init(void) 
	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]);

	for (i = 0; i < ARRAY_SIZE(mfinfo) && mfinfo[i].func; i++) {

		struct mips_frame_info *info = &mfinfo[i];

		if (get_frame_info(info)) {

			/* leaf or unknown */

			if (info->func == schedule)

				printk("Can't analyze prologue code at %p\n",

				       info->func);

		}

	}



	mfinfo_num = i;

	return 0;
@@ -427,6 +432,8 @@ unsigned long get_wchan(struct task_struct *p) 
		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;
@@ -437,3 +444,40 @@ unsigned long get_wchan(struct task_struct *p) 
	return pc;

}



#ifdef CONFIG_KALLSYMS

/* used by show_frametrace() */

unsigned long unwind_stack(struct task_struct *task,

			   unsigned long **sp, unsigned long pc)

{

	unsigned long stack_page;

	struct mips_frame_info info;

	char *modname;

	char namebuf[KSYM_NAME_LEN + 1];

	unsigned long size, ofs;



	stack_page = (unsigned long)task_stack_page(task);

	if (!stack_page)

		return 0;



	if (!kallsyms_lookup(pc, &size, &ofs, &modname, namebuf))

		return 0;

	if (ofs == 0)

		return 0;



	info.func = (void *)(pc - ofs);

	info.func_size = ofs;	/* analyze from start to ofs */

	if (get_frame_info(&info)) {

		/* leaf or unknown */

		*sp += info.frame_size / sizeof(long);

		return 0;

	}

	if ((unsigned long)*sp < stack_page ||

	    (unsigned long)*sp + info.frame_size / sizeof(long) >

	    stack_page + THREAD_SIZE - 32)

		return 0;



	pc = (*sp)[info.pc_offset];

	*sp += info.frame_size / sizeof(long);

	return pc;

}

#endif

arch/mips/kernel/traps.c

+86 −12
Original line number Diff line number Diff line
@@ -98,24 +98,53 @@ static void show_trace(unsigned long *stack) 
	printk("\n");

}



#ifdef CONFIG_KALLSYMS

static int raw_show_trace;

static int __init set_raw_show_trace(char *str)

{

	raw_show_trace = 1;

	return 1;

}

__setup("raw_show_trace", set_raw_show_trace);



extern unsigned long unwind_stack(struct task_struct *task,

				  unsigned long **sp, unsigned long pc);

static void show_frametrace(struct task_struct *task, struct pt_regs *regs)

{

	const int field = 2 * sizeof(unsigned long);

	unsigned long *stack = (long *)regs->regs[29];

	unsigned long pc = regs->cp0_epc;

	int top = 1;



	if (raw_show_trace || !__kernel_text_address(pc)) {

		show_trace(stack);

		return;

	}

	printk("Call Trace:\n");

	while (__kernel_text_address(pc)) {

		printk(" [<%0*lx>] ", field, pc);

		print_symbol("%s\n", pc);

		pc = unwind_stack(task, &stack, pc);

		if (top && pc == 0)

			pc = regs->regs[31];	/* leaf? */

		top = 0;

	}

	printk("\n");

}

#else

#define show_frametrace(task, r) show_trace((long *)(r)->regs[29]);

#endif



/*

 * This routine abuses get_user()/put_user() to reference pointers

 * with at least a bit of error checking ...

 */

void show_stack(struct task_struct *task, unsigned long *sp)

static void show_stacktrace(struct task_struct *task, struct pt_regs *regs)

{

	const int field = 2 * sizeof(unsigned long);

	long stackdata;

	int i;

	unsigned long *stack;



	if (!sp) {

		if (task && task != current)

			sp = (unsigned long *) task->thread.reg29;

		else

			sp = (unsigned long *) &sp;

	}

	stack = sp;

	unsigned long *sp = (unsigned long *)regs->regs[29];



	printk("Stack :");

	i = 0;
@@ -136,7 +165,44 @@ void show_stack(struct task_struct *task, unsigned long *sp) 
		i++;

	}

	printk("\n");

	show_trace(stack);

	show_frametrace(task, regs);

}



static noinline void prepare_frametrace(struct pt_regs *regs)

{

	__asm__ __volatile__(

		"1: la $2, 1b\n\t"

#ifdef CONFIG_64BIT

		"sd $2, %0\n\t"

		"sd $29, %1\n\t"

		"sd $31, %2\n\t"

#else

		"sw $2, %0\n\t"

		"sw $29, %1\n\t"

		"sw $31, %2\n\t"

#endif

		: "=m" (regs->cp0_epc),

		"=m" (regs->regs[29]), "=m" (regs->regs[31])

		: : "memory");

}



void show_stack(struct task_struct *task, unsigned long *sp)

{

	struct pt_regs regs;

	if (sp) {

		regs.regs[29] = (unsigned long)sp;

		regs.regs[31] = 0;

		regs.cp0_epc = 0;

	} else {

		if (task && task != current) {

			regs.regs[29] = task->thread.reg29;

			regs.regs[31] = 0;

			regs.cp0_epc = task->thread.reg31;

		} else {

			prepare_frametrace(&regs);

		}

	}

	show_stacktrace(task, &regs);

}



/*
@@ -146,6 +212,14 @@ void dump_stack(void) 
{

	unsigned long stack;



#ifdef CONFIG_KALLSYMS

	if (!raw_show_trace) {

		struct pt_regs regs;

		prepare_frametrace(&regs);

		show_frametrace(current, &regs);

		return;

	}

#endif

	show_trace(&stack);

}
@@ -265,7 +339,7 @@ void show_registers(struct pt_regs *regs) 
	print_modules();

	printk("Process %s (pid: %d, threadinfo=%p, task=%p)\n",

	        current->comm, current->pid, current_thread_info(), current);

	show_stack(current, (long *) regs->regs[29]);

	show_stacktrace(current, regs);

	show_code((unsigned int *) regs->cp0_epc);

	printk("\n");

}