// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// See the README.md in this directory for documentation.

#include <ddk/binding.h>
#include <ddk/debug.h>
#include <ddk/device.h>
#include <ddk/driver.h>
#include <ddk/io-buffer.h>

#include <zircon/device/cpu-trace/intel-pt.h>
#include <zircon/mtrace.h>
#include <zircon/syscalls.h>
#include <zircon/syscalls/resource.h>
#include <zircon/types.h>

#include <assert.h>
#include <cpuid.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "cpu-trace-private.h"

typedef enum {
    IPT_TRACE_CPUS,
    IPT_TRACE_THREADS
} ipt_trace_mode_t;

typedef struct ipt_per_trace_state {
    // the cpu or thread this buffer is assigned to
    // Which value to use is determined by the trace mode.
    union {
        uint32_t cpuno;
        zx_handle_t thread;
    } owner;

    // number of chunks, each 2^|chunk_order| pages in size
    uint32_t num_chunks;
    // log2 size of each chunk, in pages
    uint32_t chunk_order;
    // if true then the buffer is circular, otherwise tracing stops when the
    // buffer fills
    bool is_circular;
    // true if allocated
    bool allocated;
    // number of ToPA tables needed
    uint32_t num_tables;

    // msrs
    uint64_t ctl;
    uint64_t status;
    uint64_t output_base;
    uint64_t output_mask_ptrs;
    uint64_t cr3_match;
    struct {
        uint64_t a,b;
    } addr_ranges[IPT_MAX_NUM_ADDR_RANGES];

    // trace buffers and ToPA tables
    // ToPA: Table of Physical Addresses
    // A "trace buffer" is a set of N chunks.
    io_buffer_t* chunks;
    io_buffer_t* topas;
} ipt_per_trace_state_t;

typedef struct ipt_device {
    ipt_trace_mode_t mode;

    // # of entries in |per_trace_state|.
    // When tracing by cpu, this is the max number of cpus.
    // When tracing by thread, this is the max number of threads.
    // TODO(dje): Add support for dynamically growing the vector.
    uint32_t num_traces;

    // one entry for each trace
    ipt_per_trace_state_t* per_trace_state;

    // Once tracing has started various things are not allowed until it stops.
    bool active;

    // Borrowed handle from cpu_trace_device.  Must not close
    zx_handle_t bti;
} ipt_device_t;

// This struct is temporary, pending subsuming the "ipt" device driver
// within a more general "cpu-trace" device driver.
typedef struct ipt_uber_device {
    mtx_t lock;

    // Only one open of this device is supported at a time.
    bool opened;

    // At present we only support one allocated IPT session at a time.
    ipt_device_t* ipt;
} ipt_uber_device_t;

static uint32_t ipt_config_family;
static uint32_t ipt_config_model;
static uint32_t ipt_config_stepping;

static uint32_t ipt_config_addr_cfg_max = 0;
static uint32_t ipt_config_mtc_freq_mask = 0;
static uint32_t ipt_config_cyc_thresh_mask = 0;
static uint32_t ipt_config_psb_freq_mask = 0;
static uint32_t ipt_config_num_addr_ranges = 0;
static uint32_t ipt_config_bus_freq = 0;

static bool ipt_config_supported = false;

static bool ipt_config_cr3_filtering = false;
static bool ipt_config_psb = false;
static bool ipt_config_ip_filtering = false;
static bool ipt_config_mtc = false;
static bool ipt_config_ptwrite = false;
static bool ipt_config_power_events = false;
static bool ipt_config_output_topa = false;
static bool ipt_config_output_topa_multi = false;
static bool ipt_config_output_single = false;
static bool ipt_config_output_transport = false;
static bool ipt_config_lip = false;

// maximum space, in bytes, for trace buffers (per cpu)
// This isn't necessarily
// MAX_NUM_CHUNKS * (1 << (MAX_CHUNK_ORDER + PAGE_SIZE_SHIFT)).
// Buffers have to be naturally aligned contiguous pages, but we can have
// a lot of them. Supporting large buffers and/or lots of them is for
// experimentation.
#define MAX_PER_TRACE_SPACE (256 * 1024 * 1024)

// maximum number of buffers
#define MAX_NUM_CHUNKS 4096

// maximum size of each buffer, in pages (1MB)
#define MAX_CHUNK_ORDER 8

#if PAGE_SIZE == 4096
#define PAGE_SIZE_SHIFT 12
#else
#error "unsupported page size"
#endif

#define BIT(x, b) ((x) & (1u << (b)))

static zx_status_t x86_pt_free(ipt_device_t* ipt_dev);


// The userspace side of the driver

void ipt_init_once(void)
{
    unsigned a, b, c, d, max_leaf;

    max_leaf = __get_cpuid_max(0, NULL);
    if (max_leaf < 0x14) {
        zxlogf(INFO, "IntelPT: No PT support\n");
        return;
    }

    __cpuid(1, a, b, c, d);
    ipt_config_stepping = a & 0xf;
    ipt_config_model = (a >> 4) & 0xf;
    ipt_config_family = (a >> 8) & 0xf;
    if (ipt_config_family == 0xf)
        ipt_config_family += (a >> 20) & 0xff;
    if (ipt_config_family == 6 || ipt_config_family == 0xf)
        ipt_config_model += ((a >> 16) & 0xf) << 4;

