/*
 * intel_pt_decoder.c: Intel Processor Trace support
 * Copyright (c) 2013-2014, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
#include <inttypes.h>

#include "../cache.h"
#include "../util.h"

#include "intel-pt-insn-decoder.h"
#include "intel-pt-pkt-decoder.h"
#include "intel-pt-decoder.h"
#include "intel-pt-log.h"

#define INTEL_PT_BLK_SIZE 1024

#define BIT63 (((uint64_t)1 << 63))

#define INTEL_PT_RETURN 1

/* Maximum number of loops with no packets consumed i.e. stuck in a loop */
#define INTEL_PT_MAX_LOOPS 10000

struct intel_pt_blk {
        struct intel_pt_blk *prev;
        uint64_t ip[INTEL_PT_BLK_SIZE];
};

struct intel_pt_stack {
        struct intel_pt_blk *blk;
        struct intel_pt_blk *spare;
        int pos;
};

enum intel_pt_pkt_state {
        INTEL_PT_STATE_NO_PSB,
        INTEL_PT_STATE_NO_IP,
        INTEL_PT_STATE_ERR_RESYNC,
        INTEL_PT_STATE_IN_SYNC,
        INTEL_PT_STATE_TNT,
        INTEL_PT_STATE_TIP,
        INTEL_PT_STATE_TIP_PGD,
        INTEL_PT_STATE_FUP,
        INTEL_PT_STATE_FUP_NO_TIP,
};

#ifdef INTEL_PT_STRICT
#define INTEL_PT_STATE_ERR1     INTEL_PT_STATE_NO_PSB
#define INTEL_PT_STATE_ERR2     INTEL_PT_STATE_NO_PSB
#define INTEL_PT_STATE_ERR3     INTEL_PT_STATE_NO_PSB
#define INTEL_PT_STATE_ERR4     INTEL_PT_STATE_NO_PSB
#else
#define INTEL_PT_STATE_ERR1     (decoder->pkt_state)
#define INTEL_PT_STATE_ERR2     INTEL_PT_STATE_NO_IP
#define INTEL_PT_STATE_ERR3     INTEL_PT_STATE_ERR_RESYNC
#define INTEL_PT_STATE_ERR4     INTEL_PT_STATE_IN_SYNC
#endif

struct intel_pt_decoder {
        int (*get_trace)(struct intel_pt_buffer *buffer, void *data);
        int (*walk_insn)(struct intel_pt_insn *intel_pt_insn,
                         uint64_t *insn_cnt_ptr, uint64_t *ip, uint64_t to_ip,
                         uint64_t max_insn_cnt, void *data);
        void *data;
        struct intel_pt_state state;
        const unsigned char *buf;
        size_t len;
        bool return_compression;
        bool mtc_insn;
        bool pge;
        bool have_tma;
        bool have_cyc;
        uint64_t pos;
        uint64_t last_ip;
        uint64_t ip;
        uint64_t cr3;
        uint64_t timestamp;
        uint64_t tsc_timestamp;
        uint64_t ref_timestamp;
        uint64_t ret_addr;
        uint64_t ctc_timestamp;
        uint64_t ctc_delta;
        uint64_t cycle_cnt;
        uint64_t cyc_ref_timestamp;
        uint32_t last_mtc;
        uint32_t tsc_ctc_ratio_n;
        uint32_t tsc_ctc_ratio_d;
        uint32_t tsc_ctc_mult;
        uint32_t tsc_slip;
        uint32_t ctc_rem_mask;
        int mtc_shift;
        struct intel_pt_stack stack;
        enum intel_pt_pkt_state pkt_state;
        struct intel_pt_pkt packet;
        struct intel_pt_pkt tnt;
        int pkt_step;
        int pkt_len;
        int last_packet_type;
        unsigned int cbr;
        unsigned int max_non_turbo_ratio;
        double max_non_turbo_ratio_fp;
        double cbr_cyc_to_tsc;
        double calc_cyc_to_tsc;
        bool have_calc_cyc_to_tsc;
        int exec_mode;
        unsigned int insn_bytes;
        uint64_t sign_bit;
        uint64_t sign_bits;
        uint64_t period;
        enum intel_pt_period_type period_type;
        uint64_t tot_insn_cnt;
        uint64_t period_insn_cnt;
        uint64_t period_mask;
        uint64_t period_ticks;
        uint64_t last_masked_timestamp;
        bool continuous_period;
        bool overflow;
        bool set_fup_tx_flags;
        unsigned int fup_tx_flags;
        unsigned int tx_flags;
        uint64_t timestamp_insn_cnt;
        uint64_t stuck_ip;
        int no_progress;
        int stuck_ip_prd;
        int stuck_ip_cnt;
        const unsigned char *next_buf;
        size_t next_len;
        unsigned char temp_buf[INTEL_PT_PKT_MAX_SZ];
};

static uint64_t intel_pt_lower_power_of_2(uint64_t x)
{
        int i;

        for (i = 0; x != 1; i++)
                x >>= 1;

        return x << i;
}

static void intel_pt_setup_period(struct intel_pt_decoder *decoder)
{
        if (decoder->period_type == INTEL_PT_PERIOD_TICKS) {
                uint64_t period;

                period = intel_pt_lower_power_of_2(decoder->period);
                decoder->period_mask  = ~(period - 1);
                decoder->period_ticks = period;
        }
}

static uint64_t multdiv(uint64_t t, uint32_t n, uint32_t d)
{
        if (!d)
                return 0;
        return (t / d) * n + ((t % d) * n) / d;
}

struct intel_pt_decoder *intel_pt_decoder_new(struct intel_pt_params *params)
{
        struct intel_pt_decoder *decoder;

        if (!params->get_trace || !params->walk_insn)
                return NULL;

        decoder = zalloc(sizeof(struct intel_pt_decoder));
        if (!decoder)
                return NULL;

        decoder->get_trace          = params->get_trace;
        decoder->walk_insn          = params->walk_insn;
        decoder->data               = params->data;
        decoder->return_compression = params->return_compression;

        decoder->sign_bit           = (uint64_t)1 << 47;
        decoder->sign_bits          = ~(((uint64_t)1 << 48) - 1);

        decoder->period             = params->period;
        decoder->period_type        = params->period_type;

        decoder->max_non_turbo_ratio    = params->max_non_turbo_ratio;
        decoder->max_non_turbo_ratio_fp = params->max_non_turbo_ratio;

        intel_pt_setup_period(decoder);

        decoder->mtc_shift = params->mtc_period;
        decoder->ctc_rem_mask = (1 << decoder->mtc_shift) - 1;

        decoder->tsc_ctc_ratio_n = params->tsc_ctc_ratio_n;
        decoder->tsc_ctc_ratio_d = params->tsc_ctc_ratio_d;

        if (!decoder->tsc_ctc_ratio_n)
                decoder->tsc_ctc_ratio_d = 0;

        if (decoder->tsc_ctc_ratio_d) {
                if (!(decoder->tsc_ctc_ratio_n % decoder->tsc_ctc_ratio_d))
                        decoder->tsc_ctc_mult = decoder->tsc_ctc_ratio_n /
                                                decoder->tsc_ctc_ratio_d;

                /*
                 * Allow for timestamps appearing to backwards because a TSC
                 * packet has slipped past a MTC packet, so allow 2 MTC ticks
                 * or ...
                 */
                decoder->tsc_slip = multdiv(2 << decoder->mtc_shift,
                                        decoder->tsc_ctc_ratio_n,
                                        decoder->tsc_ctc_ratio_d);
        }
        /* ... or 0x100 paranoia */
        if (decoder->tsc_slip < 0x100)
                decoder->tsc_slip = 0x100;

        intel_pt_log("timestamp: mtc_shift %u\n", decoder->mtc_shift);
        intel_pt_log("timestamp: tsc_ctc_ratio_n %u\n", decoder->tsc_ctc_ratio_n);
        intel_pt_log("timestamp: tsc_ctc_ratio_d %u\n", decoder->tsc_ctc_ratio_d);
        intel_pt_log("timestamp: tsc_ctc_mult %u\n", decoder->tsc_ctc_mult);
        intel_pt_log("timestamp: tsc_slip %#x\n", decoder->tsc_slip);

        return decoder;
}

static void intel_pt_pop_blk(struct intel_pt_stack *stack)
{
        struct intel_pt_blk *blk = stack->blk;

        stack->blk = blk->prev;
        if (!stack->spare)
                stack->spare = blk;
        else
                free(blk);
}

static uint64_t intel_pt_pop(struct intel_pt_stack *stack)
{
        if (!stack->pos) {
                if (!stack->blk)
                        return 0;
                intel_pt_pop_blk(stack);
                if (!stack->blk)
                        return 0;
                stack->pos = INTEL_PT_BLK_SIZE;
        }
        return stack->blk->ip[--stack->pos];
}

static int intel_pt_alloc_blk(struct intel_pt_stack *stack)
{
        struct intel_pt_blk *blk;

        if (stack->spare) {
                blk = stack->spare;
                stack->spare = NULL;
        } else {
                blk = malloc(sizeof(struct intel_pt_blk));
                if (!blk)
                        return -ENOMEM;
        }

        blk->prev = stack->blk;
        stack->blk = blk;
        stack->pos = 0;
        return 0;
}

static int intel_pt_push(struct intel_pt_stack *stack, uint64_t ip)
{
        int err;

        if (!stack->blk || stack->pos == INTEL_PT_BLK_SIZE) {
                err = intel_pt_alloc_blk(stack);
                if (err)
                        return err;
        }

