kgdb.c

优龙2410linux2.6.8内核源代码

/*!**************************************************************************
*!
*! FILE NAME  : kgdb.c
*!
*! DESCRIPTION: Implementation of the gdb stub with respect to ETRAX 100.
*!              It is a mix of arch/m68k/kernel/kgdb.c and cris_stub.c.
*!
*!---------------------------------------------------------------------------
*! HISTORY
*!
*! DATE         NAME            CHANGES
*! ----         ----            -------
*! Apr 26 1999  Hendrik Ruijter Initial version.
*! May  6 1999  Hendrik Ruijter Removed call to strlen in libc and removed
*!                              struct assignment as it generates calls to
*!                              memcpy in libc.
*! Jun 17 1999  Hendrik Ruijter Added gdb 4.18 support. 'X', 'qC' and 'qL'.
*! Jul 21 1999  Bjorn Wesen     eLinux port
*!
*! $Log: kgdb.c,v $
*! Revision 1.4  2003/04/09 05:20:44  starvik
*! Merge of Linux 2.5.67
*!
*! Revision 1.3  2003/01/21 19:11:08  starvik
*! Modified include path for new dir layout
*!
*! Revision 1.2  2002/11/19 14:35:24  starvik
*! Changes from linux 2.4
*! Changed struct initializer syntax to the currently prefered notation
*!
*! Revision 1.1  2001/12/17 13:59:27  bjornw
*! Initial revision
*!
*! Revision 1.6  2001/10/09 13:10:03  matsfg
*! Added $ on registers and removed some underscores
*!
*! Revision 1.5  2001/04/17 13:58:39  orjanf
*! * Renamed CONFIG_KGDB to CONFIG_ETRAX_KGDB.
*!
*! Revision 1.4  2001/02/23 13:45:19  bjornw
*! config.h check
*!
*! Revision 1.3  2001/01/31 18:08:23  orjanf
*! Removed kgdb_handle_breakpoint from being the break 8 handler.
*!
*! Revision 1.2  2001/01/12 14:22:25  orjanf
*! Updated kernel debugging support to work with ETRAX 100LX.
*!
*! Revision 1.1  2000/07/10 16:25:21  bjornw
*! Initial revision
*!
*! Revision 1.1.1.1  1999/12/03 14:57:31  bjornw
*! * Initial version of arch/cris, the latest CRIS architecture with an MMU.
*!   Mostly copied from arch/etrax100 with appropriate renames of files.
*!   The mm/ subdir is copied from arch/i386.
*!   This does not compile yet at all.
*!
*!
*! Revision 1.4  1999/07/22 17:25:25  bjornw
*! Dont wait for + in putpacket if we havent hit the initial breakpoint yet. Added a kgdb_init function which sets up the break and irq vectors.
*!
*! Revision 1.3  1999/07/21 19:51:18  bjornw
*! Check if the interrupting char is a ctrl-C, ignore otherwise.
*!
*! Revision 1.2  1999/07/21 18:09:39  bjornw
*! Ported to eLinux architecture, and added some kgdb documentation.
*!
*!
*!---------------------------------------------------------------------------
*!
*! $Id: kgdb.c,v 1.4 2003/04/09 05:20:44 starvik Exp $
*!
*! (C) Copyright 1999, Axis Communications AB, LUND, SWEDEN
*!
*!**************************************************************************/
/* @(#) cris_stub.c 1.3 06/17/99 */

