esp-idf/components/esp32/gdbstub.c

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16 KiB
C

// Copyright 2015-2016 Espressif Systems (Shanghai) PTE 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.
/******************************************************************************
* Description: A stub to make the ESP32 debuggable by GDB over the serial
* port, at least enough to do a backtrace on panic. This gdbstub is read-only:
* it allows inspecting the ESP32 state
*******************************************************************************/
#include <string.h>
#include "esp32/rom/ets_sys.h"
#include "soc/uart_reg.h"
#include "soc/io_mux_reg.h"
#include "esp_private/gdbstub.h"
#include "esp_debug_helpers.h"
#include "driver/gpio.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "sdkconfig.h"
//Length of buffer used to reserve GDB commands. Has to be at least able to fit the G command, which
//implies a minimum size of about 320 bytes.
#define PBUFLEN 512
static unsigned char cmd[PBUFLEN]; //GDB command input buffer
static char chsum; //Running checksum of the output packet
#define ATTR_GDBFN
//Receive a char from the uart. Uses polling and feeds the watchdog.
static int ATTR_GDBFN gdbRecvChar() {
int i;
while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_RXFIFO_CNT_S)&UART_RXFIFO_CNT)==0) ;
i=READ_PERI_REG(UART_FIFO_REG(0));
return i;
}
//Send a char to the uart.
static void ATTR_GDBFN gdbSendChar(char c) {
while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_TXFIFO_CNT_S)&UART_TXFIFO_CNT)>=126) ;
WRITE_PERI_REG(UART_FIFO_REG(0), c);
}
//Send the start of a packet; reset checksum calculation.
static void ATTR_GDBFN gdbPacketStart() {
chsum=0;
gdbSendChar('$');
}
//Send a char as part of a packet
static void ATTR_GDBFN gdbPacketChar(char c) {
if (c=='#' || c=='$' || c=='}' || c=='*') {
gdbSendChar('}');
gdbSendChar(c^0x20);
chsum+=(c^0x20)+'}';
} else {
gdbSendChar(c);
chsum+=c;
}
}
//Send a string as part of a packet
static void ATTR_GDBFN gdbPacketStr(const char *c) {
while (*c!=0) {
gdbPacketChar(*c);
c++;
}
}
//Send a hex val as part of a packet. 'bits'/4 dictates the number of hex chars sent.
static void ATTR_GDBFN gdbPacketHex(int val, int bits) {
char hexChars[]="0123456789abcdef";
int i;
for (i=bits; i>0; i-=4) {
gdbPacketChar(hexChars[(val>>(i-4))&0xf]);
}
}
//Finish sending a packet.
static void ATTR_GDBFN gdbPacketEnd() {
gdbSendChar('#');
gdbPacketHex(chsum, 8);
}
//Error states used by the routines that grab stuff from the incoming gdb packet
#define ST_ENDPACKET -1
#define ST_ERR -2
#define ST_OK -3
#define ST_CONT -4
//Grab a hex value from the gdb packet. Ptr will get positioned on the end
//of the hex string, as far as the routine has read into it. Bits/4 indicates
//the max amount of hex chars it gobbles up. Bits can be -1 to eat up as much
//hex chars as possible.
static long ATTR_GDBFN gdbGetHexVal(unsigned char **ptr, int bits) {
int i;
int no;
unsigned int v=0;
char c;
no=bits/4;
if (bits==-1) no=64;
for (i=0; i<no; i++) {
c=**ptr;
(*ptr)++;
if (c>='0' && c<='9') {
v<<=4;
v|=(c-'0');
} else if (c>='A' && c<='F') {
v<<=4;
v|=(c-'A')+10;
} else if (c>='a' && c<='f') {
v<<=4;
v|=(c-'a')+10;
} else if (c=='#') {
if (bits==-1) {
(*ptr)--;
return v;
}
return ST_ENDPACKET;
} else {
if (bits==-1) {
(*ptr)--;
return v;
}
return ST_ERR;
}
}
return v;
}
//Swap an int into the form gdb wants it
static int ATTR_GDBFN iswap(int i) {
int r;
r=((i>>24)&0xff);
r|=((i>>16)&0xff)<<8;
r|=((i>>8)&0xff)<<16;
r|=((i>>0)&0xff)<<24;
return r;
}
//Read a byte from ESP32 memory.
static unsigned char ATTR_GDBFN readbyte(unsigned int p) {
int *i=(int*)(p&(~3));
if (p<0x20000000 || p>=0x80000000) return -1;
return *i>>((p&3)*8);
}
//Register file in the format exp108 gdb port expects it.
