intel-pt-decoder.c

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/*
 * 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 <linux/compiler.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,
};

static inline bool intel_pt_sample_time(enum intel_pt_pkt_state pkt_state)
{
    switch (pkt_state) {
    case INTEL_PT_STATE_NO_PSB:
    case INTEL_PT_STATE_NO_IP:
    case INTEL_PT_STATE_ERR_RESYNC:
    case INTEL_PT_STATE_IN_SYNC:
    case INTEL_PT_STATE_TNT:
        return true;
    case INTEL_PT_STATE_TIP:
    case INTEL_PT_STATE_TIP_PGD:
    case INTEL_PT_STATE_FUP:
    case INTEL_PT_STATE_FUP_NO_TIP:
        return false;
    default:
        return true;
    };
}

#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);
    bool (*pgd_ip)(uint64_t ip, void *data);
    void *data;
    struct intel_pt_state state;
    const unsigned char *buf;
    size_t len;
    bool return_compression;
    bool branch_enable;
    bool mtc_insn;
    bool pge;
    bool have_tma;
    bool have_cyc;
    bool fixup_last_mtc;
    bool have_last_ip;
    enum intel_pt_param_flags flags;
    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 sample_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 cbr_seen;
    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 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;
    bool set_fup_ptw;
    bool set_fup_mwait;
    bool set_fup_pwre;
    bool set_fup_exstop;
    unsigned int fup_tx_flags;
    unsigned int tx_flags;
    uint64_t fup_ptw_payload;
    uint64_t fup_mwait_payload;
    uint64_t fup_pwre_payload;
    uint64_t cbr_payload;
    uint64_t timestamp_insn_cnt;
    uint64_t sample_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->pgd_ip             = params->pgd_ip;
    decoder->data               = params->data;
    decoder->return_compression = params->return_compression;
    decoder->branch_enable      = params->branch_enable;

    decoder->flags              = params->flags;

    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(const struct intel_pt_pkt *packet,
                 uint64_t last_ip)
{
    uint64_t ip;

    switch (packet->count) {
    case 1:
        ip = (last_ip & (uint64_t)0xffffffffffff0000ULL) |
             packet->payload;
        break;
    case 2:
        ip = (last_ip & (uint64_t)0xffffffff00000000ULL) |
             packet->payload;
        break;
    case 3:
        ip = packet->payload;
        /* Sign-extend 6-byte ip */
        if (ip & (uint64_t)0x800000000000ULL)
            ip |= (uint64_t)0xffff000000000000ULL;
        break;
    case 4:
        ip = (last_ip & (uint64_t)0xffff000000000000ULL) |
             packet->payload;
        break;
    case 6:
        ip = packet->payload;
        break;
    default:
        return 0;
    }

    return ip;
}

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

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            fixup_last_mtc;
    bool            from_mtc;
    double          cbr_cyc_to_tsc;
};

/*
 * MTC provides a 8-bit slice of CTC but the TMA packet only provides the lower
 * 16 bits of CTC. If mtc_shift > 8 then some of the MTC bits are not in the CTC
 * provided by the TMA packet. Fix-up the last_mtc calculated from the TMA
 * packet by copying the missing bits from the current MTC assuming the least
 * difference between the two, and that the current MTC comes after last_mtc.
 */
static void intel_pt_fixup_last_mtc(uint32_t mtc, int mtc_shift,
                    uint32_t *last_mtc)
{
    uint32_t first_missing_bit = 1U << (16 - mtc_shift);
    uint32_t mask = ~(first_missing_bit - 1);

    *last_mtc |= mtc & mask;
    if (*last_mtc >= mtc) {
        *last_mtc -= first_missing_bit;
        *last_mtc &= 0xff;
    }
}

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:
    case INTEL_PT_PTWRITE:
    case INTEL_PT_PTWRITE_IP:
        return 0;

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

        mtc = pkt_info->packet.payload;
        if (decoder->mtc_shift > 8 && data->fixup_last_mtc) {
            data->fixup_last_mtc = false;
            intel_pt_fixup_last_mtc(mtc, decoder->mtc_shift,
                        &data->last_mtc);
        }
        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:
        /*
         * For now, do not support using TSC packets - refer
         * intel_pt_calc_cyc_to_tsc().
         */
        if (data->from_mtc)
            return 1;
        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;
        data->fixup_last_mtc = 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_EXSTOP:
    case INTEL_PT_EXSTOP_IP:
    case INTEL_PT_MWAIT:
    case INTEL_PT_PWRE:
    case INTEL_PT_PWRX:
    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,
        .fixup_last_mtc = decoder->fixup_last_mtc,
        .from_mtc       = from_mtc,
        .cbr_cyc_to_tsc = 0,
    };