/*
 *  kgdb usage notes:
 *  -----------------
 *
 * If you select CONFIG_ETRAX_KGDB in the configuration, the kernel will be 
 * built with different gcc flags: "-g" is added to get debug infos, and
 * "-fomit-frame-pointer" is omitted to make debugging easier. Since the
 * resulting kernel will be quite big (approx. > 7 MB), it will be stripped
 * before compresion. Such a kernel will behave just as usually, except if
 * given a "debug=<device>" command line option. (Only serial devices are
 * allowed for <device>, i.e. no printers or the like; possible values are
 * machine depedend and are the same as for the usual debug device, the one
 * for logging kernel messages.) If that option is given and the device can be
 * initialized, the kernel will connect to the remote gdb in trap_init(). The
 * serial parameters are fixed to 8N1 and 115200 bps, for easyness of
 * implementation.
 *
 * To start a debugging session, start that gdb with the debugging kernel
 * image (the one with the symbols, vmlinux.debug) named on the command line.
 * This file will be used by gdb to get symbol and debugging infos about the
 * kernel. Next, select remote debug mode by
 *    target remote <device>
 * where <device> is the name of the serial device over which the debugged
 * machine is connected. Maybe you have to adjust the baud rate by
 *    set remotebaud <rate>
 * or also other parameters with stty:
 *    shell stty ... </dev/...
 * If the kernel to debug has already booted, it waited for gdb and now
 * connects, and you'll see a breakpoint being reported. If the kernel isn't
 * running yet, start it now. The order of gdb and the kernel doesn't matter.
 * Another thing worth knowing about in the getting-started phase is how to
 * debug the remote protocol itself. This is activated with
 *    set remotedebug 1
 * gdb will then print out each packet sent or received. You'll also get some
 * messages about the gdb stub on the console of the debugged machine.
 *
 * If all that works, you can use lots of the usual debugging techniques on
 * the kernel, e.g. inspecting and changing variables/memory, setting
 * breakpoints, single stepping and so on. It's also possible to interrupt the
 * debugged kernel by pressing C-c in gdb. Have fun! :-)
 *
 * The gdb stub is entered (and thus the remote gdb gets control) in the
 * following situations:
 *
 *  - If breakpoint() is called. This is just after kgdb initialization, or if
 *    a breakpoint() call has been put somewhere into the kernel source.
 *    (Breakpoints can of course also be set the usual way in gdb.)
 *    In eLinux, we call breakpoint() in init/main.c after IRQ initialization.
 *
 *  - If there is a kernel exception, i.e. bad_super_trap() or die_if_kernel()
 *    are entered. All the CPU exceptions are mapped to (more or less..., see
 *    the hard_trap_info array below) appropriate signal, which are reported
 *    to gdb. die_if_kernel() is usually called after some kind of access
 *    error and thus is reported as SIGSEGV.
 *
 *  - When panic() is called. This is reported as SIGABRT.
 *
 *  - If C-c is received over the serial line, which is treated as
 *    SIGINT.
 *
 * Of course, all these signals are just faked for gdb, since there is no
 * signal concept as such for the kernel. It also isn't possible --obviously--
 * to set signal handlers from inside gdb, or restart the kernel with a
 * signal.
 *
 * Current limitations:
 *
 *  - While the kernel is stopped, interrupts are disabled for safety reasons
 *    (i.e., variables not changing magically or the like). But this also
 *    means that the clock isn't running anymore, and that interrupts from the
 *    hardware may get lost/not be served in time. This can cause some device
 *    errors...
 *
 *  - When single-stepping, only one instruction of the current thread is
 *    executed, but interrupts are allowed for that time and will be serviced
 *    if pending. Be prepared for that.
 *
 *  - All debugging happens in kernel virtual address space. There's no way to
 *    access physical memory not mapped in kernel space, or to access user
 *    space. A way to work around this is using get_user_long & Co. in gdb
 *    expressions, but only for the current process.
 *
 *  - Interrupting the kernel only works if interrupts are currently allowed,
 *    and the interrupt of the serial line isn't blocked by some other means
 *    (IPL too high, disabled, ...)
 *
 *  - The gdb stub is currently not reentrant, i.e. errors that happen therein
 *    (e.g. accessing invalid memory) may not be caught correctly. This could
 *    be removed in future by introducing a stack of struct registers.
 *
 */

/*
 *  To enable debugger support, two things need to happen.  One, a
 *  call to kgdb_init() 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(). 
 *
 *    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/string.h>
#include <linux/signal.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/linkage.h>

#include <asm/setup.h>
#include <asm/ptrace.h>

#include <asm/arch/svinto.h>
#include <asm/irq.h>

static int kgdb_started = 0;

/********************************* Register image ****************************/
/* Use the order of registers as defined in "AXIS ETRAX CRIS Programmer's
   Reference", p. 1-1, with the additional register definitions of the
   ETRAX 100LX in cris-opc.h.
   There are 16 general 32-bit registers, R0-R15, where R14 is the stack
   pointer, SP, and R15 is the program counter, PC.
   There are 16 special registers, P0-P15, where three of the unimplemented
   registers, P0, P4 and P8, are reserved as zero-registers. A read from
   any of these registers returns zero and a write has no effect. */

typedef
struct register_image
{
	/* Offset */
	unsigned int     r0;   /* 0x00 */
	unsigned int     r1;   /* 0x04 */
	unsigned int     r2;   /* 0x08 */
	unsigned int     r3;   /* 0x0C */
	unsigned int     r4;   /* 0x10 */
	unsigned int     r5;   /* 0x14 */
	unsigned int     r6;   /* 0x18 */
	unsigned int     r7;   /* 0x1C */
	unsigned int     r8;   /* 0x20 Frame pointer */
	unsigned int     r9;   /* 0x24 */
	unsigned int    r10;   /* 0x28 */
	unsigned int    r11;   /* 0x2C */
	unsigned int    r12;   /* 0x30 */
	unsigned int    r13;   /* 0x34 */
	unsigned int     sp;   /* 0x38 Stack pointer */
	unsigned int     pc;   /* 0x3C Program counter */

        unsigned char    p0;   /* 0x40 8-bit zero-register */
	unsigned char    vr;   /* 0x41 Version register */

