root/kernel/trace/trace_mmiotrace.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Memory mapped I/O tracing
 *
 * Copyright (C) 2008 Pekka Paalanen <pq@iki.fi>
 */

#include <linux/kernel.h>
#include <linux/mmiotrace.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/time.h>

#include <linux/atomic.h>

#include "trace.h"
#include "trace_output.h"

struct header_iter {
        struct pci_dev *dev;
};

static struct trace_array *mmio_trace_array;
static bool overrun_detected;
static unsigned long prev_overruns;
static atomic_t dropped_count;

static void mmio_reset_data(struct trace_array *tr)
{
        overrun_detected = false;
        prev_overruns = 0;

        tracing_reset_online_cpus(&tr->array_buffer);
}

static int mmio_trace_init(struct trace_array *tr)
{
        pr_debug("in %s\n", __func__);
        mmio_trace_array = tr;

        mmio_reset_data(tr);
        enable_mmiotrace();
        return 0;
}

static void mmio_trace_reset(struct trace_array *tr)
{
        pr_debug("in %s\n", __func__);

        disable_mmiotrace();
        mmio_reset_data(tr);
        mmio_trace_array = NULL;
}

static void mmio_trace_start(struct trace_array *tr)
{
        pr_debug("in %s\n", __func__);
        mmio_reset_data(tr);
}

static void mmio_print_pcidev(struct trace_seq *s, const struct pci_dev *dev)
{
        int i;
        resource_size_t start, end;
        const struct pci_driver *drv = pci_dev_driver(dev);

        trace_seq_printf(s, "PCIDEV %02x%02x %04x%04x %x",
                         dev->bus->number, dev->devfn,
                         dev->vendor, dev->device, dev->irq);
        for (i = 0; i < 7; i++) {
                start = dev->resource[i].start;
                trace_seq_printf(s, " %llx",
                        (unsigned long long)(start |
                        (dev->resource[i].flags & PCI_REGION_FLAG_MASK)));
        }
        for (i = 0; i < 7; i++) {
                start = dev->resource[i].start;
                end = dev->resource[i].end;
                trace_seq_printf(s, " %llx",
                        dev->resource[i].start < dev->resource[i].end ?
                        (unsigned long long)(end - start) + 1 : 0);
        }
        if (drv)
                trace_seq_printf(s, " %s\n", drv->name);
        else
                trace_seq_puts(s, " \n");
}

static void destroy_header_iter(struct header_iter *hiter)
{
        if (!hiter)
                return;
        pci_dev_put(hiter->dev);
        kfree(hiter);
}

static void mmio_pipe_open(struct trace_iterator *iter)
{
        struct header_iter *hiter;
        struct trace_seq *s = &iter->seq;

        trace_seq_puts(s, "VERSION 20070824\n");

        hiter = kzalloc_obj(*hiter);
        if (!hiter)
                return;

        hiter->dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, NULL);
        iter->private = hiter;
}

/* XXX: This is not called when the pipe is closed! */
static void mmio_close(struct trace_iterator *iter)
{
        struct header_iter *hiter = iter->private;
        destroy_header_iter(hiter);
        iter->private = NULL;
}

static unsigned long count_overruns(struct trace_iterator *iter)
{
        unsigned long cnt = atomic_xchg(&dropped_count, 0);
        unsigned long over = ring_buffer_overruns(iter->array_buffer->buffer);

        if (over > prev_overruns)
                cnt += over - prev_overruns;
        prev_overruns = over;
        return cnt;
}

static ssize_t mmio_read(struct trace_iterator *iter, struct file *filp,
                                char __user *ubuf, size_t cnt, loff_t *ppos)
{
        ssize_t ret;
        struct header_iter *hiter = iter->private;
        struct trace_seq *s = &iter->seq;
        unsigned long n;

        n = count_overruns(iter);
        if (n) {
                /* XXX: This is later than where events were lost. */
                trace_seq_printf(s, "MARK 0.000000 Lost %lu events.\n", n);
                if (!overrun_detected)
                        pr_warn("mmiotrace has lost events\n");
                overrun_detected = true;
                goto print_out;
        }

        if (!hiter)
                return 0;

        mmio_print_pcidev(s, hiter->dev);
        hiter->dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, hiter->dev);

        if (!hiter->dev) {
                destroy_header_iter(hiter);
                iter->private = NULL;
        }

print_out:
        ret = trace_seq_to_user(s, ubuf, cnt);
        return (ret == -EBUSY) ? 0 : ret;
}

static enum print_line_t mmio_print_rw(struct trace_iterator *iter)
{
        struct trace_entry *entry = iter->ent;
        struct trace_mmiotrace_rw *field;
        struct mmiotrace_rw *rw;
        struct trace_seq *s     = &iter->seq;
        unsigned long long t    = ns2usecs(iter->ts);
        unsigned long usec_rem  = do_div(t, USEC_PER_SEC);
        unsigned secs           = (unsigned long)t;

        trace_assign_type(field, entry);
        rw = &field->rw;

