arch/i386/kernel/reboot.c

   1 /*
   2  *  linux/arch/i386/kernel/reboot.c
   3  */
   4
   5 #include <linux/config.h>
   6 #include <linux/mm.h>
   7 #include <linux/module.h>
   8 #include <linux/delay.h>
   9 #include <linux/init.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/mc146818rtc.h>
  12 #include <linux/efi.h>
  13 #include <linux/dmi.h>
  14 #include <linux/ctype.h>
  15 #include <asm/uaccess.h>
  16 #include <asm/apic.h>
  17 #include <asm/desc.h>
  18 #include "mach_reboot.h"
  19 #include <linux/reboot_fixups.h>
  20
  21 /*
  22  * Power off function, if any
  23  */
  24 void (*pm_power_off)(void);
  25 EXPORT_SYMBOL(pm_power_off);
  26
  27 static int reboot_mode;
  28 static int reboot_thru_bios;
  29
  30 #ifdef CONFIG_SMP
  31 static int reboot_cpu = -1;
  32 #endif
  33 static int __init reboot_setup(char *str)
  34 {
  35         while(1) {
  36                 switch (*str) {
  37                 case 'w': /* "warm" reboot (no memory testing etc) */
  38                         reboot_mode = 0x1234;
  39                         break;
  40                 case 'c': /* "cold" reboot (with memory testing etc) */
  41                         reboot_mode = 0x0;
  42                         break;
  43                 case 'b': /* "bios" reboot by jumping through the BIOS */
  44                         reboot_thru_bios = 1;
  45                         break;
  46                 case 'h': /* "hard" reboot by toggling RESET and/or crashing the CPU */
  47                         reboot_thru_bios = 0;
  48                         break;
  49 #ifdef CONFIG_SMP
  50                 case 's': /* "smp" reboot by executing reset on BSP or other CPU*/
  51                         if (isdigit(*(str+1))) {
  52                                 reboot_cpu = (int) (*(str+1) - '0');
  53                                 if (isdigit(*(str+2)))
  54                                         reboot_cpu = reboot_cpu*10 + (int)(*(str+2) - '0');
  55                         }
  56                                 /* we will leave sorting out the final value
  57                                 when we are ready to reboot, since we might not
  58                                 have set up boot_cpu_id or smp_num_cpu */
  59                         break;
  60 #endif
  61                 }
  62                 if((str = strchr(str,',')) != NULL)
  63                         str++;
  64                 else
  65                         break;
  66         }
  67         return 1;
  68 }
  69
  70 __setup("reboot=", reboot_setup);
  71
  72 /*
  73  * Reboot options and system auto-detection code provided by
  74  * Dell Inc. so their systems "just work". :-)
  75  */
  76
  77 /*
  78  * Some machines require the "reboot=b"  commandline option, this quirk makes that automatic.
  79  */
  80 static int __init set_bios_reboot(struct dmi_system_id *d)
  81 {
  82         if (!reboot_thru_bios) {
  83                 reboot_thru_bios = 1;
  84                 printk(KERN_INFO "%s series board detected. Selecting BIOS-method for reboots.\n", d->ident);
  85         }
  86         return 0;
  87 }
  88
  89 static struct dmi_system_id __initdata reboot_dmi_table[] = {
  90         {       /* Handle problems with rebooting on Dell 1300's */
  91                 .callback = set_bios_reboot,
  92                 .ident = "Dell PowerEdge 1300",
  93                 .matches = {
  94                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
  95                         DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 1300/"),
  96                 },
  97         },
  98         {       /* Handle problems with rebooting on Dell 300's */
  99                 .callback = set_bios_reboot,
 100                 .ident = "Dell PowerEdge 300",
 101                 .matches = {
 102                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
 103                         DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 300/"),
 104                 },
 105         },
 106         {       /* Handle problems with rebooting on Dell 2400's */
 107                 .callback = set_bios_reboot,
 108                 .ident = "Dell PowerEdge 2400",
 109                 .matches = {
 110                         DMI_MATCH(DMI_SYS_VENDOR, "Dell Computer Corporation"),
 111                         DMI_MATCH(DMI_PRODUCT_NAME, "PowerEdge 2400"),
 112                 },
 113         },
 114         {       /* Handle problems with rebooting on HP laptops */
 115                 .callback = set_bios_reboot,
 116                 .ident = "HP Compaq Laptop",
 117                 .matches = {
 118                         DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 119                         DMI_MATCH(DMI_PRODUCT_NAME, "HP Compaq"),
 120                 },
 121         },
 122         { }
 123 };
 124
 125 static int __init reboot_init(void)
 126 {
 127         dmi_check_system(reboot_dmi_table);
 128         return 0;
 129 }
 130
 131 core_initcall(reboot_init);
 132
 133 /* The following code and data reboots the machine by switching to real
 134    mode and jumping to the BIOS reset entry point, as if the CPU has
 135    really been reset.  The previous version asked the keyboard
 136    controller to pulse the CPU reset line, which is more thorough, but
 137    doesn't work with at least one type of 486 motherboard.  It is easy
 138    to stop this code working; hence the copious comments. */
 139
 140 static unsigned long long
 141 real_mode_gdt_entries [3] =
 142 {
 143         0x0000000000000000ULL,  /* Null descriptor */
 144         0x00009a000000ffffULL,  /* 16-bit real-mode 64k code at 0x00000000 */
 145         0x000092000100ffffULL   /* 16-bit real-mode 64k data at 0x00000100 */
 146 };
 147
 148 static struct
 149 {
 150         unsigned short       size __attribute__ ((packed));
 151         unsigned long long * base __attribute__ ((packed));
 152 }
 153 real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, real_mode_gdt_entries },
 154 real_mode_idt = { 0x3ff, NULL },
 155 no_idt = { 0, NULL };
 156
 157
 158 /* This is 16-bit protected mode code to disable paging and the cache,
 159    switch to real mode and jump to the BIOS reset code.