    /*
     * For now, do not support using TSC packets for at least the reasons:
     * 1) timing might have stopped
     * 2) TSC packets within PSB+ can slip against CYC packets
     */
    if (!from_mtc)
        return;

    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->sample_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;
    memcpy(decoder->state.insn, intel_pt_insn->buf,
           INTEL_PT_INSN_BUF_SZ);

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

    return err;
}

static bool intel_pt_fup_event(struct intel_pt_decoder *decoder)
{
    bool ret = false;

    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 true;
    }
    if (decoder->set_fup_ptw) {
        decoder->set_fup_ptw = false;
        decoder->state.type = INTEL_PT_PTW;
        decoder->state.flags |= INTEL_PT_FUP_IP;
        decoder->state.from_ip = decoder->ip;
        decoder->state.to_ip = 0;
        decoder->state.ptw_payload = decoder->fup_ptw_payload;
        return true;
    }
    if (decoder->set_fup_mwait) {
        decoder->set_fup_mwait = false;
        decoder->state.type = INTEL_PT_MWAIT_OP;
        decoder->state.from_ip = decoder->ip;
        decoder->state.to_ip = 0;
        decoder->state.mwait_payload = decoder->fup_mwait_payload;
        ret = true;
    }
    if (decoder->set_fup_pwre) {
        decoder->set_fup_pwre = false;
        decoder->state.type |= INTEL_PT_PWR_ENTRY;
        decoder->state.type &= ~INTEL_PT_BRANCH;
        decoder->state.from_ip = decoder->ip;
        decoder->state.to_ip = 0;
        decoder->state.pwre_payload = decoder->fup_pwre_payload;
        ret = true;
    }
    if (decoder->set_fup_exstop) {
        decoder->set_fup_exstop = false;
        decoder->state.type |= INTEL_PT_EX_STOP;
        decoder->state.type &= ~INTEL_PT_BRANCH;
        decoder->state.flags |= INTEL_PT_FUP_IP;
        decoder->state.from_ip = decoder->ip;
        decoder->state.to_ip = 0;
        ret = true;
    }
    return ret;
}

static inline bool intel_pt_fup_with_nlip(struct intel_pt_decoder *decoder,
                      struct intel_pt_insn *intel_pt_insn,
                      uint64_t ip, int err)
{
    return decoder->flags & INTEL_PT_FUP_WITH_NLIP && !err &&
           intel_pt_insn->branch == INTEL_PT_BR_INDIRECT &&
           ip == decoder->ip + intel_pt_insn->length;
}

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 ||
            intel_pt_fup_with_nlip(decoder, &intel_pt_insn, ip, err)) {
            if (intel_pt_fup_event(decoder))
                return 0;
            return -EAGAIN;
        }
        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 &&
        decoder->pgd_ip &&
        decoder->pkt_state == INTEL_PT_STATE_TIP_PGD &&
        (decoder->state.type & INTEL_PT_BRANCH) &&
        decoder->pgd_ip(decoder->state.to_ip, decoder->data)) {
        /* Unconditional branch leaving filter region */
        decoder->no_progress = 0;
        decoder->pge = false;
        decoder->continuous_period = false;
        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
        decoder->state.to_ip = 0;
        return 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) {
        uint64_t to_ip = decoder->ip + intel_pt_insn.length +
                 intel_pt_insn.rel;

        if (decoder->pgd_ip &&
            decoder->pkt_state == INTEL_PT_STATE_TIP_PGD &&
            decoder->pgd_ip(to_ip, decoder->data)) {
            /* Conditional branch leaving filter region */
            decoder->pge = false;
            decoder->continuous_period = false;
            decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
            decoder->ip = to_ip;
            decoder->state.from_ip = decoder->ip;
            decoder->state.to_ip = 0;
            return 0;
        }
        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->cbr = 0;
    decoder->timestamp_insn_cnt = 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;
    decoder->fixup_last_mtc = 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 (decoder->mtc_shift > 8 && decoder->fixup_last_mtc) {
        decoder->fixup_last_mtc = false;
        intel_pt_fixup_last_mtc(mtc, decoder->mtc_shift,
                    &decoder->last_mtc);
    }