    __cpuid_count(0x07, 0, a, b, c, d);
    if (!BIT(b, 25)) {
        zxlogf(INFO, "IntelPT: No PT support\n");
        return;
    }

    ipt_config_supported = true;

    __cpuid_count(0x14, 0, a, b, c, d);
    if (BIT(b, 2))
        ipt_config_addr_cfg_max = 2;
    if (BIT(b, 1) && a >= 1) {
        unsigned a1, b1, c1, d1;
        __cpuid_count(0x14, 1, a1, b1, c1, d1);
        ipt_config_mtc_freq_mask = (a1 >> 16) & 0xffff;
        ipt_config_cyc_thresh_mask = b1 & 0xffff;
        ipt_config_psb_freq_mask = (b1 >> 16) & 0xffff;
        ipt_config_num_addr_ranges = a1 & 0x7;
    }

    if (max_leaf >= 0x15) {
        unsigned a1 = 0, b1 = 0, c1 = 0, d1 = 0;
        __cpuid(0x15, a1, b1, c1, d1);
        if (a1 && b1)
            ipt_config_bus_freq = 1. / ((float)a1 / (float)b1);
    }

    ipt_config_cr3_filtering = !!BIT(b, 0);
    ipt_config_psb = !!BIT(b, 1);
    ipt_config_ip_filtering = !!BIT(b, 2);
    ipt_config_mtc = !!BIT(b, 3);
    ipt_config_ptwrite = !!BIT(b, 4);
    ipt_config_power_events = !!BIT(b, 5);

    ipt_config_output_topa = !!BIT(c, 0);
    ipt_config_output_topa_multi = !!BIT(c, 1);
    ipt_config_output_single = !!BIT(c, 2);
    ipt_config_output_transport = !!BIT(c, 3);
    ipt_config_lip = !!BIT(c, 31);

    zxlogf(INFO, "Intel Processor Trace configuration for this chipset:\n");
    // No need to print everything, but these are useful.
    zxlogf(INFO, "mtc_freq_mask:   0x%x\n", ipt_config_mtc_freq_mask);
    zxlogf(INFO, "cyc_thresh_mask: 0x%x\n", ipt_config_cyc_thresh_mask);
    zxlogf(INFO, "psb_freq_mask:   0x%x\n", ipt_config_psb_freq_mask);
    zxlogf(INFO, "num addr ranges: %u\n", ipt_config_num_addr_ranges);
}

// Create the ToPA for the configured number of pages for |cpu|.
// A circular collection of buffers is set up, even if we're going to apply
// the stop bit to the last entry.
static void make_topa(ipt_device_t* ipt_dev, ipt_per_trace_state_t* per_trace) {
    const size_t run_len_log2 = per_trace->chunk_order;
    assert(run_len_log2 + PAGE_SIZE_SHIFT <= IPT_TOPA_MAX_SHIFT);
    assert(run_len_log2 + PAGE_SIZE_SHIFT >= IPT_TOPA_MIN_SHIFT);

    uint32_t curr_table = 0;
    uint32_t curr_idx = 0;
    uint64_t* last_entry = NULL;

    // Note: An early version of this patch auto-computed the desired grouping
    // of pages with sufficient alignment. If you find yourself needing this
    // functionality again, see change 9470.

    for (uint32_t i = 0; i < per_trace->num_chunks; ++i) {
        io_buffer_t* buffer = &per_trace->chunks[i];
        io_buffer_t* topa = &per_trace->topas[curr_table];
        zx_paddr_t pa = io_buffer_phys(buffer);

        uint64_t val = IPT_TOPA_ENTRY_PHYS_ADDR(pa) |
            IPT_TOPA_ENTRY_SIZE(run_len_log2 + PAGE_SIZE_SHIFT);
        uint64_t* table = io_buffer_virt(topa);
        table[curr_idx] = val;
        last_entry = &table[curr_idx];

        // Make sure we leave one at the end of the table for the END marker.
        if (unlikely(curr_idx >= IPT_TOPA_MAX_TABLE_ENTRIES - 2)) {
            curr_idx = 0;
            curr_table++;
        } else {
            curr_idx++;
        }
    }

    assert(curr_table + 1 == per_trace->num_tables ||
           // If the last table is full curr_table will be the next one.
           (curr_table == per_trace->num_tables && curr_idx == 0));

    // Populate END entries for completed tables
    // Assume the table is circular. We'll set the stop bit on the last
    // entry later.
    for (uint32_t i = 0; i < curr_table; ++i) {
        io_buffer_t* this_table = &per_trace->topas[i];
        io_buffer_t* next_table;
        if (i == per_trace->num_tables - 1) {
            next_table = &per_trace->topas[0];
        } else {
            next_table = &per_trace->topas[i + 1];
        }

        zx_paddr_t next_table_pa = io_buffer_phys(next_table);
        uint64_t val = IPT_TOPA_ENTRY_PHYS_ADDR(next_table_pa) | IPT_TOPA_ENTRY_END;
        uint64_t* table = io_buffer_virt(this_table);
        table[IPT_TOPA_MAX_TABLE_ENTRIES - 1] = val;
    }

