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openocd/src/target/rtt.c
Marcin Niestroj 7dd5b6a464 rtt: fix corner-cases of finding control block 
This patch fixes two corner-cases of finding RTT control block.

The first one is when there was a partial match (even single byte) at
the end of loaded buffer (uint8_t buf[1024]), but this was not part of
full match. In that case `cb_offset` was not updated correctly and the
returned `*address` was lower by the legth of the partial match. In case
of searched 'SEGGER RTT' (the default control block ID) string, it was
enough to match `buf[1023] == 'S'`, which is quite likely to happen, and
the `*address` was offset by 1 (e.g. it was 0x20000fff instead of
0x20010000).

Updating (or even maintaining) `cb_offset` is not needed, as start
address of control block can be calculated based on memory address that
was loaded into `uint8_t buf[1024]`, the offset within this buffer and
the length of expected string.

The second issue is when control block is prepended with a byte that
matches first ID character, e.g. there is `SEGGER RTT` control block ID
is prepended by another `S`, making memory contents be `SSEGGER RTT`. In
that case there was no match found.

Fix that issue by making sure that tested byte is always compared with
first byte of expected control block ID.

While at it, change names of local variables to better describe their
meaning.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>
Change-Id: I12aa6e202bf12bedcbb888ab595751a2a2518a24
Reviewed-on: https://review.openocd.org/c/openocd/+/7429
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
2023-01-11 17:02:25 +00:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2016-2020 by Marc Schink <dev@zapb.de>
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stddef.h>
#include <stdint.h>
#include <helper/log.h>
#include <helper/binarybuffer.h>
#include <helper/command.h>
#include <rtt/rtt.h>
#include "target.h"
static int read_rtt_channel(struct target *target,
const struct rtt_control *ctrl, unsigned int channel_index,
enum rtt_channel_type type, struct rtt_channel *channel)
{
int ret;
uint8_t buf[RTT_CHANNEL_SIZE];
target_addr_t address;
address = ctrl->address + RTT_CB_SIZE + (channel_index * RTT_CHANNEL_SIZE);
if (type == RTT_CHANNEL_TYPE_DOWN)
address += ctrl->num_up_channels * RTT_CHANNEL_SIZE;
ret = target_read_buffer(target, address, RTT_CHANNEL_SIZE, buf);
if (ret != ERROR_OK)
return ret;
channel->address = address;
channel->name_addr = buf_get_u32(buf + 0, 0, 32);
channel->buffer_addr = buf_get_u32(buf + 4, 0, 32);
channel->size = buf_get_u32(buf + 8, 0, 32);
channel->write_pos = buf_get_u32(buf + 12, 0, 32);
channel->read_pos = buf_get_u32(buf + 16, 0, 32);
channel->flags = buf_get_u32(buf + 20, 0, 32);
return ERROR_OK;
}
int target_rtt_start(struct target *target, const struct rtt_control *ctrl,
void *user_data)
{
return ERROR_OK;
}
int target_rtt_stop(struct target *target, void *user_data)
{
return ERROR_OK;
}
static int read_channel_name(struct target *target, target_addr_t address,
char *name, size_t length)
{
size_t offset;
offset = 0;
while (offset < length) {
int ret;
size_t read_length;
read_length = MIN(32, length - offset);
ret = target_read_buffer(target, address + offset, read_length,
(uint8_t *)name + offset);
if (ret != ERROR_OK)
return ret;
if (memchr(name + offset, '\0', read_length))
return ERROR_OK;
offset += read_length;
}
name[length - 1] = '\0';