    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 & 0xff;

    decoder->cbr_payload = 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;

    decoder->timestamp_insn_cnt = 0;
}

/* 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:
        case INTEL_PT_PTWRITE:
        case INTEL_PT_PTWRITE_IP:
        case INTEL_PT_EXSTOP:
        case INTEL_PT_EXSTOP_IP:
        case INTEL_PT_MWAIT:
        case INTEL_PT_PWRE:
        case INTEL_PT_PWRX:
            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;
            if (decoder->packet.count)
                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_MODE_TSX:
        case INTEL_PT_BAD:
        case INTEL_PT_PSBEND:
        case INTEL_PT_PTWRITE:
        case INTEL_PT_PTWRITE_IP:
        case INTEL_PT_EXSTOP:
        case INTEL_PT_EXSTOP_IP:
        case INTEL_PT_MWAIT:
        case INTEL_PT_PWRE:
        case INTEL_PT_PWRX:
            intel_pt_log("ERROR: Missing TIP after FUP\n");
            decoder->pkt_state = INTEL_PT_STATE_ERR3;
            decoder->pkt_step = 0;
            return -ENOENT;

        case INTEL_PT_CBR:
            intel_pt_calc_cbr(decoder);
            break;

        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);
            if (!decoder->branch_enable) {
                decoder->ip = decoder->last_ip;
                if (intel_pt_fup_event(decoder))
                    return 0;
                no_tip = false;
                break;
            }
            if (decoder->set_fup_mwait)
                no_tip = true;
            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:
            decoder->last_ip = 0;
            decoder->have_last_ip = true;
            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);
            if (!decoder->branch_enable &&
                decoder->cbr != decoder->cbr_seen) {
                decoder->cbr_seen = decoder->cbr;
                decoder->state.type = INTEL_PT_CBR_CHG;
                decoder->state.from_ip = decoder->ip;
                decoder->state.to_ip = 0;
                decoder->state.cbr_payload =
                            decoder->packet.payload;
                return 0;
            }
            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;

        case INTEL_PT_PTWRITE_IP:
            decoder->fup_ptw_payload = decoder->packet.payload;
            err = intel_pt_get_next_packet(decoder);
            if (err)
                return err;
            if (decoder->packet.type == INTEL_PT_FUP) {
                decoder->set_fup_ptw = true;
                no_tip = true;
            } else {
                intel_pt_log_at("ERROR: Missing FUP after PTWRITE",
                        decoder->pos);
            }
            goto next;

        case INTEL_PT_PTWRITE:
            decoder->state.type = INTEL_PT_PTW;
            decoder->state.from_ip = decoder->ip;
            decoder->state.to_ip = 0;
            decoder->state.ptw_payload = decoder->packet.payload;
            return 0;

        case INTEL_PT_MWAIT:
            decoder->fup_mwait_payload = decoder->packet.payload;
            decoder->set_fup_mwait = true;
            break;

        case INTEL_PT_PWRE:
            if (decoder->set_fup_mwait) {
                decoder->fup_pwre_payload =
                            decoder->packet.payload;
                decoder->set_fup_pwre = true;
                break;
            }
            decoder->state.type = INTEL_PT_PWR_ENTRY;
            decoder->state.from_ip = decoder->ip;
            decoder->state.to_ip = 0;
            decoder->state.pwrx_payload = decoder->packet.payload;
            return 0;

        case INTEL_PT_EXSTOP_IP:
            err = intel_pt_get_next_packet(decoder);
            if (err)
                return err;
            if (decoder->packet.type == INTEL_PT_FUP) {
                decoder->set_fup_exstop = true;
                no_tip = true;
            } else {
                intel_pt_log_at("ERROR: Missing FUP after EXSTOP",
                        decoder->pos);
            }
            goto next;

        case INTEL_PT_EXSTOP:
            decoder->state.type = INTEL_PT_EX_STOP;
            decoder->state.from_ip = decoder->ip;
            decoder->state.to_ip = 0;
            return 0;

        case INTEL_PT_PWRX:
            decoder->state.type = INTEL_PT_PWR_EXIT;
            decoder->state.from_ip = decoder->ip;
            decoder->state.to_ip = 0;
            decoder->state.pwrx_payload = decoder->packet.payload;
            return 0;

        default:
            return intel_pt_bug(decoder);
        }
    }
}

static inline bool intel_pt_have_ip(struct intel_pt_decoder *decoder)
{
    return decoder->packet.count &&
           (decoder->have_last_ip || decoder->packet.count == 3 ||
        decoder->packet.count == 6);
}

