// SPDX-License-Identifier: GPL-2.0
#include "arm64-frame-pointer-unwind-support.h"
#include "callchain.h"
#include "event.h"
#include "unwind.h"
#include <string.h>

#define perf_event_arm_regs perf_event_arm64_regs
#include "../../arch/arm64/include/uapi/asm/perf_regs.h"
#undef perf_event_arm_regs

struct entries {
        u64 stack[2];
        size_t length;
};

#define SMPL_REG_MASK(b) (1ULL << (b))

static bool get_leaf_frame_caller_enabled(struct perf_sample *sample)
{
        struct regs_dump *regs;

        if (callchain_param.record_mode != CALLCHAIN_FP)
                return false;

        regs = perf_sample__user_regs(sample);
        return  regs->regs && regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_LR);
}

static int add_entry(struct unwind_entry *entry, void *arg)
{
        struct entries *entries = arg;

        entries->stack[entries->length++] = entry->ip;
        return 0;
}

u64 get_leaf_frame_caller_aarch64(struct perf_sample *sample, struct thread *thread, int usr_idx)
{
        int ret;
        struct entries entries = {};
        struct regs_dump old_regs, *regs;

        if (!get_leaf_frame_caller_enabled(sample))
                return 0;

        /*
         * If PC and SP are not recorded, get the value of PC from the stack
         * and set its mask. SP is not used when doing the unwinding but it
         * still needs to be set to prevent failures.
         */
        regs = perf_sample__user_regs(sample);
        memcpy(&old_regs, regs, sizeof(*regs));
        if (!(regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_PC))) {
                regs->cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_PC);
                regs->cache_regs[PERF_REG_ARM64_PC] = sample->callchain->ips[usr_idx+1];
        }

        if (!(regs->mask & SMPL_REG_MASK(PERF_REG_ARM64_SP))) {
                regs->cache_mask |= SMPL_REG_MASK(PERF_REG_ARM64_SP);
                regs->cache_regs[PERF_REG_ARM64_SP] = 0;
        }

        ret = unwind__get_entries(add_entry, &entries, thread, sample, 2, true);
        memcpy(regs, &old_regs, sizeof(*regs));

        if (ret || entries.length != 2)
                return ret;

        return callchain_param.order == ORDER_CALLER ? entries.stack[0] : entries.stack[1];
}