metag: Stack unwinding

#ifndef __ASM_STACKTRACE_H

#define __ASM_STACKTRACE_H

struct stackframe {

	unsigned long fp;

	unsigned long sp;

	unsigned long lr;

	unsigned long pc;

};

struct metag_frame {

	unsigned long fp;

	unsigned long lr;

};

extern int unwind_frame(struct stackframe *frame);

extern void walk_stackframe(struct stackframe *frame,

			    int (*fn)(struct stackframe *, void *), void *data);

#endif	/* __ASM_STACKTRACE_H */

#include <linux/export.h>

#include <linux/sched.h>

#include <linux/stacktrace.h>

#include <asm/stacktrace.h>

#if defined(CONFIG_FRAME_POINTER)

#ifdef CONFIG_KALLSYMS

#include <linux/kallsyms.h>

#include <linux/module.h>

static unsigned long tbi_boing_addr;

static unsigned long tbi_boing_size;

static void tbi_boing_init(void)

{

	/* We need to know where TBIBoingVec is and it's size */

	unsigned long size;

	unsigned long offset;

	char modname[MODULE_NAME_LEN];

	char name[KSYM_NAME_LEN];

	tbi_boing_addr = kallsyms_lookup_name("___TBIBoingVec");

	if (!tbi_boing_addr)

		tbi_boing_addr = 1;

	else if (!lookup_symbol_attrs(tbi_boing_addr, &size,

				      &offset, modname, name))

		tbi_boing_size = size;

}

#endif

#define ALIGN_DOWN(addr, size)  ((addr)&(~((size)-1)))

/*

 * Unwind the current stack frame and store the new register values in the

 * structure passed as argument. Unwinding is equivalent to a function return,

 * hence the new PC value rather than LR should be used for backtrace.

 */

int notrace unwind_frame(struct stackframe *frame)

{

	struct metag_frame *fp = (struct metag_frame *)frame->fp;

	unsigned long lr;

	unsigned long fpnew;

	if (frame->fp & 0x7)

		return -EINVAL;

	fpnew = fp->fp;

	lr = fp->lr - 4;

#ifdef CONFIG_KALLSYMS

	/* If we've reached TBIBoingVec then we're at an interrupt

	 * entry point or a syscall entry point. The frame pointer

	 * points to a pt_regs which can be used to continue tracing on

	 * the other side of the boing.

	 */

	if (!tbi_boing_addr)

		tbi_boing_init();

	if (tbi_boing_size && lr >= tbi_boing_addr &&

	    lr < tbi_boing_addr + tbi_boing_size) {

		struct pt_regs *regs = (struct pt_regs *)fpnew;

		if (user_mode(regs))

			return -EINVAL;

		fpnew = regs->ctx.AX[1].U0;

		lr = regs->ctx.DX[4].U1;

	}

#endif

	/* stack grows up, so frame pointers must decrease */

	if (fpnew < (ALIGN_DOWN((unsigned long)fp, THREAD_SIZE) +

		     sizeof(struct thread_info)) || fpnew >= (unsigned long)fp)

		return -EINVAL;

	/* restore the registers from the stack frame */

	frame->fp = fpnew;

	frame->pc = lr;

	return 0;

}

#else

int notrace unwind_frame(struct stackframe *frame)

{

	struct metag_frame *sp = (struct metag_frame *)frame->sp;

	if (frame->sp & 0x7)

		return -EINVAL;

	while (!kstack_end(sp)) {

		unsigned long addr = sp->lr - 4;

		sp--;

		if (__kernel_text_address(addr)) {

			frame->sp = (unsigned long)sp;

			frame->pc = addr;

			return 0;

		}

	}

	return -EINVAL;

}

#endif

void notrace walk_stackframe(struct stackframe *frame,

		     int (*fn)(struct stackframe *, void *), void *data)

{

	while (1) {

		int ret;

		if (fn(frame, data))

			break;

		ret = unwind_frame(frame);

		if (ret < 0)

			break;

	}

}

EXPORT_SYMBOL(walk_stackframe);

#ifdef CONFIG_STACKTRACE

struct stack_trace_data {

	struct stack_trace *trace;

	unsigned int no_sched_functions;

	unsigned int skip;

};

static int save_trace(struct stackframe *frame, void *d)

{

	struct stack_trace_data *data = d;

	struct stack_trace *trace = data->trace;

	unsigned long addr = frame->pc;

	if (data->no_sched_functions && in_sched_functions(addr))

		return 0;

	if (data->skip) {

		data->skip--;

		return 0;

	}

	trace->entries[trace->nr_entries++] = addr;

	return trace->nr_entries >= trace->max_entries;

}

void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)

{

	struct stack_trace_data data;

	struct stackframe frame;

	data.trace = trace;

	data.skip = trace->skip;

	if (tsk != current) {

#ifdef CONFIG_SMP

		/*

		 * What guarantees do we have here that 'tsk' is not

		 * running on another CPU?  For now, ignore it as we

		 * can't guarantee we won't explode.

		 */

		if (trace->nr_entries < trace->max_entries)

			trace->entries[trace->nr_entries++] = ULONG_MAX;

		return;

#else

		data.no_sched_functions = 1;

		frame.fp = thread_saved_fp(tsk);

		frame.sp = thread_saved_sp(tsk);

		frame.lr = 0;		/* recovered from the stack */

		frame.pc = thread_saved_pc(tsk);

#endif

	} else {

		register unsigned long current_sp asm ("A0StP");

		data.no_sched_functions = 0;

		frame.fp = (unsigned long)__builtin_frame_address(0);

		frame.sp = current_sp;

		frame.lr = (unsigned long)__builtin_return_address(0);

		frame.pc = (unsigned long)save_stack_trace_tsk;

	}

	walk_stackframe(&frame, save_trace, &data);

	if (trace->nr_entries < trace->max_entries)

		trace->entries[trace->nr_entries++] = ULONG_MAX;

}

void save_stack_trace(struct stack_trace *trace)

{

	save_stack_trace_tsk(current, trace);

}

EXPORT_SYMBOL_GPL(save_stack_trace);

#endif