/* 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;
            __fallthrough;
        case INTEL_PT_TIP_PGE:
        case INTEL_PT_TIP:
        case INTEL_PT_PTWRITE:
        case INTEL_PT_PTWRITE_IP:
        case INTEL_PT_EXSTOP:
        case INTEL_PT_EXSTOP_IP:
        case INTEL_PT_MWAIT:
        case INTEL_PT_PWRE:
        case INTEL_PT_PWRX:
            intel_pt_log("ERROR: Unexpected packet\n");
            return -ENOENT;

        case INTEL_PT_FUP:
            decoder->pge = true;
            if (intel_pt_have_ip(decoder)) {
                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);
            __fallthrough;

        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;
            __fallthrough;
        case INTEL_PT_TIP_PGE:
        case INTEL_PT_TIP:
            decoder->pge = decoder->packet.type != INTEL_PT_TIP_PGD;
            if (intel_pt_have_ip(decoder))
                intel_pt_set_ip(decoder);
            if (decoder->ip)
                return 0;
            break;

        case INTEL_PT_FUP:
            if (intel_pt_have_ip(decoder))
                intel_pt_set_ip(decoder);
            if (decoder->ip)
                return 0;
            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:
            decoder->last_ip = 0;
            decoder->have_last_ip = true;
            intel_pt_clear_stack(&decoder->stack);
            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:
        case INTEL_PT_PTWRITE:
        case INTEL_PT_PTWRITE_IP:
        case INTEL_PT_EXSTOP:
        case INTEL_PT_EXSTOP_IP:
        case INTEL_PT_MWAIT:
        case INTEL_PT_PWRE:
        case INTEL_PT_PWRX:
        default:
            break;
        }
    }
}

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

    decoder->set_fup_tx_flags = false;
    decoder->set_fup_ptw = false;
    decoder->set_fup_mwait = false;
    decoder->set_fup_pwre = false;
    decoder->set_fup_exstop = false;

    if (!decoder->branch_enable) {
        decoder->pkt_state = INTEL_PT_STATE_IN_SYNC;
        decoder->overflow = false;
        decoder->state.type = 0; /* Do not have a sample */
        return 0;
    }

    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->have_last_ip = 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->have_last_ip = true;
    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->sample_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->sample_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->have_last_ip = false;
            decoder->last_ip = 0;
            decoder->ip = 0;
            __fallthrough;
        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);

    if (err) {
        decoder->state.err = intel_pt_ext_err(err);
        decoder->state.from_ip = decoder->ip;
        decoder->sample_timestamp = decoder->timestamp;
        decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
    } else {
        decoder->state.err = 0;
        if (decoder->cbr != decoder->cbr_seen && decoder->state.type) {
            decoder->cbr_seen = decoder->cbr;
            decoder->state.type |= INTEL_PT_CBR_CHG;
            decoder->state.cbr_payload = decoder->cbr_payload;
        }
        if (intel_pt_sample_time(decoder->pkt_state)) {
            decoder->sample_timestamp = decoder->timestamp;
            decoder->sample_insn_cnt = decoder->timestamp_insn_cnt;
        }
    }

    decoder->state.timestamp = decoder->sample_timestamp;
    decoder->state.est_timestamp = intel_pt_est_timestamp(decoder);
    decoder->state.cr3 = decoder->cr3;
    decoder->state.tot_insn_cnt = decoder->tot_insn_cnt;

    return &decoder->state;
}

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;
}

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;
}

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;
    }
}

static bool intel_pt_next_tsc(unsigned char *buf, size_t len, uint64_t *tsc,
                  size_t *rem)
{
    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;
            *rem = len;
            return true;
        }
        if (packet.type == INTEL_PT_PSBEND)
            return false;
        buf += ret;
        len -= ret;
    }
    return false;
}

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;
    }
}

static unsigned char *intel_pt_find_overlap_tsc(unsigned char *buf_a,
                        size_t len_a,
                        unsigned char *buf_b,
                        size_t len_b, bool *consecutive)
{
    uint64_t tsc_a, tsc_b;
    unsigned char *p;
    size_t len, rem_a, rem_b;

    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, &rem_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, &rem_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, &rem_b)) {
            int cmp = intel_pt_tsc_cmp(tsc_a, tsc_b);

            /* Same TSC, so buffers are consecutive */
            if (!cmp && rem_b >= rem_a) {
                *consecutive = true;
                return buf_b + len_b - (rem_b - rem_a);
            }
            if (cmp < 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 */
    }
}

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, bool *consecutive)
{
    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,
                          consecutive);
        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 */
    while (1) {
        /* Potential overlap so check the bytes */
        found = memmem(buf_a, len_a, buf_b, len_a);
        if (found) {
            *consecutive = true;
            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 */
    }
}