    // Populate the END entry for a possibly non-full last table
    if (curr_table < per_trace->num_tables) {
        io_buffer_t* this_table = &per_trace->topas[curr_table];
        io_buffer_t* first_table = &per_trace->topas[0];
        zx_paddr_t first_table_pa = io_buffer_phys(first_table);
        uint64_t val = IPT_TOPA_ENTRY_PHYS_ADDR(first_table_pa) | IPT_TOPA_ENTRY_END;
        uint64_t* table = io_buffer_virt(this_table);
        table[curr_idx] = val;
    }

    // Add the STOP flag to the last non-END entry in the tables
    assert(last_entry);
    if (!per_trace->is_circular)
        *last_entry |= IPT_TOPA_ENTRY_STOP;
}

// Compute the number of ToPA entries needed for the configured number of
// buffers.
// The output count includes the END entries across all needed tables.
static uint32_t compute_topa_entry_count(ipt_device_t* ipt_dev, ipt_per_trace_state_t* per_trace) {
    uint32_t num_entries = per_trace->num_chunks;
    uint32_t num_end_entries = (num_entries + IPT_TOPA_MAX_TABLE_ENTRIES - 2) /
        (IPT_TOPA_MAX_TABLE_ENTRIES - 1);
    uint32_t result = num_entries + num_end_entries;

    zxlogf(DEBUG1, "IPT: compute_topa_entry_count: num_entries: %u\n", num_entries);
    zxlogf(DEBUG1, "IPT: compute_topa_entry_count: num_end_entries: %u\n", num_end_entries);
    zxlogf(DEBUG1, "IPT: compute_topa_entry_count: total entries: %u\n", result);

    return result;
}

// Walk the tables to discover how much data has been captured for |per_trace|.
// Note: If this is a circular buffer this is just where tracing stopped.
static size_t compute_capture_size(ipt_device_t* ipt_dev, const ipt_per_trace_state_t* per_trace) {
    uint64_t curr_table_paddr = per_trace->output_base;
    uint32_t curr_table_entry_idx = (uint32_t)per_trace->output_mask_ptrs >> 7;
    uint32_t curr_entry_offset = (uint32_t)(per_trace->output_mask_ptrs >> 32);

    zxlogf(DEBUG1, "IPT: compute_capture_size: trace %tu\n", per_trace - ipt_dev->per_trace_state);
    zxlogf(DEBUG1, "IPT: curr_table_paddr 0x%" PRIx64 ", curr_table_entry_idx %u, curr_entry_offset %u\n",
           curr_table_paddr, curr_table_entry_idx, curr_entry_offset);

    size_t total_size = 0;
    for (uint32_t table = 0; table < per_trace->num_tables; ++table) {
        // Get the physical address so that we can compare it with the value
        // in output_base.
        zx_paddr_t table_paddr = io_buffer_phys(&per_trace->topas[table]);

        for (uint32_t entry = 0; entry < IPT_TOPA_MAX_TABLE_ENTRIES - 1; ++entry) {
            if (table_paddr == curr_table_paddr && entry >= curr_table_entry_idx) {
                total_size += curr_entry_offset;
                return total_size;
            }
            uint64_t* table_ptr = io_buffer_virt(&per_trace->topas[table]);
            uint64_t topa_entry = table_ptr[entry];
            total_size += 1UL << IPT_TOPA_ENTRY_EXTRACT_SIZE(topa_entry);
        }
    }

    // Should be unreachable.
    // TODO(dje): Later flag state as broken.
    zxlogf(ERROR, "IPT: unexpectedly exited capture loop\n");
    return 0;
}

static zx_status_t x86_pt_alloc_buffer1(ipt_device_t* ipt_dev, ipt_per_trace_state_t* per_trace,
                                        uint32_t num, uint32_t order, bool is_circular) {
    zx_status_t status;
    size_t chunk_pages = 1 << order;

    memset(per_trace, 0, sizeof(*per_trace));

    per_trace->chunks = calloc(num, sizeof(io_buffer_t));
    if (per_trace->chunks == NULL)
        return ZX_ERR_NO_MEMORY;

    for (uint32_t i = 0; i < num; ++i) {
        // ToPA entries of size N must be aligned to N, too.
        uint32_t alignment_log2 = PAGE_SIZE_SHIFT + order;
        status = io_buffer_init_aligned(&per_trace->chunks[i], ipt_dev->bti,
                                        chunk_pages * PAGE_SIZE, alignment_log2,
                                        IO_BUFFER_RW | IO_BUFFER_CONTIG);
        if (status != ZX_OK)
            return status;
        // Keep track of allocated buffers as we go in case we later fail:
        // we want to be able to free those that got allocated.
        ++per_trace->num_chunks;
        // Catch bugs in io_buffer_init_aligned. If it doesn't give us a
        // properly aligned buffer we'll get an "operational error" later.
        // See Intel Vol3 36.2.6.2.
        zx_paddr_t pa = io_buffer_phys(&per_trace->chunks[i]);
        zx_paddr_t align_mask = (1ull << alignment_log2) - 1;
        if (pa & align_mask) {
            zxlogf(ERROR, "%s: WARNING: chunk has bad alignment: alignment %u, got 0x%" PRIx64 "\n",
                   __func__, alignment_log2, pa);
            return ZX_ERR_INTERNAL;
        }
    }
    assert(per_trace->num_chunks == num);

    per_trace->chunk_order = order;
    per_trace->is_circular = is_circular;

