#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.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

/*
 * 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