blob: 1f772112959ce804c660190818f8c20d95884e93 [file] [log] [blame]
/*
* Copyright (c) 2020 Intel Corporation.
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <device.h>
#include <kernel.h>
#include <logging/log.h>
LOG_MODULE_REGISTER(gdbstub);
#include <sys/util.h>
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <toolchain.h>
#include <sys/types.h>
#include <sys/util.h>
#include <debug/gdbstub.h>
#include "gdbstub_backend.h"
/* +1 is for the NULL character added during receive */
#define GDB_PACKET_SIZE (CONFIG_GDBSTUB_BUF_SZ + 1)
/* GDB remote serial protocol does not define errors value properly
* and handle all error packets as the same the code error is not
* used. There are informal values used by others gdbstub
* implementation, like qemu. Lets use the same here.
*/
#define GDB_ERROR_GENERAL "E01"
#define GDB_ERROR_MEMORY "E14"
#define GDB_ERROR_OVERFLOW "E22"
static bool not_first_start;
/* Empty memory region array */
__weak const struct gdb_mem_region gdb_mem_region_array[0];
/* Number of memory regions, default to 0 */
__weak const size_t gdb_mem_num_regions;
/**
* Given a starting address and length of a memory block, find a memory
* region descriptor from the memory region array where the memory block
* fits inside the memory region.
*
* @param addr Starting address of the memory block
* @param len Length of the memory block
*
* @return Pointer to the memory region description if found.
* NULL if not found.
*/
static inline const
struct gdb_mem_region *find_memory_region(const uintptr_t addr, const size_t len)
{
const struct gdb_mem_region *r, *ret = NULL;
unsigned int idx;
for (idx = 0; idx < gdb_mem_num_regions; idx++) {
r = &gdb_mem_region_array[idx];
if ((addr >= r->start) &&
(addr < r->end) &&
((addr + len) >= r->start) &&
((addr + len) < r->end)) {
ret = r;
break;
}
}
return ret;
}
bool gdb_mem_can_read(const uintptr_t addr, const size_t len, uint8_t *align)
{
bool ret = false;
const struct gdb_mem_region *r;
if (gdb_mem_num_regions == 0) {
/*
* No region is defined.
* Assume memory access is not restricted, and there is
* no alignment requirement.
*/
*align = 1;
ret = true;
} else {
r = find_memory_region(addr, len);
if (r != NULL) {
if ((r->attributes & GDB_MEM_REGION_READ) ==
GDB_MEM_REGION_READ) {
if (r->alignment > 0) {
*align = r->alignment;
} else {
*align = 1;
}
ret = true;
}
}
}
return ret;
}
bool gdb_mem_can_write(const uintptr_t addr, const size_t len, uint8_t *align)
{
bool ret = false;
const struct gdb_mem_region *r;
if (gdb_mem_num_regions == 0) {
/*
* No region is defined.
* Assume memory access is not restricted, and there is
* no alignment requirement.
*/
*align = 1;
ret = true;
} else {
r = find_memory_region(addr, len);
if (r != NULL) {
if ((r->attributes & GDB_MEM_REGION_WRITE) ==
GDB_MEM_REGION_WRITE) {
if (r->alignment > 0) {
*align = r->alignment;
} else {
*align = 1;
}
ret = true;
}
}
}
return ret;
}
size_t gdb_bin2hex(const uint8_t *buf, size_t buflen, char *hex, size_t hexlen)
{
if ((hexlen + 1) < buflen * 2) {
return 0;
}
for (size_t i = 0; i < buflen; i++) {
if (hex2char(buf[i] >> 4, &hex[2 * i]) < 0) {
return 0;
}
if (hex2char(buf[i] & 0xf, &hex[2 * i + 1]) < 0) {
return 0;
}
}
return 2 * buflen;
}
__weak
int arch_gdb_add_breakpoint(struct gdb_ctx *ctx, uint8_t type,
uintptr_t addr, uint32_t kind)
{
return -2;
}
__weak
int arch_gdb_remove_breakpoint(struct gdb_ctx *ctx, uint8_t type,
uintptr_t addr, uint32_t kind)
{
return -2;
}
/**
* Add preamble and termination to the given data.
*
* It returns 0 if the packet was acknowledge, -1 otherwise.
*/
static int gdb_send_packet(const uint8_t *data, size_t len)
{
uint8_t buf[2];
uint8_t checksum = 0;
/* Send packet start */
z_gdb_putchar('$');
/* Send packet data and calculate checksum */
while (len-- > 0) {
checksum += *data;
z_gdb_putchar(*data++);
}
/* Send the checksum */
z_gdb_putchar('#');
if (gdb_bin2hex(&checksum, 1, buf, sizeof(buf)) == 0) {
return -1;
}
z_gdb_putchar(buf[0]);
z_gdb_putchar(buf[1]);
if (z_gdb_getchar() == '+') {
return 0;
}
/* Just got an invalid response */
return -1;
}
/**
* Receives one whole GDB packet.