    // TODO(dje): No need to allocate the max on the last table.
    uint32_t entry_count = compute_topa_entry_count(ipt_dev, per_trace);
    uint32_t table_count = (entry_count + IPT_TOPA_MAX_TABLE_ENTRIES - 1) /
            IPT_TOPA_MAX_TABLE_ENTRIES;

    if (entry_count < 2) {
        zxlogf(INFO, "IPT: INVALID ENTRY COUNT: %u\n", entry_count);
        return ZX_ERR_INVALID_ARGS;
    }

    // Some early Processor Trace implementations only supported having a
    // table with a single real entry and an END.
    if (!ipt_config_output_topa_multi && entry_count > 2)
        return ZX_ERR_NOT_SUPPORTED;

    // Allocate Table(s) of Physical Addresses (ToPA) for each cpu.

    per_trace->topas = calloc(table_count, sizeof(io_buffer_t));
    if (per_trace->topas == NULL)
        return ZX_ERR_NO_MEMORY;

    for (uint32_t i = 0; i < table_count; ++i) {
        status = io_buffer_init(&per_trace->topas[i], ipt_dev->bti,
                                sizeof(uint64_t) * IPT_TOPA_MAX_TABLE_ENTRIES,
                                IO_BUFFER_RW | IO_BUFFER_CONTIG);
        if (status != ZX_OK)
            return ZX_ERR_NO_MEMORY;
        // Keep track of allocated tables as we go in case we later fail:
        // we want to be able to free those that got allocated.
        ++per_trace->num_tables;
    }
    assert(per_trace->num_tables == table_count);

    make_topa(ipt_dev, per_trace);

    return ZX_OK;
}

static void x86_pt_free_buffer1(ipt_device_t* ipt_dev, ipt_per_trace_state_t* per_trace) {
    for (uint32_t i = 0; i < per_trace->num_chunks; ++i) {
        io_buffer_release(&per_trace->chunks[i]);
    }
    free(per_trace->chunks);
    per_trace->chunks = NULL;

    for (uint32_t i = 0; i < per_trace->num_tables; ++i) {
        io_buffer_release(&per_trace->topas[i]);
    }
    free(per_trace->topas);
    per_trace->topas = NULL;

    per_trace->allocated = false;
}

static zx_status_t x86_pt_alloc_buffer(ipt_device_t* ipt_dev,
                                       const ioctl_ipt_buffer_config_t* config,
                                       uint32_t* out_index) {
    zxlogf(DEBUG1, "%s: num_chunks %u, chunk_order %u\n",
           __func__, config->num_chunks, config->chunk_order);

    if (config->num_chunks == 0 || config->num_chunks > MAX_NUM_CHUNKS)
        return ZX_ERR_INVALID_ARGS;
    if (config->chunk_order > MAX_CHUNK_ORDER)
        return ZX_ERR_INVALID_ARGS;
    size_t chunk_pages = 1 << config->chunk_order;
    size_t nr_pages = config->num_chunks * chunk_pages;
    size_t total_per_trace = nr_pages * PAGE_SIZE;
    if (total_per_trace > MAX_PER_TRACE_SPACE)
        return ZX_ERR_INVALID_ARGS;

    uint64_t settable_ctl_mask = (
        IPT_CTL_OS_ALLOWED_MASK |
        IPT_CTL_USER_ALLOWED_MASK |
        IPT_CTL_TSC_EN_MASK |
        IPT_CTL_DIS_RETC_MASK |
        IPT_CTL_BRANCH_EN_MASK
        );
    if (ipt_config_ptwrite)
        settable_ctl_mask |= IPT_CTL_PTW_EN_MASK | IPT_CTL_FUP_ON_PTW_MASK;
    if (ipt_config_cr3_filtering)
        settable_ctl_mask |= IPT_CTL_CR3_FILTER_MASK;
    if (ipt_config_mtc)
        settable_ctl_mask |= IPT_CTL_MTC_EN_MASK | IPT_CTL_MTC_FREQ_MASK;
    if (ipt_config_power_events)
        settable_ctl_mask |= IPT_CTL_POWER_EVENT_EN_MASK;
    if (ipt_config_ip_filtering) {
        if (ipt_config_num_addr_ranges >= 1)
            settable_ctl_mask |= IPT_CTL_ADDR0_MASK;
        if (ipt_config_num_addr_ranges >= 2)
            settable_ctl_mask |= IPT_CTL_ADDR1_MASK;
        if (ipt_config_num_addr_ranges >= 3)
            settable_ctl_mask |= IPT_CTL_ADDR2_MASK;
        if (ipt_config_num_addr_ranges >= 4)
            settable_ctl_mask |= IPT_CTL_ADDR3_MASK;
    }
    if (ipt_config_psb)
        settable_ctl_mask |= (IPT_CTL_CYC_EN_MASK |
                              IPT_CTL_PSB_FREQ_MASK |
                              IPT_CTL_CYC_THRESH_MASK);
    if ((config->ctl & ~settable_ctl_mask) != 0) {
        zxlogf(ERROR, "bad ctl, requested 0x%" PRIx64 ", valid 0x%" PRIx64 "\n",
               config->ctl, settable_ctl_mask);
        return ZX_ERR_INVALID_ARGS;
    }

