gdb-stub.c
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- /*
- * arch/s390/kernel/gdb-stub.c
- *
- * S390 version
- * Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
- * Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com),
- *
- * Originally written by Glenn Engel, Lake Stevens Instrument Division
- *
- * Contributed by HP Systems
- *
- * Modified for SPARC by Stu Grossman, Cygnus Support.
- *
- * Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
- * Send complaints, suggestions etc. to <andy@waldorf-gmbh.de>
- *
- * Copyright (C) 1995 Andreas Busse
- */
- /*
- * To enable debugger support, two things need to happen. One, a
- * call to set_debug_traps() is necessary in order to allow any breakpoints
- * or error conditions to be properly intercepted and reported to gdb.
- * Two, a breakpoint needs to be generated to begin communication. This
- * is most easily accomplished by a call to breakpoint(). Breakpoint()
- * simulates a breakpoint by executing a BREAK instruction.
- *
- *
- * The following gdb commands are supported:
- *
- * command function Return value
- *
- * g return the value of the CPU registers hex data or ENN
- * G set the value of the CPU registers OK or ENN
- *
- * mAA..AA,LLLL Read LLLL bytes at address AA..AA hex data or ENN
- * MAA..AA,LLLL: Write LLLL bytes at address AA.AA OK or ENN
- *
- * c Resume at current address SNN ( signal NN)
- * cAA..AA Continue at address AA..AA SNN
- *
- * s Step one instruction SNN
- * sAA..AA Step one instruction from AA..AA SNN
- *
- * k kill
- *
- * ? What was the last sigval ? SNN (signal NN)
- *
- *
- * All commands and responses are sent with a packet which includes a
- * checksum. A packet consists of
- *
- * $<packet info>#<checksum>.
- *
- * where
- * <packet info> :: <characters representing the command or response>
- * <checksum> :: < two hex digits computed as modulo 256 sum of <packetinfo>>
- *
- * When a packet is received, it is first acknowledged with either '+' or '-'.
- * '+' indicates a successful transfer. '-' indicates a failed transfer.
- *
- * Example:
- *
- * Host: Reply:
- * $m0,10#2a +$00010203040506070809101112131415#42
- *
- */
- #include <asm/gdb-stub.h>
- #include <linux/string.h>
- #include <linux/kernel.h>
- #include <linux/signal.h>
- #include <linux/sched.h>
- #include <linux/mm.h>
- #include <asm/pgtable.h>
- #include <asm/system.h>
- /*
- * external low-level support routines
- */
- extern int putDebugChar(char c); /* write a single character */
- extern char getDebugChar(void); /* read and return a single char */
- extern void fltr_set_mem_err(void);
- extern void trap_low(void);
- /*
- * breakpoint and test functions
- */
- extern void breakpoint(void);
- extern void breakinst(void);
- /*
- * local prototypes
- */
- static void getpacket(char *buffer);
- static void putpacket(char *buffer);
- static int hex(unsigned char ch);
- static int hexToInt(char **ptr, int *intValue);
- static unsigned char *mem2hex(char *mem, char *buf, int count, int may_fault);
- /*
- * BUFMAX defines the maximum number of characters in inbound/outbound buffers
- * at least NUMREGBYTES*2 are needed for register packets
- */
- #define BUFMAX 2048
- static char input_buffer[BUFMAX];
- static char output_buffer[BUFMAX];
- int gdb_stub_initialised = FALSE;
- static const char hexchars[]="0123456789abcdef";
- /*
- * Convert ch from a hex digit to an int
- */
- static int hex(unsigned char ch)
- {
- if (ch >= 'a' && ch <= 'f')
- return ch-'a'+10;
- if (ch >= '0' && ch <= '9')
- return ch-'0';
- if (ch >= 'A' && ch <= 'F')
- return ch-'A'+10;
- return -1;
- }
- /*
- * scan for the sequence $<data>#<checksum>
- */
- static void getpacket(char *buffer)
- {
- unsigned char checksum;
- unsigned char xmitcsum;
- int i;
- int count;
- unsigned char ch;
- do {
- /*
- * wait around for the start character,
- * ignore all other characters
- */
- while ((ch = (getDebugChar() & 0x7f)) != '$') ;
- checksum = 0;
- xmitcsum = -1;
- count = 0;
-
- /*
- * now, read until a # or end of buffer is found
- */
- while (count < BUFMAX) {
- ch = getDebugChar() & 0x7f;
- if (ch == '#')
- break;
- checksum = checksum + ch;
- buffer[count] = ch;
- count = count + 1;
- }
- if (count >= BUFMAX)
- continue;
- buffer[count] = 0;
- if (ch == '#') {
- xmitcsum = hex(getDebugChar() & 0x7f) << 4;
- xmitcsum |= hex(getDebugChar() & 0x7f);
- if (checksum != xmitcsum)
- putDebugChar('-'); /* failed checksum */
- else {
- putDebugChar('+'); /* successful transfer */
- /*
- * if a sequence char is present,
- * reply the sequence ID
- */
- if (buffer[2] == ':') {
- putDebugChar(buffer[0]);
- putDebugChar(buffer[1]);
- /*
- * remove sequence chars from buffer
- */
- count = strlen(buffer);
- for (i=3; i <= count; i++)
- buffer[i-3] = buffer[i];
- }
- }
- }
- }
- while (checksum != xmitcsum);
- }
- /*
- * send the packet in buffer.