        stack->blk->ip[stack->pos++] = ip;
        return 0;
}

static void intel_pt_clear_stack(struct intel_pt_stack *stack)
{
        while (stack->blk)
                intel_pt_pop_blk(stack);
        stack->pos = 0;
}

static void intel_pt_free_stack(struct intel_pt_stack *stack)
{
        intel_pt_clear_stack(stack);
        zfree(&stack->blk);
        zfree(&stack->spare);
}

void intel_pt_decoder_free(struct intel_pt_decoder *decoder)
{
        intel_pt_free_stack(&decoder->stack);
        free(decoder);
}

static int intel_pt_ext_err(int code)
{
        switch (code) {
        case -ENOMEM:
                return INTEL_PT_ERR_NOMEM;
        case -ENOSYS:
                return INTEL_PT_ERR_INTERN;
        case -EBADMSG:
                return INTEL_PT_ERR_BADPKT;
        case -ENODATA:
                return INTEL_PT_ERR_NODATA;
        case -EILSEQ:
                return INTEL_PT_ERR_NOINSN;
        case -ENOENT:
                return INTEL_PT_ERR_MISMAT;
        case -EOVERFLOW:
                return INTEL_PT_ERR_OVR;
        case -ENOSPC:
                return INTEL_PT_ERR_LOST;
        case -ELOOP:
                return INTEL_PT_ERR_NELOOP;
        default:
                return INTEL_PT_ERR_UNK;
        }
}

static const char *intel_pt_err_msgs[] = {
        [INTEL_PT_ERR_NOMEM]  = "Memory allocation failed",
        [INTEL_PT_ERR_INTERN] = "Internal error",
        [INTEL_PT_ERR_BADPKT] = "Bad packet",
        [INTEL_PT_ERR_NODATA] = "No more data",
        [INTEL_PT_ERR_NOINSN] = "Failed to get instruction",
        [INTEL_PT_ERR_MISMAT] = "Trace doesn't match instruction",
        [INTEL_PT_ERR_OVR]    = "Overflow packet",
        [INTEL_PT_ERR_LOST]   = "Lost trace data",
        [INTEL_PT_ERR_UNK]    = "Unknown error!",
        [INTEL_PT_ERR_NELOOP] = "Never-ending loop",
};

int intel_pt__strerror(int code, char *buf, size_t buflen)
{
        if (code < 1 || code > INTEL_PT_ERR_MAX)
                code = INTEL_PT_ERR_UNK;
        strlcpy(buf, intel_pt_err_msgs[code], buflen);
        return 0;
}

static uint64_t intel_pt_calc_ip(struct intel_pt_decoder *decoder,
                                 const struct intel_pt_pkt *packet,
                                 uint64_t last_ip)
{
        uint64_t ip;

        switch (packet->count) {
        case 2:
                ip = (last_ip & (uint64_t)0xffffffffffff0000ULL) |
                     packet->payload;
                break;
        case 4:
                ip = (last_ip & (uint64_t)0xffffffff00000000ULL) |
                     packet->payload;
                break;
        case 6:
                ip = packet->payload;
                break;
        default:
                return 0;
        }

        if (ip & decoder->sign_bit)
                return ip | decoder->sign_bits;

        return ip;
}

static inline void intel_pt_set_last_ip(struct intel_pt_decoder *decoder)
{
        decoder->last_ip = intel_pt_calc_ip(decoder, &decoder->packet,
                                            decoder->last_ip);
}

static inline void intel_pt_set_ip(struct intel_pt_decoder *decoder)
{
        intel_pt_set_last_ip(decoder);
        decoder->ip = decoder->last_ip;
}

static void intel_pt_decoder_log_packet(struct intel_pt_decoder *decoder)
{
        intel_pt_log_packet(&decoder->packet, decoder->pkt_len, decoder->pos,
                            decoder->buf);
}

static int intel_pt_bug(struct intel_pt_decoder *decoder)
{
        intel_pt_log("ERROR: Internal error\n");
        decoder->pkt_state = INTEL_PT_STATE_NO_PSB;
        return -ENOSYS;
}

static inline void intel_pt_clear_tx_flags(struct intel_pt_decoder *decoder)
{
        decoder->tx_flags = 0;
}

static inline void intel_pt_update_in_tx(struct intel_pt_decoder *decoder)
{
        decoder->tx_flags = decoder->packet.payload & INTEL_PT_IN_TX;
}

static int intel_pt_bad_packet(struct intel_pt_decoder *decoder)
{
        intel_pt_clear_tx_flags(decoder);
        decoder->have_tma = false;
        decoder->pkt_len = 1;
        decoder->pkt_step = 1;
        intel_pt_decoder_log_packet(decoder);
        if (decoder->pkt_state != INTEL_PT_STATE_NO_PSB) {
                intel_pt_log("ERROR: Bad packet\n");
                decoder->pkt_state = INTEL_PT_STATE_ERR1;
        }
        return -EBADMSG;
}

static int intel_pt_get_data(struct intel_pt_decoder *decoder)
{
        struct intel_pt_buffer buffer = { .buf = 0, };
        int ret;

        decoder->pkt_step = 0;

        intel_pt_log("Getting more data\n");
        ret = decoder->get_trace(&buffer, decoder->data);
        if (ret)
                return ret;
        decoder->buf = buffer.buf;
        decoder->len = buffer.len;
        if (!decoder->len) {
                intel_pt_log("No more data\n");
                return -ENODATA;
        }
        if (!buffer.consecutive) {
                decoder->ip = 0;
                decoder->pkt_state = INTEL_PT_STATE_NO_PSB;
                decoder->ref_timestamp = buffer.ref_timestamp;
                decoder->timestamp = 0;
                decoder->have_tma = false;
                decoder->state.trace_nr = buffer.trace_nr;
                intel_pt_log("Reference timestamp 0x%" PRIx64 "\n",
                             decoder->ref_timestamp);
                return -ENOLINK;
        }

        return 0;
}

static int intel_pt_get_next_data(struct intel_pt_decoder *decoder)
{
        if (!decoder->next_buf)
                return intel_pt_get_data(decoder);

        decoder->buf = decoder->next_buf;
        decoder->len = decoder->next_len;
        decoder->next_buf = 0;
        decoder->next_len = 0;
        return 0;
}

static int intel_pt_get_split_packet(struct intel_pt_decoder *decoder)
{
        unsigned char *buf = decoder->temp_buf;
        size_t old_len, len, n;
        int ret;

        old_len = decoder->len;
        len = decoder->len;
        memcpy(buf, decoder->buf, len);

        ret = intel_pt_get_data(decoder);
        if (ret) {
                decoder->pos += old_len;
                return ret < 0 ? ret : -EINVAL;
        }

        n = INTEL_PT_PKT_MAX_SZ - len;
        if (n > decoder->len)
                n = decoder->len;
        memcpy(buf + len, decoder->buf, n);
        len += n;

        ret = intel_pt_get_packet(buf, len, &decoder->packet);
        if (ret < (int)old_len) {
                decoder->next_buf = decoder->buf;
                decoder->next_len = decoder->len;
                decoder->buf = buf;
                decoder->len = old_len;
                return intel_pt_bad_packet(decoder);
        }

        decoder->next_buf = decoder->buf + (ret - old_len);
        decoder->next_len = decoder->len - (ret - old_len);

        decoder->buf = buf;
        decoder->len = ret;

        return ret;
}

struct intel_pt_pkt_info {
        struct intel_pt_decoder   *decoder;
        struct intel_pt_pkt       packet;
        uint64_t                  pos;
        int                       pkt_len;
        int                       last_packet_type;
        void                      *data;
};

typedef int (*intel_pt_pkt_cb_t)(struct intel_pt_pkt_info *pkt_info);

/* Lookahead packets in current buffer */
static int intel_pt_pkt_lookahead(struct intel_pt_decoder *decoder,
                                  intel_pt_pkt_cb_t cb, void *data)
{
        struct intel_pt_pkt_info pkt_info;
        const unsigned char *buf = decoder->buf;
        size_t len = decoder->len;
        int ret;

        pkt_info.decoder          = decoder;
        pkt_info.pos              = decoder->pos;
        pkt_info.pkt_len          = decoder->pkt_step;
        pkt_info.last_packet_type = decoder->last_packet_type;
        pkt_info.data             = data;

        while (1) {
                do {
                        pkt_info.pos += pkt_info.pkt_len;
                        buf          += pkt_info.pkt_len;
                        len          -= pkt_info.pkt_len;

                        if (!len)
                                return INTEL_PT_NEED_MORE_BYTES;

                        ret = intel_pt_get_packet(buf, len, &pkt_info.packet);
                        if (!ret)
                                return INTEL_PT_NEED_MORE_BYTES;
                        if (ret < 0)
                                return ret;

