patch-1.3.44 linux/arch/sparc/kernel/sparc-stub.c

• Lines: 692
• Date: Sat Nov 25 02:58:28 1995
• Orig file: v1.3.43/linux/arch/sparc/kernel/sparc-stub.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.43/linux/arch/sparc/kernel/sparc-stub.c linux/arch/sparc/kernel/sparc-stub.c
@@ -0,0 +1,691 @@
+/* $Id: sparc-stub.c,v 1.7 1995/11/25 00:58:26 davem Exp $
+ * sparc-stub.c:  KGDB support for the Linux kernel.
+ *
+ * Modifications to run under Linux
+ * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
+ *
+ * This file origionally came from the gdb sources, and the
+ * copyright notices have been retained below.
+ */
+
+/****************************************************************************
+
+		THIS SOFTWARE IS NOT COPYRIGHTED
+
+   HP offers the following for use in the public domain.  HP makes no
+   warranty with regard to the software or it's performance and the
+   user accepts the software "AS IS" with all faults.
+
+   HP DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WITH REGARD
+   TO THIS SOFTWARE INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+   OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+
+****************************************************************************/
+
+/****************************************************************************
+ *  Header: remcom.c,v 1.34 91/03/09 12:29:49 glenne Exp $
+ *
+ *  Module name: remcom.c $
+ *  Revision: 1.34 $
+ *  Date: 91/03/09 12:29:49 $
+ *  Contributor:     Lake Stevens Instrument Division$
+ *
+ *  Description:     low level support for gdb debugger. $
+ *
+ *  Considerations:  only works on target hardware $
+ *
+ *  Written by:      Glenn Engel $
+ *  ModuleState:     Experimental $
+ *
+ *  NOTES:           See Below $
+ *
+ *  Modified for SPARC by Stu Grossman, Cygnus Support.
+ *
+ *  This code has been extensively tested on the Fujitsu SPARClite demo board.
+ *
+ *  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 trap #1.
+ *
+ *************
+ *
+ *    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)
+ *
+ *    bBB..BB	    Set baud rate to BB..BB		   OK or BNN, then sets
+ *							   baud rate
+ *
+ * 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 <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+
+#include <asm/system.h>
+#include <asm/signal.h>
+#include <asm/oplib.h>
+#include <asm/head.h>
+#include <asm/traps.h>
+#include <asm/system.h>
+#include <asm/vac-ops.h>
+#include <asm/kgdb.h>
+
+/*
+ *
+ * external low-level support routines
+ */
+
+extern void putDebugChar(char);   /* write a single character      */
+extern char getDebugChar(void);   /* read and return a single char */
+
+/*
+ * BUFMAX defines the maximum number of characters in inbound/outbound buffers
+ * at least NUMREGBYTES*2 are needed for register packets
+ */
+#define BUFMAX 2048
+
+static int initialized = 0;	/* !0 means we've been initialized */
+
+static const char hexchars[]="0123456789abcdef";
+
+#define NUMREGS 72
+
+/* Number of bytes of registers.  */
+#define NUMREGBYTES (NUMREGS * 4)
+enum regnames {G0, G1, G2, G3, G4, G5, G6, G7,
+		 O0, O1, O2, O3, O4, O5, SP, O7,
+		 L0, L1, L2, L3, L4, L5, L6, L7,
+		 I0, I1, I2, I3, I4, I5, FP, I7,
+
+		 F0, F1, F2, F3, F4, F5, F6, F7,
+		 F8, F9, F10, F11, F12, F13, F14, F15,
+		 F16, F17, F18, F19, F20, F21, F22, F23,
+		 F24, F25, F26, F27, F28, F29, F30, F31,
+		 Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR };
+
+
+extern void trap_low(void);  /* In arch/sparc/kernel/entry.S */
+
+unsigned long get_sun4cpte(unsigned long addr)
+{
+	unsigned long entry;
+
+	__asm__ __volatile__("\n\tlda [%1] %2, %0\n\t" : 
+			     "=r" (entry) :
+			     "r" (addr), "i" (ASI_PTE));
+	return entry;
+}
+
+unsigned long get_sun4csegmap(unsigned long addr)
+{
+	unsigned long entry;
+
+	__asm__ __volatile__("\n\tlduba [%1] %2, %0\n\t" : 
+			     "=r" (entry) :
+			     "r" (addr), "i" (ASI_SEGMAP));
+	return entry;
+}
+
+/* Place where we save old trap entries for restoration */
