arch/x86_64/kernel/reboot.c

   1 /* Various gunk just to reboot the machine. */
   2 #include <linux/module.h>
   3 #include <linux/reboot.h>
   4 #include <linux/init.h>
   5 #include <linux/smp.h>
   6 #include <linux/kernel.h>
   7 #include <linux/ctype.h>
   8 #include <linux/string.h>
   9 #include <asm/io.h>
  10 #include <asm/kdebug.h>
  11 #include <asm/delay.h>
  12 #include <asm/hw_irq.h>
  13 #include <asm/system.h>
  14 #include <asm/pgtable.h>
  15 #include <asm/tlbflush.h>
  16 #include <asm/apic.h>
  17
  18 /*
  19  * Power off function, if any
  20  */
  21 void (*pm_power_off)(void);
  22
  23 static long no_idt[3];
  24 static enum {
  25         BOOT_BIOS = 'b',
  26         BOOT_TRIPLE = 't',
  27         BOOT_KBD = 'k'
  28 } reboot_type = BOOT_KBD;
  29 static int reboot_mode = 0;
  30
  31 /* reboot=b[ios] | t[riple] | k[bd] [, [w]arm | [c]old]
  32    bios   Use the CPU reboot vector for warm reset
  33    warm   Don't set the cold reboot flag
  34    cold   Set the cold reboot flag
  35    triple Force a triple fault (init)
  36    kbd    Use the keyboard controller. cold reset (default)
  37  */
  38 static int __init reboot_setup(char *str)
  39 {
  40         for (;;) {
  41                 switch (*str) {
  42                 case 'w':
  43                         reboot_mode = 0x1234;
  44                         break;
  45
  46                 case 'c':
  47                         reboot_mode = 0;
  48                         break;
  49
  50                 case 't':
  51                 case 'b':
  52                 case 'k':
  53                         reboot_type = *str;
  54                         break;
  55                 }
  56                 if((str = strchr(str,',')) != NULL)
  57                         str++;
  58                 else
  59                         break;
  60         }
  61         return 1;
  62 }
  63
  64 __setup("reboot=", reboot_setup);
  65
  66 /* overwrites random kernel memory. Should not be kernel .text */
  67 #define WARMBOOT_TRAMP 0x1000UL
  68
  69 static void reboot_warm(void)
  70 {
  71         extern unsigned char warm_reboot[], warm_reboot_end[];
  72         printk("warm reboot\n");
  73
  74         local_irq_disable();
  75
  76         /* restore identity mapping */
  77         init_level4_pgt[0] = __pml4(__pa(level3_ident_pgt) | 7);
  78         __flush_tlb_all();
  79
  80         /* Move the trampoline to low memory */
  81         memcpy(__va(WARMBOOT_TRAMP), warm_reboot, warm_reboot_end - warm_reboot);
  82
  83         /* Start it in compatibility mode. */
  84         asm volatile( "   pushq $0\n"           /* ss */
  85                      "   pushq $0x2000\n"       /* rsp */
  86                      "   pushfq\n"              /* eflags */
  87                      "   pushq %[cs]\n"
  88                      "   pushq %[target]\n"
  89                      "   iretq" ::
  90                       [cs] "i" (__KERNEL_COMPAT32_CS),
  91                       [target] "b" (WARMBOOT_TRAMP));
  92 }
  93
  94 #ifdef CONFIG_SMP
  95 static void smp_halt(void)
  96 {
  97         int cpuid = safe_smp_processor_id();
  98                 static int first_entry = 1;
  99
 100                 if (first_entry) {
 101                         first_entry = 0;
 102                         smp_call_function((void *)machine_restart, NULL, 1, 0);
 103                 }
 104
 105         smp_stop_cpu();
 106
 107         /* AP calling this. Just halt */
 108         if (cpuid != boot_cpu_id) {
 109                 for (;;)
 110                         asm("hlt");
 111         }
 112
 113         /* Wait for all other CPUs to have run smp_stop_cpu */
 114         while (!cpus_empty(cpu_online_map))
 115                 rep_nop();
 116 }
 117 #endif
 118
 119 static inline void kb_wait(void)
 120 {
 121         int i;
 122
 123         for (i=0; i<0x10000; i++)
 124                 if ((inb_p(0x64) & 0x02) == 0)
 125                         break;
 126 }
 127
 128 void machine_restart(char * __unused)
 129 {
 130         int i;
 131
 132 #ifdef CONFIG_SMP
 133         smp_halt();
 134 #endif
 135
 136         local_irq_disable();
 137
 138 #ifndef CONFIG_SMP
 139         disable_local_APIC();
 140 #endif
 141
 142         disable_IO_APIC();
 143
 144         local_irq_enable();
 145
 146         /* Tell the BIOS if we want cold or warm reboot */
 147         *((unsigned short *)__va(0x472)) = reboot_mode;
 148
 149         for (;;) {
 150                 /* Could also try the reset bit in the Hammer NB */
 151                 switch (reboot_type) {
 152                 case BOOT_BIOS:
 153                         reboot_warm();
 154
 155                 case BOOT_KBD:
 156                 for (i=0; i<100; i++) {
 157                         kb_wait();
 158                         udelay(50);
 159                         outb(0xfe,0x64);         /* pulse reset low */
 160                         udelay(50);
 161                 }
 162
 163                 case BOOT_TRIPLE:
 164                 __asm__ __volatile__("lidt (%0)": :"r" (&no_idt));
 165                 __asm__ __volatile__("int3");
 166
 167                         reboot_type = BOOT_KBD;
 168                         break;
 169                 }
 170         }
 171 }
 172
 173 EXPORT_SYMBOL(machine_restart);
 174
 175 void machine_halt(void)
 176 {
 177 }
 178
 179 EXPORT_SYMBOL(machine_halt);
 180
 181 void machine_power_off(void)
 182 {
 183         if (pm_power_off)
 184                 pm_power_off();
 185 }
 186
 187 EXPORT_SYMBOL(machine_power_off);