        unsigned short   p4;   /* 0x42 16-bit zero-register */
	unsigned short  ccr;   /* 0x44 Condition code register */
	
	unsigned int    mof;   /* 0x46 Multiply overflow register */
	
        unsigned int     p8;   /* 0x4A 32-bit zero-register */
	unsigned int    ibr;   /* 0x4E Interrupt base register */
	unsigned int    irp;   /* 0x52 Interrupt return pointer */
	unsigned int    srp;   /* 0x56 Subroutine return pointer */
	unsigned int    bar;   /* 0x5A Breakpoint address register */
	unsigned int   dccr;   /* 0x5E Double condition code register */
	unsigned int    brp;   /* 0x62 Breakpoint return pointer (pc in caller) */
	unsigned int    usp;   /* 0x66 User mode stack pointer */
} registers;

/************** Prototypes for local library functions ***********************/

/* Copy of strcpy from libc. */
static char *gdb_cris_strcpy (char *s1, const char *s2);

/* Copy of strlen from libc. */
static int gdb_cris_strlen (const char *s);

/* Copy of memchr from libc. */
static void *gdb_cris_memchr (const void *s, int c, int n);

/* Copy of strtol from libc. Does only support base 16. */
static int gdb_cris_strtol (const char *s, char **endptr, int base);

/********************** Prototypes for local functions. **********************/
/* Copy the content of a register image into another. The size n is
   the size of the register image. Due to struct assignment generation of
   memcpy in libc. */
static void copy_registers (registers *dptr, registers *sptr, int n);

/* Copy the stored registers from the stack. Put the register contents
   of thread thread_id in the struct reg. */
static void copy_registers_from_stack (int thread_id, registers *reg);

/* Copy the registers to the stack. Put the register contents of thread
   thread_id from struct reg to the stack. */
static void copy_registers_to_stack (int thread_id, registers *reg);

/* Write a value to a specified register regno in the register image
   of the current thread. */
static int write_register (int regno, char *val);

/* Write a value to a specified register in the stack of a thread other
   than the current thread. */
static write_stack_register (int thread_id, int regno, char *valptr);

/* Read a value from a specified register in the register image. Returns the
   status of the read operation. The register value is returned in valptr. */
static int read_register (char regno, unsigned int *valptr);

/* Serial port, reads one character. ETRAX 100 specific. from debugport.c */
int getDebugChar (void);

/* Serial port, writes one character. ETRAX 100 specific. from debugport.c */
void putDebugChar (int val);

void enableDebugIRQ (void);

/* Returns the character equivalent of a nibble, bit 7, 6, 5, and 4 of a byte,
   represented by int x. */
static char highhex (int x);

/* Returns the character equivalent of a nibble, bit 3, 2, 1, and 0 of a byte,
   represented by int x. */
static char lowhex (int x);

/* Returns the integer equivalent of a hexadecimal character. */
static int hex (char ch);

/* Convert the memory, pointed to by mem into hexadecimal representation.
   Put the result in buf, and return a pointer to the last character
   in buf (null). */
static char *mem2hex (char *buf, unsigned char *mem, int count);

/* Convert the array, in hexadecimal representation, pointed to by buf into
   binary representation. Put the result in mem, and return a pointer to
   the character after the last byte written. */
static unsigned char *hex2mem (unsigned char *mem, char *buf, int count);

/* Put the content of the array, in binary representation, pointed to by buf
   into memory pointed to by mem, and return a pointer to
   the character after the last byte written. */
static unsigned char *bin2mem (unsigned char *mem, unsigned char *buf, int count);

/* Await the sequence $<data>#<checksum> and store <data> in the array buffer
   returned. */
static void getpacket (char *buffer);

/* Send $<data>#<checksum> from the <data> in the array buffer. */
static void putpacket (char *buffer);

/* Build and send a response packet in order to inform the host the
   stub is stopped. */
static void stub_is_stopped (int sigval);

/* All expected commands are sent from remote.c. Send a response according
   to the description in remote.c. */
static void handle_exception (int sigval);

/* Performs a complete re-start from scratch. ETRAX specific. */
static void kill_restart (void);

/******************** Prototypes for global functions. ***********************/

/* The string str is prepended with the GDB printout token and sent. */
void putDebugString (const unsigned char *str, int length); /* used by etrax100ser.c */

/* The hook for both static (compiled) and dynamic breakpoints set by GDB.
   ETRAX 100 specific. */
void handle_breakpoint (void);                          /* used by irq.c */

/* The hook for an interrupt generated by GDB. ETRAX 100 specific. */
void handle_interrupt (void);                           /* used by irq.c */

/* A static breakpoint to be used at startup. */
void breakpoint (void);                                 /* called by init/main.c */

/* From osys_int.c, executing_task contains the number of the current
   executing task in osys. Does not know of object-oriented threads. */
extern unsigned char executing_task;