linux/arch/um/os-Linux/main.c
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   1/*
   2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3 * Licensed under the GPL
   4 */
   5
   6#include <stdio.h>
   7#include <stdlib.h>
   8#include <unistd.h>
   9#include <errno.h>
  10#include <signal.h>
  11#include <string.h>
  12#include <sys/resource.h>
  13#include "as-layout.h"
  14#include "init.h"
  15#include "kern_util.h"
  16#include "os.h"
  17#include "um_malloc.h"
  18
  19#define PGD_BOUND (4 * 1024 * 1024)
  20#define STACKSIZE (8 * 1024 * 1024)
  21#define THREAD_NAME_LEN (256)
  22
  23long elf_aux_hwcap;
  24
  25static void set_stklim(void)
  26{
  27        struct rlimit lim;
  28
  29        if (getrlimit(RLIMIT_STACK, &lim) < 0) {
  30                perror("getrlimit");
  31                exit(1);
  32        }
  33        if ((lim.rlim_cur == RLIM_INFINITY) || (lim.rlim_cur > STACKSIZE)) {
  34                lim.rlim_cur = STACKSIZE;
  35                if (setrlimit(RLIMIT_STACK, &lim) < 0) {
  36                        perror("setrlimit");
  37                        exit(1);
  38                }
  39        }
  40}
  41
  42static __init void do_uml_initcalls(void)
  43{
  44        initcall_t *call;
  45
  46        call = &__uml_initcall_start;
  47        while (call < &__uml_initcall_end) {
  48                (*call)();
  49                call++;
  50        }
  51}
  52
  53static void last_ditch_exit(int sig)
  54{
  55        uml_cleanup();
  56        exit(1);
  57}
  58
  59static void install_fatal_handler(int sig)
  60{
  61        struct sigaction action;
  62
  63        /* All signals are enabled in this handler ... */
  64        sigemptyset(&action.sa_mask);
  65
  66        /*
  67         * ... including the signal being handled, plus we want the
  68         * handler reset to the default behavior, so that if an exit
  69         * handler is hanging for some reason, the UML will just die
  70         * after this signal is sent a second time.
  71         */
  72        action.sa_flags = SA_RESETHAND | SA_NODEFER;
  73        action.sa_restorer = NULL;
  74        action.sa_handler = last_ditch_exit;
  75        if (sigaction(sig, &action, NULL) < 0) {
  76                printf("failed to install handler for signal %d - errno = %d\n",
  77                       sig, errno);
  78                exit(1);
  79        }
  80}
  81
  82#define UML_LIB_PATH    ":" OS_LIB_PATH "/uml"
  83
  84static void setup_env_path(void)
  85{
  86        char *new_path = NULL;
  87        char *old_path = NULL;
  88        int path_len = 0;
  89
  90        old_path = getenv("PATH");
  91        /*
  92         * if no PATH variable is set or it has an empty value
  93         * just use the default + /usr/lib/uml
  94         */
  95        if (!old_path || (path_len = strlen(old_path)) == 0) {
  96                if (putenv("PATH=:/bin:/usr/bin/" UML_LIB_PATH))
  97                        perror("couldn't putenv");
  98                return;
  99        }
 100
 101        /* append /usr/lib/uml to the existing path */
 102        path_len += strlen("PATH=" UML_LIB_PATH) + 1;
 103        new_path = malloc(path_len);
 104        if (!new_path) {
 105                perror("couldn't malloc to set a new PATH");
 106                return;
 107        }
 108        snprintf(new_path, path_len, "PATH=%s" UML_LIB_PATH, old_path);
 109        if (putenv(new_path)) {
 110                perror("couldn't putenv to set a new PATH");
 111                free(new_path);
 112        }
 113}
 114
 115extern void scan_elf_aux( char **envp);
 116
 117int __init main(int argc, char **argv, char **envp)
 118{
 119        char **new_argv;
 120        int ret, i, err;
 121
 122        set_stklim();
 123
 124        setup_env_path();
 125
 126        new_argv = malloc((argc + 1) * sizeof(char *));
 127        if (new_argv == NULL) {
 128                perror("Mallocing argv");
 129                exit(1);
 130        }
 131        for (i = 0; i < argc; i++) {
 132                new_argv[i] = strdup(argv[i]);
 133                if (new_argv[i] == NULL) {
 134                        perror("Mallocing an arg");
 135                        exit(1);
 136                }
 137        }
 138        new_argv[argc] = NULL;
 139
 140        /*
 141         * Allow these signals to bring down a UML if all other
 142         * methods of control fail.