return ERROR_OK;
}
static int write_to_channel(struct target *target,
const struct rtt_channel *channel, const uint8_t *buffer,
size_t *length)
{
int ret;
uint32_t len;
if (!*length)
return ERROR_OK;
if (channel->write_pos == channel->read_pos) {
uint32_t first_length;
len = MIN(*length, channel->size - 1);
first_length = MIN(len, channel->size - channel->write_pos);
ret = target_write_buffer(target,
channel->buffer_addr + channel->write_pos, first_length,
buffer);
if (ret != ERROR_OK)
return ret;
ret = target_write_buffer(target, channel->buffer_addr,
len - first_length, buffer + first_length);
if (ret != ERROR_OK)
return ret;
} else if (channel->write_pos < channel->read_pos) {
len = MIN(*length, channel->read_pos - channel->write_pos - 1);
if (!len) {
*length = 0;
return ERROR_OK;
}
ret = target_write_buffer(target,
channel->buffer_addr + channel->write_pos, len, buffer);
if (ret != ERROR_OK)
return ret;
} else {
uint32_t first_length;
len = MIN(*length,
channel->size - channel->write_pos + channel->read_pos - 1);
if (!len) {
*length = 0;
return ERROR_OK;
}
first_length = MIN(len, channel->size - channel->write_pos);
ret = target_write_buffer(target,
channel->buffer_addr + channel->write_pos, first_length,
buffer);
if (ret != ERROR_OK)
return ret;
buffer = buffer + first_length;
ret = target_write_buffer(target, channel->buffer_addr,
len - first_length, buffer);
if (ret != ERROR_OK)
return ret;
}
ret = target_write_u32(target, channel->address + 12,
(channel->write_pos + len) % channel->size);
if (ret != ERROR_OK)
return ret;
*length = len;
return ERROR_OK;
}
static bool channel_is_active(const struct rtt_channel *channel)
{
if (!channel)
return false;
if (!channel->size)
return false;
return true;
}
int target_rtt_write_callback(struct target *target, struct rtt_control *ctrl,
unsigned int channel_index, const uint8_t *buffer, size_t *length,
void *user_data)
{
int ret;
struct rtt_channel channel;
ret = read_rtt_channel(target, ctrl, channel_index,
RTT_CHANNEL_TYPE_DOWN, &channel);
if (ret != ERROR_OK) {
LOG_ERROR("rtt: Failed to read down-channel %u description",
channel_index);
return ret;
}
if (!channel_is_active(&channel)) {
LOG_WARNING("rtt: Down-channel %u is not active", channel_index);
return ERROR_OK;
}
if (channel.size < RTT_CHANNEL_BUFFER_MIN_SIZE) {
LOG_WARNING("rtt: Down-channel %u is not large enough",
channel_index);
return ERROR_OK;
}
ret = write_to_channel(target, &channel, buffer, length);
if (ret != ERROR_OK)
return ret;
LOG_DEBUG("rtt: Wrote %zu bytes into down-channel %u", *length,
channel_index);
return ERROR_OK;
}
int target_rtt_read_control_block(struct target *target,
target_addr_t address, struct rtt_control *ctrl, void *user_data)
{
int ret;
uint8_t buf[RTT_CB_SIZE];
ret = target_read_buffer(target, address, RTT_CB_SIZE, buf);
if (ret != ERROR_OK)
return ret;
memcpy(ctrl->id, buf, RTT_CB_MAX_ID_LENGTH);
ctrl->id[RTT_CB_MAX_ID_LENGTH - 1] = '\0';
ctrl->num_up_channels = buf_get_u32(buf + RTT_CB_MAX_ID_LENGTH + 0,
0, 32);
ctrl->num_down_channels = buf_get_u32(buf + RTT_CB_MAX_ID_LENGTH + 4,
0, 32);
return ERROR_OK;
}
int target_rtt_find_control_block(struct target *target,
target_addr_t *address, size_t size, const char *id, bool *found,
void *user_data)
{
target_addr_t address_end = *address + size;
uint8_t buf[1024];
*found = false;
size_t id_matched_length = 0;
const size_t id_length = strlen(id);
LOG_INFO("rtt: Searching for control block '%s'", id);