                        pkt_info.pkt_len = ret;
                } while (pkt_info.packet.type == INTEL_PT_PAD);

                ret = cb(&pkt_info);
                if (ret)
                        return 0;

                pkt_info.last_packet_type = pkt_info.packet.type;
        }
}

struct intel_pt_calc_cyc_to_tsc_info {
        uint64_t        cycle_cnt;
        unsigned int    cbr;
        uint32_t        last_mtc;
        uint64_t        ctc_timestamp;
        uint64_t        ctc_delta;
        uint64_t        tsc_timestamp;
        uint64_t        timestamp;
        bool            have_tma;
        bool            from_mtc;
        double          cbr_cyc_to_tsc;
};

static int intel_pt_calc_cyc_cb(struct intel_pt_pkt_info *pkt_info)
{
        struct intel_pt_decoder *decoder = pkt_info->decoder;
        struct intel_pt_calc_cyc_to_tsc_info *data = pkt_info->data;
        uint64_t timestamp;
        double cyc_to_tsc;
        unsigned int cbr;
        uint32_t mtc, mtc_delta, ctc, fc, ctc_rem;

        switch (pkt_info->packet.type) {
        case INTEL_PT_TNT:
        case INTEL_PT_TIP_PGE:
        case INTEL_PT_TIP:
        case INTEL_PT_FUP:
        case INTEL_PT_PSB:
        case INTEL_PT_PIP:
        case INTEL_PT_MODE_EXEC:
        case INTEL_PT_MODE_TSX:
        case INTEL_PT_PSBEND:
        case INTEL_PT_PAD:
        case INTEL_PT_VMCS:
        case INTEL_PT_MNT:
                return 0;

        case INTEL_PT_MTC:
                if (!data->have_tma)
                        return 0;

                mtc = pkt_info->packet.payload;
                if (mtc > data->last_mtc)
                        mtc_delta = mtc - data->last_mtc;
                else
                        mtc_delta = mtc + 256 - data->last_mtc;
                data->ctc_delta += mtc_delta << decoder->mtc_shift;
                data->last_mtc = mtc;

                if (decoder->tsc_ctc_mult) {
                        timestamp = data->ctc_timestamp +
                                data->ctc_delta * decoder->tsc_ctc_mult;
                } else {
                        timestamp = data->ctc_timestamp +
                                multdiv(data->ctc_delta,
                                        decoder->tsc_ctc_ratio_n,
                                        decoder->tsc_ctc_ratio_d);
                }

                if (timestamp < data->timestamp)
                        return 1;

                if (pkt_info->last_packet_type != INTEL_PT_CYC) {
                        data->timestamp = timestamp;
                        return 0;
                }

                break;

        case INTEL_PT_TSC:
                timestamp = pkt_info->packet.payload |
                            (data->timestamp & (0xffULL << 56));
                if (data->from_mtc && timestamp < data->timestamp &&
                    data->timestamp - timestamp < decoder->tsc_slip)
                        return 1;
                if (timestamp < data->timestamp)
                        timestamp += (1ULL << 56);
                if (pkt_info->last_packet_type != INTEL_PT_CYC) {
                        if (data->from_mtc)
                                return 1;
                        data->tsc_timestamp = timestamp;
                        data->timestamp = timestamp;
                        return 0;
                }
                break;

        case INTEL_PT_TMA:
                if (data->from_mtc)
                        return 1;

                if (!decoder->tsc_ctc_ratio_d)
                        return 0;

                ctc = pkt_info->packet.payload;
                fc = pkt_info->packet.count;
                ctc_rem = ctc & decoder->ctc_rem_mask;

                data->last_mtc = (ctc >> decoder->mtc_shift) & 0xff;

                data->ctc_timestamp = data->tsc_timestamp - fc;
                if (decoder->tsc_ctc_mult) {
                        data->ctc_timestamp -= ctc_rem * decoder->tsc_ctc_mult;
                } else {
                        data->ctc_timestamp -=
                                multdiv(ctc_rem, decoder->tsc_ctc_ratio_n,
                                        decoder->tsc_ctc_ratio_d);
                }

                data->ctc_delta = 0;
                data->have_tma = true;

                return 0;

        case INTEL_PT_CYC:
                data->cycle_cnt += pkt_info->packet.payload;
                return 0;

        case INTEL_PT_CBR:
                cbr = pkt_info->packet.payload;
                if (data->cbr && data->cbr != cbr)
                        return 1;
                data->cbr = cbr;
                data->cbr_cyc_to_tsc = decoder->max_non_turbo_ratio_fp / cbr;
                return 0;

        case INTEL_PT_TIP_PGD:
        case INTEL_PT_TRACESTOP:
        case INTEL_PT_OVF:
        case INTEL_PT_BAD: /* Does not happen */
        default:
                return 1;
        }

        if (!data->cbr && decoder->cbr) {
                data->cbr = decoder->cbr;
                data->cbr_cyc_to_tsc = decoder->cbr_cyc_to_tsc;
        }

        if (!data->cycle_cnt)
                return 1;

        cyc_to_tsc = (double)(timestamp - decoder->timestamp) / data->cycle_cnt;

        if (data->cbr && cyc_to_tsc > data->cbr_cyc_to_tsc &&
            cyc_to_tsc / data->cbr_cyc_to_tsc > 1.25) {
                intel_pt_log("Timestamp: calculated %g TSC ticks per cycle too big (c.f. CBR-based value %g), pos " x64_fmt "\n",
                             cyc_to_tsc, data->cbr_cyc_to_tsc, pkt_info->pos);
                return 1;
        }

        decoder->calc_cyc_to_tsc = cyc_to_tsc;
        decoder->have_calc_cyc_to_tsc = true;

        if (data->cbr) {
                intel_pt_log("Timestamp: calculated %g TSC ticks per cycle c.f. CBR-based value %g, pos " x64_fmt "\n",
                             cyc_to_tsc, data->cbr_cyc_to_tsc, pkt_info->pos);
        } else {
                intel_pt_log("Timestamp: calculated %g TSC ticks per cycle c.f. unknown CBR-based value, pos " x64_fmt "\n",
                             cyc_to_tsc, pkt_info->pos);
        }

        return 1;
}

static void intel_pt_calc_cyc_to_tsc(struct intel_pt_decoder *decoder,
                                     bool from_mtc)
{
        struct intel_pt_calc_cyc_to_tsc_info data = {
                .cycle_cnt      = 0,
                .cbr            = 0,
                .last_mtc       = decoder->last_mtc,
                .ctc_timestamp  = decoder->ctc_timestamp,
                .ctc_delta      = decoder->ctc_delta,
                .tsc_timestamp  = decoder->tsc_timestamp,
                .timestamp      = decoder->timestamp,
                .have_tma       = decoder->have_tma,
                .from_mtc       = from_mtc,
                .cbr_cyc_to_tsc = 0,
        };

        intel_pt_pkt_lookahead(decoder, intel_pt_calc_cyc_cb, &data);
}

static int intel_pt_get_next_packet(struct intel_pt_decoder *decoder)
{
        int ret;

        decoder->last_packet_type = decoder->packet.type;

        do {
                decoder->pos += decoder->pkt_step;
                decoder->buf += decoder->pkt_step;
                decoder->len -= decoder->pkt_step;

                if (!decoder->len) {
                        ret = intel_pt_get_next_data(decoder);
                        if (ret)
                                return ret;
                }

                ret = intel_pt_get_packet(decoder->buf, decoder->len,
                                          &decoder->packet);
                if (ret == INTEL_PT_NEED_MORE_BYTES &&
                    decoder->len < INTEL_PT_PKT_MAX_SZ && !decoder->next_buf) {
                        ret = intel_pt_get_split_packet(decoder);
                        if (ret < 0)
                                return ret;
                }
                if (ret <= 0)
                        return intel_pt_bad_packet(decoder);

                decoder->pkt_len = ret;
                decoder->pkt_step = ret;
                intel_pt_decoder_log_packet(decoder);
        } while (decoder->packet.type == INTEL_PT_PAD);

        return 0;
}

static uint64_t intel_pt_next_period(struct intel_pt_decoder *decoder)
{
        uint64_t timestamp, masked_timestamp;

        timestamp = decoder->timestamp + decoder->timestamp_insn_cnt;
        masked_timestamp = timestamp & decoder->period_mask;
        if (decoder->continuous_period) {
                if (masked_timestamp != decoder->last_masked_timestamp)
                        return 1;
        } else {
                timestamp += 1;
                masked_timestamp = timestamp & decoder->period_mask;
                if (masked_timestamp != decoder->last_masked_timestamp) {
                        decoder->last_masked_timestamp = masked_timestamp;
                        decoder->continuous_period = true;
                }
        }
        return decoder->period_ticks - (timestamp - masked_timestamp);
}

static uint64_t intel_pt_next_sample(struct intel_pt_decoder *decoder)
{
        switch (decoder->period_type) {
        case INTEL_PT_PERIOD_INSTRUCTIONS:
                return decoder->period - decoder->period_insn_cnt;
        case INTEL_PT_PERIOD_TICKS:
                return intel_pt_next_period(decoder);
        case INTEL_PT_PERIOD_NONE:
        case INTEL_PT_PERIOD_MTC:
        default:
                return 0;
        }
}

static void intel_pt_sample_insn(struct intel_pt_decoder *decoder)
{
        uint64_t timestamp, masked_timestamp;

        switch (decoder->period_type) {
        case INTEL_PT_PERIOD_INSTRUCTIONS:
                decoder->period_insn_cnt = 0;
                break;
        case INTEL_PT_PERIOD_TICKS:
                timestamp = decoder->timestamp + decoder->timestamp_insn_cnt;
                masked_timestamp = timestamp & decoder->period_mask;
                decoder->last_masked_timestamp = masked_timestamp;
                break;
        case INTEL_PT_PERIOD_NONE:
        case INTEL_PT_PERIOD_MTC:
        default:
                break;
        }

        decoder->state.type |= INTEL_PT_INSTRUCTION;
}

static int intel_pt_walk_insn(struct intel_pt_decoder *decoder,
                              struct intel_pt_insn *intel_pt_insn, uint64_t ip)
{
        uint64_t max_insn_cnt, insn_cnt = 0;
        int err;

        if (!decoder->mtc_insn)
                decoder->mtc_insn = true;

        max_insn_cnt = intel_pt_next_sample(decoder);

        err = decoder->walk_insn(intel_pt_insn, &insn_cnt, &decoder->ip, ip,
                                 max_insn_cnt, decoder->data);

