user.h

Go to the documentation of this file.

/* user.h: FR-V core file format stuff
 *
 * Copyright (C) 2003 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells ([email protected])
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#ifndef _ASM_USER_H
#define _ASM_USER_H

#include <asm/page.h>
#include <asm/registers.h>

/* Core file format: The core file is written in such a way that gdb
 * can understand it and provide useful information to the user (under
 * linux we use the 'trad-core' bfd).  There are quite a number of
 * obstacles to being able to view the contents of the floating point
 * registers, and until these are solved you will not be able to view
 * the contents of them.  Actually, you can read in the core file and
 * look at the contents of the user struct to find out what the
 * floating point registers contain.
 *
 * The actual file contents are as follows:
 * UPAGE:
 *   1 page consisting of a user struct that tells gdb what is present
 *   in the file.  Directly after this is a copy of the task_struct,
 *   which is currently not used by gdb, but it may come in useful at
 *   some point.  All of the registers are stored as part of the
 *   upage.  The upage should always be only one page.
 *
 * DATA:
 *   The data area is stored.  We use current->end_text to
 *   current->brk to pick up all of the user variables, plus any
 *   memory that may have been malloced.  No attempt is made to
 *   determine if a page is demand-zero or if a page is totally
 *   unused, we just cover the entire range.  All of the addresses are
 *   rounded in such a way that an integral number of pages is
 *   written.
 *
 * STACK:
 *   We need the stack information in order to get a meaningful
 *   backtrace.  We need to write the data from (esp) to
 *   current->start_stack, so we round each of these off in order to
 *   be able to write an integer number of pages.  The minimum core
 *   file size is 3 pages, or 12288 bytes.
 */

/* When the kernel dumps core, it starts by dumping the user struct -
 * this will be used by gdb to figure out where the data and stack segments
 *  are within the file, and what virtual addresses to use.
 */
struct user {
    /* We start with the registers, to mimic the way that "memory" is returned
     * from the ptrace(3,...) function.  */
    struct user_context regs;

    /* The rest of this junk is to help gdb figure out what goes where */
    unsigned long       u_tsize;    /* Text segment size (pages). */
    unsigned long       u_dsize;    /* Data segment size (pages). */
    unsigned long       u_ssize;    /* Stack segment size (pages). */
    unsigned long       start_code;     /* Starting virtual address of text. */
    unsigned long       start_stack;    /* Starting virtual address of stack area.
                         * This is actually the bottom of the stack,
                         * the top of the stack is always found in the
                         * esp register.  */
    long int        signal;     /* Signal that caused the core dump. */

    unsigned long       magic;      /* To uniquely identify a core file */
    char            u_comm[32]; /* User command that was responsible */
};

#define NBPG            PAGE_SIZE
#define UPAGES          1
#define HOST_TEXT_START_ADDR    (u.start_code)
#define HOST_STACK_END_ADDR (u.start_stack + u.u_ssize * NBPG)

#endif