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Commit 4d157d5e authored by Franck Bui-Huu's avatar Franck Bui-Huu Committed by Ralf Baechle
Browse files

[MIPS] Improve unwind_stack() 



This patch allows unwind_stack() to return ra for leaf function.
But it tries to detects cases where get_frame_info() wrongly
consider nested function as a leaf one.

It also pass 'unsinged long *sp' instead of 'unsigned long **sp'
as second parameter. The code looks cleaner.

Signed-off-by: default avatarFranck Bui-Huu <vagabon.xyz@gmail.com>
Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 0cceb4aa

arch/mips/kernel/process.c

+22 −13
Original line number Diff line number Diff line
@@ -448,15 +448,16 @@ unsigned long get_wchan(struct task_struct *p) 
}



#ifdef CONFIG_KALLSYMS

/* used by show_frametrace() */

unsigned long unwind_stack(struct task_struct *task,

			   unsigned long **sp, unsigned long pc)

/* used by show_backtrace() */

unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,

			   unsigned long pc, unsigned long ra)

{

	unsigned long stack_page;

	struct mips_frame_info info;

	char *modname;

	char namebuf[KSYM_NAME_LEN + 1];

	unsigned long size, ofs;

	int leaf;



	stack_page = (unsigned long)task_stack_page(task);

	if (!stack_page)
@@ -469,18 +470,26 @@ unsigned long unwind_stack(struct task_struct *task, 


	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);

	leaf = get_frame_info(&info);

	if (leaf < 0)

		return 0;

	}

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

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

	    stack_page + THREAD_SIZE - 32)



	if (*sp < stack_page ||

	    *sp + info.frame_size > stack_page + THREAD_SIZE - 32)

		return 0;



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

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

	return pc;

	if (leaf)

		/*

		 * For some extreme cases, get_frame_info() can

		 * consider wrongly a nested function as a leaf

		 * one. In that cases avoid to return always the

		 * same value.

		 */

		pc = pc != ra ? ra : 0;

	else

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



	*sp += info.frame_size;

	return __kernel_text_address(pc) ? pc : 0;

}

#endif

arch/mips/kernel/traps.c

+12 −12
Original line number Diff line number Diff line
@@ -74,8 +74,9 @@ void (*board_ejtag_handler_setup)(void); 
void (*board_bind_eic_interrupt)(int irq, int regset);





static void show_raw_backtrace(unsigned long *sp)

static void show_raw_backtrace(unsigned long reg29)

{

	unsigned long *sp = (unsigned long *)reg29;

	unsigned long addr;



	printk("Call Trace:");
@@ -99,30 +100,29 @@ static int __init set_raw_show_trace(char *str) 
}

__setup("raw_show_trace", set_raw_show_trace);



extern unsigned long unwind_stack(struct task_struct *task,

				  unsigned long **sp, unsigned long pc);

extern unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,

				  unsigned long pc, unsigned long ra);



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

{

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

	unsigned long sp = regs->regs[29];

	unsigned long ra = regs->regs[31];

	unsigned long pc = regs->cp0_epc;

	int top = 1;



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

		show_raw_backtrace(sp);

		return;

	}

	printk("Call Trace:\n");

	while (__kernel_text_address(pc)) {

	do {

		print_ip_sym(pc);

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

		if (top && pc == 0)

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

		top = 0;

	}

		pc = unwind_stack(task, &sp, pc, ra);

		ra = 0;

	} while (pc);

	printk("\n");

}

#else

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

#define show_backtrace(task, r) show_raw_backtrace((r)->regs[29]);

#endif



/*