coreboot-kgpe-d16/payloads/libpayload/gdb/transport.c

253 lines
6.5 KiB
C

/*
* Copyright 2014 Google Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc.
*/
#include <endian.h>
#include <gdb.h>
#include <libpayload.h>
/* MMIO word size is not standardized, but *usually* 32 (even on ARM64) */
typedef u32 mmio_word_t;
static const int timeout_us = 100 * 1000;
static const char output_overrun[] = "GDB output buffer overrun (try "
"increasing reply.size)!\n";
static const char input_underrun[] = "GDB input message truncated (bug or "
"communication problem)?\n";
/* Serial-specific glue code... add more transport layers here when desired. */
static void gdb_raw_putchar(u8 c)
{
serial_putchar(c);
}
static int gdb_raw_getchar(void)
{
u64 start = timer_us(0);
while (!serial_havechar())
if (timer_us(start) > timeout_us)
return -1;
return serial_getchar();
}
void gdb_transport_init(void)
{
console_remove_output_driver(serial_putchar);
}
void gdb_transport_teardown(void)
{
serial_console_init();
}
/* Hex digit character <-> number conversion (illegal chars undefined!). */
static u8 from_hex(unsigned char c)
{
static const s8 values[] = {
-1, 10, 11, 12, 13, 14, 15, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
0, 1, 2, 3, 4, 5, 6, 7,
8, 9, -1, -1, -1, -1, -1, -1,
};
return values[c & 0x1f];
}
static char to_hex(u8 v)
{
static const char digits[] = "0123456789abcdef";
return digits[v & 0xf];
}
/* Message encode/decode functions (must access whole aligned words for MMIO) */
void gdb_message_encode_bytes(struct gdb_message *message, const void *data,
int length)
{
die_if(message->used + length * 2 > message->size, output_overrun);
const mmio_word_t *aligned =
(mmio_word_t *)ALIGN_DOWN((uintptr_t)data, sizeof(*aligned));
mmio_word_t word = be32toh(readl(aligned++));
while (length--) {
u8 byte = (word >> ((((void *)aligned - data) - 1) * 8));
message->buf[message->used++] = to_hex(byte >> 4);
message->buf[message->used++] = to_hex(byte & 0xf);
if (length && ++data == (void *)aligned)
word = be32toh(readl(aligned++));
}
}
void gdb_message_decode_bytes(const struct gdb_message *message, int offset,
void *data, int length)
{
die_if(offset + 2 * length > message->used, "Decode overrun in GDB "
"message: %.*s", message->used, message->buf);
mmio_word_t *aligned =
(mmio_word_t *)ALIGN_DOWN((uintptr_t)data, sizeof(*aligned));
int shift = ((void *)(aligned + 1) - data) * 8;
mmio_word_t word = be32toh(readl(aligned)) >> shift;
while (length--) {
word <<= 8;
word |= from_hex(message->buf[offset++]) << 4;
word |= from_hex(message->buf[offset++]);
if (++data - (void *)aligned == sizeof(*aligned))
writel(htobe32(word), aligned++);
}
if (data != (void *)aligned) {
shift = ((void *)(aligned + 1) - data) * 8;
clrsetbits_be32(aligned, ~((1 << shift) - 1), word << shift);
}
}
void gdb_message_encode_zero_bytes(struct gdb_message *message, int length)
{
die_if(message->used + length * 2 > message->size, output_overrun);
memset(message->buf + message->used, '0', length * 2);
message->used += length * 2;
}
void gdb_message_add_string(struct gdb_message *message, const char *string)
{
message->used += strlcpy((char *)message->buf + message->used,
string, message->size - message->used);
/* Check >= instead of > to account for strlcpy's trailing '\0'. */
die_if(message->used >= message->size, output_overrun);
}
void gdb_message_encode_int(struct gdb_message *message, uintptr_t val)
{
int length = sizeof(uintptr_t) * 2 - __builtin_clz(val) / 4;
die_if(message->used + length > message->size, output_overrun);
while (length--)
message->buf[message->used++] =
to_hex((val >> length * 4) & 0xf);
}
uintptr_t gdb_message_decode_int(const struct gdb_message *message, int offset,
int length)
{
uintptr_t val = 0;
die_if(length > sizeof(uintptr_t) * 2, "GDB decoding invalid number: "
"%.*s", message->used, message->buf);
while (length--) {
val <<= 4;
val |= from_hex(message->buf[offset++]);
}
return val;
}
/* Like strtok/strsep: writes back offset argument, returns original offset. */
int gdb_message_tokenize(const struct gdb_message *message, int *offset)
{
int token = *offset;
while (!strchr(",;:", message->buf[(*offset)++]))
die_if(*offset >= message->used, "Undelimited token in GDB "
"message at offset %d: %.*s",
token, message->used, message->buf);
return token;
}
/* High-level send/receive functions. */
void gdb_get_command(struct gdb_message *command)
{
enum command_state {
STATE_WAITING,
STATE_COMMAND,
STATE_CHECKSUM0,
STATE_CHECKSUM1,
};
u8 checksum = 0;
u8 running_checksum = 0;
enum command_state state = STATE_WAITING;
while (1) {
int c = gdb_raw_getchar();
if (c < 0) {
/*
* Timeout waiting for a byte. Reset the
* state machine.
*/
state = STATE_WAITING;
continue;
}
switch (state) {
case STATE_WAITING:
if (c == '$') {
running_checksum = 0;
command->used = 0;
state = STATE_COMMAND;
}
break;
case STATE_COMMAND:
if (c == '#') {
state = STATE_CHECKSUM0;
break;
}
die_if(command->used >= command->size, "GDB input buf"
"fer overrun (try increasing command.size)!\n");
command->buf[command->used++] = c;
running_checksum += c;
break;
case STATE_CHECKSUM0:
checksum = from_hex(c) << 4;
state = STATE_CHECKSUM1;
break;
case STATE_CHECKSUM1:
checksum += from_hex(c);
if (running_checksum == checksum) {
gdb_raw_putchar('+');
return;
} else {
state = STATE_WAITING;
gdb_raw_putchar('-');
}
break;
}
}
}
void gdb_send_reply(const struct gdb_message *reply)
{
int i;
int retries = 1 * 1000 * 1000 / timeout_us;
u8 checksum = 0;
for (i = 0; i < reply->used; i++)
checksum += reply->buf[i];
do {
gdb_raw_putchar('$');
for (i = 0; i < reply->used; i++)
gdb_raw_putchar(reply->buf[i]);
gdb_raw_putchar('#');
gdb_raw_putchar(to_hex(checksum >> 4));
gdb_raw_putchar(to_hex(checksum & 0xf));
} while (gdb_raw_getchar() != '+' && retries--);
}