esp-idf/tools/gdb_panic_server.py

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#!/usr/bin/env python
# coding=utf-8
#
# A script which parses ESP-IDF panic handler output (registers & stack dump),
# and then acts as a GDB server over stdin/stdout, presenting the information
# from the panic handler to GDB.
# This allows for generating backtraces out of raw stack dumps on architectures
# where backtracing on the target side is not possible.
#
# Note that the "act as a GDB server" approach is somewhat a hack.
# A much nicer solution would have been to convert the panic handler output
# into a core file, and point GDB to the core file.
# However, RISC-V baremetal GDB currently lacks core dump support.
#
# The approach is inspired by Cesanta's ESP8266 GDB server:
# https://github.com/cesanta/mongoose-os/blob/27777c8977/platforms/esp8266/tools/serve_core.py
#
# Copyright 2020 Espressif Systems (Shanghai) Co. Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
from builtins import bytes
import argparse
import struct
import sys
import logging
import binascii
from collections import namedtuple
from pyparsing import Literal, Word, nums, OneOrMore, srange, Group, Combine
# Used for type annotations only. Silence linter warnings.
from pyparsing import ParseResults, ParserElement # noqa: F401 # pylint: disable=unused-import
try:
import typing # noqa: F401 # pylint: disable=unused-import
except ImportError:
pass
# pyparsing helper
hexnumber = srange("[0-9a-f]")
# List of registers to be passed to GDB, in the order GDB expects.
# The names should match those used in IDF panic handler.
# Registers not present in IDF panic handler output (like X0) will be assumed to be 0.
GDB_REGS_INFO_RISCV_ILP32 = [
"X0", "RA", "SP", "GP",
"TP", "T0", "T1", "T2",
"S0/FP", "S1", "A0", "A1",
"A2", "A3", "A4", "A5",
"A6", "A7", "S2", "S3",
"S4", "S5", "S6", "S7",
"S8", "S9", "S10", "S11",
"T3", "T4", "T5", "T6",
"MEPC"
]
GDB_REGS_INFO = {
"esp32c3": GDB_REGS_INFO_RISCV_ILP32
}
PanicInfo = namedtuple("PanicInfo", "core_id regs stack_base_addr stack_data")
def build_riscv_panic_output_parser(): # type: () -> typing.Type[ParserElement]
"""Builds a parser for the panic handler output using pyparsing"""
# We don't match the first line, since "Guru Meditation" will not be printed in case of an abort:
# Guru Meditation Error: Core 0 panic'ed (Store access fault). Exception was unhandled.
# Core 0 register dump:
reg_dump_header = Group(Literal("Core") +
Word(nums)("core_id") +
Literal("register dump:"))("reg_dump_header")
# MEPC : 0x4200232c RA : 0x42009694 SP : 0x3fc93a80 GP : 0x3fc8b320
reg_name = Word(srange("[A-Z_0-9/-]"))("name")
hexnumber_with_0x = Combine(Literal("0x") + Word(hexnumber))
reg_value = hexnumber_with_0x("value")
reg_dump_one_reg = Group(reg_name + Literal(":") + reg_value) # not named because there will be OneOrMore
reg_dump_all_regs = Group(OneOrMore(reg_dump_one_reg))("regs")
reg_dump = Group(reg_dump_header + reg_dump_all_regs) # not named because there will be OneOrMore
reg_dumps = Group(OneOrMore(reg_dump))("reg_dumps")
# Stack memory:
# 3fc93a80: 0x00000030 0x00000021 0x3fc8aedc 0x4200232a 0xa5a5a5a5 0xa5a5a5a5 0x3fc8aedc 0x420099b0
stack_line = Group(Word(hexnumber)("base") + Literal(":") +
Group(OneOrMore(hexnumber_with_0x))("data"))
stack_dump = Group(Literal("Stack memory:") +
Group(OneOrMore(stack_line))("lines"))("stack_dump")
# Parser for the complete panic output:
panic_output = reg_dumps + stack_dump
return panic_output
def get_stack_addr_and_data(res): # type: (ParseResults) -> typing.Tuple[int, bytes]
""" Extract base address and bytes from the parsed stack dump """
stack_base_addr = 0 # First reported address in the dump
base_addr = 0 # keeps track of the address for the given line of the dump
bytes_in_line = 0 # bytes of stack parsed on the previous line; used to validate the next base address
stack_data = b"" # accumulates all the dumped stack data
for line in res.stack_dump.lines:
# update and validate the base address
prev_base_addr = base_addr
base_addr = int(line.base, 16)
if stack_base_addr == 0:
stack_base_addr = base_addr
else:
assert base_addr == prev_base_addr + bytes_in_line
# convert little-endian hex words to byte representation
words = [int(w, 16) for w in line.data]
line_data = b"".join([struct.pack("<I", w) for w in words])
bytes_in_line = len(line_data)
# accumulate in the whole stack data
stack_data += line_data
return stack_base_addr, stack_data
def parse_idf_riscv_panic_output(panic_text): # type: (str) -> PanicInfo
""" Decode panic handler output from a file """
panic_output = build_riscv_panic_output_parser()
results = panic_output.searchString(panic_text)
