udebug-remote.c

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/*
 * udebug - debug ring buffer library
 *
 * Copyright (C) 2023 Felix Fietkau <nbd@nbd.name>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include "udebug-priv.h"
 
static int
udebug_remote_get_handle(struct udebug *ctx)
{
        struct udebug_client_msg *msg;
        struct udebug_client_msg send_msg = {
                .type = CL_MSG_GET_HANDLE,
        };
 
        if (ctx->poll_handle >= 0 || !udebug_is_connected(ctx))
                return 0;
 
        msg = udebug_send_and_wait(ctx, &send_msg, NULL);
        if (!msg)
                return -1;
 
        ctx->poll_handle = msg->id;
        return 0;
}
 
struct udebug_remote_buf *udebug_remote_buf_get(struct udebug *ctx, uint32_t id)
{
        struct udebug_remote_buf *rb;
        void *key = (void *)(uintptr_t)id;
 
        return avl_find_element(&ctx->remote_rings, key, rb, node);
}
 
int udebug_remote_buf_map(struct udebug *ctx, struct udebug_remote_buf *rb, uint32_t id)
{
        void *key = (void *)(uintptr_t)id;
        struct udebug_client_msg *msg;
        struct udebug_client_msg send_msg = {
                .type = CL_MSG_RING_GET,
                .id = id,
        };
        int fd = -1;
 
        if (rb->buf.data || !udebug_is_connected(ctx))
                return -1;
 
        msg = udebug_send_and_wait(ctx, &send_msg, &fd);
        if (!msg || fd < 0)
                return -1;
 
        if (udebug_buf_open(&rb->buf, fd, msg->ring_size, msg->data_size)) {
                fprintf(stderr, "failed to open fd %d, ring_size=%d, data_size=%d\n", fd, msg->ring_size, msg->data_size);
                close(fd);
                return -1;
        }
 
        rb->pcap_iface = ~0;
        rb->node.key = key;
        avl_insert(&ctx->remote_rings, &rb->node);
 
        return 0;
}
 
void udebug_remote_buf_unmap(struct udebug *ctx, struct udebug_remote_buf *rb)
{
        if (!rb->buf.data)
                return;
 
        avl_delete(&ctx->remote_rings, &rb->node);
        udebug_buf_free(&rb->buf);
        rb->poll = 0;
        rb->node.key = NULL;
        rb->pcap_iface = ~0;
}
 
int udebug_remote_buf_set_poll(struct udebug *ctx, struct udebug_remote_buf *rb, bool val)
{
        int handle;
 
        if (!rb->buf.data)
                return -1;
 
        if (rb->poll == val)
                return 0;
 
        rb->poll = val;
        if (!val)
                return 0;
 
        handle = udebug_remote_get_handle(ctx);
        if (handle < 0)
                return -1;
 
        __atomic_fetch_or(&rb->buf.hdr->notify, 1UL << handle, __ATOMIC_RELAXED);
        return 0;
}
 
static void
rbuf_advance_read_head(struct udebug_remote_buf *rb, uint32_t head,
                       uint32_t *data_start)
{
        struct udebug_hdr *hdr = rb->buf.hdr;
        uint32_t min_head = head + 1 - rb->buf.ring_size;
        uint32_t min_data = u32_get(&hdr->data_used) - rb->buf.data_size;
        struct udebug_ptr *last_ptr = udebug_ring_ptr(hdr, head - 1);
 
        if (!u32_get(&hdr->head_hi) && u32_sub(0, min_head) > 0)
                min_head = 0;
 
        /* advance head to skip over any entries that are guaranteed
         * to be overwritten now. final check will be performed after
         * data copying */
 
        if (u32_sub(rb->head, min_head) < 0)
                rb->head = min_head;
 
        for (size_t i = 0; i < rb->buf.ring_size; i++) {
                struct udebug_ptr *ptr = udebug_ring_ptr(hdr, rb->head);
 
                if (data_start) {
                        *data_start = u32_get(&ptr->start);
                        __sync_synchronize();
                }
 
                if (ptr->timestamp > last_ptr->timestamp)
                        continue;
 
                if (u32_sub(ptr->start, min_data) > 0)
                        break;
 
                rb->head++;
        }
}
 
void udebug_remote_buf_set_start_time(struct udebug_remote_buf *rb, uint64_t ts)
{
        struct udebug_hdr *hdr = rb->buf.hdr;
        uint32_t head = u32_get(&hdr->head);
        uint32_t start = rb->head, end = head;
        uint32_t diff;
 
        if (!hdr)
                return;
 
        rbuf_advance_read_head(rb, head, NULL);
        while ((diff = u32_sub(end, start)) > 0) {
                uint32_t cur = start + diff / 2;
                struct udebug_ptr *ptr;
 
                ptr = udebug_ring_ptr(hdr, cur);
                if (ptr->timestamp > ts)
                        end = cur - 1;
                else
                        start = cur + 1;
        }
 
        rb->head = start;
}
 
void udebug_remote_buf_set_start_offset(struct udebug_remote_buf *rb, uint32_t idx)
{
        if (!rb->buf.hdr)
                return;
 
        rb->head = rb->buf.hdr->head - idx;
}
 
void udebug_remote_buf_set_flags(struct udebug_remote_buf *rb, uint64_t mask, uint64_t set)
{
        struct udebug_hdr *hdr = rb->buf.hdr;
 
        if (!hdr)
                return;
 
        if ((uintptr_t)mask)
                __atomic_and_fetch(&hdr->flags[0], (uintptr_t)~mask, __ATOMIC_RELAXED);
        if ((uintptr_t)set)
                __atomic_or_fetch(&hdr->flags[0], (uintptr_t)set, __ATOMIC_RELAXED);
 