 143         */
 144        install_fatal_handler(SIGINT);
 145        install_fatal_handler(SIGTERM);
 146
 147#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 148        scan_elf_aux(envp);
 149#endif
 150
 151        do_uml_initcalls();
 152        ret = linux_main(argc, argv);
 153
 154        /*
 155         * Disable SIGPROF - I have no idea why libc doesn't do this or turn
 156         * off the profiling time, but UML dies with a SIGPROF just before
 157         * exiting when profiling is active.
 158         */
 159        change_sig(SIGPROF, 0);
 160
 161        /*
 162         * This signal stuff used to be in the reboot case.  However,
 163         * sometimes a SIGVTALRM can come in when we're halting (reproducably
 164         * when writing out gcov information, presumably because that takes
 165         * some time) and cause a segfault.
 166         */
 167
 168        /* stop timers and set SIGVTALRM to be ignored */
 169        disable_timer();
 170
 171        /* disable SIGIO for the fds and set SIGIO to be ignored */
 172        err = deactivate_all_fds();
 173        if (err)
 174                printf("deactivate_all_fds failed, errno = %d\n", -err);
 175
 176        /*
 177         * Let any pending signals fire now.  This ensures
 178         * that they won't be delivered after the exec, when
 179         * they are definitely not expected.
 180         */
 181        unblock_signals();
 182
 183        /* Reboot */
 184        if (ret) {
 185                printf("\n");
 186                execvp(new_argv[0], new_argv);
 187                perror("Failed to exec kernel");
 188                ret = 1;
 189        }
 190        printf("\n");
 191        return uml_exitcode;
 192}
 193
 194extern void *__real_malloc(int);
 195
 196void *__wrap_malloc(int size)
 197{
 198        void *ret;
 199
 200        if (!kmalloc_ok)
 201                return __real_malloc(size);
 202        else if (size <= UM_KERN_PAGE_SIZE)
 203                /* finding contiguous pages can be hard*/
 204                ret = uml_kmalloc(size, UM_GFP_KERNEL);
 205        else ret = vmalloc(size);
 206
 207        /*
 208         * glibc people insist that if malloc fails, errno should be
 209         * set by malloc as well. So we do.
 210         */
 211        if (ret == NULL)
 212                errno = ENOMEM;
 213
 214        return ret;
 215}
 216
 217void *__wrap_calloc(int n, int size)
 218{
 219        void *ptr = __wrap_malloc(n * size);
 220
 221        if (ptr == NULL)
 222                return NULL;
 223        memset(ptr, 0, n * size);
 224        return ptr;
 225}
 226
 227extern void __real_free(void *);
 228
 229extern unsigned long high_physmem;
 230
 231void __wrap_free(void *ptr)
 232{
 233        unsigned long addr = (unsigned long) ptr;
 234
 235        /*
 236         * We need to know how the allocation happened, so it can be correctly
 237         * freed.  This is done by seeing what region of memory the pointer is
 238         * in -
 239         *      physical memory - kmalloc/kfree
 240         *      kernel virtual memory - vmalloc/vfree
 241         *      anywhere else - malloc/free
 242         * If kmalloc is not yet possible, then either high_physmem and/or
 243         * end_vm are still 0 (as at startup), in which case we call free, or
 244         * we have set them, but anyway addr has not been allocated from those
 245         * areas. So, in both cases __real_free is called.
 246         *
 247         * CAN_KMALLOC is checked because it would be bad to free a buffer
 248         * with kmalloc/vmalloc after they have been turned off during
 249         * shutdown.
 250         * XXX: However, we sometimes shutdown CAN_KMALLOC temporarily, so
 251         * there is a possibility for memory leaks.
 252         */
 253
 254        if ((addr >= uml_physmem) && (addr < high_physmem)) {
 255                if (kmalloc_ok)
 256                        kfree(ptr);
 257        }
 258        else if ((addr >= start_vm) && (addr < end_vm)) {
 259                if (kmalloc_ok)
 260                        vfree(ptr);
 261        }
 262        else __real_free(ptr);
 263}
 264
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