- */
- static void putpacket(char *buffer)
- {
- unsigned char checksum;
- int count;
- unsigned char ch;
- /*
- * $<packet info>#<checksum>.
- */
- do {
- putDebugChar('$');
- checksum = 0;
- count = 0;
- while ((ch = buffer[count]) != 0) {
- if (!(putDebugChar(ch)))
- return;
- checksum += ch;
- count += 1;
- }
- putDebugChar('#');
- putDebugChar(hexchars[checksum >> 4]);
- putDebugChar(hexchars[checksum & 0xf]);
- }
- while ((getDebugChar() & 0x7f) != '+');
- }
- /*
- * Convert the memory pointed to by mem into hex, placing result in buf.
- * Return a pointer to the last char put in buf (null), in case of mem fault,
- * return 0.
- * If MAY_FAULT is non-zero, then we will handle memory faults by returning
- * a 0, else treat a fault like any other fault in the stub.
- */
- static unsigned char *mem2hex(char *mem, char *buf, int count, int may_fault)
- {
- unsigned char ch;
- /* set_mem_fault_trap(may_fault); */
- while (count-- > 0) {
- ch = *(mem++);
- if (mem_err)
- return 0;
- *buf++ = hexchars[ch >> 4];
- *buf++ = hexchars[ch & 0xf];
- }
- *buf = 0;
- /* set_mem_fault_trap(0); */
- return buf;
- }
- /*
- * convert the hex array pointed to by buf into binary to be placed in mem
- * return a pointer to the character AFTER the last byte written
- */
- static char *hex2mem(char *buf, char *mem, int count, int may_fault)
- {
- int i;
- unsigned char ch;
- /* set_mem_fault_trap(may_fault); */
- for (i=0; i<count; i++)
- {
- ch = hex(*buf++) << 4;
- ch |= hex(*buf++);
- *(mem++) = ch;
- if (mem_err)
- return 0;
- }
- /* set_mem_fault_trap(0); */
- return mem;
- }
- /*
- * Set up exception handlers for tracing and breakpoints
- */
- void set_debug_traps(void)
- {
- // unsigned long flags;
- unsigned char c;
- // save_and_cli(flags);
- /*
- * In case GDB is started before us, ack any packets
- * (presumably "$?#xx") sitting there.
- */
- while((c = getDebugChar()) != '$');
- while((c = getDebugChar()) != '#');
- c = getDebugChar(); /* eat first csum byte */
- c = getDebugChar(); /* eat second csum byte */
- putDebugChar('+'); /* ack it */
- gdb_stub_initialised = TRUE;
- // restore_flags(flags);
- }
- /*
- * Trap handler for memory errors. This just sets mem_err to be non-zero. It
- * assumes that %l1 is non-zero. This should be safe, as it is doubtful that
- * 0 would ever contain code that could mem fault. This routine will skip
- * past the faulting instruction after setting mem_err.
- */
- extern void fltr_set_mem_err(void)
- {
- /* FIXME: Needs to be written... */
- }
- /*
- * While we find nice hex chars, build an int.
- * Return number of chars processed.
- */
- static int hexToInt(char **ptr, int *intValue)
- {
- int numChars = 0;
- int hexValue;
- *intValue = 0;
- while (**ptr)
- {
- hexValue = hex(**ptr);
- if (hexValue < 0)
- break;
- *intValue = (*intValue << 4) | hexValue;
- numChars ++;
- (*ptr)++;
- }
- return (numChars);
- }
- void gdb_stub_get_non_pt_regs(gdb_pt_regs *regs)
- {
- s390_fp_regs *fpregs=®s->fp_regs;
- int has_ieee=save_fp_regs1(fpregs);
- if(!has_ieee)
- {
- fpregs->fpc=0;
- fpregs->fprs[1].d=
- fpregs->fprs[3].d=
- fpregs->fprs[5].d=
- fpregs->fprs[7].d=0;
- memset(&fpregs->fprs[8].d,0,sizeof(freg_t)*8);
- }
- }
- void gdb_stub_set_non_pt_regs(gdb_pt_regs *regs)
- {
- restore_fp_regs1(®s->fp_regs);
- }
- void gdb_stub_send_signal(int sigval)
- {
- char *ptr;
- ptr = output_buffer;
- /*
- * Send trap type (converted to signal)
- */
- *ptr++ = 'S';
- *ptr++ = hexchars[sigval >> 4];
- *ptr++ = hexchars[sigval & 0xf];
- *ptr++ = 0;
- putpacket(output_buffer); /* send it off... */
- }
- /*
- * This function does all command processing for interfacing to gdb. It
- * returns 1 if you should skip the instruction at the trap address, 0
- * otherwise.
