// SPDX-License-Identifier: GPL-2.0-only
#include <linux/sched.h>
#include <linux/ftrace.h>
#include <asm/ptrace.h>
#include <asm/bitops.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>

unsigned long unwind_get_return_address(struct unwind_state *state)
{
        unsigned long addr;

        if (unwind_done(state))
                return 0;

        addr = READ_ONCE_NOCHECK(*state->sp);

        return unwind_recover_ret_addr(state, addr, state->sp);
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);

unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
{
        return NULL;
}

bool unwind_next_frame(struct unwind_state *state)
{
        struct stack_info *info = &state->stack_info;

        if (unwind_done(state))
                return false;

        do {
                for (state->sp++; state->sp < info->end; state->sp++) {
                        unsigned long addr = READ_ONCE_NOCHECK(*state->sp);

                        if (__kernel_text_address(addr))
                                return true;
                }

                state->sp = PTR_ALIGN(info->next_sp, sizeof(long));

        } while (!get_stack_info(state->sp, state->task, info,
                                 &state->stack_mask));

        return false;
}
EXPORT_SYMBOL_GPL(unwind_next_frame);

void __unwind_start(struct unwind_state *state, struct task_struct *task,
                    struct pt_regs *regs, unsigned long *first_frame)
{
        memset(state, 0, sizeof(*state));

        state->task = task;
        state->sp   = PTR_ALIGN(first_frame, sizeof(long));

        get_stack_info(first_frame, state->task, &state->stack_info,
                       &state->stack_mask);

        /*
         * The caller can provide the address of the first frame directly
         * (first_frame) or indirectly (regs->sp) to indicate which stack frame
         * to start unwinding at.  Skip ahead until we reach it.
         */
        if (!unwind_done(state) &&
            (!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
            !__kernel_text_address(*first_frame)))
                unwind_next_frame(state);
}
EXPORT_SYMBOL_GPL(__unwind_start);