        if (sizeof(mask) == sizeof(unsigned long))
                return;
 
        mask >>= 32;
        if ((uintptr_t)mask)
                __atomic_and_fetch(&hdr->flags[1], (uintptr_t)~mask, __ATOMIC_RELAXED);
        if ((uintptr_t)set)
                __atomic_or_fetch(&hdr->flags[1], (uintptr_t)set, __ATOMIC_RELAXED);
}
 
struct udebug_snapshot *
udebug_remote_buf_snapshot(struct udebug_remote_buf *rb)
{
        struct udebug_hdr *hdr = rb->buf.hdr;
        struct udebug_ptr *last_ptr;
        uint32_t data_start, data_end, data_used;
        struct udebug_snapshot *s = NULL;
        struct udebug_ptr *ptr_buf, *first_ptr;
        uint32_t data_size, ptr_size;
        uint32_t head, first_idx;
        uint32_t prev_read_head = rb->head;
        void *data_buf;
 
        if (!hdr)
                return NULL;
 
        head = u32_get(&hdr->head);
        rbuf_advance_read_head(rb, head, &data_start);
        if (rb->head == head)
                return NULL;
 
        first_idx = rb->head;
        first_ptr = udebug_ring_ptr(hdr, first_idx);
        last_ptr = udebug_ring_ptr(hdr, head - 1);
        data_end = last_ptr->start + last_ptr->len;
 
        data_size = data_end - data_start;
        ptr_size = head - rb->head;
        if (data_size > rb->buf.data_size || ptr_size > rb->buf.ring_size) {
                fprintf(stderr, "Invalid data size: %x > %x, %x > %x\n", data_size, (int)rb->buf.data_size, ptr_size, (int)rb->buf.ring_size);
                goto out;
        }
 
        s = calloc_a(sizeof(*s),
                     &ptr_buf, ptr_size * sizeof(*ptr_buf),
                     &data_buf, data_size);
 
        s->data = memcpy(data_buf, udebug_buf_ptr(&rb->buf, data_start), data_size);
        s->data_size = data_size;
        s->entries = ptr_buf;
        s->dropped = rb->head - prev_read_head;
 
        if (first_ptr > last_ptr) {
                struct udebug_ptr *start_ptr = udebug_ring_ptr(hdr, 0);
                struct udebug_ptr *end_ptr = udebug_ring_ptr(hdr, rb->buf.ring_size - 1) + 1;
                uint32_t size = end_ptr - first_ptr;
                memcpy(s->entries, first_ptr, size * sizeof(*s->entries));
                memcpy(s->entries + size, start_ptr, (last_ptr + 1 - start_ptr) * sizeof(*s->entries));
        } else {
                memcpy(s->entries, first_ptr, (last_ptr + 1 - first_ptr) * sizeof(*s->entries));
        }
 
        /* get a snapshot of the counter that indicates how much data has been
         * clobbered by newly added entries */
        __sync_synchronize();
        data_used = u32_get(&hdr->data_used) - rb->buf.data_size;
 
        s->n_entries = head - first_idx;
 
        rbuf_advance_read_head(rb, head, NULL);
        if (s->n_entries < rb->head - first_idx) {
                free(s);
                s = NULL;
                goto out;
        }
 
        s->entries += rb->head - first_idx;
        s->n_entries -= rb->head - first_idx;
        while (s->n_entries > 0 &&
               u32_sub(s->entries[0].start, data_used) < 0) {
                s->entries++;
                s->n_entries--;
                s->dropped++;
        }
 
        for (size_t i = 0; i < s->n_entries; i++)
                s->entries[i].start -= data_start;
 
        s->format = hdr->format;
        s->sub_format = hdr->sub_format;
        s->rbuf_idx = (uint32_t)(uintptr_t)rb->node.key;
 
out:
        rb->head = head;
        return s;
}
 
bool udebug_snapshot_get_entry(struct udebug_snapshot *s, struct udebug_iter *it, unsigned int entry)
{
        struct udebug_ptr *ptr;
 
        it->len = 0;
        if (entry >= s->n_entries)
                goto error;
 
        ptr = &s->entries[entry];
        if (ptr->start > s->data_size || ptr->len > s->data_size ||
            ptr->start + ptr->len > s->data_size)
                goto error;
 
        it->s = s;
        it->data = s->data + ptr->start;
        it->len = ptr->len;
        it->timestamp = ptr->timestamp;
        return true;
 
error:
        it->data = NULL;
        return false;
}
 
void udebug_iter_start(struct udebug_iter *it, struct udebug_snapshot **s, size_t n)
{
        memset(it, 0, sizeof(*it));
 
        it->list = s;
        it->n = n;
 
        for (size_t i = 0; i < it->n; i++)
                it->list[i]->iter_idx = 0;
}
 
bool udebug_iter_next(struct udebug_iter *it)
{
        while (1) {
                struct udebug_snapshot *s;
                uint64_t cur_ts;
                int cur = -1;
 
                for (size_t i = 0; i < it->n; i++) {
                        struct udebug_ptr *ptr;
 
                        s = it->list[i];
                        if (s->iter_idx >= s->n_entries)
                                continue;
 
                        ptr = &s->entries[s->iter_idx];
                        if (cur >= 0 && ptr->timestamp > cur_ts)
                                continue;
 
                        cur = i;
                        cur_ts = ptr->timestamp;
                }
 
                if (cur < 0)
                        return false;
 
                s = it->list[cur];
                it->s_idx = cur;
                if (!udebug_snapshot_get_entry(s, it, s->iter_idx++))
                        continue;
 
                return true;
        }
}