patch-2.4.2 linux/arch/s390x/kernel/gdb-stub.c

• Lines: 576
• Date: Tue Feb 13 14:13:44 2001
• Orig file: v2.4.1/linux/arch/s390x/kernel/gdb-stub.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.1/linux/arch/s390x/kernel/gdb-stub.c linux/arch/s390x/kernel/gdb-stub.c
@@ -0,0 +1,575 @@
+/*
+ *  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)
+				:
+				);
+}
+
+
+
+
+
+
+