 160
 161    The instruction that switches to real mode by writing to CR0 must be
 162    followed immediately by a far jump instruction, which set CS to a
 163    valid value for real mode, and flushes the prefetch queue to avoid
 164    running instructions that have already been decoded in protected
 165    mode.
 166
 167    Clears all the flags except ET, especially PG (paging), PE
 168    (protected-mode enable) and TS (task switch for coprocessor state
 169    save).  Flushes the TLB after paging has been disabled.  Sets CD and
 170    NW, to disable the cache on a 486, and invalidates the cache.  This
 171    is more like the state of a 486 after reset.  I don't know if
 172    something else should be done for other chips.
 173
 174    More could be done here to set up the registers as if a CPU reset had
 175    occurred; hopefully real BIOSs don't assume much. */
 176
 177 static unsigned char real_mode_switch [] =
 178 {
 179         0x66, 0x0f, 0x20, 0xc0,                 /*    movl  %cr0,%eax        */
 180         0x66, 0x83, 0xe0, 0x11,                 /*    andl  $0x00000011,%eax */
 181         0x66, 0x0d, 0x00, 0x00, 0x00, 0x60,     /*    orl   $0x60000000,%eax */
 182         0x66, 0x0f, 0x22, 0xc0,                 /*    movl  %eax,%cr0        */
 183         0x66, 0x0f, 0x22, 0xd8,                 /*    movl  %eax,%cr3        */
 184         0x66, 0x0f, 0x20, 0xc3,                 /*    movl  %cr0,%ebx        */
 185         0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60,       /*    andl  $0x60000000,%ebx */
 186         0x74, 0x02,                             /*    jz    f                */
 187         0x0f, 0x09,                             /*    wbinvd                 */
 188         0x24, 0x10,                             /* f: andb  $0x10,al         */
 189         0x66, 0x0f, 0x22, 0xc0                  /*    movl  %eax,%cr0        */
 190 };
 191 static unsigned char jump_to_bios [] =
 192 {
 193         0xea, 0x00, 0x00, 0xff, 0xff            /*    ljmp  $0xffff,$0x0000  */
 194 };
 195
 196 /*
 197  * Switch to real mode and then execute the code
 198  * specified by the code and length parameters.
 199  * We assume that length will aways be less that 100!
 200  */
 201 void machine_real_restart(unsigned char *code, int length)
 202 {
 203         unsigned long flags;
 204
 205         local_irq_disable();
 206
 207         /* Write zero to CMOS register number 0x0f, which the BIOS POST
 208            routine will recognize as telling it to do a proper reboot.  (Well
 209            that's what this book in front of me says -- it may only apply to
 210            the Phoenix BIOS though, it's not clear).  At the same time,
 211            disable NMIs by setting the top bit in the CMOS address register,
 212            as we're about to do peculiar things to the CPU.  I'm not sure if
 213            `outb_p' is needed instead of just `outb'.  Use it to be on the
 214            safe side.  (Yes, CMOS_WRITE does outb_p's. -  Paul G.)
 215          */
 216
 217         spin_lock_irqsave(&rtc_lock, flags);
 218         CMOS_WRITE(0x00, 0x8f);
 219         spin_unlock_irqrestore(&rtc_lock, flags);
 220
 221         /* Remap the kernel at virtual address zero, as well as offset zero
 222            from the kernel segment.  This assumes the kernel segment starts at
 223            virtual address PAGE_OFFSET. */
 224
 225         memcpy (swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,
 226                 sizeof (swapper_pg_dir [0]) * KERNEL_PGD_PTRS);
 227
 228         /*
 229          * Use `swapper_pg_dir' as our page directory.