//Inspired by gdb/regformats/reg-xtensa.dat
typedef struct {
uint32_t pc;
uint32_t a[64];
uint32_t lbeg;
uint32_t lend;
uint32_t lcount;
uint32_t sar;
uint32_t windowbase;
uint32_t windowstart;
uint32_t configid0;
uint32_t configid1;
uint32_t ps;
uint32_t threadptr;
uint32_t br;
uint32_t scompare1;
uint32_t acclo;
uint32_t acchi;
uint32_t m0;
uint32_t m1;
uint32_t m2;
uint32_t m3;
uint32_t expstate; //I'm going to assume this is exccause...
uint32_t f64r_lo;
uint32_t f64r_hi;
uint32_t f64s;
uint32_t f[16];
uint32_t fcr;
uint32_t fsr;
} GdbRegFile;
GdbRegFile gdbRegFile;
/*
//Register format as the Xtensa HAL has it:
STRUCT_FIELD (long, 4, XT_STK_EXIT, exit)
STRUCT_FIELD (long, 4, XT_STK_PC, pc)
STRUCT_FIELD (long, 4, XT_STK_PS, ps)
STRUCT_FIELD (long, 4, XT_STK_A0, a0)
[..]
STRUCT_FIELD (long, 4, XT_STK_A15, a15)
STRUCT_FIELD (long, 4, XT_STK_SAR, sar)
STRUCT_FIELD (long, 4, XT_STK_EXCCAUSE, exccause)
STRUCT_FIELD (long, 4, XT_STK_EXCVADDR, excvaddr)
STRUCT_FIELD (long, 4, XT_STK_LBEG, lbeg)
STRUCT_FIELD (long, 4, XT_STK_LEND, lend)
STRUCT_FIELD (long, 4, XT_STK_LCOUNT, lcount)
// Temporary space for saving stuff during window spill
STRUCT_FIELD (long, 4, XT_STK_TMP0, tmp0)
STRUCT_FIELD (long, 4, XT_STK_TMP1, tmp1)
STRUCT_FIELD (long, 4, XT_STK_TMP2, tmp2)
STRUCT_FIELD (long, 4, XT_STK_VPRI, vpri)
STRUCT_FIELD (long, 4, XT_STK_OVLY, ovly)
#endif
STRUCT_END(XtExcFrame)
*/
static void commonRegfile() {
if (gdbRegFile.a[0] & 0x8000000U) gdbRegFile.a[0] = (gdbRegFile.a[0] & 0x3fffffffU) | 0x40000000U;
if (!esp_stack_ptr_is_sane(gdbRegFile.a[1])) gdbRegFile.a[1] = 0xDEADBEEF;
gdbRegFile.windowbase=0; //0
gdbRegFile.windowstart=0x1; //1
gdbRegFile.configid0=0xdeadbeef; //ToDo
gdbRegFile.configid1=0xdeadbeef; //ToDo
gdbRegFile.threadptr=0xdeadbeef; //ToDo
gdbRegFile.br=0xdeadbeef; //ToDo
gdbRegFile.scompare1=0xdeadbeef; //ToDo
gdbRegFile.acclo=0xdeadbeef; //ToDo
gdbRegFile.acchi=0xdeadbeef; //ToDo
gdbRegFile.m0=0xdeadbeef; //ToDo
gdbRegFile.m1=0xdeadbeef; //ToDo
gdbRegFile.m2=0xdeadbeef; //ToDo
gdbRegFile.m3=0xdeadbeef; //ToDo
}
static void dumpHwToRegfile(XtExcFrame *frame) {
int i;
long *frameAregs=&frame->a0;
gdbRegFile.pc=(frame->pc & 0x3fffffffU)|0x40000000U;
for (i=0; i<16; i++) gdbRegFile.a[i]=frameAregs[i];
for (i=16; i<64; i++) gdbRegFile.a[i]=0xDEADBEEF;
gdbRegFile.lbeg=frame->lbeg;
gdbRegFile.lend=frame->lend;
gdbRegFile.lcount=frame->lcount;
gdbRegFile.ps=(frame->ps & PS_UM) ? (frame->ps & ~PS_EXCM) : frame->ps;
//All windows have been spilled to the stack by the ISR routines. The following values should indicate that.
