360 lines
9.3 KiB
C
360 lines
9.3 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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/******************************************************************************
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* Description: A stub to make the ESP32 debuggable by GDB over the serial
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* port, at least enough to do a backtrace on panic. This gdbstub is read-only:
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* it allows inspecting the ESP32 state
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*******************************************************************************/
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#include "rom/ets_sys.h"
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#include "soc/uart_reg.h"
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#include "soc/io_mux_reg.h"
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#include "esp_gdbstub.h"
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#include "driver/gpio.h"
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//Length of buffer used to reserve GDB commands. Has to be at least able to fit the G command, which
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//implies a minimum size of about 320 bytes.
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#define PBUFLEN 512
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static unsigned char cmd[PBUFLEN]; //GDB command input buffer
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static char chsum; //Running checksum of the output packet
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#define ATTR_GDBFN
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//Receive a char from the uart. Uses polling and feeds the watchdog.
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static int ATTR_GDBFN gdbRecvChar() {
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int i;
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while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_RXFIFO_CNT_S)&UART_RXFIFO_CNT)==0) ;
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i=READ_PERI_REG(UART_FIFO_REG(0));
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return i;
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}
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//Send a char to the uart.
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static void ATTR_GDBFN gdbSendChar(char c) {
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while (((READ_PERI_REG(UART_STATUS_REG(0))>>UART_TXFIFO_CNT_S)&UART_TXFIFO_CNT)>=126) ;
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WRITE_PERI_REG(UART_FIFO_REG(0), c);
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}
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//Send the start of a packet; reset checksum calculation.
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static void ATTR_GDBFN gdbPacketStart() {
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chsum=0;
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gdbSendChar('$');
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}
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//Send a char as part of a packet
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static void ATTR_GDBFN gdbPacketChar(char c) {
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if (c=='#' || c=='$' || c=='}' || c=='*') {
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gdbSendChar('}');
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gdbSendChar(c^0x20);
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chsum+=(c^0x20)+'}';
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} else {
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gdbSendChar(c);
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chsum+=c;
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}
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}
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//Send a string as part of a packet
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static void ATTR_GDBFN gdbPacketStr(const char *c) {
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while (*c!=0) {
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gdbPacketChar(*c);
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c++;
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}
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}
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//Send a hex val as part of a packet. 'bits'/4 dictates the number of hex chars sent.
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static void ATTR_GDBFN gdbPacketHex(int val, int bits) {
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char hexChars[]="0123456789abcdef";
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int i;
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for (i=bits; i>0; i-=4) {
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gdbPacketChar(hexChars[(val>>(i-4))&0xf]);
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}
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}
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//Finish sending a packet.
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static void ATTR_GDBFN gdbPacketEnd() {
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gdbSendChar('#');
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gdbPacketHex(chsum, 8);
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}
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//Error states used by the routines that grab stuff from the incoming gdb packet
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#define ST_ENDPACKET -1
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#define ST_ERR -2
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#define ST_OK -3
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#define ST_CONT -4
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//Grab a hex value from the gdb packet. Ptr will get positioned on the end
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//of the hex string, as far as the routine has read into it. Bits/4 indicates
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//the max amount of hex chars it gobbles up. Bits can be -1 to eat up as much
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//hex chars as possible.
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static long ATTR_GDBFN gdbGetHexVal(unsigned char **ptr, int bits) {
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int i;
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int no;
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unsigned int v=0;
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char c;
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no=bits/4;
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if (bits==-1) no=64;
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for (i=0; i<no; i++) {
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c=**ptr;
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(*ptr)++;
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if (c>='0' && c<='9') {
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v<<=4;
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v|=(c-'0');
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} else if (c>='A' && c<='F') {
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v<<=4;
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v|=(c-'A')+10;
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} else if (c>='a' && c<='f') {
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v<<=4;
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v|=(c-'a')+10;
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} else if (c=='#') {
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if (bits==-1) {
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(*ptr)--;
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return v;
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}
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return ST_ENDPACKET;
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} else {
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if (bits==-1) {
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(*ptr)--;
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return v;
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}
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return ST_ERR;
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}
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}
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return v;
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}
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//Swap an int into the form gdb wants it
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static int ATTR_GDBFN iswap(int i) {
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int r;
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r=((i>>24)&0xff);
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r|=((i>>16)&0xff)<<8;
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r|=((i>>8)&0xff)<<16;
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r|=((i>>0)&0xff)<<24;
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return r;
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}
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//Read a byte from ESP32 memory.