        decoder->tot_insn_cnt += insn_cnt;
        decoder->timestamp_insn_cnt += insn_cnt;
        decoder->period_insn_cnt += insn_cnt;

        if (err) {
                decoder->no_progress = 0;
                decoder->pkt_state = INTEL_PT_STATE_ERR2;
                intel_pt_log_at("ERROR: Failed to get instruction",
                                decoder->ip);
                if (err == -ENOENT)
                        return -ENOLINK;
                return -EILSEQ;
        }

        if (ip && decoder->ip == ip) {
                err = -EAGAIN;
                goto out;
        }

        if (max_insn_cnt && insn_cnt >= max_insn_cnt)
                intel_pt_sample_insn(decoder);

        if (intel_pt_insn->branch == INTEL_PT_BR_NO_BRANCH) {
                decoder->state.type = INTEL_PT_INSTRUCTION;
                decoder->state.from_ip = decoder->ip;
                decoder->state.to_ip = 0;
                decoder->ip += intel_pt_insn->length;
                err = INTEL_PT_RETURN;
                goto out;
        }

        if (intel_pt_insn->op == INTEL_PT_OP_CALL) {
                /* Zero-length calls are excluded */
                if (intel_pt_insn->branch != INTEL_PT_BR_UNCONDITIONAL ||
                    intel_pt_insn->rel) {
                        err = intel_pt_push(&decoder->stack, decoder->ip +
                                            intel_pt_insn->length);
                        if (err)
                                goto out;
                }
        } else if (intel_pt_insn->op == INTEL_PT_OP_RET) {
                decoder->ret_addr = intel_pt_pop(&decoder->stack);
        }

        if (intel_pt_insn->branch == INTEL_PT_BR_UNCONDITIONAL) {
                int cnt = decoder->no_progress++;

                decoder->state.from_ip = decoder->ip;
                decoder->ip += intel_pt_insn->length +
                                intel_pt_insn->rel;
                decoder->state.to_ip = decoder->ip;
                err = INTEL_PT_RETURN;

                /*
                 * Check for being stuck in a loop.  This can happen if a
                 * decoder error results in the decoder erroneously setting the
                 * ip to an address that is itself in an infinite loop that
                 * consumes no packets.  When that happens, there must be an
                 * unconditional branch.
                 */
                if (cnt) {
                        if (cnt == 1) {
                                decoder->stuck_ip = decoder->state.to_ip;
                                decoder->stuck_ip_prd = 1;
                                decoder->stuck_ip_cnt = 1;
                        } else if (cnt > INTEL_PT_MAX_LOOPS ||
                                   decoder->state.to_ip == decoder->stuck_ip) {
                                intel_pt_log_at("ERROR: Never-ending loop",
                                                decoder->state.to_ip);
                                decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
                                err = -ELOOP;
                                goto out;
                        } else if (!--decoder->stuck_ip_cnt) {
                                decoder->stuck_ip_prd += 1;
                                decoder->stuck_ip_cnt = decoder->stuck_ip_prd;
                                decoder->stuck_ip = decoder->state.to_ip;
                        }
                }
                goto out_no_progress;
        }
out:
        decoder->no_progress = 0;
out_no_progress:
        decoder->state.insn_op = intel_pt_insn->op;
        decoder->state.insn_len = intel_pt_insn->length;

        if (decoder->tx_flags & INTEL_PT_IN_TX)
                decoder->state.flags |= INTEL_PT_IN_TX;

        return err;
}

static int intel_pt_walk_fup(struct intel_pt_decoder *decoder)
{
        struct intel_pt_insn intel_pt_insn;
        uint64_t ip;
        int err;

        ip = decoder->last_ip;

        while (1) {
                err = intel_pt_walk_insn(decoder, &intel_pt_insn, ip);
                if (err == INTEL_PT_RETURN)
                        return 0;
                if (err == -EAGAIN) {
                        if (decoder->set_fup_tx_flags) {
                                decoder->set_fup_tx_flags = false;
                                decoder->tx_flags = decoder->fup_tx_flags;
                                decoder->state.type = INTEL_PT_TRANSACTION;
                                decoder->state.from_ip = decoder->ip;
                                decoder->state.to_ip = 0;
                                decoder->state.flags = decoder->fup_tx_flags;
                                return 0;
                        }
                        return err;
                }
                decoder->set_fup_tx_flags = false;
                if (err)
                        return err;

                if (intel_pt_insn.branch == INTEL_PT_BR_INDIRECT) {
                        intel_pt_log_at("ERROR: Unexpected indirect branch",
                                        decoder->ip);
                        decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
                        return -ENOENT;
                }

                if (intel_pt_insn.branch == INTEL_PT_BR_CONDITIONAL) {
                        intel_pt_log_at("ERROR: Unexpected conditional branch",
                                        decoder->ip);
                        decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
                        return -ENOENT;
                }

                intel_pt_bug(decoder);
        }
}

static int intel_pt_walk_tip(struct intel_pt_decoder *decoder)
{
        struct intel_pt_insn intel_pt_insn;
        int err;

        err = intel_pt_walk_insn(decoder, &intel_pt_insn, 0);
        if (err == INTEL_PT_RETURN)
                return 0;
        if (err)
                return err;

        if (intel_pt_insn.branch == INTEL_PT_BR_INDIRECT) {
                if (decoder->pkt_state == INTEL_PT_STATE_TIP_PGD) {
                        decoder->pge = false;
                        decoder->continuous_period = false;
                        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
                        decoder->state.from_ip = decoder->ip;
                        decoder->state.to_ip = 0;
                        if (decoder->packet.count != 0)
                                decoder->ip = decoder->last_ip;
                } else {
                        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
                        decoder->state.from_ip = decoder->ip;
                        if (decoder->packet.count == 0) {
                                decoder->state.to_ip = 0;
                        } else {
                                decoder->state.to_ip = decoder->last_ip;
                                decoder->ip = decoder->last_ip;
                        }
                }
                return 0;
        }

        if (intel_pt_insn.branch == INTEL_PT_BR_CONDITIONAL) {
                intel_pt_log_at("ERROR: Conditional branch when expecting indirect branch",
                                decoder->ip);
                decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
                return -ENOENT;
        }

        return intel_pt_bug(decoder);
}

static int intel_pt_walk_tnt(struct intel_pt_decoder *decoder)
{
        struct intel_pt_insn intel_pt_insn;
        int err;

        while (1) {
                err = intel_pt_walk_insn(decoder, &intel_pt_insn, 0);
                if (err == INTEL_PT_RETURN)
                        return 0;
                if (err)
                        return err;

                if (intel_pt_insn.op == INTEL_PT_OP_RET) {
                        if (!decoder->return_compression) {
                                intel_pt_log_at("ERROR: RET when expecting conditional branch",
                                                decoder->ip);
                                decoder->pkt_state = INTEL_PT_STATE_ERR3;
                                return -ENOENT;
                        }
                        if (!decoder->ret_addr) {
                                intel_pt_log_at("ERROR: Bad RET compression (stack empty)",
                                                decoder->ip);
                                decoder->pkt_state = INTEL_PT_STATE_ERR3;
                                return -ENOENT;
                        }
                        if (!(decoder->tnt.payload & BIT63)) {
                                intel_pt_log_at("ERROR: Bad RET compression (TNT=N)",
                                                decoder->ip);
                                decoder->pkt_state = INTEL_PT_STATE_ERR3;
                                return -ENOENT;
                        }
                        decoder->tnt.count -= 1;
                        if (!decoder->tnt.count)
                                decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
                        decoder->tnt.payload <<= 1;
                        decoder->state.from_ip = decoder->ip;
                        decoder->ip = decoder->ret_addr;
                        decoder->state.to_ip = decoder->ip;
                        return 0;
                }

                if (intel_pt_insn.branch == INTEL_PT_BR_INDIRECT) {
                        /* Handle deferred TIPs */
                        err = intel_pt_get_next_packet(decoder);
                        if (err)
                                return err;
                        if (decoder->packet.type != INTEL_PT_TIP ||
                            decoder->packet.count == 0) {
                                intel_pt_log_at("ERROR: Missing deferred TIP for indirect branch",
                                                decoder->ip);
                                decoder->pkt_state = INTEL_PT_STATE_ERR3;
                                decoder->pkt_step = 0;
                                return -ENOENT;
                        }
                        intel_pt_set_last_ip(decoder);
                        decoder->state.from_ip = decoder->ip;
                        decoder->state.to_ip = decoder->last_ip;
                        decoder->ip = decoder->last_ip;
                        return 0;
                }

                if (intel_pt_insn.branch == INTEL_PT_BR_CONDITIONAL) {
                        decoder->tnt.count -= 1;
                        if (!decoder->tnt.count)
                                decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
                        if (decoder->tnt.payload & BIT63) {
                                decoder->tnt.payload <<= 1;
                                decoder->state.from_ip = decoder->ip;
                                decoder->ip += intel_pt_insn.length +
                                               intel_pt_insn.rel;
                                decoder->state.to_ip = decoder->ip;
                                return 0;
                        }
                        /* Instruction sample for a non-taken branch */
                        if (decoder->state.type & INTEL_PT_INSTRUCTION) {
                                decoder->tnt.payload <<= 1;
                                decoder->state.type = INTEL_PT_INSTRUCTION;
                                decoder->state.from_ip = decoder->ip;
                                decoder->state.to_ip = 0;
                                decoder->ip += intel_pt_insn.length;
                                return 0;
                        }
                        decoder->ip += intel_pt_insn.length;
                        if (!decoder->tnt.count)
                                return -EAGAIN;
                        decoder->tnt.payload <<= 1;
                        continue;
                }