for (target_addr_t addr = *address; addr < address_end; addr += sizeof(buf)) {
int ret;
const size_t buf_size = MIN(sizeof(buf), address_end - addr);
ret = target_read_buffer(target, addr, buf_size, buf);
if (ret != ERROR_OK)
return ret;
for (size_t buf_off = 0; buf_off < buf_size; buf_off++) {
if (id_matched_length > 0 &&
buf[buf_off] != id[id_matched_length]) {
/* Start from beginning */
id_matched_length = 0;
}
if (buf[buf_off] == id[id_matched_length])
id_matched_length++;
if (id_matched_length == id_length) {
*address = addr + buf_off + 1 - id_length;
*found = true;
return ERROR_OK;
}
}
}
return ERROR_OK;
}
int target_rtt_read_channel_info(struct target *target,
const struct rtt_control *ctrl, unsigned int channel_index,
enum rtt_channel_type type, struct rtt_channel_info *info,
void *user_data)
{
int ret;
struct rtt_channel channel;
ret = read_rtt_channel(target, ctrl, channel_index, type, &channel);
if (ret != ERROR_OK) {
LOG_ERROR("rtt: Failed to read channel %u description",
channel_index);
return ret;
}
ret = read_channel_name(target, channel.name_addr, info->name,
info->name_length);
if (ret != ERROR_OK)
return ret;
info->size = channel.size;
info->flags = channel.flags;
return ERROR_OK;
}
static int read_from_channel(struct target *target,
const struct rtt_channel *channel, uint8_t *buffer,
size_t *length)
{
int ret;
uint32_t len;
if (!*length)
return ERROR_OK;
if (channel->read_pos == channel->write_pos) {
len = 0;
} else if (channel->read_pos < channel->write_pos) {
len = MIN(*length, channel->write_pos - channel->read_pos);
ret = target_read_buffer(target,
channel->buffer_addr + channel->read_pos, len, buffer);
if (ret != ERROR_OK)
return ret;
} else {
uint32_t first_length;
len = MIN(*length,
channel->size - channel->read_pos + channel->write_pos);
first_length = MIN(len, channel->size - channel->read_pos);
ret = target_read_buffer(target,
channel->buffer_addr + channel->read_pos, first_length, buffer);
if (ret != ERROR_OK)
return ret;
ret = target_read_buffer(target, channel->buffer_addr,
len - first_length, buffer + first_length);
if (ret != ERROR_OK)
return ret;
}
if (len > 0) {
ret = target_write_u32(target, channel->address + 16,
(channel->read_pos + len) % channel->size);
if (ret != ERROR_OK)
return ret;
}
*length = len;
return ERROR_OK;
}
int target_rtt_read_callback(struct target *target,
const struct rtt_control *ctrl, struct rtt_sink_list **sinks,
size_t num_channels, void *user_data)
{
num_channels = MIN(num_channels, ctrl->num_up_channels);
for (size_t i = 0; i < num_channels; i++) {
int ret;
struct rtt_channel channel;
uint8_t buffer[1024];
size_t length;
if (!sinks[i])
continue;
ret = read_rtt_channel(target, ctrl, i, RTT_CHANNEL_TYPE_UP,
&channel);
if (ret != ERROR_OK) {
LOG_ERROR("rtt: Failed to read up-channel %zu description", i);
return ret;
}
if (!channel_is_active(&channel)) {
LOG_WARNING("rtt: Up-channel %zu is not active", i);
continue;
}
if (channel.size < RTT_CHANNEL_BUFFER_MIN_SIZE) {
LOG_WARNING("rtt: Up-channel %zu is not large enough", i);
continue;
}
length = sizeof(buffer);
ret = read_from_channel(target, &channel, buffer, &length);
if (ret != ERROR_OK) {
LOG_ERROR("rtt: Failed to read from up-channel %zu", i);
return ret;
}
for (struct rtt_sink_list *sink = sinks[i]; sink; sink = sink->next)
sink->read(i, buffer, length, sink->user_data);
}
return ERROR_OK;
}
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