gdbRegFile.sar=frame->sar;
commonRegfile();
gdbRegFile.expstate=frame->exccause; //ToDo
}
//Send the reason execution is stopped to GDB.
static void sendReason() {
//exception-to-signal mapping
char exceptionSignal[]={4,31,11,11,2,6,8,0,6,7,0,0,7,7,7,7};
int i=0;
gdbPacketStart();
gdbPacketChar('T');
i=gdbRegFile.expstate&0x7f;
if (i<sizeof(exceptionSignal)) {
gdbPacketHex(exceptionSignal[i], 8);
} else {
gdbPacketHex(11, 8);
}
gdbPacketEnd();
}
static int sendPacket(const char * text) {
gdbPacketStart();
if (text != NULL) gdbPacketStr(text);
gdbPacketEnd();
return ST_OK;
}
#if CONFIG_GDBSTUB_SUPPORT_TASKS
#define STUB_TASKS_NUM CONFIG_GDBSTUB_MAX_TASKS
//Remember the exception frame that caused panic since it's not saved in TCB
static XtExcFrame paniced_frame;
//Allows GDBStub to disable task support after a crash
//(e.g. if GDBStub crashes while trying to get task list, e.g. due to corrupted list structures)
static enum {
HANDLER_NOT_STARTED,
HANDLER_STARTED,
HANDLER_TASK_SUPPORT_DISABLED
} handlerState;
static void dumpTaskToRegfile(XtSolFrame *frame) {
int i;
long *frameAregs=&frame->a0;
gdbRegFile.pc=(frame->pc & 0x3fffffffU)|0x40000000U;
for (i=0; i<4; i++) gdbRegFile.a[i]=frameAregs[i];
for (i=4; i<64; i++) gdbRegFile.a[i]=0xDEADBEEF;
gdbRegFile.lbeg=0;
gdbRegFile.lend=0;
gdbRegFile.lcount=0;
gdbRegFile.ps=(frame->ps & PS_UM) ? (frame->ps & ~PS_EXCM) : frame->ps;
//All windows have been spilled to the stack by the ISR routines. The following values should indicate that.
gdbRegFile.sar=0;
commonRegfile();
gdbRegFile.expstate=0; //ToDo
}
// Fetch the task status. Returns the total number of tasks.
static unsigned getTaskInfo(unsigned index, unsigned * handle, const char ** name, unsigned * coreId) {
static unsigned taskCount = 0;
static TaskSnapshot_t tasks[STUB_TASKS_NUM];
if (!taskCount) {
unsigned tcbSize = 0;
taskCount = uxTaskGetSnapshotAll(tasks, STUB_TASKS_NUM, &tcbSize);
}
if (index < taskCount) {
TaskHandle_t h = (TaskHandle_t)tasks[index].pxTCB;
if (handle) *handle = (unsigned)h;
if (name) *name = pcTaskGetTaskName(h);
if (coreId) *coreId = xTaskGetAffinity(h);
}
return taskCount;
}
typedef struct
{
uint8_t * topOfStack;
} DumpTCB;
static void dumpTCBToRegFile(unsigned handle) {
// A task handle is a pointer to a TCB in FreeRTOS
DumpTCB * tcb = (DumpTCB*)handle;
uint8_t * pxTopOfStack = tcb->topOfStack;
//Deduced from coredump code
XtExcFrame * frame = (XtExcFrame*)pxTopOfStack;
if (frame->exit) {
// It's an exception frame
dumpHwToRegfile(frame);
} else {
XtSolFrame * taskFrame = (XtSolFrame*)pxTopOfStack;
dumpTaskToRegfile(taskFrame);
}
}
#define CUR_TASK_INDEX_NOT_SET -2
#define CUR_TASK_INDEX_UNKNOWN -1
// Get the index of the task currently running on the current CPU, and cache the result
static int findCurrentTaskIndex() {
static int curTaskIndex = CUR_TASK_INDEX_NOT_SET;
if (curTaskIndex == CUR_TASK_INDEX_NOT_SET) {
unsigned curHandle = (unsigned)xTaskGetCurrentTaskHandleForCPU(xPortGetCoreID());
unsigned handle;
unsigned count = getTaskInfo(0, 0, 0, 0);
for(int k=0; k<(int)count; k++) {
if (getTaskInfo(k, &handle, 0, 0) && curHandle == handle) {
curTaskIndex = k;
return curTaskIndex;
}
}
curTaskIndex = CUR_TASK_INDEX_UNKNOWN;
}
return curTaskIndex;
}
#endif // CONFIG_GDBSTUB_SUPPORT_TASKS
//Handle a command as received from GDB.