                return intel_pt_bug(decoder);
        }
}

static int intel_pt_mode_tsx(struct intel_pt_decoder *decoder, bool *no_tip)
{
        unsigned int fup_tx_flags;
        int err;

        fup_tx_flags = decoder->packet.payload &
                       (INTEL_PT_IN_TX | INTEL_PT_ABORT_TX);
        err = intel_pt_get_next_packet(decoder);
        if (err)
                return err;
        if (decoder->packet.type == INTEL_PT_FUP) {
                decoder->fup_tx_flags = fup_tx_flags;
                decoder->set_fup_tx_flags = true;
                if (!(decoder->fup_tx_flags & INTEL_PT_ABORT_TX))
                        *no_tip = true;
        } else {
                intel_pt_log_at("ERROR: Missing FUP after MODE.TSX",
                                decoder->pos);
                intel_pt_update_in_tx(decoder);
        }
        return 0;
}

static void intel_pt_calc_tsc_timestamp(struct intel_pt_decoder *decoder)
{
        uint64_t timestamp;

        decoder->have_tma = false;

        if (decoder->ref_timestamp) {
                timestamp = decoder->packet.payload |
                            (decoder->ref_timestamp & (0xffULL << 56));
                if (timestamp < decoder->ref_timestamp) {
                        if (decoder->ref_timestamp - timestamp > (1ULL << 55))
                                timestamp += (1ULL << 56);
                } else {
                        if (timestamp - decoder->ref_timestamp > (1ULL << 55))
                                timestamp -= (1ULL << 56);
                }
                decoder->tsc_timestamp = timestamp;
                decoder->timestamp = timestamp;
                decoder->ref_timestamp = 0;
                decoder->timestamp_insn_cnt = 0;
        } else if (decoder->timestamp) {
                timestamp = decoder->packet.payload |
                            (decoder->timestamp & (0xffULL << 56));
                decoder->tsc_timestamp = timestamp;
                if (timestamp < decoder->timestamp &&
                    decoder->timestamp - timestamp < decoder->tsc_slip) {
                        intel_pt_log_to("Suppressing backwards timestamp",
                                        timestamp);
                        timestamp = decoder->timestamp;
                }
                if (timestamp < decoder->timestamp) {
                        intel_pt_log_to("Wraparound timestamp", timestamp);
                        timestamp += (1ULL << 56);
                        decoder->tsc_timestamp = timestamp;
                }
                decoder->timestamp = timestamp;
                decoder->timestamp_insn_cnt = 0;
        }

        if (decoder->last_packet_type == INTEL_PT_CYC) {
                decoder->cyc_ref_timestamp = decoder->timestamp;
                decoder->cycle_cnt = 0;
                decoder->have_calc_cyc_to_tsc = false;
                intel_pt_calc_cyc_to_tsc(decoder, false);
        }

        intel_pt_log_to("Setting timestamp", decoder->timestamp);
}

static int intel_pt_overflow(struct intel_pt_decoder *decoder)
{
        intel_pt_log("ERROR: Buffer overflow\n");
        intel_pt_clear_tx_flags(decoder);
        decoder->have_tma = false;
        decoder->cbr = 0;
        decoder->pkt_state = INTEL_PT_STATE_ERR_RESYNC;
        decoder->overflow = true;
        return -EOVERFLOW;
}

static void intel_pt_calc_tma(struct intel_pt_decoder *decoder)
{
        uint32_t ctc = decoder->packet.payload;
        uint32_t fc = decoder->packet.count;
        uint32_t ctc_rem = ctc & decoder->ctc_rem_mask;

        if (!decoder->tsc_ctc_ratio_d)
                return;

        decoder->last_mtc = (ctc >> decoder->mtc_shift) & 0xff;
        decoder->ctc_timestamp = decoder->tsc_timestamp - fc;
        if (decoder->tsc_ctc_mult) {
                decoder->ctc_timestamp -= ctc_rem * decoder->tsc_ctc_mult;
        } else {
                decoder->ctc_timestamp -= multdiv(ctc_rem,
                                                  decoder->tsc_ctc_ratio_n,
                                                  decoder->tsc_ctc_ratio_d);
        }
        decoder->ctc_delta = 0;
        decoder->have_tma = true;
        intel_pt_log("CTC timestamp " x64_fmt " last MTC %#x  CTC rem %#x\n",
                     decoder->ctc_timestamp, decoder->last_mtc, ctc_rem);
}

static void intel_pt_calc_mtc_timestamp(struct intel_pt_decoder *decoder)
{
        uint64_t timestamp;
        uint32_t mtc, mtc_delta;

        if (!decoder->have_tma)
                return;

        mtc = decoder->packet.payload;

        if (mtc > decoder->last_mtc)
                mtc_delta = mtc - decoder->last_mtc;
        else
                mtc_delta = mtc + 256 - decoder->last_mtc;

        decoder->ctc_delta += mtc_delta << decoder->mtc_shift;

        if (decoder->tsc_ctc_mult) {
                timestamp = decoder->ctc_timestamp +
                            decoder->ctc_delta * decoder->tsc_ctc_mult;
        } else {
                timestamp = decoder->ctc_timestamp +
                            multdiv(decoder->ctc_delta,
                                    decoder->tsc_ctc_ratio_n,
                                    decoder->tsc_ctc_ratio_d);
        }

        if (timestamp < decoder->timestamp)
                intel_pt_log("Suppressing MTC timestamp " x64_fmt " less than current timestamp " x64_fmt "\n",
                             timestamp, decoder->timestamp);
        else
                decoder->timestamp = timestamp;

        decoder->timestamp_insn_cnt = 0;
        decoder->last_mtc = mtc;

        if (decoder->last_packet_type == INTEL_PT_CYC) {
                decoder->cyc_ref_timestamp = decoder->timestamp;
                decoder->cycle_cnt = 0;
                decoder->have_calc_cyc_to_tsc = false;
                intel_pt_calc_cyc_to_tsc(decoder, true);
        }
}

static void intel_pt_calc_cbr(struct intel_pt_decoder *decoder)
{
        unsigned int cbr = decoder->packet.payload;

        if (decoder->cbr == cbr)
                return;

        decoder->cbr = cbr;
        decoder->cbr_cyc_to_tsc = decoder->max_non_turbo_ratio_fp / cbr;
}

static void intel_pt_calc_cyc_timestamp(struct intel_pt_decoder *decoder)
{
        uint64_t timestamp = decoder->cyc_ref_timestamp;

        decoder->have_cyc = true;

        decoder->cycle_cnt += decoder->packet.payload;

        if (!decoder->cyc_ref_timestamp)
                return;

        if (decoder->have_calc_cyc_to_tsc)
                timestamp += decoder->cycle_cnt * decoder->calc_cyc_to_tsc;
        else if (decoder->cbr)
                timestamp += decoder->cycle_cnt * decoder->cbr_cyc_to_tsc;
        else
                return;

        if (timestamp < decoder->timestamp)
                intel_pt_log("Suppressing CYC timestamp " x64_fmt " less than current timestamp " x64_fmt "\n",
                             timestamp, decoder->timestamp);
        else
                decoder->timestamp = timestamp;
}

/* Walk PSB+ packets when already in sync. */
static int intel_pt_walk_psbend(struct intel_pt_decoder *decoder)
{
        int err;

        while (1) {
                err = intel_pt_get_next_packet(decoder);
                if (err)
                        return err;

                switch (decoder->packet.type) {
                case INTEL_PT_PSBEND:
                        return 0;

                case INTEL_PT_TIP_PGD:
                case INTEL_PT_TIP_PGE:
                case INTEL_PT_TIP:
                case INTEL_PT_TNT:
                case INTEL_PT_TRACESTOP:
                case INTEL_PT_BAD:
                case INTEL_PT_PSB:
                        decoder->have_tma = false;
                        intel_pt_log("ERROR: Unexpected packet\n");
                        return -EAGAIN;

                case INTEL_PT_OVF:
                        return intel_pt_overflow(decoder);

                case INTEL_PT_TSC:
                        intel_pt_calc_tsc_timestamp(decoder);
                        break;

                case INTEL_PT_TMA:
                        intel_pt_calc_tma(decoder);
                        break;

                case INTEL_PT_CBR:
                        intel_pt_calc_cbr(decoder);
                        break;

                case INTEL_PT_MODE_EXEC:
                        decoder->exec_mode = decoder->packet.payload;
                        break;

                case INTEL_PT_PIP:
                        decoder->cr3 = decoder->packet.payload & (BIT63 - 1);
                        break;

                case INTEL_PT_FUP:
                        decoder->pge = true;
                        intel_pt_set_last_ip(decoder);
                        break;

                case INTEL_PT_MODE_TSX:
                        intel_pt_update_in_tx(decoder);
                        break;

                case INTEL_PT_MTC:
                        intel_pt_calc_mtc_timestamp(decoder);
                        if (decoder->period_type == INTEL_PT_PERIOD_MTC)
                                decoder->state.type |= INTEL_PT_INSTRUCTION;
                        break;

                case INTEL_PT_CYC:
                case INTEL_PT_VMCS:
                case INTEL_PT_MNT:
                case INTEL_PT_PAD:
                default:
                        break;
                }
        }
}

static int intel_pt_walk_fup_tip(struct intel_pt_decoder *decoder)
{
        int err;

        if (decoder->tx_flags & INTEL_PT_ABORT_TX) {
                decoder->tx_flags = 0;
                decoder->state.flags &= ~INTEL_PT_IN_TX;
                decoder->state.flags |= INTEL_PT_ABORT_TX;
        } else {
                decoder->state.flags |= INTEL_PT_ASYNC;
        }