*
* @retval 0 Success
* @retval -1 Checksum error
* @retval -2 Incoming packet too large
*/
static int gdb_get_packet(uint8_t *buf, size_t buf_len, size_t *len)
{
uint8_t ch = '0';
uint8_t expected_checksum, checksum = 0;
uint8_t checksum_buf[2];
/* Wait for packet start */
checksum = 0;
/* wait for the start character, ignore the rest */
while (ch != '$') {
ch = z_gdb_getchar();
}
*len = 0;
/* Read until receive '#' */
while (true) {
ch = z_gdb_getchar();
if (ch == '#') {
break;
}
/* Only put into buffer if not full */
if (*len < (buf_len - 1)) {
buf[*len] = ch;
}
checksum += ch;
(*len)++;
}
buf[*len] = '\0';
/* Get checksum now */
checksum_buf[0] = z_gdb_getchar();
checksum_buf[1] = z_gdb_getchar();
if (hex2bin(checksum_buf, 2, &expected_checksum, 1) == 0) {
return -1;
}
/* Verify checksum */
if (checksum != expected_checksum) {
LOG_DBG("Bad checksum. Got 0x%x but was expecting: 0x%x",
checksum, expected_checksum);
/* NACK packet */
z_gdb_putchar('-');
return -1;
}
/* ACK packet */
z_gdb_putchar('+');
if (*len >= (buf_len - 1)) {
return -2;
} else {
return 0;
}
}
/* Read memory byte-by-byte */
static inline int gdb_mem_read_unaligned(uint8_t *buf, size_t buf_len,
uintptr_t addr, size_t len)
{
uint8_t data;
size_t pos, count = 0;
/* Read from system memory */
for (pos = 0; pos < len; pos++) {
data = *(uint8_t *)(addr + pos);
count += gdb_bin2hex(&data, 1, buf + count, buf_len - count);
}
return count;
}
/* Read memory with alignment constraint */
static inline int gdb_mem_read_aligned(uint8_t *buf, size_t buf_len,
uintptr_t addr, size_t len,
uint8_t align)
{
/*
* Memory bus cannot do byte-by-byte access and
* each access must be aligned.
*/
size_t read_sz, pos;
size_t remaining = len;
uint8_t *mem_ptr;
size_t count = 0;
int ret;
union {
uint32_t u32;
uint8_t b8[4];
} data;
/* Max alignment */
if (align > 4) {
ret = -1;
goto out;
}
/* Round down according to alignment. */
mem_ptr = UINT_TO_POINTER(ROUND_DOWN(addr, align));
/*
* Figure out how many bytes to skip (pos) and how many
* bytes to read at the beginning of aligned memory access.
*/
pos = addr & (align - 1);
read_sz = MIN(len, align - pos);
/* Loop till there is nothing more to read. */
while (remaining > 0) {
data.u32 = *(uint32_t *)mem_ptr;
/*
* Read read_sz bytes from memory and
* convert the binary data into hexadecimal.
*/
count += gdb_bin2hex(&data.b8[pos], read_sz,
buf + count, buf_len - count);
remaining -= read_sz;
if (remaining > align) {
read_sz = align;
} else {
read_sz = remaining;
}
/* Read the next aligned datum. */
mem_ptr += align;
/*
* Any memory accesses after the first one are
* aligned by design. So there is no need to skip
* any bytes.
*/
pos = 0;
};
ret = count;
out:
return ret;
}
/**
* Read data from a given memory address and length.
*
* @return Number of bytes read from memory, or -1 if error
*/
static int gdb_mem_read(uint8_t *buf, size_t buf_len,
uintptr_t addr, size_t len)
{
uint8_t align;
int ret;
/*
* Make sure there is enough space in the output
* buffer for hexadecimal representation.
*/
if ((len * 2) > buf_len) {
ret = -1;
goto out;
}
if (!gdb_mem_can_read(addr, len, &align)) {
ret = -1;
goto out;
}
if (align > 1) {
ret = gdb_mem_read_aligned(buf, buf_len,
addr, len,
align);
} else {
ret = gdb_mem_read_unaligned(buf, buf_len,
addr, len);
}
out:
return ret;
}
/* Write memory byte-by-byte */
static int gdb_mem_write_unaligned(const uint8_t *buf, uintptr_t addr,
size_t len)
{
uint8_t data;
int ret;
size_t count = 0;
while (len > 0) {
size_t cnt = hex2bin(buf, 2, &data, sizeof(data));
if (cnt == 0) {
ret = -1;
goto out;
}
*(uint8_t *)addr = data;
count += cnt;
addr++;
buf += 2;
len--;
}
ret = count;
out:
return ret;
}
/* Write memory with alignment constraint */
static int gdb_mem_write_aligned(const uint8_t *buf, uintptr_t addr,
size_t len, uint8_t align)
{
size_t pos, write_sz;
uint8_t *mem_ptr;
size_t count = 0;
int ret;
/*
* Incoming buf is of hexadecimal characters,
* so binary data size is half of that.