static int gdbHandleCommand(unsigned char *cmd, int len) {
//Handle a command
int i, j, k;
unsigned char *data=cmd+1;
if (cmd[0]=='g') { //send all registers to gdb
int *p=(int*)&gdbRegFile;
gdbPacketStart();
for (i=0; i<sizeof(GdbRegFile)/4; i++) gdbPacketHex(iswap(*p++), 32);
gdbPacketEnd();
} else if (cmd[0]=='G') { //receive content for all registers from gdb
int *p=(int*)&gdbRegFile;
for (i=0; i<sizeof(GdbRegFile)/4; i++) *p++=iswap(gdbGetHexVal(&data, 32));
sendPacket("OK");
} else if (cmd[0]=='m') { //read memory to gdb
i=gdbGetHexVal(&data, -1);
data++;
j=gdbGetHexVal(&data, -1);
gdbPacketStart();
for (k=0; k<j; k++) {
gdbPacketHex(readbyte(i++), 8);
}
gdbPacketEnd();
} else if (cmd[0]=='?') { //Reply with stop reason
sendReason();
#if CONFIG_GDBSTUB_SUPPORT_TASKS
} else if (handlerState != HANDLER_TASK_SUPPORT_DISABLED) {
if (cmd[0]=='H') { //Continue with task
if (cmd[1]=='g' || cmd[1]=='c') {
const char * ret = "OK";
data++;
i=gdbGetHexVal(&data, -1);
handlerState = HANDLER_STARTED; //Hg0 is the first packet received after connect
j = findCurrentTaskIndex();
if (i == j || (j == CUR_TASK_INDEX_UNKNOWN && i == 0)) {
//GDB has asked us for the current task on this CPU.
//This task either was executing when we have entered the panic handler,
//or was already switched out and we have paniced during the context switch.
//Either way we are interested in the stack frame where panic has happened,
//so obtain the state from the exception frame rather than the TCB.
dumpHwToRegfile(&paniced_frame);
} else {
unsigned handle, count;
//Get the handle for that task
count = getTaskInfo(i, &handle, 0, 0);
//Then extract TCB and gdbRegFile from it
if (i < count) dumpTCBToRegFile(handle);
else ret = "E00";
}
return sendPacket(ret);
}
return sendPacket(NULL);
} else if (cmd[0]=='T') { //Task alive check
unsigned count;
data++;
i=gdbGetHexVal(&data, -1);
count = getTaskInfo(i, 0, 0, 0);
return sendPacket(i < count ? "OK": "E00");
} else if (cmd[0]=='q') { //Extended query
// React to qThreadExtraInfo or qfThreadInfo or qsThreadInfo or qC, without using strcmp
if (len > 16 && cmd[1] == 'T' && cmd[2] == 'h' && cmd[3] == 'r' && cmd[7] == 'E' && cmd[12] == 'I' && cmd[16] == ',') {
data=&cmd[17];
i=gdbGetHexVal(&data, -1);
unsigned handle = 0, coreId = 3;
const char * name = 0;
// Extract the task name and CPU from freeRTOS
unsigned tCount = getTaskInfo(i, &handle, &name, &coreId);
if (i < tCount) {
gdbPacketStart();
for(k=0; name[k]; k++) gdbPacketHex(name[k], 8);
gdbPacketStr("20435055"); // CPU
gdbPacketStr(coreId == 0 ? "30": coreId == 1 ? "31" : "78"); // 0 or 1 or x
gdbPacketEnd();
return ST_OK;
}
} else if (len >= 12 && (cmd[1] == 'f' || cmd[1] == 's') && (cmd[2] == 'T' && cmd[3] == 'h' && cmd[4] == 'r' && cmd[5] == 'e' && cmd[6] == 'a' && cmd[7] == 'd' && cmd[8] == 'I')) {
