include/asm-i386/system.h

   1 #ifndef __ASM_SYSTEM_H
   2 #define __ASM_SYSTEM_H
   3
   4 #include <linux/kernel.h>
   5 #include <asm/segment.h>
   6 #include <asm/cpufeature.h>
   7 #include <asm/cmpxchg.h>
   8
   9 #ifdef __KERNEL__
  10
  11 struct task_struct;     /* one of the stranger aspects of C forward declarations.. */
  12 extern struct task_struct * FASTCALL(__switch_to(struct task_struct *prev, struct task_struct *next));
  13
  14 /*
  15  * Saving eflags is important. It switches not only IOPL between tasks,
  16  * it also protects other tasks from NT leaking through sysenter etc.
  17  */
  18 #define switch_to(prev,next,last) do {                                  \
  19         unsigned long esi,edi;                                          \
  20         asm volatile("pushfl\n\t"               /* Save flags */        \
  21                      "pushl %%ebp\n\t"                                  \
  22                      "movl %%esp,%0\n\t"        /* save ESP */          \
  23                      "movl %5,%%esp\n\t"        /* restore ESP */       \
  24                      "movl $1f,%1\n\t"          /* save EIP */          \
  25                      "pushl %6\n\t"             /* restore EIP */       \
  26                      "jmp __switch_to\n"                                \
  27                      "1:\t"                                             \
  28                      "popl %%ebp\n\t"                                   \
  29                      "popfl"                                            \
  30                      :"=m" (prev->thread.esp),"=m" (prev->thread.eip),  \
  31                       "=a" (last),"=S" (esi),"=D" (edi)                 \
  32                      :"m" (next->thread.esp),"m" (next->thread.eip),    \
  33                       "2" (prev), "d" (next));                          \
  34 } while (0)
  35
  36 #define _set_base(addr,base) do { unsigned long __pr; \
  37 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
  38         "rorl $16,%%edx\n\t" \
  39         "movb %%dl,%2\n\t" \
  40         "movb %%dh,%3" \
  41         :"=&d" (__pr) \
  42         :"m" (*((addr)+2)), \
  43          "m" (*((addr)+4)), \
  44          "m" (*((addr)+7)), \
  45          "0" (base) \
  46         ); } while(0)
  47
  48 #define _set_limit(addr,limit) do { unsigned long __lr; \
  49 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
  50         "rorl $16,%%edx\n\t" \
  51         "movb %2,%%dh\n\t" \
  52         "andb $0xf0,%%dh\n\t" \
  53         "orb %%dh,%%dl\n\t" \
  54         "movb %%dl,%2" \
  55         :"=&d" (__lr) \
  56         :"m" (*(addr)), \
  57          "m" (*((addr)+6)), \
  58          "0" (limit) \
  59         ); } while(0)
  60
  61 #define set_base(ldt,base) _set_base( ((char *)&(ldt)) , (base) )
  62 #define set_limit(ldt,limit) _set_limit( ((char *)&(ldt)) , ((limit)-1) )
  63
  64 /*
  65  * Load a segment. Fall back on loading the zero
  66  * segment if something goes wrong..