*/
size_t remaining = len;
union {
uint32_t u32;
uint8_t b8[4];
} data;
/* Max alignment */
if (align > 4) {
ret = -1;
goto out;
}
/*
* Round down according to alignment.
* Read the data (of aligned size) first
* as we need to do read-modify-write.
*/
mem_ptr = UINT_TO_POINTER(ROUND_DOWN(addr, align));
data.u32 = *(uint32_t *)mem_ptr;
/*
* Figure out how many bytes to skip (pos) and how many
* bytes to write at the beginning of aligned memory access.
*/
pos = addr & (align - 1);
write_sz = MIN(len, align - pos);
/* Loop till there is nothing more to write. */
while (remaining > 0) {
/*
* Write write_sz bytes from memory and
* convert the binary data into hexadecimal.
*/
size_t cnt = hex2bin(buf, write_sz * 2,
&data.b8[pos], write_sz);
if (cnt == 0) {
ret = -1;
goto out;
}
count += cnt;
buf += write_sz * 2;
remaining -= write_sz;
if (remaining > align) {
write_sz = align;
} else {
write_sz = remaining;
}
/* Write data to memory */
*(uint32_t *)mem_ptr = data.u32;
/* Point to the next aligned datum. */
mem_ptr += align;
if (write_sz != align) {
/*
* Since we are not writing a full aligned datum,
* we need to do read-modify-write. Hence reading
* it here before the next hex2bin() call.
*/
data.u32 = *(uint32_t *)mem_ptr;
}
/*
* Any memory accesses after the first one are
* aligned by design. So there is no need to skip
* any bytes.
*/
pos = 0;
};
ret = count;
out:
return ret;
}
/**
* Write data to a given memory address and length.
*
* @return Number of bytes written to memory, or -1 if error
*/
static int gdb_mem_write(const uint8_t *buf, uintptr_t addr,
size_t len)
{
uint8_t align;
int ret;
if (!gdb_mem_can_write(addr, len, &align)) {
ret = -1;
goto out;
}
if (align > 1) {
ret = gdb_mem_write_aligned(buf, addr, len, align);
} else {
ret = gdb_mem_write_unaligned(buf, addr, len);
}
out:
return ret;
}
/**
* Send a exception packet "T <value>"
*/
static int gdb_send_exception(uint8_t *buf, size_t len, uint8_t exception)
{
size_t size;
*buf = 'T';
size = gdb_bin2hex(&exception, 1, buf + 1, len - 1);
if (size == 0) {
return -1;
}
/* Related to 'T' */
size++;
return gdb_send_packet(buf, size);
}
/**
* Synchronously communicate with gdb on the host
*/
int z_gdb_main_loop(struct gdb_ctx *ctx)
{
/* 'static' modifier is intentional so the buffer
* is not declared inside running stack, which may
* not have enough space.
*/
static uint8_t buf[GDB_PACKET_SIZE];
enum loop_state {
RECEIVING,
CONTINUE,
ERROR,
} state;
state = RECEIVING;
/* Only send exception if this is not the first
* GDB break.
*/
if (not_first_start) {
gdb_send_exception(buf, sizeof(buf), ctx->exception);
} else {
not_first_start = true;
}
#define CHECK_ERROR(condition) \
{ \
if ((condition)) { \
state = ERROR; \
break; \
} \
}
#define CHECK_SYMBOL(c) \
{ \
CHECK_ERROR(ptr == NULL || *ptr != (c)); \
ptr++; \
}
#define CHECK_INT(arg) \
{ \
arg = strtol((const char *)ptr, (char **)&ptr, 16); \
CHECK_ERROR(ptr == NULL); \
}
while (state == RECEIVING) {
uint8_t *ptr;
size_t data_len, pkt_len;
uintptr_t addr;
uint32_t type;
int ret;
ret = gdb_get_packet(buf, sizeof(buf), &pkt_len);
if ((ret == -1) || (ret == -2)) {
/*
* Send error and wait for next packet.
*
* -1: Checksum error.
* -2: Packet too big.