    uint32_t mtc_freq = (uint32_t) ((config->ctl & IPT_CTL_MTC_FREQ_MASK) >> IPT_CTL_MTC_FREQ_SHIFT);
    if (mtc_freq != 0 && ((1 << mtc_freq) & ipt_config_mtc_freq_mask) == 0) {
        zxlogf(ERROR, "bad mtc_freq value, requested 0x%x, valid mask 0x%x\n",
               mtc_freq, ipt_config_mtc_freq_mask);
        return ZX_ERR_INVALID_ARGS;
    }
    uint32_t cyc_thresh = (uint32_t) ((config->ctl & IPT_CTL_CYC_THRESH_MASK) >> IPT_CTL_CYC_THRESH_SHIFT);
    if (cyc_thresh != 0 && ((1 << cyc_thresh) & ipt_config_cyc_thresh_mask) == 0) {
        zxlogf(ERROR, "bad cyc_thresh value, requested 0x%x, valid mask 0x%x\n",
               cyc_thresh, ipt_config_cyc_thresh_mask);
        return ZX_ERR_INVALID_ARGS;
    }
    uint32_t psb_freq = (uint32_t) ((config->ctl & IPT_CTL_PSB_FREQ_MASK) >> IPT_CTL_PSB_FREQ_SHIFT);
    if (psb_freq != 0 && ((1 << psb_freq) & ipt_config_psb_freq_mask) == 0) {
        zxlogf(ERROR, "bad psb_freq value, requested 0x%x, valid mask 0x%x\n",
               psb_freq, ipt_config_psb_freq_mask);
        return ZX_ERR_INVALID_ARGS;
    }

    // Find an unallocated buffer entry.
    uint32_t index;
    for (index = 0; index < ipt_dev->num_traces; ++index) {
        if (!ipt_dev->per_trace_state[index].allocated)
            break;
    }
    if (index == ipt_dev->num_traces)
        return ZX_ERR_NO_RESOURCES;

    ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[index];
    memset(per_trace, 0, sizeof(*per_trace));
    zx_status_t status = x86_pt_alloc_buffer1(ipt_dev, per_trace,
                                              config->num_chunks, config->chunk_order, config->is_circular);
    if (status != ZX_OK) {
        x86_pt_free_buffer1(ipt_dev, per_trace);
        return status;
    }

    per_trace->ctl = config->ctl;
    per_trace->status = 0;
    per_trace->output_base = io_buffer_phys(&per_trace->topas[0]);
    per_trace->output_mask_ptrs = 0;
    per_trace->cr3_match = config->cr3_match;
    static_assert(sizeof(per_trace->addr_ranges) == sizeof(config->addr_ranges),
                  "addr range size mismatch");
    memcpy(per_trace->addr_ranges, config->addr_ranges, sizeof(config->addr_ranges));
    per_trace->allocated = true;
    *out_index = index;
    return ZX_OK;
}

static zx_status_t x86_pt_assign_buffer_thread(ipt_device_t* ipt_dev, uint32_t index, zx_handle_t thread) {
    zx_handle_close(thread);
    // TODO(dje): Thread support is still work-in-progress.
    return ZX_ERR_NOT_SUPPORTED;
}

static zx_status_t x86_pt_release_buffer_thread(ipt_device_t* ipt_dev, uint32_t index, zx_handle_t thread) {
    zx_handle_close(thread);
    // TODO(dje): Thread support is still work-in-progress.
    return ZX_ERR_NOT_SUPPORTED;
}

static zx_status_t x86_pt_free_buffer(ipt_device_t* ipt_dev, uint32_t index) {
    if (ipt_dev->active)
        return ZX_ERR_BAD_STATE;
    if (index >= ipt_dev->num_traces)
        return ZX_ERR_INVALID_ARGS;
    assert(ipt_dev->per_trace_state);
    ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[index];
    if (!per_trace->allocated)
        return ZX_ERR_INVALID_ARGS;
    x86_pt_free_buffer1(ipt_dev, per_trace);
    return ZX_OK;
}


// ioctl handlers

static zx_status_t ipt_alloc_trace(cpu_trace_device_t* dev,
                                   const void* cmd, size_t cmdlen) {
    if (!ipt_config_supported)
        return ZX_ERR_NOT_SUPPORTED;
    // For now we only support ToPA.
    if (!ipt_config_output_topa)
        return ZX_ERR_NOT_SUPPORTED;

    ioctl_ipt_trace_config_t config;
    if (cmdlen != sizeof(config))
        return ZX_ERR_INVALID_ARGS;
    memcpy(&config, cmd, sizeof(config));