  67  */
  68 #define loadsegment(seg,value)                  \
  69         asm volatile("\n"                       \
  70                 "1:\t"                          \
  71                 "mov %0,%%" #seg "\n"           \
  72                 "2:\n"                          \
  73                 ".section .fixup,\"ax\"\n"      \
  74                 "3:\t"                          \
  75                 "pushl $0\n\t"                  \
  76                 "popl %%" #seg "\n\t"           \
  77                 "jmp 2b\n"                      \
  78                 ".previous\n"                   \
  79                 ".section __ex_table,\"a\"\n\t" \
  80                 ".align 4\n\t"                  \
  81                 ".long 1b,3b\n"                 \
  82                 ".previous"                     \
  83                 : :"rm" (value))
  84
  85 /*
  86  * Save a segment register away
  87  */
  88 #define savesegment(seg, value) \
  89         asm volatile("mov %%" #seg ",%0":"=rm" (value))
  90
  91
  92 static inline void native_clts(void)
  93 {
  94         asm volatile ("clts");
  95 }
  96
  97 static inline unsigned long native_read_cr0(void)
  98 {
  99         unsigned long val;
 100         asm volatile("movl %%cr0,%0\n\t" :"=r" (val));
 101         return val;
 102 }
 103
 104 static inline void native_write_cr0(unsigned long val)
 105 {
 106         asm volatile("movl %0,%%cr0": :"r" (val));
 107 }
 108
 109 static inline unsigned long native_read_cr2(void)
 110 {
 111         unsigned long val;
 112         asm volatile("movl %%cr2,%0\n\t" :"=r" (val));
 113         return val;
 114 }
 115
 116 static inline void native_write_cr2(unsigned long val)
 117 {
 118         asm volatile("movl %0,%%cr2": :"r" (val));
 119 }
 120
 121 static inline unsigned long native_read_cr3(void)
 122 {
 123         unsigned long val;
 124         asm volatile("movl %%cr3,%0\n\t" :"=r" (val));
 125         return val;
 126 }
 127
 128 static inline void native_write_cr3(unsigned long val)
 129 {
 130         asm volatile("movl %0,%%cr3": :"r" (val));
 131 }
 132
 133 static inline unsigned long native_read_cr4(void)
 134 {
 135         unsigned long val;
 136         asm volatile("movl %%cr4,%0\n\t" :"=r" (val));
 137         return val;
 138 }
 139
 140 static inline unsigned long native_read_cr4_safe(void)
 141 {
 142         unsigned long val;
 143         /* This could fault if %cr4 does not exist */
 144         asm("1: movl %%cr4, %0          \n"
 145                 "2:                             \n"
 146                 ".section __ex_table,\"a\"      \n"
 147                 ".long 1b,2b                    \n"
 148                 ".previous                      \n"
 149                 : "=r" (val): "0" (0));
 150         return val;
 151 }
 152
 153 static inline void native_write_cr4(unsigned long val)
 154 {
 155         asm volatile("movl %0,%%cr4": :"r" (val));
 156 }
 157
 158 static inline void native_wbinvd(void)
 159 {
 160         asm volatile("wbinvd": : :"memory");
 161 }
 162
 163
 164 #ifdef CONFIG_PARAVIRT
 165 #include <asm/paravirt.h>
 166 #else
 167 #define read_cr0()      (native_read_cr0())
 168 #define write_cr0(x)    (native_write_cr0(x))
 169 #define read_cr2()      (native_read_cr2())
 170 #define write_cr2(x)    (native_write_cr2(x))
 171 #define read_cr3()      (native_read_cr3())
 172 #define write_cr3(x)    (native_write_cr3(x))
 173 #define read_cr4()      (native_read_cr4())
 174 #define read_cr4_safe() (native_read_cr4_safe())
 175 #define write_cr4(x)    (native_write_cr4(x))
 176 #define wbinvd()        (native_wbinvd())
 177
 178 /* Clear the 'TS' bit */
 179 #define clts()          (native_clts())
 180
 181 #endif/* CONFIG_PARAVIRT */
 182
 183 /* Set the 'TS' bit */
 184 #define stts() write_cr0(8 | read_cr0())
 185
 186 #endif  /* __KERNEL__ */
 187
 188 static inline unsigned long get_limit(unsigned long segment)
 189 {
 190         unsigned long __limit;
 191         __asm__("lsll %1,%0"
 192                 :"=r" (__limit):"r" (segment));
 193         return __limit+1;
 194 }
 195
 196 #define nop() __asm__ __volatile__ ("nop")
 197
 198 /*
 199  * Force strict CPU ordering.
 200  * And yes, this is required on UP too when we're talking
 201  * to devices.
 202  *
 203  * For now, "wmb()" doesn't actually do anything, as all
 204  * Intel CPU's follow what Intel calls a *Processor Order*,
 205  * in which all writes are seen in the program order even
 206  * outside the CPU.
 207  *
 208  * I expect future Intel CPU's to have a weaker ordering,
 209  * but I'd also expect them to finally get their act together
 210  * and add some real memory barriers if so.