+struct tt_entry kgdb_savettable[256];
+typedef void (*trapfunc_t)(void);
+
+/* Helper routine for manipulation of kgdb_savettable */
+static inline void copy_ttentry(struct tt_entry *src, struct tt_entry *dest)
+{
+	dest->inst_one = src->inst_one;
+	dest->inst_two = src->inst_two;
+	dest->inst_three = src->inst_three;
+	dest->inst_four = src->inst_four;
+}
+
+/* Initialize the kgdb_savettable so that debugging can commence */
+static void eh_init(void)
+{
+	int i, flags;
+
+	save_flags(flags); cli();
+	for(i=0; i < 256; i++)
+		copy_ttentry(&sparc_ttable[i], &kgdb_savettable[i]);
+	restore_flags(flags);
+}
+
+/* Install an exception handler for kgdb */
+static void exceptionHandler(int tnum, trapfunc_t trap_entry)
+{
+	unsigned long te_addr = (unsigned long) trap_entry;
+	int flags;
+
+	/* We are dorking with a live trap table, all irqs off */
+	save_flags(flags); cli();
+
+	/* Make new vector */
+	sparc_ttable[tnum].inst_one =
+		SPARC_BRANCH((unsigned long) te_addr,
+			     (unsigned long) &sparc_ttable[tnum].inst_one);
+	sparc_ttable[tnum].inst_two = SPARC_RD_PSR_L0;
+	sparc_ttable[tnum].inst_three = SPARC_NOP;
+	sparc_ttable[tnum].inst_four = SPARC_NOP;
+
+	restore_flags(flags);
+}
+
+/* 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 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(unsigned char *buffer)
+{
+	unsigned char checksum;
+	int count;
+	unsigned char ch, recv;
+
+	/*  $<packet info>#<checksum>. */
+	do {
+		putDebugChar('$');
+		checksum = 0;
+		count = 0;
+
+		while ((ch = buffer[count])) {
+			putDebugChar(ch);
+			checksum += ch;
+			count += 1;
+		}
+
+		putDebugChar('#');
+		putDebugChar(hexchars[checksum >> 4]);
+		putDebugChar(hexchars[checksum & 0xf]);
+		recv = getDebugChar();
+	} while ((recv & 0x7f) != '+');
+}
+
+static char remcomInBuffer[BUFMAX];
+static char remcomOutBuffer[BUFMAX];
+
+/* 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.
+ */
+
+static unsigned char *
+mem2hex(char *mem, char *buf, int count)
+{
+	unsigned char ch;
+
+	while (count-- > 0) {
+		ch = *mem++;
+		*buf++ = hexchars[ch >> 4];
+		*buf++ = hexchars[ch & 0xf];
+	}
+
+	*buf = 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 i;
+	unsigned char ch;
+
+	for (i=0; i<count; i++) {
+
+		ch = hex(*buf++) << 4;
+		ch |= hex(*buf++);
+		*mem++ = ch;
+	}
+	return mem;
+}
+
+/* This table contains the mapping between SPARC hardware trap types, and
+   signals, which are primarily what GDB understands.  It also indicates
+   which hardware traps we need to commandeer when initializing the stub. */
+
+static struct hard_trap_info
+{
+  unsigned char tt;		/* Trap type code for SPARC */
+  unsigned char signo;		/* Signal that we map this trap into */
+} hard_trap_info[] = {
+  {SP_TRAP_SBPT, SIGTRAP},      /* ta 1 - Linux/KGDB software breakpoint */
+  {0, 0}			/* Must be last */
+};
+
+/* Set up exception handlers for tracing and breakpoints */
+
+void
+set_debug_traps(void)
+{
+	struct hard_trap_info *ht;
+	unsigned char c;
+
+	/* Initialize our copy of the Linux Sparc trap table */
+	eh_init();
+
+	for (ht = hard_trap_info; ht->tt && ht->signo; ht++) {
+		/* Only if it doesn't destroy our fault handlers */
+		if((ht->tt != SP_TRAP_TFLT) && 
+		   (ht->tt != SP_TRAP_DFLT))
+			exceptionHandler(ht->tt, trap_low);
+	}
+
+	/* 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 */
+
+	initialized = 1; /* connect! */
+}
+
+/* Convert the SPARC hardware trap type code to a unix signal number. */
+
+static int
+computeSignal(int tt)
+{
+	struct hard_trap_info *ht;
+
+	for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
+		if (ht->tt == tt)
+			return ht->signo;
+
+	return SIGHUP;         /* default for things we don't know about */
+}
+
+/*
+ * 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);
+}
+
+/*
+ * This function does all command procesing for interfacing to gdb.  It
+ * returns 1 if you should skip the instruction at the trap address, 0
+ * otherwise.
