#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