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static unsigned char ATTR_GDBFN readbyte(unsigned int p) {
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int *i=(int*)(p&(~3));
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if (p<0x20000000 || p>=0x80000000) return -1;
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return *i>>((p&3)*8);
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}
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//Register file in the format exp108 gdb port expects it.
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//Inspired by gdb/regformats/reg-xtensa.dat
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typedef struct {
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uint32_t pc;
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uint32_t a[64];
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uint32_t lbeg;
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uint32_t lend;
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uint32_t lcount;
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uint32_t sar;
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uint32_t windowbase;
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uint32_t windowstart;
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uint32_t configid0;
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uint32_t configid1;
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uint32_t ps;
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uint32_t threadptr;
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uint32_t br;
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uint32_t scompare1;
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uint32_t acclo;
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uint32_t acchi;
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uint32_t m0;
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uint32_t m1;
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uint32_t m2;
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uint32_t m3;
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uint32_t expstate; //I'm going to assume this is exccause...
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uint32_t f64r_lo;
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uint32_t f64r_hi;
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uint32_t f64s;
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uint32_t f[16];
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uint32_t fcr;
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uint32_t fsr;
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} GdbRegFile;
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GdbRegFile gdbRegFile;
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/*
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//Register format as the Xtensa HAL has it:
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STRUCT_FIELD (long, 4, XT_STK_EXIT, exit)
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STRUCT_FIELD (long, 4, XT_STK_PC, pc)
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STRUCT_FIELD (long, 4, XT_STK_PS, ps)
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STRUCT_FIELD (long, 4, XT_STK_A0, a0)
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[..]
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STRUCT_FIELD (long, 4, XT_STK_A15, a15)
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STRUCT_FIELD (long, 4, XT_STK_SAR, sar)
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STRUCT_FIELD (long, 4, XT_STK_EXCCAUSE, exccause)
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STRUCT_FIELD (long, 4, XT_STK_EXCVADDR, excvaddr)
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STRUCT_FIELD (long, 4, XT_STK_LBEG, lbeg)
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STRUCT_FIELD (long, 4, XT_STK_LEND, lend)
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STRUCT_FIELD (long, 4, XT_STK_LCOUNT, lcount)
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// Temporary space for saving stuff during window spill
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STRUCT_FIELD (long, 4, XT_STK_TMP0, tmp0)
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STRUCT_FIELD (long, 4, XT_STK_TMP1, tmp1)
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STRUCT_FIELD (long, 4, XT_STK_TMP2, tmp2)
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STRUCT_FIELD (long, 4, XT_STK_VPRI, vpri)
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STRUCT_FIELD (long, 4, XT_STK_OVLY, ovly)
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#endif
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STRUCT_END(XtExcFrame)
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*/
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static void dumpHwToRegfile(XtExcFrame *frame) {
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int i;
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long *frameAregs=&frame->a0;
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gdbRegFile.pc=frame->pc;
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for (i=0; i<16; i++) gdbRegFile.a[i]=frameAregs[i];
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for (i=16; i<64; i++) gdbRegFile.a[i]=0xDEADBEEF;
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gdbRegFile.lbeg=frame->lbeg;
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gdbRegFile.lend=frame->lend;
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gdbRegFile.lcount=frame->lcount;
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gdbRegFile.sar=frame->sar;
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//All windows have been spilled to the stack by the ISR routines. The following values should indicate that.
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gdbRegFile.sar=frame->sar;
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gdbRegFile.windowbase=0; //0
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gdbRegFile.windowstart=0x1; //1
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gdbRegFile.configid0=0xdeadbeef; //ToDo
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gdbRegFile.configid1=0xdeadbeef; //ToDo
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gdbRegFile.ps=frame->ps-PS_EXCM_MASK;
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gdbRegFile.threadptr=0xdeadbeef; //ToDo
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gdbRegFile.br=0xdeadbeef; //ToDo
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gdbRegFile.scompare1=0xdeadbeef; //ToDo
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gdbRegFile.acclo=0xdeadbeef; //ToDo
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gdbRegFile.acchi=0xdeadbeef; //ToDo
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gdbRegFile.m0=0xdeadbeef; //ToDo
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gdbRegFile.m1=0xdeadbeef; //ToDo
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gdbRegFile.m2=0xdeadbeef; //ToDo
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gdbRegFile.m3=0xdeadbeef; //ToDo
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gdbRegFile.expstate=frame->exccause; //ToDo
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}
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//Send the reason execution is stopped to GDB.