    // TODO(dje): Until thread tracing is supported.
    if (config.mode == IPT_MODE_THREADS)
        return ZX_ERR_NOT_SUPPORTED;

    uint32_t internal_mode;
    switch (config.mode) {
    case IPT_MODE_CPUS:
        internal_mode = IPT_TRACE_CPUS;
        break;
    case IPT_MODE_THREADS:
        internal_mode = IPT_TRACE_THREADS;
        break;
    default:
        return ZX_ERR_INVALID_ARGS;
    }

    if (dev->ipt)
        return ZX_ERR_BAD_STATE;

    ipt_device_t* ipt_dev = calloc(1, sizeof(*dev->ipt));
    if (!ipt_dev)
        return ZX_ERR_NO_MEMORY;

    ipt_dev->num_traces = zx_system_get_num_cpus();
    ipt_dev->bti = dev->bti;

    ipt_dev->per_trace_state = calloc(ipt_dev->num_traces, sizeof(ipt_dev->per_trace_state[0]));
    if (!ipt_dev->per_trace_state) {
        free(ipt_dev);
        return ZX_ERR_NO_MEMORY;
    }

    zx_handle_t resource = get_root_resource();
    zx_status_t status =
        zx_mtrace_control(resource, MTRACE_KIND_IPT, MTRACE_IPT_ALLOC_TRACE, 0,
                          &internal_mode, sizeof(internal_mode));
    if (status != ZX_OK) {
        free(ipt_dev->per_trace_state);
        free(ipt_dev);
        return status;
    }

    ipt_dev->mode = internal_mode;
    dev->ipt = ipt_dev;
    return ZX_OK;
}

static zx_status_t ipt_free_trace(cpu_trace_device_t* dev) {
    ipt_device_t* ipt_dev = dev->ipt;
    if (ipt_dev->active)
        return ZX_ERR_BAD_STATE;

    for (uint32_t i = 0; i < ipt_dev->num_traces; ++i) {
        ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[i];
        if (per_trace->allocated)
            x86_pt_free_buffer1(ipt_dev, per_trace);
    }

    zx_handle_t resource = get_root_resource();
    zx_status_t status =
        zx_mtrace_control(resource, MTRACE_KIND_IPT, MTRACE_IPT_FREE_TRACE, 0, NULL, 0);
    // TODO(dje): This really shouldn't fail. What to do?
    // For now flag things as busted and prevent further use.
    if (status != ZX_OK)
        return ZX_OK;

    free(ipt_dev->per_trace_state);
    free(ipt_dev);
    dev->ipt = NULL;
    return ZX_OK;
}

static zx_status_t ipt_get_trace_config(ipt_device_t* ipt_dev,
                                        void* reply, size_t replymax,
                                        size_t* out_actual) {
    ioctl_ipt_trace_config_t config;
    if (replymax < sizeof(config))
        return ZX_ERR_BUFFER_TOO_SMALL;

    switch (ipt_dev->mode) {
        case IPT_TRACE_CPUS:
            config.mode = IPT_MODE_CPUS;
            break;
        case IPT_TRACE_THREADS:
            config.mode = IPT_MODE_THREADS;
            break;
        default:
            __UNREACHABLE;
    }
    memcpy(reply, &config, sizeof(config));
    *out_actual = sizeof(config);
    return ZX_OK;
}

static zx_status_t ipt_alloc_buffer(ipt_device_t* ipt_dev,
                                    const void* cmd, size_t cmdlen,
                                    void* reply, size_t replymax,
                                    size_t* out_actual) {
    ioctl_ipt_buffer_config_t config;
    if (cmdlen != sizeof(config))
        return ZX_ERR_INVALID_ARGS;
    memcpy(&config, cmd, sizeof(config));
    uint32_t index;
    if (replymax < sizeof(index))
        return ZX_ERR_BUFFER_TOO_SMALL;

    zx_status_t status = x86_pt_alloc_buffer(ipt_dev, &config, &index);
    if (status != ZX_OK)
        return status;
    memcpy(reply, &index, sizeof(index));
    *out_actual = sizeof(index);
    return ZX_OK;
}

static zx_status_t ipt_assign_buffer_thread(ipt_device_t* ipt_dev,
                                            const void* cmd, size_t cmdlen) {
    ioctl_ipt_assign_buffer_thread_t assign;
    if (cmdlen != sizeof(assign))
        return ZX_ERR_INVALID_ARGS;

    memcpy(&assign, cmd, sizeof(assign));
    return x86_pt_assign_buffer_thread(ipt_dev, assign.descriptor, assign.thread);
}

static zx_status_t ipt_release_buffer_thread(ipt_device_t* ipt_dev,
                                             const void* cmd, size_t cmdlen) {
    ioctl_ipt_assign_buffer_thread_t assign;
    if (cmdlen != sizeof(assign))
        return ZX_ERR_INVALID_ARGS;

    memcpy(&assign, cmd, sizeof(assign));
    return x86_pt_release_buffer_thread(ipt_dev, assign.descriptor, assign.thread);
}

static zx_status_t ipt_get_buffer_config(ipt_device_t* ipt_dev,
                                         const void* cmd, size_t cmdlen,
                                         void* reply, size_t replymax,
                                         size_t* out_actual) {
    uint32_t index;
    ioctl_ipt_buffer_config_t config;

