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 <asm/uaccess.h>
  15 #include <asm/apic.h>
  16 #include "mach_reboot.h"
  17 #include <linux/reboot_fixups.h>
  18
  19 /*
  20  * Power off function, if any
  21  */
  22 void (*pm_power_off)(void);
  23 EXPORT_SYMBOL(pm_power_off);
  24
  25 static int reboot_mode;
  26 static int reboot_thru_bios;
  27
  28 #ifdef CONFIG_SMP
  29 static int reboot_cpu = -1;
  30 /* shamelessly grabbed from lib/vsprintf.c for readability */
  31 #define is_digit(c)     ((c) >= '0' && (c) <= '9')
  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 (is_digit(*(str+1))) {
  52                                 reboot_cpu = (int) (*(str+1) - '0');
  53                                 if (is_digit(*(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         { }
 115 };
 116
 117 static int __init reboot_init(void)
 118 {
 119         dmi_check_system(reboot_dmi_table);
 120         return 0;
 121 }
 122
 123 core_initcall(reboot_init);
 124
 125 /* The following code and data reboots the machine by switching to real
 126    mode and jumping to the BIOS reset entry point, as if the CPU has
 127    really been reset.  The previous version asked the keyboard
 128    controller to pulse the CPU reset line, which is more thorough, but
 129    doesn't work with at least one type of 486 motherboard.  It is easy
 130    to stop this code working; hence the copious comments. */
 131
 132 static unsigned long long
 133 real_mode_gdt_entries [3] =
 134 {
 135         0x0000000000000000ULL,  /* Null descriptor */
 136         0x00009a000000ffffULL,  /* 16-bit real-mode 64k code at 0x00000000 */
 137         0x000092000100ffffULL   /* 16-bit real-mode 64k data at 0x00000100 */
 138 };
 139
 140 static struct
 141 {
 142         unsigned short       size __attribute__ ((packed));
 143         unsigned long long * base __attribute__ ((packed));
 144 }
 145 real_mode_gdt = { sizeof (real_mode_gdt_entries) - 1, real_mode_gdt_entries },
 146 real_mode_idt = { 0x3ff, NULL },
 147 no_idt = { 0, NULL };
 148
 149
 150 /* This is 16-bit protected mode code to disable paging and the cache,
 151    switch to real mode and jump to the BIOS reset code.
 152
 153    The instruction that switches to real mode by writing to CR0 must be
 154    followed immediately by a far jump instruction, which set CS to a
 155    valid value for real mode, and flushes the prefetch queue to avoid
 156    running instructions that have already been decoded in protected
 157    mode.
 158
 159    Clears all the flags except ET, especially PG (paging), PE
 160    (protected-mode enable) and TS (task switch for coprocessor state
 161    save).  Flushes the TLB after paging has been disabled.  Sets CD and
 162    NW, to disable the cache on a 486, and invalidates the cache.  This
 163    is more like the state of a 486 after reset.  I don't know if
 164    something else should be done for other chips.
 165
 166    More could be done here to set up the registers as if a CPU reset had
 167    occurred; hopefully real BIOSs don't assume much. */
 168
 169 static unsigned char real_mode_switch [] =
 170 {
 171         0x66, 0x0f, 0x20, 0xc0,                 /*    movl  %cr0,%eax        */
 172         0x66, 0x83, 0xe0, 0x11,                 /*    andl  $0x00000011,%eax */
 173         0x66, 0x0d, 0x00, 0x00, 0x00, 0x60,     /*    orl   $0x60000000,%eax */
 174         0x66, 0x0f, 0x22, 0xc0,                 /*    movl  %eax,%cr0        */
 175         0x66, 0x0f, 0x22, 0xd8,                 /*    movl  %eax,%cr3        */
 176         0x66, 0x0f, 0x20, 0xc3,                 /*    movl  %cr0,%ebx        */
 177         0x66, 0x81, 0xe3, 0x00, 0x00, 0x00, 0x60,       /*    andl  $0x60000000,%ebx */
 178         0x74, 0x02,                             /*    jz    f                */
 179         0x0f, 0x09,                             /*    wbinvd                 */
 180         0x24, 0x10,                             /* f: andb  $0x10,al         */
 181         0x66, 0x0f, 0x22, 0xc0                  /*    movl  %eax,%cr0        */
 182 };
 183 static unsigned char jump_to_bios [] =
 184 {
 185         0xea, 0x00, 0x00, 0xff, 0xff            /*    ljmp  $0xffff,$0x0000  */
 186 };
 187
 188 /*
 189  * Switch to real mode and then execute the code
 190  * specified by the code and length parameters.
