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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=&regs->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(&regs->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 *)&regs->crs[0],ptr,NUM_CRS*CR_SIZE,FALSE);

                        ptr = mem2hex((char *)&regs->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 breakinst\n"

                        "breakinst:\t.word   %0\n\t"

                        :

                        : "i" (S390_BREAKPOINT_U16)

                                :

                                );

}