        switch (rw->opcode) {
        case MMIO_READ:
                trace_seq_printf(s,
                        "R %d %u.%06lu %d 0x%llx 0x%lx 0x%lx %d\n",
                        rw->width, secs, usec_rem, rw->map_id,
                        (unsigned long long)rw->phys,
                        rw->value, rw->pc, 0);
                break;
        case MMIO_WRITE:
                trace_seq_printf(s,
                        "W %d %u.%06lu %d 0x%llx 0x%lx 0x%lx %d\n",
                        rw->width, secs, usec_rem, rw->map_id,
                        (unsigned long long)rw->phys,
                        rw->value, rw->pc, 0);
                break;
        case MMIO_UNKNOWN_OP:
                trace_seq_printf(s,
                        "UNKNOWN %u.%06lu %d 0x%llx %02lx,%02lx,"
                        "%02lx 0x%lx %d\n",
                        secs, usec_rem, rw->map_id,
                        (unsigned long long)rw->phys,
                        (rw->value >> 16) & 0xff, (rw->value >> 8) & 0xff,
                        (rw->value >> 0) & 0xff, rw->pc, 0);
                break;
        default:
                trace_seq_puts(s, "rw what?\n");
                break;
        }

        return trace_handle_return(s);
}

static enum print_line_t mmio_print_map(struct trace_iterator *iter)
{
        struct trace_entry *entry = iter->ent;
        struct trace_mmiotrace_map *field;
        struct mmiotrace_map *m;
        struct trace_seq *s     = &iter->seq;
        unsigned long long t    = ns2usecs(iter->ts);
        unsigned long usec_rem  = do_div(t, USEC_PER_SEC);
        unsigned secs           = (unsigned long)t;

        trace_assign_type(field, entry);
        m = &field->map;

        switch (m->opcode) {
        case MMIO_PROBE:
                trace_seq_printf(s,
                        "MAP %u.%06lu %d 0x%llx 0x%lx 0x%lx 0x%lx %d\n",
                        secs, usec_rem, m->map_id,
                        (unsigned long long)m->phys, m->virt, m->len,
                        0UL, 0);
                break;
        case MMIO_UNPROBE:
                trace_seq_printf(s,
                        "UNMAP %u.%06lu %d 0x%lx %d\n",
                        secs, usec_rem, m->map_id, 0UL, 0);
                break;
        default:
                trace_seq_puts(s, "map what?\n");
                break;
        }

        return trace_handle_return(s);
}

static enum print_line_t mmio_print_mark(struct trace_iterator *iter)
{
        struct trace_entry *entry = iter->ent;
        struct print_entry *print = (struct print_entry *)entry;
        const char *msg         = print->buf;
        struct trace_seq *s     = &iter->seq;
        unsigned long long t    = ns2usecs(iter->ts);
        unsigned long usec_rem  = do_div(t, USEC_PER_SEC);
        unsigned secs           = (unsigned long)t;

        /* The trailing newline must be in the message. */
        trace_seq_printf(s, "MARK %u.%06lu %s", secs, usec_rem, msg);

        return trace_handle_return(s);
}

static enum print_line_t mmio_print_line(struct trace_iterator *iter)
{
        switch (iter->ent->type) {
        case TRACE_MMIO_RW:
                return mmio_print_rw(iter);
        case TRACE_MMIO_MAP:
                return mmio_print_map(iter);
        case TRACE_PRINT:
                return mmio_print_mark(iter);
        default:
                return TRACE_TYPE_HANDLED; /* ignore unknown entries */
        }
}

static struct tracer mmio_tracer __read_mostly =
{
        .name           = "mmiotrace",
        .init           = mmio_trace_init,
        .reset          = mmio_trace_reset,
        .start          = mmio_trace_start,
        .pipe_open      = mmio_pipe_open,
        .close          = mmio_close,
        .read           = mmio_read,
        .print_line     = mmio_print_line,
        .noboot         = true,
};

__init static int init_mmio_trace(void)
{
        return register_tracer(&mmio_tracer);
}
device_initcall(init_mmio_trace);

static void __trace_mmiotrace_rw(struct trace_array *tr,
                                struct mmiotrace_rw *rw)
{
        struct trace_buffer *buffer = tr->array_buffer.buffer;
        struct ring_buffer_event *event;
        struct trace_mmiotrace_rw *entry;
        unsigned int trace_ctx;

        trace_ctx = tracing_gen_ctx_flags(0);
        event = trace_buffer_lock_reserve(buffer, TRACE_MMIO_RW,
                                          sizeof(*entry), trace_ctx);
        if (!event) {
                atomic_inc(&dropped_count);
                return;
        }
        entry   = ring_buffer_event_data(event);
        entry->rw                       = *rw;

        trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
}

void mmio_trace_rw(struct mmiotrace_rw *rw)
{
        struct trace_array *tr = mmio_trace_array;
        __trace_mmiotrace_rw(tr, rw);
}

static void __trace_mmiotrace_map(struct trace_array *tr,
                                struct mmiotrace_map *map)
{
        struct trace_buffer *buffer = tr->array_buffer.buffer;
        struct ring_buffer_event *event;
        struct trace_mmiotrace_map *entry;
        unsigned int trace_ctx;

        trace_ctx = tracing_gen_ctx_flags(0);
        event = trace_buffer_lock_reserve(buffer, TRACE_MMIO_MAP,
                                          sizeof(*entry), trace_ctx);
        if (!event) {
                atomic_inc(&dropped_count);
                return;
        }
        entry   = ring_buffer_event_data(event);
        entry->map                      = *map;

        trace_buffer_unlock_commit(tr, buffer, event, trace_ctx);
}

void mmio_trace_mapping(struct mmiotrace_map *map)
{
        struct trace_array *tr = mmio_trace_array;
        __trace_mmiotrace_map(tr, map);
}

int mmio_trace_printk(const char *fmt, va_list args)
{
        return trace_vprintk(0, fmt, args);
}