 191  * We assume that length will aways be less that 100!
 192  */
 193 void machine_real_restart(unsigned char *code, int length)
 194 {
 195         unsigned long flags;
 196
 197         local_irq_disable();
 198
 199         /* Write zero to CMOS register number 0x0f, which the BIOS POST
 200            routine will recognize as telling it to do a proper reboot.  (Well
 201            that's what this book in front of me says -- it may only apply to
 202            the Phoenix BIOS though, it's not clear).  At the same time,
 203            disable NMIs by setting the top bit in the CMOS address register,
 204            as we're about to do peculiar things to the CPU.  I'm not sure if
 205            `outb_p' is needed instead of just `outb'.  Use it to be on the
 206            safe side.  (Yes, CMOS_WRITE does outb_p's. -  Paul G.)
 207          */
 208
 209         spin_lock_irqsave(&rtc_lock, flags);
 210         CMOS_WRITE(0x00, 0x8f);
 211         spin_unlock_irqrestore(&rtc_lock, flags);
 212
 213         /* Remap the kernel at virtual address zero, as well as offset zero
 214            from the kernel segment.  This assumes the kernel segment starts at
 215            virtual address PAGE_OFFSET. */
 216
 217         memcpy (swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,
 218                 sizeof (swapper_pg_dir [0]) * KERNEL_PGD_PTRS);
 219
 220         /*
 221          * Use `swapper_pg_dir' as our page directory.
 222          */
 223         load_cr3(swapper_pg_dir);
 224
 225         /* Write 0x1234 to absolute memory location 0x472.  The BIOS reads
 226            this on booting to tell it to "Bypass memory test (also warm
 227            boot)".  This seems like a fairly standard thing that gets set by
 228            REBOOT.COM programs, and the previous reset routine did this
 229            too. */
 230
 231         *((unsigned short *)0x472) = reboot_mode;
 232
 233         /* For the switch to real mode, copy some code to low memory.  It has
 234            to be in the first 64k because it is running in 16-bit mode, and it
 235            has to have the same physical and virtual address, because it turns
 236            off paging.  Copy it near the end of the first page, out of the way
 237            of BIOS variables. */
 238
 239         memcpy ((void *) (0x1000 - sizeof (real_mode_switch) - 100),
 240                 real_mode_switch, sizeof (real_mode_switch));
 241         memcpy ((void *) (0x1000 - 100), code, length);
 242
 243         /* Set up the IDT for real mode. */
 244
 245         __asm__ __volatile__ ("lidt %0" : : "m" (real_mode_idt));
 246
 247         /* Set up a GDT from which we can load segment descriptors for real
 248            mode.  The GDT is not used in real mode; it is just needed here to
 249            prepare the descriptors. */
 250
 251         __asm__ __volatile__ ("lgdt %0" : : "m" (real_mode_gdt));
 252
 253         /* Load the data segment registers, and thus the descriptors ready for
 254            real mode.  The base address of each segment is 0x100, 16 times the
 255            selector value being loaded here.  This is so that the segment
 256            registers don't have to be reloaded after switching to real mode:
 257            the values are consistent for real mode operation already. */
 258
 259         __asm__ __volatile__ ("movl $0x0010,%%eax\n"
 260                                 "\tmovl %%eax,%%ds\n"