- */
- void gdb_stub_handle_exception(gdb_pt_regs *regs,int sigval)
- {
- int trap; /* Trap type */
- int addr;
- int length;
- char *ptr;
- unsigned long *stack;
-
- /*
- * reply to host that an exception has occurred
- */
- send_signal(sigval);
- /*
- * Wait for input from remote GDB
- */
- while (1) {
- output_buffer[0] = 0;
- getpacket(input_buffer);
- switch (input_buffer[0])
- {
- case '?':
- send_signal(sigval);
- continue;
- case 'd':
- /* toggle debug flag */
- break;
- /*
- * Return the value of the CPU registers
- */
- case 'g':
- gdb_stub_get_non_pt_regs(regs);
- ptr = output_buffer;
- ptr= mem2hex((char *)regs,ptr,sizeof(s390_regs_common),FALSE);
- ptr= mem2hex((char *)®s->crs[0],ptr,NUM_CRS*CR_SIZE,FALSE);
- ptr = mem2hex((char *)®s->fp_regs, ptr,sizeof(s390_fp_regs));
- break;
-
- /*
- * set the value of the CPU registers - return OK
- * FIXME: Needs to be written
- */
- case 'G':
- ptr=input_buffer;
- hex2mem (ptr, (char *)regs,sizeof(s390_regs_common), FALSE);
- ptr+=sizeof(s390_regs_common)*2;
- hex2mem (ptr, (char *)regs->crs[0],NUM_CRS*CR_SIZE, FALSE);
- ptr+=NUM_CRS*CR_SIZE*2;
- hex2mem (ptr, (char *)regs->fp_regs,sizeof(s390_fp_regs), FALSE);
- gdb_stub_set_non_pt_regs(regs);
- strcpy(output_buffer,"OK");
- break;
- /*
- * mAA..AA,LLLL Read LLLL bytes at address AA..AA
- */
- case 'm':
- ptr = &input_buffer[1];
- if (hexToInt(&ptr, &addr)
- && *ptr++ == ','
- && hexToInt(&ptr, &length)) {
- if (mem2hex((char *)addr, output_buffer, length, 1))
- break;
- strcpy (output_buffer, "E03");
- } else
- strcpy(output_buffer,"E01");
- break;
- /*
- * MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK
- */
- case 'M':
- ptr = &input_buffer[1];
- if (hexToInt(&ptr, &addr)
- && *ptr++ == ','
- && hexToInt(&ptr, &length)
- && *ptr++ == ':') {
- if (hex2mem(ptr, (char *)addr, length, 1))
- strcpy(output_buffer, "OK");
- else
- strcpy(output_buffer, "E03");
- }
- else
- strcpy(output_buffer, "E02");
- break;
- /*
- * cAA..AA Continue at address AA..AA(optional)
- */
- case 'c':
- /* try to read optional parameter, pc unchanged if no parm */
- ptr = &input_buffer[1];
- if (hexToInt(&ptr, &addr))
- regs->cp0_epc = addr;
-
- /*
- * Need to flush the instruction cache here, as we may
- * have deposited a breakpoint, and the icache probably
- * has no way of knowing that a data ref to some location
- * may have changed something that is in the instruction
- * cache.
- * NB: We flush both caches, just to be sure...
- */
- flush_cache_all();
- return;
- /* NOTREACHED */
- break;
- /*
- * kill the program
- */
- case 'k' :
- break; /* do nothing */
- /*
- * Reset the whole machine (FIXME: system dependent)
- */
- case 'r':
- break;
- /*
- * Step to next instruction
- */
- case 's':
- /*
- * There is no single step insn in the MIPS ISA, so we
- * use breakpoints and continue, instead.
- */
- single_step(regs);
- flush_cache_all();
- return;
- /* NOTREACHED */
- }
- break;
- } /* switch */
- /*
- * reply to the request
- */
- putpacket(output_buffer);
- } /* while */
- }
- /*
- * This function will generate a breakpoint exception. It is used at the
- * beginning of a program to sync up with a debugger and can be used
- * otherwise as a quick means to stop program execution and "break" into
- * the debugger.
- */
- void breakpoint(void)
- {
- if (!gdb_stub_initialised)
- return;
- __asm__ __volatile__(
- ".globl breakinstn"
- "breakinst:t.word %0nt"
- :
- : "i" (S390_BREAKPOINT_U16)
- :
- );
- }