        while (1) {
                err = intel_pt_get_next_packet(decoder);
                if (err)
                        return err;

                switch (decoder->packet.type) {
                case INTEL_PT_TNT:
                case INTEL_PT_FUP:
                case INTEL_PT_TRACESTOP:
                case INTEL_PT_PSB:
                case INTEL_PT_TSC:
                case INTEL_PT_TMA:
                case INTEL_PT_CBR:
                case INTEL_PT_MODE_TSX:
                case INTEL_PT_BAD:
                case INTEL_PT_PSBEND:
                        intel_pt_log("ERROR: Missing TIP after FUP\n");
                        decoder->pkt_state = INTEL_PT_STATE_ERR3;
                        return -ENOENT;

                case INTEL_PT_OVF:
                        return intel_pt_overflow(decoder);

                case INTEL_PT_TIP_PGD:
                        decoder->state.from_ip = decoder->ip;
                        decoder->state.to_ip = 0;
                        if (decoder->packet.count != 0) {
                                intel_pt_set_ip(decoder);
                                intel_pt_log("Omitting PGD ip " x64_fmt "\n",
                                             decoder->ip);
                        }
                        decoder->pge = false;
                        decoder->continuous_period = false;
                        return 0;

                case INTEL_PT_TIP_PGE:
                        decoder->pge = true;
                        intel_pt_log("Omitting PGE ip " x64_fmt "\n",
                                     decoder->ip);
                        decoder->state.from_ip = 0;
                        if (decoder->packet.count == 0) {
                                decoder->state.to_ip = 0;
                        } else {
                                intel_pt_set_ip(decoder);
                                decoder->state.to_ip = decoder->ip;
                        }
                        return 0;

                case INTEL_PT_TIP:
                        decoder->state.from_ip = decoder->ip;
                        if (decoder->packet.count == 0) {
                                decoder->state.to_ip = 0;
                        } else {
                                intel_pt_set_ip(decoder);
                                decoder->state.to_ip = decoder->ip;
                        }
                        return 0;

                case INTEL_PT_PIP:
                        decoder->cr3 = decoder->packet.payload & (BIT63 - 1);
                        break;

                case INTEL_PT_MTC:
                        intel_pt_calc_mtc_timestamp(decoder);
                        if (decoder->period_type == INTEL_PT_PERIOD_MTC)
                                decoder->state.type |= INTEL_PT_INSTRUCTION;
                        break;

                case INTEL_PT_CYC:
                        intel_pt_calc_cyc_timestamp(decoder);
                        break;

                case INTEL_PT_MODE_EXEC:
                        decoder->exec_mode = decoder->packet.payload;
                        break;

                case INTEL_PT_VMCS:
                case INTEL_PT_MNT:
                case INTEL_PT_PAD:
                        break;

                default:
                        return intel_pt_bug(decoder);
                }
        }
}

static int intel_pt_walk_trace(struct intel_pt_decoder *decoder)
{
        bool no_tip = false;
        int err;

        while (1) {
                err = intel_pt_get_next_packet(decoder);
                if (err)
                        return err;
next:
                switch (decoder->packet.type) {
                case INTEL_PT_TNT:
                        if (!decoder->packet.count)
                                break;
                        decoder->tnt = decoder->packet;
                        decoder->pkt_state = INTEL_PT_STATE_TNT;
                        err = intel_pt_walk_tnt(decoder);
                        if (err == -EAGAIN)
                                break;
                        return err;

                case INTEL_PT_TIP_PGD:
                        if (decoder->packet.count != 0)
                                intel_pt_set_last_ip(decoder);
                        decoder->pkt_state = INTEL_PT_STATE_TIP_PGD;
                        return intel_pt_walk_tip(decoder);

                case INTEL_PT_TIP_PGE: {
                        decoder->pge = true;
                        if (decoder->packet.count == 0) {
                                intel_pt_log_at("Skipping zero TIP.PGE",
                                                decoder->pos);
                                break;
                        }
                        intel_pt_set_ip(decoder);
                        decoder->state.from_ip = 0;
                        decoder->state.to_ip = decoder->ip;
                        return 0;
                }

                case INTEL_PT_OVF:
                        return intel_pt_overflow(decoder);

                case INTEL_PT_TIP:
                        if (decoder->packet.count != 0)
                                intel_pt_set_last_ip(decoder);
                        decoder->pkt_state = INTEL_PT_STATE_TIP;
                        return intel_pt_walk_tip(decoder);

                case INTEL_PT_FUP:
                        if (decoder->packet.count == 0) {
                                intel_pt_log_at("Skipping zero FUP",
                                                decoder->pos);
                                no_tip = false;
                                break;
                        }
                        intel_pt_set_last_ip(decoder);
                        err = intel_pt_walk_fup(decoder);
                        if (err != -EAGAIN) {
                                if (err)
                                        return err;
                                if (no_tip)
                                        decoder->pkt_state =
                                                INTEL_PT_STATE_FUP_NO_TIP;
                                else
                                        decoder->pkt_state = INTEL_PT_STATE_FUP;
                                return 0;
                        }
                        if (no_tip) {
                                no_tip = false;
                                break;
                        }
                        return intel_pt_walk_fup_tip(decoder);

                case INTEL_PT_TRACESTOP:
                        decoder->pge = false;
                        decoder->continuous_period = false;
                        intel_pt_clear_tx_flags(decoder);
                        decoder->have_tma = false;
                        break;

                case INTEL_PT_PSB:
                        intel_pt_clear_stack(&decoder->stack);
                        err = intel_pt_walk_psbend(decoder);
                        if (err == -EAGAIN)
                                goto next;
                        if (err)
                                return err;
                        break;

                case INTEL_PT_PIP:
                        decoder->cr3 = decoder->packet.payload & (BIT63 - 1);
                        break;

                case INTEL_PT_MTC:
                        intel_pt_calc_mtc_timestamp(decoder);
                        if (decoder->period_type != INTEL_PT_PERIOD_MTC)
                                break;
                        /*
                         * Ensure that there has been an instruction since the
                         * last MTC.
                         */
                        if (!decoder->mtc_insn)
                                break;
                        decoder->mtc_insn = false;
                        /* Ensure that there is a timestamp */
                        if (!decoder->timestamp)
                                break;
                        decoder->state.type = INTEL_PT_INSTRUCTION;
                        decoder->state.from_ip = decoder->ip;
                        decoder->state.to_ip = 0;
                        decoder->mtc_insn = false;
                        return 0;

                case INTEL_PT_TSC:
                        intel_pt_calc_tsc_timestamp(decoder);
                        break;

                case INTEL_PT_TMA:
                        intel_pt_calc_tma(decoder);
                        break;

                case INTEL_PT_CYC:
                        intel_pt_calc_cyc_timestamp(decoder);
                        break;

                case INTEL_PT_CBR:
                        intel_pt_calc_cbr(decoder);
                        break;

                case INTEL_PT_MODE_EXEC:
                        decoder->exec_mode = decoder->packet.payload;
                        break;

                case INTEL_PT_MODE_TSX:
                        /* MODE_TSX need not be followed by FUP */
                        if (!decoder->pge) {
                                intel_pt_update_in_tx(decoder);
                                break;
                        }
                        err = intel_pt_mode_tsx(decoder, &no_tip);
                        if (err)
                                return err;
                        goto next;

                case INTEL_PT_BAD: /* Does not happen */
                        return intel_pt_bug(decoder);

                case INTEL_PT_PSBEND:
                case INTEL_PT_VMCS:
                case INTEL_PT_MNT:
                case INTEL_PT_PAD:
                        break;

                default:
                        return intel_pt_bug(decoder);
                }
        }
}

/* Walk PSB+ packets to get in sync. */
static int intel_pt_walk_psb(struct intel_pt_decoder *decoder)
{
        int err;

        while (1) {
                err = intel_pt_get_next_packet(decoder);
                if (err)
                        return err;

                switch (decoder->packet.type) {
                case INTEL_PT_TIP_PGD:
                        decoder->continuous_period = false;
                case INTEL_PT_TIP_PGE:
                case INTEL_PT_TIP:
                        intel_pt_log("ERROR: Unexpected packet\n");
                        return -ENOENT;

                case INTEL_PT_FUP:
                        decoder->pge = true;
                        if (decoder->last_ip || decoder->packet.count == 6 ||
                            decoder->packet.count == 0) {
                                uint64_t current_ip = decoder->ip;