 261                                 "\tmovl %%eax,%%es\n"
 262                                 "\tmovl %%eax,%%fs\n"
 263                                 "\tmovl %%eax,%%gs\n"
 264                                 "\tmovl %%eax,%%ss" : : : "eax");
 265
 266         /* Jump to the 16-bit code that we copied earlier.  It disables paging
 267            and the cache, switches to real mode, and jumps to the BIOS reset
 268            entry point. */
 269
 270         __asm__ __volatile__ ("ljmp $0x0008,%0"
 271                                 :
 272                                 : "i" ((void *) (0x1000 - sizeof (real_mode_switch) - 100)));
 273 }
 274 #ifdef CONFIG_APM_MODULE
 275 EXPORT_SYMBOL(machine_real_restart);
 276 #endif
 277
 278 void machine_shutdown(void)
 279 {
 280 #ifdef CONFIG_SMP
 281         int reboot_cpu_id;
 282
 283         /* The boot cpu is always logical cpu 0 */
 284         reboot_cpu_id = 0;
 285
 286         /* See if there has been given a command line override */
 287         if ((reboot_cpu != -1) && (reboot_cpu < NR_CPUS) &&
 288                 cpu_isset(reboot_cpu, cpu_online_map)) {
 289                 reboot_cpu_id = reboot_cpu;
 290         }
 291
 292         /* Make certain the cpu I'm rebooting on is online */
 293         if (!cpu_isset(reboot_cpu_id, cpu_online_map)) {
 294                 reboot_cpu_id = smp_processor_id();
 295         }
 296
 297         /* Make certain I only run on the appropriate processor */
 298         set_cpus_allowed(current, cpumask_of_cpu(reboot_cpu_id));
 299
 300         /* O.K. Now that I'm on the appropriate processor, stop
 301          * all of the others, and disable their local APICs.
 302          */
 303
 304         smp_send_stop();
 305 #endif /* CONFIG_SMP */
 306
 307         lapic_shutdown();
 308
 309 #ifdef CONFIG_X86_IO_APIC
 310         disable_IO_APIC();
 311 #endif
 312 }
 313
 314 void machine_emergency_restart(void)
 315 {
 316         if (!reboot_thru_bios) {
 317                 if (efi_enabled) {
 318                         efi.reset_system(EFI_RESET_COLD, EFI_SUCCESS, 0, NULL);
 319                         __asm__ __volatile__("lidt %0": :"m" (no_idt));
 320                         __asm__ __volatile__("int3");
 321                 }
 322                 /* rebooting needs to touch the page at absolute addr 0 */
 323                 *((unsigned short *)__va(0x472)) = reboot_mode;
 324                 for (;;) {
 325                         mach_reboot_fixups(); /* for board specific fixups */
 326                         mach_reboot();
 327                         /* That didn't work - force a triple fault.. */
 328                         __asm__ __volatile__("lidt %0": :"m" (no_idt));
 329                         __asm__ __volatile__("int3");
 330                 }
 331         }
 332         if (efi_enabled)
 333                 efi.reset_system(EFI_RESET_WARM, EFI_SUCCESS, 0, NULL);
 334
 335         machine_real_restart(jump_to_bios, sizeof(jump_to_bios));
 336 }
 337
 338 void machine_restart(char * __unused)
 339 {
 340         machine_shutdown();
 341         machine_emergency_restart();
 342 }
 343
 344 void machine_halt(void)
 345 {
 346 }
 347
 348 void machine_power_off(void)
 349 {
 350         lapic_shutdown();
 351
 352         if (efi_enabled)
 353                 efi.reset_system(EFI_RESET_SHUTDOWN, EFI_SUCCESS, 0, NULL);
 354         if (pm_power_off)
 355                 pm_power_off();
 356 }
 357
 358