+ */
+
+extern void breakinst(void);
+
+void
+handle_exception (unsigned long *registers)
+{
+	int tt;       /* Trap type */
+	int sigval;
+	int addr;
+	int length;
+	char *ptr;
+	unsigned long *sp;
+
+	/* First, we must force all of the windows to be spilled out */
+
+	asm("save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "save %sp, -64, %sp\n\t"
+	    "restore\n\t"
+	    "restore\n\t"
+	    "restore\n\t"
+	    "restore\n\t"
+	    "restore\n\t"
+	    "restore\n\t"
+	    "restore\n\t"
+	    "restore\n\t");
+
+	if (registers[PC] == (unsigned long)breakinst) {
+		/* Skip over breakpoint trap insn */
+		registers[PC] = registers[NPC];
+		registers[NPC] += 4;
+	}
+
+	sp = (unsigned long *)registers[SP];
+
+	tt = (registers[TBR] >> 4) & 0xff;
+
+	/* reply to host that an exception has occurred */
+	sigval = computeSignal(tt);
+	ptr = remcomOutBuffer;
+
+	*ptr++ = 'T';
+	*ptr++ = hexchars[sigval >> 4];
+	*ptr++ = hexchars[sigval & 0xf];
+
+	*ptr++ = hexchars[PC >> 4];
+	*ptr++ = hexchars[PC & 0xf];
+	*ptr++ = ':';
+	ptr = mem2hex((char *)&registers[PC], ptr, 4);
+	*ptr++ = ';';
+
+	*ptr++ = hexchars[FP >> 4];
+	*ptr++ = hexchars[FP & 0xf];
+	*ptr++ = ':';
+	ptr = mem2hex((char *) (sp + 8 + 6), ptr, 4); /* FP */
+	*ptr++ = ';';
+
+	*ptr++ = hexchars[SP >> 4];
+	*ptr++ = hexchars[SP & 0xf];
+	*ptr++ = ':';
+	ptr = mem2hex((char *)&sp, ptr, 4);
+	*ptr++ = ';';
+
+	*ptr++ = hexchars[NPC >> 4];
+	*ptr++ = hexchars[NPC & 0xf];
+	*ptr++ = ':';
+	ptr = mem2hex((char *)&registers[NPC], ptr, 4);
+	*ptr++ = ';';
+
+	*ptr++ = hexchars[O7 >> 4];
+	*ptr++ = hexchars[O7 & 0xf];
+	*ptr++ = ':';
+	ptr = mem2hex((char *)&registers[O7], ptr, 4);
+	*ptr++ = ';';
+
+	*ptr++ = 0;
+
+	putpacket(remcomOutBuffer);
+
+	/* XXX We may want to add some features dealing with poking the
+	 * XXX page tables, the real ones on the srmmu, and what is currently
+	 * XXX loaded in the sun4/sun4c tlb at this point in time.  But this
+	 * XXX also required hacking to the gdb sources directly...