 211  *
 212  * Some non intel clones support out of order store. wmb() ceases to be a
 213  * nop for these.
 214  */
 215
 216
 217 /*
 218  * Actually only lfence would be needed for mb() because all stores done
 219  * by the kernel should be already ordered. But keep a full barrier for now.
 220  */
 221
 222 #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
 223 #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
 224
 225 /**
 226  * read_barrier_depends - Flush all pending reads that subsequents reads
 227  * depend on.
 228  *
 229  * No data-dependent reads from memory-like regions are ever reordered
 230  * over this barrier.  All reads preceding this primitive are guaranteed
 231  * to access memory (but not necessarily other CPUs' caches) before any
 232  * reads following this primitive that depend on the data return by
 233  * any of the preceding reads.  This primitive is much lighter weight than
 234  * rmb() on most CPUs, and is never heavier weight than is
 235  * rmb().
 236  *
 237  * These ordering constraints are respected by both the local CPU
 238  * and the compiler.
 239  *
 240  * Ordering is not guaranteed by anything other than these primitives,
 241  * not even by data dependencies.  See the documentation for
 242  * memory_barrier() for examples and URLs to more information.
 243  *
 244  * For example, the following code would force ordering (the initial
 245  * value of "a" is zero, "b" is one, and "p" is "&a"):
 246  *
 247  * <programlisting>
 248  *      CPU 0                           CPU 1
 249  *
 250  *      b = 2;
 251  *      memory_barrier();
 252  *      p = &b;                         q = p;
 253  *                                      read_barrier_depends();
 254  *                                      d = *q;
 255  * </programlisting>
 256  *
 257  * because the read of "*q" depends on the read of "p" and these
 258  * two reads are separated by a read_barrier_depends().  However,
 259  * the following code, with the same initial values for "a" and "b":
 260  *
 261  * <programlisting>
 262  *      CPU 0                           CPU 1
 263  *
 264  *      a = 2;
 265  *      memory_barrier();
 266  *      b = 3;                          y = b;
 267  *                                      read_barrier_depends();
 268  *                                      x = a;
 269  * </programlisting>
 270  *
 271  * does not enforce ordering, since there is no data dependency between
 272  * the read of "a" and the read of "b".  Therefore, on some CPUs, such
 273  * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
 274  * in cases like this where there are no data dependencies.
 275  **/
 276
 277 #define read_barrier_depends()  do { } while(0)
 278
 279 #ifdef CONFIG_X86_OOSTORE
 280 /* Actually there are no OOO store capable CPUs for now that do SSE,
 281    but make it already an possibility. */
 282 #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
 283 #else
 284 #define wmb()   __asm__ __volatile__ ("": : :"memory")
 285 #endif
 286
 287 #ifdef CONFIG_SMP
 288 #define smp_mb()        mb()
 289 #define smp_rmb()       rmb()
 290 #define smp_wmb()       wmb()
 291 #define smp_read_barrier_depends()      read_barrier_depends()
 292 #define set_mb(var, value) do { (void) xchg(&var, value); } while (0)
 293 #else
 294 #define smp_mb()        barrier()
 295 #define smp_rmb()       barrier()
 296 #define smp_wmb()       barrier()
 297 #define smp_read_barrier_depends()      do { } while(0)
 298 #define set_mb(var, value) do { var = value; barrier(); } while (0)
 299 #endif
 300
 301 #include <linux/irqflags.h>
 302
 303 /*
 304  * disable hlt during certain critical i/o operations
 305  */
 306 #define HAVE_DISABLE_HLT
 307 void disable_hlt(void);
 308 void enable_hlt(void);
 309
 310 extern int es7000_plat;
 311 void cpu_idle_wait(void);
 312
 313 /*
 314  * On SMP systems, when the scheduler does migration-cost autodetection,
 315  * it needs a way to flush as much of the CPU's caches as possible:
 316  */
 317 static inline void sched_cacheflush(void)
 318 {
 319         wbinvd();
 320 }
 321
 322 extern unsigned long arch_align_stack(unsigned long sp);
 323 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
 324
 325 void default_idle(void);
 326
 327 #endif