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static void sendReason() {
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//exception-to-signal mapping
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char exceptionSignal[]={4,31,11,11,2,6,8,0,6,7,0,0,7,7,7,7};
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int i=0;
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gdbPacketStart();
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gdbPacketChar('T');
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i=gdbRegFile.expstate&0x7f;
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if (i<sizeof(exceptionSignal)) {
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gdbPacketHex(exceptionSignal[i], 8);
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} else {
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gdbPacketHex(11, 8);
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}
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gdbPacketEnd();
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}
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//Handle a command as received from GDB.
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static int gdbHandleCommand(unsigned char *cmd, int len) {
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//Handle a command
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int i, j, k;
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unsigned char *data=cmd+1;
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if (cmd[0]=='g') { //send all registers to gdb
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int *p=(int*)&gdbRegFile;
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gdbPacketStart();
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for (i=0; i<sizeof(GdbRegFile)/4; i++) gdbPacketHex(iswap(*p++), 32);
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gdbPacketEnd();
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} else if (cmd[0]=='G') { //receive content for all registers from gdb
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int *p=(int*)&gdbRegFile;
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for (i=0; i<sizeof(GdbRegFile)/4; i++) *p++=iswap(gdbGetHexVal(&data, 32));;
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gdbPacketStart();
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gdbPacketStr("OK");
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gdbPacketEnd();
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} else if (cmd[0]=='m') { //read memory to gdb
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i=gdbGetHexVal(&data, -1);
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data++;
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j=gdbGetHexVal(&data, -1);
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gdbPacketStart();
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for (k=0; k<j; k++) {
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gdbPacketHex(readbyte(i++), 8);
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}
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gdbPacketEnd();
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} else if (cmd[0]=='?') { //Reply with stop reason
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sendReason();
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} else {
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//We don't recognize or support whatever GDB just sent us.
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gdbPacketStart();
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gdbPacketEnd();
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return ST_ERR;
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}
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return ST_OK;
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}
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//Lower layer: grab a command packet and check the checksum
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//Calls gdbHandleCommand on the packet if the checksum is OK
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//Returns ST_OK on success, ST_ERR when checksum fails, a
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//character if it is received instead of the GDB packet
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//start char.
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static int gdbReadCommand() {
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unsigned char c;
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unsigned char chsum=0, rchsum;
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unsigned char sentchs[2];
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int p=0;
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unsigned char *ptr;
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c=gdbRecvChar();
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if (c!='$') return c;
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while(1) {
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c=gdbRecvChar();
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if (c=='#') { //end of packet, checksum follows
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cmd[p]=0;
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break;
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}
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chsum+=c;
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if (c=='$') {
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//Wut, restart packet?
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chsum=0;
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p=0;
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continue;
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}
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if (c=='}') { //escape the next char
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c=gdbRecvChar();
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chsum+=c;
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c^=0x20;
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}
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cmd[p++]=c;
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if (p>=PBUFLEN) return ST_ERR;
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}
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//A # has been received. Get and check the received chsum.
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sentchs[0]=gdbRecvChar();
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sentchs[1]=gdbRecvChar();
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ptr=&sentchs[0];
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rchsum=gdbGetHexVal(&ptr, 8);
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if (rchsum!=chsum) {
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gdbSendChar('-');
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return ST_ERR;
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} else {
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gdbSendChar('+');
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return gdbHandleCommand(cmd, p);
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}
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}
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void esp_gdbstub_panic_handler(XtExcFrame *frame) {
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dumpHwToRegfile(frame);
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//Make sure txd/rxd are enabled
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gpio_pullup_dis(1);
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PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0RXD_U, FUNC_U0RXD_U0RXD);
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PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0TXD_U, FUNC_U0TXD_U0TXD);
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sendReason();
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while(gdbReadCommand()!=ST_CONT);
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while(1);
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}
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