crash.c

/*
 * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
 *      The President and Fellows of Harvard College.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * crash.c
 *
 *      Commit a variety of exceptions, primarily address faults.
 *
 * Once the basic system calls assignment is complete, none of these
 * should crash the kernel.
 *
 * They should all, however, terminate this program, except for the
 * one that writes to the code segment. (That one won't cause program
 * termination until/unless you implement read-only segments in your
 * VM system.)
 */

#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include <err.h>

#if defined(__mips__)
#define KERNEL_ADDR     0x80000000
#define INVAL_ADDR      0x40000000
#define INSN_TYPE       uint32_t
#define INVAL_INSN      0x0000003f
#else
#error "Please fix this"
#endif

typedef void (*func)(void);

static
void
read_from_null(void)
{
        int *null = NULL;
        volatile int x;
        x = *null;
}

static
void
read_from_inval(void)
{
        int *ptr = (int *) INVAL_ADDR;
        volatile int x;
        x = *ptr;
}

static
void
read_from_kernel(void)
{
        int *ptr = (int *) KERNEL_ADDR;
        volatile int x;
        x = *ptr;
}

static
void
write_to_null(void)
{
        int *null = NULL;
        *null = 6;
}

static
void
write_to_inval(void)
{
        int *ptr = (int *) INVAL_ADDR;
        *ptr = 8;
}

static
void
write_to_code(void)
{
        INSN_TYPE *x = (INSN_TYPE *)write_to_code;
        *x = INVAL_INSN;
}

static
void
write_to_kernel(void)
{
        int *ptr = (int *) KERNEL_ADDR;
        *ptr = 8;
}

static
void
jump_to_null(void)
{
        func f = NULL;
        f();
}

static
void
jump_to_inval(void)
{
        func f = (func) INVAL_ADDR;
        f();
}

static
void
jump_to_kernel(void)
{
        func f = (func) KERNEL_ADDR;
        f();
}


static
void
illegal_instruction(void)
{
#if defined(__mips__)
        asm(".long 0x0000003f");
#else
#error "Please fix this"
#endif
}

static
void
alignment_error(void)
{
        int x;
        int *ptr = &x;
        int *badptr = (int *)(((char *)ptr)+1);

        volatile int j;
        j = *badptr;
}

static
void
divide_by_zero(void)
{
        volatile int x = 6;
        volatile int z = 0;
        volatile int a;

        a = x/z;
}

static
void
mod_by_zero(void)
{
        volatile int x = 6;
        volatile int z = 0;
        volatile int a;

        a = x%z;
}

static
void
recurse_inf(void)
{
        volatile char buf[16];
        buf[0] = 0;
        recurse_inf();
        buf[0] = 1;
}


static
struct {
        int ch;
        const char *name;
        func f;
} ops[] = {
        { 'a', "read from NULL",                read_from_null },
        { 'b', "read from invalid address",     read_from_inval },
        { 'c', "read from kernel address",      read_from_kernel },
        { 'd', "write to NULL",                 write_to_null },
        { 'e', "write to invalid address",      write_to_inval },
        { 'f', "write to code segment",         write_to_code },
        { 'g', "write to kernel address",       write_to_kernel },
        { 'h', "jump to NULL",                  jump_to_null },
        { 'i', "jump to invalid address",       jump_to_inval },
        { 'j', "jump to kernel address",        jump_to_kernel },
        { 'k', "alignment error",               alignment_error },
        { 'l', "illegal instruction",           illegal_instruction },
        { 'm', "divide by zero",                divide_by_zero },
        { 'n', "mod by zero",                   mod_by_zero },
        { 'o', "Recurse infinitely",            recurse_inf },
        { 0, NULL, NULL }
};

int
main(int argc, char **argv)
{
        int op, i, status;
        pid_t pid;

        if (argc == 2) {
                op = argv[1][0];
        }
        else {
                for (i=0; ops[i].name; i++) {
                        printf("[%c] %s\n", ops[i].ch, ops[i].name);
                }
                printf("[*] Run everything (in subprocesses)\n");
                printf("Note: [f] may not cause an exception on some "
                       "platforms, in which\ncase it'll appear to fail.\n");

                printf("Choose: ");
                op = getchar();
        }

        if (op=='*') {
                for (i=0; ops[i].name; i++) {
                        printf("Running: [%c] %s\n", ops[i].ch, ops[i].name);
                        pid = fork();
                        if (pid<0) {
                                /* error */
                                warn("fork");
                        }
                        else if (pid==0) {
                                /* child */
                                ops[i].f();
                                printf("I wasn't killed - test fails!\n");
                                _exit(1);
                        }
                        waitpid(pid, &status, 0);
                        if (WIFSIGNALED(status)) {
                                printf("Signal %d\n", WTERMSIG(status));
                        }
                        else {
                                printf("Exit %d\n", WEXITSTATUS(status));
                        }
                }
        }
        else {
                /* intentionally don't check if op is in bounds :) */
                ops[op-'a'].f();

                printf("I wasn't killed - test fails!\n");
        }
  
        return 0;
}