    if (cmdlen != sizeof(index))
        return ZX_ERR_INVALID_ARGS;
    if (replymax < sizeof(config))
        return ZX_ERR_BUFFER_TOO_SMALL;

    memcpy(&index, cmd, sizeof(index));
    if (index >= ipt_dev->num_traces)
        return ZX_ERR_INVALID_ARGS;
    const ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[index];
    if (!per_trace->allocated)
        return ZX_ERR_INVALID_ARGS;

    config.num_chunks = per_trace->num_chunks;
    config.chunk_order = per_trace->chunk_order;
    config.is_circular = per_trace->is_circular;
    config.ctl = per_trace->ctl;
    config.cr3_match = per_trace->cr3_match;
    static_assert(sizeof(config.addr_ranges) == sizeof(per_trace->addr_ranges),
                  "addr range size mismatch");
    memcpy(config.addr_ranges, per_trace->addr_ranges, sizeof(per_trace->addr_ranges));
    memcpy(reply, &config, sizeof(config));
    *out_actual = sizeof(config);
    return ZX_OK;
}

static zx_status_t ipt_get_buffer_info(ipt_device_t* ipt_dev,
                                       const void* cmd, size_t cmdlen,
                                       void* reply, size_t replymax,
                                       size_t* out_actual) {
    uint32_t index;
    ioctl_ipt_buffer_info_t data;

    if (cmdlen != sizeof(index))
        return ZX_ERR_INVALID_ARGS;
    if (replymax < sizeof(data))
        return ZX_ERR_BUFFER_TOO_SMALL;

    if (ipt_dev->active)
        return ZX_ERR_BAD_STATE;

    memcpy(&index, cmd, sizeof(index));
    if (index >= ipt_dev->num_traces)
        return ZX_ERR_INVALID_ARGS;
    const ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[index];
    if (!per_trace->allocated)
        return ZX_ERR_INVALID_ARGS;

    // Note: If this is a circular buffer this is just where tracing stopped.
    data.capture_end = compute_capture_size(ipt_dev, per_trace);
    memcpy(reply, &data, sizeof(data));
    *out_actual = sizeof(data);
    return ZX_OK;
}

static zx_status_t ipt_get_chunk_handle(ipt_device_t* ipt_dev,
                                        const void* cmd, size_t cmdlen,
                                        void* reply, size_t replymax,
                                        size_t* out_actual) {
    ioctl_ipt_chunk_handle_req_t req;
    zx_handle_t h;

    if (cmdlen != sizeof(req))
        return ZX_ERR_INVALID_ARGS;
    if (replymax < sizeof(h))
        return ZX_ERR_BUFFER_TOO_SMALL;

    memcpy(&req, cmd, sizeof(req));
    if (req.descriptor >= ipt_dev->num_traces)
        return ZX_ERR_INVALID_ARGS;
    const ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[req.descriptor];
    if (!per_trace->allocated)
        return ZX_ERR_INVALID_ARGS;
    if (req.chunk_num >= per_trace->num_chunks)
        return ZX_ERR_INVALID_ARGS;

    zx_status_t status = zx_handle_duplicate(per_trace->chunks[req.chunk_num].vmo_handle, ZX_RIGHT_SAME_RIGHTS, &h);
    if (status < 0)
        return status;
    memcpy(reply, &h, sizeof(h));
    *out_actual = sizeof(h);
    return ZX_OK;
}

static zx_status_t ipt_free_buffer(ipt_device_t* ipt_dev,
                                   const void* cmd, size_t cmdlen) {
    uint32_t index;
    if (cmdlen != sizeof(index))
        return ZX_ERR_INVALID_ARGS;

    memcpy(&index, cmd, sizeof(index));
    x86_pt_free_buffer(ipt_dev, index);
    return 0;
}

// Begin tracing.
static zx_status_t ipt_start(ipt_device_t* ipt_dev) {
    if (ipt_dev->active)
        return ZX_ERR_BAD_STATE;
    if (ipt_dev->mode != IPT_TRACE_CPUS)
        return ZX_ERR_BAD_STATE;
    assert(ipt_dev->per_trace_state);

    zx_handle_t resource = get_root_resource();
    zx_status_t status;

    // First verify a buffer has been allocated for each cpu.
    for (uint32_t cpu = 0; cpu < ipt_dev->num_traces; ++cpu) {
        const ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[cpu];
        if (!per_trace->allocated)
            return ZX_ERR_BAD_STATE;
    }

    for (uint32_t cpu = 0; cpu < ipt_dev->num_traces; ++cpu) {
        const ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[cpu];

        zx_x86_pt_regs_t regs;
        regs.ctl = per_trace->ctl;
        regs.ctl |= IPT_CTL_TOPA_MASK | IPT_CTL_TRACE_EN_MASK;
        regs.status = per_trace->status;
        regs.output_base = per_trace->output_base;
        regs.output_mask_ptrs = per_trace->output_mask_ptrs;
        regs.cr3_match = per_trace->cr3_match;
        static_assert(sizeof(regs.addr_ranges) == sizeof(per_trace->addr_ranges),
                      "addr range size mismatch");
        memcpy(regs.addr_ranges, per_trace->addr_ranges, sizeof(per_trace->addr_ranges));

        status = zx_mtrace_control(resource, MTRACE_KIND_IPT, MTRACE_IPT_STAGE_CPU_DATA,
                                   cpu, &regs, sizeof(regs));
        if (status != ZX_OK)
            return status;
    }

    status = zx_mtrace_control(resource, MTRACE_KIND_IPT, MTRACE_IPT_CPU_MODE_START,
                               0, NULL, 0);
    if (status != ZX_OK)
        return status;
    ipt_dev->active = true;
    return ZX_OK;
}

