esp-idf/components/esp32/gdbstub.c

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9.2 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 "rom/ets_sys.h"
#include "soc/uart_reg.h"
#include "soc/io_mux_reg.h"
#include "esp_gdbstub.h"
#include "driver/gpio.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(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 dumpHwToRegfile(XtExcFrame *frame) {
int i;
long *frameAregs=&frame->a0;
gdbRegFile.pc=frame->pc;
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.sar=frame->sar;
//All windows have been spilled to the stack by the ISR routines. The following values should indicate that.
gdbRegFile.sar=frame->sar;
gdbRegFile.windowbase=0; //0
gdbRegFile.windowstart=0x1; //1
gdbRegFile.configid0=0xdeadbeef; //ToDo
gdbRegFile.configid1=0xdeadbeef; //ToDo
gdbRegFile.ps=frame->ps-PS_EXCM_MASK;
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
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();
}
//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));;
gdbPacketStart();
gdbPacketStr("OK");
gdbPacketEnd();
} 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();
} else {
//We don't recognize or support whatever GDB just sent us.
gdbPacketStart();
gdbPacketEnd();
return ST_ERR;
}
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) {
dumpHwToRegfile(frame);
//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);
}