*/
gdb_send_packet(GDB_ERROR_GENERAL, 3);
continue;
}
if (pkt_len == 0) {
continue;
}
ptr = buf;
switch (*ptr++) {
/**
* Read from the memory
* Format: m addr,length
*/
case 'm':
CHECK_INT(addr);
CHECK_SYMBOL(',');
CHECK_INT(data_len);
/* Read Memory */
/*
* GDB ask the guest to read parameters when
* the user request backtrace. If the
* parameter is a NULL pointer this will cause
* a fault. Just send a packet informing that
* this address is invalid
*/
if (addr == 0L) {
gdb_send_packet(GDB_ERROR_MEMORY, 3);
break;
}
ret = gdb_mem_read(buf, sizeof(buf), addr, data_len);
CHECK_ERROR(ret == -1);
gdb_send_packet(buf, ret);
break;
/**
* Write to memory
* Format: M addr,length:val
*/
case 'M':
CHECK_INT(addr);
CHECK_SYMBOL(',');
CHECK_INT(data_len);
CHECK_SYMBOL(':');
if (addr == 0L) {
gdb_send_packet(GDB_ERROR_MEMORY, 3);
break;
}
/* Write Memory */
pkt_len = gdb_mem_write(ptr, addr, data_len);
CHECK_ERROR(pkt_len == -1);
gdb_send_packet("OK", 2);
break;
/*
* Continue ignoring the optional address
* Format: c addr
*/
case 'c':
arch_gdb_continue();
state = CONTINUE;
break;
/*
* Step one instruction ignoring the optional address
* s addr..addr
*/
case 's':
arch_gdb_step();
state = CONTINUE;
break;
/*
* Read all registers
* Format: g
*/
case 'g':
pkt_len = arch_gdb_reg_readall(ctx, buf, sizeof(buf));
CHECK_ERROR(pkt_len == 0);
gdb_send_packet(buf, pkt_len);
break;
/**
* Write the value of the CPU registers
* Format: G XX...
*/
case 'G':
pkt_len = arch_gdb_reg_writeall(ctx, ptr, pkt_len - 1);
CHECK_ERROR(pkt_len == 0);
gdb_send_packet("OK", 2);
break;
/**
* Read the value of a register
* Format: p n
*/
case 'p':
CHECK_INT(addr);
/* Read Register */
pkt_len = arch_gdb_reg_readone(ctx, buf, sizeof(buf), addr);
CHECK_ERROR(pkt_len == 0);
gdb_send_packet(buf, pkt_len);
break;
/**
* Write data into a specific register
* Format: P register=value
*/
case 'P':
CHECK_INT(addr);
CHECK_SYMBOL('=');
pkt_len = arch_gdb_reg_writeone(ctx, ptr, strlen(ptr), addr);
CHECK_ERROR(pkt_len == 0);
gdb_send_packet("OK", 2);
break;
/*
* Breakpoints and Watchpoints
*/
case 'z':
__fallthrough;
case 'Z':
CHECK_INT(type);
CHECK_SYMBOL(',');
CHECK_INT(addr);
CHECK_SYMBOL(',');
CHECK_INT(data_len);
if (buf[0] == 'Z') {
ret = arch_gdb_add_breakpoint(ctx, type,
addr, data_len);
} else if (buf[0] == 'z') {
ret = arch_gdb_remove_breakpoint(ctx, type,
addr, data_len);
}
if (ret == -2) {
/* breakpoint/watchpoint not supported */
gdb_send_packet(NULL, 0);
} else if (ret == -1) {
state = ERROR;
} else {
gdb_send_packet("OK", 2);
}
break;
/* What cause the pause */
case '?':
gdb_send_exception(buf, sizeof(buf),
ctx->exception);
break;
/*
* Not supported action
*/
default:
gdb_send_packet(NULL, 0);
break;
}
/*
* If this is an recoverable error, send an error message to
* GDB and continue the debugging session.
*/
if (state == ERROR) {
gdb_send_packet(GDB_ERROR_GENERAL, 3);
state = RECEIVING;
}
}
#undef CHECK_ERROR
#undef CHECK_INT
#undef CHECK_SYMBOL
return 0;
}
int gdb_init(const struct device *arg)
{
ARG_UNUSED(arg);
if (z_gdb_backend_init() == -1) {
LOG_ERR("Could not initialize gdbstub backend.");
return -1;
}
arch_gdb_init();
return 0;
}
#ifdef CONFIG_XTENSA
/*
* Interrupt stacks are being setup during init and are not
* available before POST_KERNEL. Xtensa needs to trigger
* interrupts to get into GDB stub. So this can only be
* initialized in POST_KERNEL, or else the interrupt would not be
* using the correct interrupt stack and will result in
* double exception.
*/
SYS_INIT(gdb_init, POST_KERNEL, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
#else
SYS_INIT(gdb_init, PRE_KERNEL_2, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
#endif