if len(results) != 1:
raise ValueError("Couldn't parse panic handler output")
res = results[0]
if len(res.reg_dumps) > 1:
raise NotImplementedError("Handling of multi-core register dumps not implemented")
# Build a dict of register names/values
rd = res.reg_dumps[0]
core_id = int(rd.reg_dump_header.core_id)
regs = dict()
for reg in rd.regs:
reg_value = int(reg.value, 16)
regs[reg.name] = reg_value
stack_base_addr, stack_data = get_stack_addr_and_data(res)
return PanicInfo(core_id=core_id,
regs=regs,
stack_base_addr=stack_base_addr,
stack_data=stack_data)
PANIC_OUTPUT_PARSERS = {
"esp32c3": parse_idf_riscv_panic_output
}
class GdbServer(object):
def __init__(self, panic_info, target, log_file=None): # type: (PanicInfo, str, str) -> None
self.panic_info = panic_info
self.in_stream = sys.stdin
self.out_stream = sys.stdout
self.reg_list = GDB_REGS_INFO[target]
self.logger = logging.getLogger("GdbServer")
if log_file:
handler = logging.FileHandler(log_file, "w+")
self.logger.setLevel(logging.DEBUG)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler.setFormatter(formatter)
self.logger.addHandler(handler)
def run(self): # type: () -> None
""" Process GDB commands from stdin until GDB tells us to quit """
buffer = ""
while True:
buffer += self.in_stream.read(1)
if len(buffer) > 3 and buffer[-3] == '#':
self._handle_command(buffer)
buffer = ""
def _handle_command(self, buffer): # type: (str) -> None
command = buffer[1:-3] # ignore checksums
# Acknowledge the command
self.out_stream.write("+")
self.out_stream.flush()
self.logger.debug("Got command: %s", command)
if command == "?":
# report sigtrap as the stop reason; the exact reason doesn't matter for backtracing
self._respond("T05")
elif command.startswith("Hg") or command.startswith("Hc"):
# Select thread command
self._respond("OK")
elif command == "qfThreadInfo":
# Get list of threads.
# Only one thread for now, can be extended to show one thread for each core,
# if we dump both cores (e.g. on an interrupt watchdog)
self._respond("m1")
elif command == "qC":
# That single thread is selected.
self._respond("QC1")
elif command == "g":
# Registers read
self._respond_regs()
elif command.startswith("m"):
# Memory read
addr, size = [int(v, 16) for v in command[1:].split(",")]
self._respond_mem(addr, size)
elif command.startswith("vKill") or command == "k":
# Quit
self._respond("OK")
raise SystemExit(0)
else:
# Empty response required for any unknown command
self._respond("")
def _respond(self, data): # type: (str) -> None
# calculate checksum
data_bytes = bytes(data.encode("ascii")) # bytes() for Py2 compatibility
checksum = sum(data_bytes) & 0xff
# format and write the response
res = "${}#{:02x}".format(data, checksum)
self.logger.debug("Wrote: %s", res)
self.out_stream.write(res)
self.out_stream.flush()
# get the result ('+' or '-')
ret = self.in_stream.read(1)
self.logger.debug("Response: %s", ret)
if ret != '+':
sys.stderr.write("GDB responded with '-' to {}".format(res))
raise SystemExit(1)
def _respond_regs(self): # type: () -> None
response = ""
for reg_name in self.reg_list:
# register values are reported as hexadecimal strings
# in target byte order (i.e. LSB first for RISC-V)
reg_val = self.panic_info.regs.get(reg_name, 0)
reg_bytes = struct.pack("<L", reg_val)
response += binascii.hexlify(reg_bytes).decode("ascii")
self._respond(response)
def _respond_mem(self, start_addr, size): # type: (int, int) -> None
stack_addr_min = self.panic_info.stack_base_addr
stack_data = self.panic_info.stack_data
stack_len = len(self.panic_info.stack_data)
stack_addr_max = stack_addr_min + stack_len
# For any memory address that is not on the stack, pretend the value is 0x00.
# GDB should never ask us for program memory, it will be obtained from the ELF file.
def in_stack(addr):
return stack_addr_min <= addr < stack_addr_max
result = ""
for addr in range(start_addr, start_addr + size):
if not in_stack(addr):
result += "00"
else:
result += "{:02x}".format(stack_data[addr - stack_addr_min])
self._respond(result)
def main():
parser = argparse.ArgumentParser()
parser.add_argument("input_file", type=argparse.FileType("r"),
help="File containing the panic handler output")
parser.add_argument("--target", choices=GDB_REGS_INFO.keys(),
help="Chip to use (determines the architecture)")
parser.add_argument("--gdb-log", default=None,
help="If specified, the file for logging GDB server debug information")
args = parser.parse_args()
panic_info = PANIC_OUTPUT_PARSERS[args.target](args.input_file.read())
server = GdbServer(panic_info, target=args.target, log_file=args.gdb_log)
try:
server.run()
except KeyboardInterrupt:
sys.exit(0)
if __name__ == "__main__":
main()