                                intel_pt_set_ip(decoder);
                                if (current_ip)
                                        intel_pt_log_to("Setting IP",
                                                        decoder->ip);
                        }
                        break;

                case INTEL_PT_MTC:
                        intel_pt_calc_mtc_timestamp(decoder);
                        break;

                case INTEL_PT_TSC:
                        intel_pt_calc_tsc_timestamp(decoder);
                        break;

                case INTEL_PT_TMA:
                        intel_pt_calc_tma(decoder);
                        break;

                case INTEL_PT_CYC:
                        intel_pt_calc_cyc_timestamp(decoder);
                        break;

                case INTEL_PT_CBR:
                        intel_pt_calc_cbr(decoder);
                        break;

                case INTEL_PT_PIP:
                        decoder->cr3 = decoder->packet.payload & (BIT63 - 1);
                        break;

                case INTEL_PT_MODE_EXEC:
                        decoder->exec_mode = decoder->packet.payload;
                        break;

                case INTEL_PT_MODE_TSX:
                        intel_pt_update_in_tx(decoder);
                        break;

                case INTEL_PT_TRACESTOP:
                        decoder->pge = false;
                        decoder->continuous_period = false;
                        intel_pt_clear_tx_flags(decoder);
                case INTEL_PT_TNT:
                        decoder->have_tma = false;
                        intel_pt_log("ERROR: Unexpected packet\n");
                        if (decoder->ip)
                                decoder->pkt_state = INTEL_PT_STATE_ERR4;
                        else
                                decoder->pkt_state = INTEL_PT_STATE_ERR3;
                        return -ENOENT;

                case INTEL_PT_BAD: /* Does not happen */
                        return intel_pt_bug(decoder);

                case INTEL_PT_OVF:
                        return intel_pt_overflow(decoder);

                case INTEL_PT_PSBEND:
                        return 0;

                case INTEL_PT_PSB:
                case INTEL_PT_VMCS:
                case INTEL_PT_MNT:
                case INTEL_PT_PAD:
                default:
                        break;
                }
        }
}

static int intel_pt_walk_to_ip(struct intel_pt_decoder *decoder)
{
        int err;

        while (1) {
                err = intel_pt_get_next_packet(decoder);
                if (err)
                        return err;

                switch (decoder->packet.type) {
                case INTEL_PT_TIP_PGD:
                        decoder->continuous_period = false;
                case INTEL_PT_TIP_PGE:
                case INTEL_PT_TIP:
                        decoder->pge = decoder->packet.type != INTEL_PT_TIP_PGD;
                        if (decoder->last_ip || decoder->packet.count == 6 ||
                            decoder->packet.count == 0)
                                intel_pt_set_ip(decoder);
                        if (decoder->ip)
                                return 0;
                        break;

                case INTEL_PT_FUP:
                        if (decoder->overflow) {
                                if (decoder->last_ip ||
                                    decoder->packet.count == 6 ||
                                    decoder->packet.count == 0)
                                        intel_pt_set_ip(decoder);
                                if (decoder->ip)
                                        return 0;
                        }
                        if (decoder->packet.count)
                                intel_pt_set_last_ip(decoder);
                        break;

                case INTEL_PT_MTC:
                        intel_pt_calc_mtc_timestamp(decoder);
                        break;

                case INTEL_PT_TSC:
                        intel_pt_calc_tsc_timestamp(decoder);
                        break;

                case INTEL_PT_TMA:
                        intel_pt_calc_tma(decoder);
                        break;

                case INTEL_PT_CYC:
                        intel_pt_calc_cyc_timestamp(decoder);
                        break;

                case INTEL_PT_CBR:
                        intel_pt_calc_cbr(decoder);
                        break;

                case INTEL_PT_PIP:
                        decoder->cr3 = decoder->packet.payload & (BIT63 - 1);
                        break;

                case INTEL_PT_MODE_EXEC:
                        decoder->exec_mode = decoder->packet.payload;
                        break;

                case INTEL_PT_MODE_TSX:
                        intel_pt_update_in_tx(decoder);
                        break;

                case INTEL_PT_OVF:
                        return intel_pt_overflow(decoder);

                case INTEL_PT_BAD: /* Does not happen */
                        return intel_pt_bug(decoder);

                case INTEL_PT_TRACESTOP:
                        decoder->pge = false;
                        decoder->continuous_period = false;
                        intel_pt_clear_tx_flags(decoder);
                        decoder->have_tma = false;
                        break;

                case INTEL_PT_PSB:
                        err = intel_pt_walk_psb(decoder);
                        if (err)
                                return err;
                        if (decoder->ip) {
                                /* Do not have a sample */
                                decoder->state.type = 0;
                                return 0;
                        }
                        break;

                case INTEL_PT_TNT:
                case INTEL_PT_PSBEND:
                case INTEL_PT_VMCS:
                case INTEL_PT_MNT:
                case INTEL_PT_PAD:
                default:
                        break;
                }
        }
}

static int intel_pt_sync_ip(struct intel_pt_decoder *decoder)
{
        int err;

        intel_pt_log("Scanning for full IP\n");
        err = intel_pt_walk_to_ip(decoder);
        if (err)
                return err;

        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
        decoder->overflow = false;

        decoder->state.from_ip = 0;
        decoder->state.to_ip = decoder->ip;
        intel_pt_log_to("Setting IP", decoder->ip);

        return 0;
}

static int intel_pt_part_psb(struct intel_pt_decoder *decoder)
{
        const unsigned char *end = decoder->buf + decoder->len;
        size_t i;

        for (i = INTEL_PT_PSB_LEN - 1; i; i--) {
                if (i > decoder->len)
                        continue;
                if (!memcmp(end - i, INTEL_PT_PSB_STR, i))
                        return i;
        }
        return 0;
}

static int intel_pt_rest_psb(struct intel_pt_decoder *decoder, int part_psb)
{
        size_t rest_psb = INTEL_PT_PSB_LEN - part_psb;
        const char *psb = INTEL_PT_PSB_STR;

        if (rest_psb > decoder->len ||
            memcmp(decoder->buf, psb + part_psb, rest_psb))
                return 0;

        return rest_psb;
}

static int intel_pt_get_split_psb(struct intel_pt_decoder *decoder,
                                  int part_psb)
{
        int rest_psb, ret;

        decoder->pos += decoder->len;
        decoder->len = 0;

        ret = intel_pt_get_next_data(decoder);
        if (ret)
                return ret;

        rest_psb = intel_pt_rest_psb(decoder, part_psb);
        if (!rest_psb)
                return 0;

        decoder->pos -= part_psb;
        decoder->next_buf = decoder->buf + rest_psb;
        decoder->next_len = decoder->len - rest_psb;
        memcpy(decoder->temp_buf, INTEL_PT_PSB_STR, INTEL_PT_PSB_LEN);
        decoder->buf = decoder->temp_buf;
        decoder->len = INTEL_PT_PSB_LEN;

        return 0;
}

static int intel_pt_scan_for_psb(struct intel_pt_decoder *decoder)
{
        unsigned char *next;
        int ret;

        intel_pt_log("Scanning for PSB\n");
        while (1) {
                if (!decoder->len) {
                        ret = intel_pt_get_next_data(decoder);
                        if (ret)
                                return ret;
                }

                next = memmem(decoder->buf, decoder->len, INTEL_PT_PSB_STR,
                              INTEL_PT_PSB_LEN);
                if (!next) {
                        int part_psb;

                        part_psb = intel_pt_part_psb(decoder);
                        if (part_psb) {
                                ret = intel_pt_get_split_psb(decoder, part_psb);
                                if (ret)
                                        return ret;
                        } else {
                                decoder->pos += decoder->len;
                                decoder->len = 0;
                        }
                        continue;
                }

                decoder->pkt_step = next - decoder->buf;
                return intel_pt_get_next_packet(decoder);
        }
}

static int intel_pt_sync(struct intel_pt_decoder *decoder)
{
        int err;

        decoder->pge = false;
        decoder->continuous_period = false;
        decoder->last_ip = 0;
        decoder->ip = 0;
        intel_pt_clear_stack(&decoder->stack);

        err = intel_pt_scan_for_psb(decoder);
        if (err)
                return err;

        decoder->pkt_state = INTEL_PT_STATE_NO_IP;

        err = intel_pt_walk_psb(decoder);
        if (err)
                return err;

        if (decoder->ip) {
                decoder->state.type = 0; /* Do not have a sample */
                decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
        } else {
                return intel_pt_sync_ip(decoder);
        }

        return 0;
}

static uint64_t intel_pt_est_timestamp(struct intel_pt_decoder *decoder)
{
        uint64_t est = decoder->timestamp_insn_cnt << 1;

        if (!decoder->cbr || !decoder->max_non_turbo_ratio)
                goto out;

        est *= decoder->max_non_turbo_ratio;

        est /= decoder->cbr;
out:
        return decoder->timestamp + est;
}

const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
{
        int err;

        do {
                decoder->state.type = INTEL_PT_BRANCH;
                decoder->state.flags = 0;

                switch (decoder->pkt_state) {
                case INTEL_PT_STATE_NO_PSB:
                        err = intel_pt_sync(decoder);
                        break;
                case INTEL_PT_STATE_NO_IP:
                        decoder->last_ip = 0;
                        /* Fall through */
                case INTEL_PT_STATE_ERR_RESYNC:
                        err = intel_pt_sync_ip(decoder);
                        break;
                case INTEL_PT_STATE_IN_SYNC:
                        err = intel_pt_walk_trace(decoder);
                        break;
                case INTEL_PT_STATE_TNT:
                        err = intel_pt_walk_tnt(decoder);
                        if (err == -EAGAIN)
                                err = intel_pt_walk_trace(decoder);
                        break;
                case INTEL_PT_STATE_TIP:
                case INTEL_PT_STATE_TIP_PGD:
                        err = intel_pt_walk_tip(decoder);
                        break;
                case INTEL_PT_STATE_FUP:
                        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
                        err = intel_pt_walk_fup(decoder);
                        if (err == -EAGAIN)
                                err = intel_pt_walk_fup_tip(decoder);
                        else if (!err)
                                decoder->pkt_state = INTEL_PT_STATE_FUP;
                        break;
                case INTEL_PT_STATE_FUP_NO_TIP:
                        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
                        err = intel_pt_walk_fup(decoder);
                        if (err == -EAGAIN)
                                err = intel_pt_walk_trace(decoder);
                        break;
                default:
                        err = intel_pt_bug(decoder);
                        break;
                }
        } while (err == -ENOLINK);

        decoder->state.err = err ? intel_pt_ext_err(err) : 0;
        decoder->state.timestamp = decoder->timestamp;
        decoder->state.est_timestamp = intel_pt_est_timestamp(decoder);
        decoder->state.cr3 = decoder->cr3;
        decoder->state.tot_insn_cnt = decoder->tot_insn_cnt;

        if (err)
                decoder->state.from_ip = decoder->ip;

        return &decoder->state;
}

static bool intel_pt_at_psb(unsigned char *buf, size_t len)
{
        if (len < INTEL_PT_PSB_LEN)
                return false;
        return memmem(buf, INTEL_PT_PSB_LEN, INTEL_PT_PSB_STR,
                      INTEL_PT_PSB_LEN);
}