// Stop tracing.
static zx_status_t ipt_stop(ipt_device_t* ipt_dev) {
    if (!ipt_dev->active)
        return ZX_ERR_BAD_STATE;
    assert(ipt_dev->per_trace_state);

    zx_handle_t resource = get_root_resource();

    zx_status_t status = zx_mtrace_control(resource, MTRACE_KIND_IPT, MTRACE_IPT_CPU_MODE_STOP,
                                           0, NULL, 0);
    if (status != ZX_OK)
        return status;
    ipt_dev->active = false;

    for (uint32_t cpu = 0; cpu < ipt_dev->num_traces; ++cpu) {
        ipt_per_trace_state_t* per_trace = &ipt_dev->per_trace_state[cpu];

        zx_x86_pt_regs_t regs;
        status = zx_mtrace_control(resource, MTRACE_KIND_IPT, MTRACE_IPT_GET_CPU_DATA,
                                   cpu, &regs, sizeof(regs));
        if (status != ZX_OK)
            return status;
        per_trace->ctl = regs.ctl;
        per_trace->status = regs.status;
        per_trace->output_base = regs.output_base;
        per_trace->output_mask_ptrs = regs.output_mask_ptrs;
        per_trace->cr3_match = regs.cr3_match;
        static_assert(sizeof(per_trace->addr_ranges) == sizeof(regs.addr_ranges),
                      "addr range size mismatch");
        memcpy(per_trace->addr_ranges, regs.addr_ranges, sizeof(regs.addr_ranges));

        // If there was an operational error, report it.
        if (per_trace->status & IPT_STATUS_ERROR_MASK) {
            printf("%s: WARNING: operational error detected on cpu %u\n",
                   __func__, cpu);
        }
    }

    return ZX_OK;
}

zx_status_t ipt_ioctl(cpu_trace_device_t* dev, uint32_t op,
                      const void* cmd, size_t cmdlen,
                      void* reply, size_t replymax,
                      size_t* out_actual) {
    assert(IOCTL_FAMILY(op) == IOCTL_FAMILY_IPT);

    ipt_device_t* ipt_dev = dev->ipt;
    if (op != IOCTL_IPT_ALLOC_TRACE) {
        if (!ipt_dev)
            return ZX_ERR_BAD_STATE;
    }

    switch (op) {
    case IOCTL_IPT_ALLOC_TRACE:
        if (replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_alloc_trace(dev, cmd, cmdlen);

    case IOCTL_IPT_FREE_TRACE:
        if (cmdlen != 0 || replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_free_trace(dev);

    case IOCTL_IPT_GET_TRACE_CONFIG:
        if (cmdlen != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_get_trace_config(ipt_dev, reply, replymax, out_actual);

    case IOCTL_IPT_ALLOC_BUFFER:
        return ipt_alloc_buffer(ipt_dev, cmd, cmdlen, reply, replymax, out_actual);

    case IOCTL_IPT_ASSIGN_BUFFER_THREAD:
        if (replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_assign_buffer_thread(ipt_dev, cmd, cmdlen);

    case IOCTL_IPT_RELEASE_BUFFER_THREAD:
        if (replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_release_buffer_thread(ipt_dev, cmd, cmdlen);

    case IOCTL_IPT_GET_BUFFER_CONFIG:
        return ipt_get_buffer_config(ipt_dev, cmd, cmdlen, reply, replymax, out_actual);

    case IOCTL_IPT_GET_BUFFER_INFO:
        return ipt_get_buffer_info(ipt_dev, cmd, cmdlen, reply, replymax, out_actual);

    case IOCTL_IPT_GET_CHUNK_HANDLE:
        return ipt_get_chunk_handle(ipt_dev, cmd, cmdlen, reply, replymax, out_actual);

    case IOCTL_IPT_FREE_BUFFER:
        if (replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_free_buffer(ipt_dev, cmd, cmdlen);

    case IOCTL_IPT_START:
        if (cmdlen != 0 || replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_start(ipt_dev);

    case IOCTL_IPT_STOP:
        if (cmdlen != 0 || replymax != 0)
            return ZX_ERR_INVALID_ARGS;
        return ipt_stop(ipt_dev);

    default:
        return ZX_ERR_INVALID_ARGS;
    }
}

void ipt_release(cpu_trace_device_t* dev) {
    // TODO(dje): None of these should fail. What to do?
    // For now flag things as busted and prevent further use.
    if (dev->ipt) {
        ipt_stop(dev->ipt);
        ipt_free_trace(dev);
    }
}