// Only react to qfThreadInfo and qsThreadInfo, not using strcmp here since it can be in ROM
// Extract the number of task from freeRTOS
static int taskIndex = 0;
unsigned tCount = 0;
if (cmd[1] == 'f') {
taskIndex = 0;
handlerState = HANDLER_STARTED; //It seems it's the first request GDB is sending
}
tCount = getTaskInfo(0, 0, 0, 0);
if (taskIndex < tCount) {
gdbPacketStart();
gdbPacketStr("m");
gdbPacketHex(taskIndex, 32);
gdbPacketEnd();
taskIndex++;
} else return sendPacket("l");
} else if (len >= 2 && cmd[1] == 'C') {
// Get current task id
gdbPacketStart();
k = findCurrentTaskIndex();
if (k != CUR_TASK_INDEX_UNKNOWN) {
gdbPacketStr("QC");
gdbPacketHex(k, 32);
} else gdbPacketStr("bad");
gdbPacketEnd();
return ST_OK;
}
return sendPacket(NULL);
}
#endif // CONFIG_GDBSTUB_SUPPORT_TASKS
} else {
//We don't recognize or support whatever GDB just sent us.
return sendPacket(NULL);
}
return ST_OK;
}
//Lower layer: grab a command packet and check the checksum
//Calls gdbHandleCommand on the packet if the checksum is OK
//Returns ST_OK on success, ST_ERR when checksum fails, a
//character if it is received instead of the GDB packet
//start char.
static int gdbReadCommand() {
unsigned char c;
unsigned char chsum=0, rchsum;
unsigned char sentchs[2];
int p=0;
unsigned char *ptr;
c=gdbRecvChar();
if (c!='$') return c;
while(1) {
c=gdbRecvChar();
if (c=='#') { //end of packet, checksum follows
cmd[p]=0;
break;
}
chsum+=c;
if (c=='$') {
//Wut, restart packet?
chsum=0;
p=0;
continue;
}
if (c=='}') { //escape the next char
c=gdbRecvChar();
chsum+=c;
c^=0x20;
}
cmd[p++]=c;
if (p>=PBUFLEN) return ST_ERR;
}
//A # has been received. Get and check the received chsum.
sentchs[0]=gdbRecvChar();
sentchs[1]=gdbRecvChar();
ptr=&sentchs[0];
rchsum=gdbGetHexVal(&ptr, 8);
if (rchsum!=chsum) {
gdbSendChar('-');
return ST_ERR;
} else {
gdbSendChar('+');
return gdbHandleCommand(cmd, p);
}
}
void esp_gdbstub_panic_handler(XtExcFrame *frame) {
#if CONFIG_GDBSTUB_SUPPORT_TASKS
if (handlerState == HANDLER_STARTED) {
//We have re-entered GDB Stub. Try disabling task support.
handlerState = HANDLER_TASK_SUPPORT_DISABLED;
gdbPacketEnd(); // Ends up any pending GDB packet (this creates a garbage value)
} else if (handlerState == HANDLER_NOT_STARTED) {
//Need to remember the frame that panic'd since gdb will ask for all threads before ours
memcpy(&paniced_frame, frame, sizeof(paniced_frame));
dumpHwToRegfile(&paniced_frame);
}
#else // CONFIG_GDBSTUB_SUPPORT_TASKS
dumpHwToRegfile(frame);
#endif // CONFIG_GDBSTUB_SUPPORT_TASKS
//Make sure txd/rxd are enabled
gpio_pullup_dis(1);
PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0RXD_U, FUNC_U0RXD_U0RXD);
PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0TXD_U, FUNC_U0TXD_U0TXD);
sendReason();
while(gdbReadCommand()!=ST_CONT);
while(1);
}