/**
 * intel_pt_next_psb - move buffer pointer to the start of the next PSB packet.
 * @buf: pointer to buffer pointer
 * @len: size of buffer
 *
 * Updates the buffer pointer to point to the start of the next PSB packet if
 * there is one, otherwise the buffer pointer is unchanged.  If @buf is updated,
 * @len is adjusted accordingly.
 *
 * Return: %true if a PSB packet is found, %false otherwise.
 */
static bool intel_pt_next_psb(unsigned char **buf, size_t *len)
{
        unsigned char *next;

        next = memmem(*buf, *len, INTEL_PT_PSB_STR, INTEL_PT_PSB_LEN);
        if (next) {
                *len -= next - *buf;
                *buf = next;
                return true;
        }
        return false;
}

/**
 * intel_pt_step_psb - move buffer pointer to the start of the following PSB
 *                     packet.
 * @buf: pointer to buffer pointer
 * @len: size of buffer
 *
 * Updates the buffer pointer to point to the start of the following PSB packet
 * (skipping the PSB at @buf itself) if there is one, otherwise the buffer
 * pointer is unchanged.  If @buf is updated, @len is adjusted accordingly.
 *
 * Return: %true if a PSB packet is found, %false otherwise.
 */
static bool intel_pt_step_psb(unsigned char **buf, size_t *len)
{
        unsigned char *next;

        if (!*len)
                return false;

        next = memmem(*buf + 1, *len - 1, INTEL_PT_PSB_STR, INTEL_PT_PSB_LEN);
        if (next) {
                *len -= next - *buf;
                *buf = next;
                return true;
        }
        return false;
}

/**
 * intel_pt_last_psb - find the last PSB packet in a buffer.
 * @buf: buffer
 * @len: size of buffer
 *
 * This function finds the last PSB in a buffer.
 *
 * Return: A pointer to the last PSB in @buf if found, %NULL otherwise.
 */
static unsigned char *intel_pt_last_psb(unsigned char *buf, size_t len)
{
        const char *n = INTEL_PT_PSB_STR;
        unsigned char *p;
        size_t k;

        if (len < INTEL_PT_PSB_LEN)
                return NULL;

        k = len - INTEL_PT_PSB_LEN + 1;
        while (1) {
                p = memrchr(buf, n[0], k);
                if (!p)
                        return NULL;
                if (!memcmp(p + 1, n + 1, INTEL_PT_PSB_LEN - 1))
                        return p;
                k = p - buf;
                if (!k)
                        return NULL;
        }
}

/**
 * intel_pt_next_tsc - find and return next TSC.
 * @buf: buffer
 * @len: size of buffer
 * @tsc: TSC value returned
 *
 * Find a TSC packet in @buf and return the TSC value.  This function assumes
 * that @buf starts at a PSB and that PSB+ will contain TSC and so stops if a
 * PSBEND packet is found.
 *
 * Return: %true if TSC is found, false otherwise.
 */
static bool intel_pt_next_tsc(unsigned char *buf, size_t len, uint64_t *tsc)
{
        struct intel_pt_pkt packet;
        int ret;

        while (len) {
                ret = intel_pt_get_packet(buf, len, &packet);
                if (ret <= 0)
                        return false;
                if (packet.type == INTEL_PT_TSC) {
                        *tsc = packet.payload;
                        return true;
                }
                if (packet.type == INTEL_PT_PSBEND)
                        return false;
                buf += ret;
                len -= ret;
        }
        return false;
}

/**
 * intel_pt_tsc_cmp - compare 7-byte TSCs.
 * @tsc1: first TSC to compare
 * @tsc2: second TSC to compare
 *
 * This function compares 7-byte TSC values allowing for the possibility that
 * TSC wrapped around.  Generally it is not possible to know if TSC has wrapped
 * around so for that purpose this function assumes the absolute difference is
 * less than half the maximum difference.
 *
 * Return: %-1 if @tsc1 is before @tsc2, %0 if @tsc1 == @tsc2, %1 if @tsc1 is
 * after @tsc2.
 */
static int intel_pt_tsc_cmp(uint64_t tsc1, uint64_t tsc2)
{
        const uint64_t halfway = (1ULL << 55);

        if (tsc1 == tsc2)
                return 0;

        if (tsc1 < tsc2) {
                if (tsc2 - tsc1 < halfway)
                        return -1;
                else
                        return 1;
        } else {
                if (tsc1 - tsc2 < halfway)
                        return 1;
                else
                        return -1;
        }
}

/**
 * intel_pt_find_overlap_tsc - determine start of non-overlapped trace data
 *                             using TSC.
 * @buf_a: first buffer
 * @len_a: size of first buffer
 * @buf_b: second buffer
 * @len_b: size of second buffer
 *
 * If the trace contains TSC we can look at the last TSC of @buf_a and the
 * first TSC of @buf_b in order to determine if the buffers overlap, and then
 * walk forward in @buf_b until a later TSC is found.  A precondition is that
 * @buf_a and @buf_b are positioned at a PSB.
 *
 * Return: A pointer into @buf_b from where non-overlapped data starts, or
 * @buf_b + @len_b if there is no non-overlapped data.
 */
static unsigned char *intel_pt_find_overlap_tsc(unsigned char *buf_a,
                                                size_t len_a,
                                                unsigned char *buf_b,
                                                size_t len_b)
{
        uint64_t tsc_a, tsc_b;
        unsigned char *p;
        size_t len;

        p = intel_pt_last_psb(buf_a, len_a);
        if (!p)
                return buf_b; /* No PSB in buf_a => no overlap */

        len = len_a - (p - buf_a);
        if (!intel_pt_next_tsc(p, len, &tsc_a)) {
                /* The last PSB+ in buf_a is incomplete, so go back one more */
                len_a -= len;
                p = intel_pt_last_psb(buf_a, len_a);
                if (!p)
                        return buf_b; /* No full PSB+ => assume no overlap */
                len = len_a - (p - buf_a);
                if (!intel_pt_next_tsc(p, len, &tsc_a))
                        return buf_b; /* No TSC in buf_a => assume no overlap */
        }

        while (1) {
                /* Ignore PSB+ with no TSC */
                if (intel_pt_next_tsc(buf_b, len_b, &tsc_b) &&
                    intel_pt_tsc_cmp(tsc_a, tsc_b) < 0)
                        return buf_b; /* tsc_a < tsc_b => no overlap */

                if (!intel_pt_step_psb(&buf_b, &len_b))
                        return buf_b + len_b; /* No PSB in buf_b => no data */
        }
}

/**
 * intel_pt_find_overlap - determine start of non-overlapped trace data.
 * @buf_a: first buffer
 * @len_a: size of first buffer
 * @buf_b: second buffer
 * @len_b: size of second buffer
 * @have_tsc: can use TSC packets to detect overlap
 *
 * When trace samples or snapshots are recorded there is the possibility that
 * the data overlaps.  Note that, for the purposes of decoding, data is only
 * useful if it begins with a PSB packet.
 *
 * Return: A pointer into @buf_b from where non-overlapped data starts, or
 * @buf_b + @len_b if there is no non-overlapped data.
 */
unsigned char *intel_pt_find_overlap(unsigned char *buf_a, size_t len_a,
                                     unsigned char *buf_b, size_t len_b,
                                     bool have_tsc)
{
        unsigned char *found;

        /* Buffer 'b' must start at PSB so throw away everything before that */
        if (!intel_pt_next_psb(&buf_b, &len_b))
                return buf_b + len_b; /* No PSB */

        if (!intel_pt_next_psb(&buf_a, &len_a))
                return buf_b; /* No overlap */

        if (have_tsc) {
                found = intel_pt_find_overlap_tsc(buf_a, len_a, buf_b, len_b);
                if (found)
                        return found;
        }

        /*
         * Buffer 'b' cannot end within buffer 'a' so, for comparison purposes,
         * we can ignore the first part of buffer 'a'.
         */
        while (len_b < len_a) {
                if (!intel_pt_step_psb(&buf_a, &len_a))
                        return buf_b; /* No overlap */
        }

        /* Now len_b >= len_a */
        if (len_b > len_a) {
                /* The leftover buffer 'b' must start at a PSB */
                while (!intel_pt_at_psb(buf_b + len_a, len_b - len_a)) {
                        if (!intel_pt_step_psb(&buf_a, &len_a))
                                return buf_b; /* No overlap */
                }
        }

        while (1) {
                /* Potential overlap so check the bytes */
                found = memmem(buf_a, len_a, buf_b, len_a);
                if (found)
                        return buf_b + len_a;

                /* Try again at next PSB in buffer 'a' */
                if (!intel_pt_step_psb(&buf_a, &len_a))
                        return buf_b; /* No overlap */

                /* The leftover buffer 'b' must start at a PSB */
                while (!intel_pt_at_psb(buf_b + len_a, len_b - len_a)) {
                        if (!intel_pt_step_psb(&buf_a, &len_a))
                                return buf_b; /* No overlap */
                }
        }
}