+	 */
+
+	while (1) {
+		remcomOutBuffer[0] = 0;
+
+		getpacket(remcomInBuffer);
+		switch (remcomInBuffer[0]) {
+		case '?':
+			remcomOutBuffer[0] = 'S';
+			remcomOutBuffer[1] = hexchars[sigval >> 4];
+			remcomOutBuffer[2] = hexchars[sigval & 0xf];
+			remcomOutBuffer[3] = 0;
+			break;
+
+		case 'd':
+			/* toggle debug flag */
+			break;
+
+		case 'g':		/* return the value of the CPU registers */
+		{
+			ptr = remcomOutBuffer;
+			/* G & O regs */
+			ptr = mem2hex((char *)registers, ptr, 16 * 4);
+			/* L & I regs */
+			ptr = mem2hex((char *) (sp + 0), ptr, 16 * 4);
+			/* Floating point */
+			memset(ptr, '0', 32 * 8);
+			/* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */
+			mem2hex((char *)&registers[Y], (ptr + 32 * 4 * 2), (8 * 4));
+		}
+			break;
+
+		case 'G':	   /* set the value of the CPU registers - return OK */
+		{
+			unsigned long *newsp, psr;
+
+			psr = registers[PSR];
+
+			ptr = &remcomInBuffer[1];
+			/* G & O regs */
+			hex2mem(ptr, (char *)registers, 16 * 4);
+			/* L & I regs */
+			hex2mem(ptr + 16 * 4 * 2, (char *) (sp + 0), 16 * 4);
+			/* Y, PSR, WIM, TBR, PC, NPC, FPSR, CPSR */
+			hex2mem(ptr + 64 * 4 * 2, (char *)&registers[Y], 8 * 4);
+
+			/* See if the stack pointer has moved.  If so,
+			 * then copy the saved locals and ins to the
+			 * new location.  This keeps the window
+			 * overflow and underflow routines happy.
+			 */
+
+			newsp = (unsigned long *)registers[SP];
+			if (sp != newsp)
+				sp = memcpy(newsp, sp, 16 * 4);
+
+			/* Don't allow CWP to be modified. */
+
+			if (psr != registers[PSR])
+				registers[PSR] = (psr & 0x1f) | (registers[PSR] & ~0x1f);
+
+			strcpy(remcomOutBuffer,"OK");
+		}
+			break;
+
+		case 'm':	  /* mAA..AA,LLLL  Read LLLL bytes at address AA..AA */
+			/* Try to read %x,%x.  */
+
+			ptr = &remcomInBuffer[1];
+
+			if (hexToInt(&ptr, &addr)
+			    && *ptr++ == ','
+			    && hexToInt(&ptr, &length))	{
+				if (mem2hex((char *)addr, remcomOutBuffer, length))
+					break;
+
+				strcpy (remcomOutBuffer, "E03");
+			} else {
+				strcpy(remcomOutBuffer,"E01");
+			}
+			break;
+
+		case 'M': /* MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK */
+			/* Try to read '%x,%x:'.  */
+
+			ptr = &remcomInBuffer[1];
+
+			if (hexToInt(&ptr, &addr)
+			    && *ptr++ == ','
+			    && hexToInt(&ptr, &length)
+			    && *ptr++ == ':') {
+				if (hex2mem(ptr, (char *)addr, length)) {
+					strcpy(remcomOutBuffer, "OK");
+				} else {
+					strcpy(remcomOutBuffer, "E03");
+				}
+			} else {
+				strcpy(remcomOutBuffer, "E02");
+			}
+			break;
+
+		case 'c':    /* cAA..AA    Continue at address AA..AA(optional) */
+			/* try to read optional parameter, pc unchanged if no parm */
+
+			ptr = &remcomInBuffer[1];
+			if (hexToInt(&ptr, &addr)) {
+				registers[PC] = addr;
+				registers[NPC] = addr + 4;
+			}
+
+/* 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.
+ */
+
+			/* Only instruction cache flushing on the sun4c/sun4
+			 * for now.  We assume control flow during the kgdb
+			 * transaction has not left the context in which it
+			 * was entered.
+			 */
+			if((sparc_cpu_model==sun4 || sparc_cpu_model==sun4c) &&
+			   (sun4c_vacinfo.num_bytes && sun4c_vacinfo.on))
+				sun4c_flush_context();
+			/* XXX SRMMU and on-chip v8 instruction cache
+			 * XXX flushing goes here!
+			 */
+
+			return;
+
+			/* kill the program */
+		case 'k' :		/* do nothing */
+			break;
+		case 'r':		/* Reset */
+			asm ("call 0\n\t"
+			     "nop\n\t");
+			break;
+		}			/* switch */
+
+		/* reply to the request */
+		putpacket(remcomOutBuffer);
+	} /* while(1) */
+}
+
+/* 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 (!initialized)
+		return;
+
+	/* Again, watch those c-prefixes for solaris/elf kernels */
+#ifndef __svr4__
+	asm("	.globl _breakinst
+
+	     _breakinst: ta 1
+            ");
+#else
+	asm("	.globl breakinst
+
+	     breakinst: ta 1
+            ");
+#endif
+}