 230          */
 231         load_cr3(swapper_pg_dir);
 232
 233         /* Write 0x1234 to absolute memory location 0x472.  The BIOS reads
 234            this on booting to tell it to "Bypass memory test (also warm
 235            boot)".  This seems like a fairly standard thing that gets set by
 236            REBOOT.COM programs, and the previous reset routine did this
 237            too. */
 238
 239         *((unsigned short *)0x472) = reboot_mode;
 240
 241         /* For the switch to real mode, copy some code to low memory.  It has
 242            to be in the first 64k because it is running in 16-bit mode, and it
 243            has to have the same physical and virtual address, because it turns
 244            off paging.  Copy it near the end of the first page, out of the way
 245            of BIOS variables. */
 246
 247         memcpy ((void *) (0x1000 - sizeof (real_mode_switch) - 100),
 248                 real_mode_switch, sizeof (real_mode_switch));
 249         memcpy ((void *) (0x1000 - 100), code, length);
 250
 251         /* Set up the IDT for real mode. */
 252
 253         load_idt(&real_mode_idt);
 254
 255         /* Set up a GDT from which we can load segment descriptors for real
 256            mode.  The GDT is not used in real mode; it is just needed here to
 257            prepare the descriptors. */
 258
 259         load_gdt(&real_mode_gdt);
 260
 261         /* Load the data segment registers, and thus the descriptors ready for
 262            real mode.  The base address of each segment is 0x100, 16 times the
 263            selector value being loaded here.  This is so that the segment
 264            registers don't have to be reloaded after switching to real mode:
 265            the values are consistent for real mode operation already. */
 266
 267         __asm__ __volatile__ ("movl $0x0010,%%eax\n"
 268                                 "\tmovl %%eax,%%ds\n"
 269                                 "\tmovl %%eax,%%es\n"
 270                                 "\tmovl %%eax,%%fs\n"
 271                                 "\tmovl %%eax,%%gs\n"
 272                                 "\tmovl %%eax,%%ss" : : : "eax");
 273
 274         /* Jump to the 16-bit code that we copied earlier.  It disables paging
 275            and the cache, switches to real mode, and jumps to the BIOS reset
 276            entry point. */
 277
 278         __asm__ __volatile__ ("ljmp $0x0008,%0"
 279                                 :
 280                                 : "i" ((void *) (0x1000 - sizeof (real_mode_switch) - 100)));
 281 }
 282 #ifdef CONFIG_APM_MODULE
 283 EXPORT_SYMBOL(machine_real_restart);
 284 #endif
 285
 286 void machine_shutdown(void)
 287 {
 288 #ifdef CONFIG_SMP
 289         int reboot_cpu_id;
 290
 291         /* The boot cpu is always logical cpu 0 */
 292         reboot_cpu_id = 0;
 293
 294         /* See if there has been given a command line override */
 295         if ((reboot_cpu != -1) && (reboot_cpu < NR_CPUS) &&
 296                 cpu_isset(reboot_cpu, cpu_online_map)) {
 297                 reboot_cpu_id = reboot_cpu;
 298         }
 299
 300         /* Make certain the cpu I'm rebooting on is online */
 301         if (!cpu_isset(reboot_cpu_id, cpu_online_map)) {
 302                 reboot_cpu_id = smp_processor_id();
 303         }
 304
 305         /* Make certain I only run on the appropriate processor */
 306         set_cpus_allowed(current, cpumask_of_cpu(reboot_cpu_id));
 307
 308         /* O.K. Now that I'm on the appropriate processor, stop
 309          * all of the others, and disable their local APICs.
 310          */
 311
 312         smp_send_stop();
 313 #endif /* CONFIG_SMP */
 314
 315         lapic_shutdown();
 316
 317 #ifdef CONFIG_X86_IO_APIC
 318         disable_IO_APIC();
 319 #endif
 320 }
 321
 322 void machine_emergency_restart(void)
 323 {
 324         if (!reboot_thru_bios) {
 325                 if (efi_enabled) {
 326                         efi.reset_system(EFI_RESET_COLD, EFI_SUCCESS, 0, NULL);
 327                         load_idt(&no_idt);
 328                         __asm__ __volatile__("int3");
 329                 }
 330                 /* rebooting needs to touch the page at absolute addr 0 */
 331                 *((unsigned short *)__va(0x472)) = reboot_mode;
 332                 for (;;) {
 333                         mach_reboot_fixups(); /* for board specific fixups */
 334                         mach_reboot();
 335                         /* That didn't work - force a triple fault.. */
 336                         load_idt(&no_idt);
 337                         __asm__ __volatile__("int3");
 338                 }
 339         }
 340         if (efi_enabled)
 341                 efi.reset_system(EFI_RESET_WARM, EFI_SUCCESS, 0, NULL);
 342
 343         machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
 344 }
 345
 346 void machine_restart(char * __unused)
 347 {
 348         machine_shutdown();
 349         machine_emergency_restart();
 350 }
 351
 352 void machine_halt(void)
 353 {
 354 }
 355
 356 void machine_power_off(void)
 357 {
 358         machine_shutdown();
 359
 360         if (pm_power_off)
 361                 pm_power_off();
 362 }
 363
 364