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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
*
*/
#define TRUE 1
#define FALSE 0
#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>
#include <linux/stddef.h>
#define S390_REGS_COMMON_SIZE offsetof(struct gdb_pt_regs,orig_gpr2)
/*
* external low-level support routines
*/
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 0
if (mem_err)
return 0;
#endif
*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 0
if (mem_err)
return 0;
#endif
}
/* 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(struct 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(struct 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(struct 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
*/
#if 0
send_signal(sigval);
#endif
/*
* Wait for input from remote GDB
*/
while (1)
{
output_buffer[0] = 0;
getpacket(input_buffer);
switch (input_buffer[0])
{
case '?':
#if 0
send_signal(sigval);
#endif
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,S390_REGS_COMMON_SIZE,FALSE);
ptr= mem2hex((char *)®s->crs[0],ptr,NUM_CRS*CR_SIZE,FALSE);
ptr = mem2hex((char *)®s->fp_regs, ptr,sizeof(s390_fp_regs),FALSE);
break;
/*
* set the value of the CPU registers - return OK
* FIXME: Needs to be written
*/
case 'G':
ptr=input_buffer;
hex2mem (ptr, (char *)regs,S390_REGS_COMMON_SIZE, FALSE);
ptr+=S390_REGS_COMMON_SIZE*2;
hex2mem (ptr, (char *)regs->crs[0],NUM_CRS*CR_SIZE, FALSE);
ptr+=NUM_CRS*CR_SIZE*2;
hex2mem (ptr, (char *)®s->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->psw.addr = 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.
*/
#if 0
single_step(regs);
#endif
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"
: : "i" (S390_BREAKPOINT_U16) );
}
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