include/asm-x86/system.h

   1 #ifndef _ASM_X86_SYSTEM_H_
   2 #define _ASM_X86_SYSTEM_H_
   3
   4 #include <asm/asm.h>
   5 #include <asm/segment.h>
   6 #include <asm/cpufeature.h>
   7 #include <asm/cmpxchg.h>
   8 #include <asm/nops.h>
   9
  10 #include <linux/kernel.h>
  11 #include <linux/irqflags.h>
  12
  13 /* entries in ARCH_DLINFO: */
  14 #ifdef CONFIG_IA32_EMULATION
  15 # define AT_VECTOR_SIZE_ARCH 2
  16 #else
  17 # define AT_VECTOR_SIZE_ARCH 1
  18 #endif
  19
  20 #ifdef CONFIG_X86_32
  21
  22 struct task_struct; /* one of the stranger aspects of C forward declarations */
  23 struct task_struct *__switch_to(struct task_struct *prev,
  24                                 struct task_struct *next);
  25
  26 /*
  27  * Saving eflags is important. It switches not only IOPL between tasks,
  28  * it also protects other tasks from NT leaking through sysenter etc.
  29  */
  30 #define switch_to(prev, next, last)                                     \
  31 do {                                                                    \
  32         /*                                                              \
  33          * Context-switching clobbers all registers, so we clobber      \
  34          * them explicitly, via unused output variables.                \
  35          * (EAX and EBP is not listed because EBP is saved/restored     \
  36          * explicitly for wchan access and EAX is the return value of   \
  37          * __switch_to())                                               \
  38          */                                                             \
  39         unsigned long ebx, ecx, edx, esi, edi;                          \
  40                                                                         \
  41         asm volatile("pushfl\n\t"               /* save    flags */     \
  42                      "pushl %%ebp\n\t"          /* save    EBP   */     \
  43                      "movl %%esp,%[prev_sp]\n\t"        /* save    ESP   */ \
  44                      "movl %[next_sp],%%esp\n\t"        /* restore ESP   */ \
  45                      "movl $1f,%[prev_ip]\n\t"  /* save    EIP   */     \
  46                      "pushl %[next_ip]\n\t"     /* restore EIP   */     \
  47                      "jmp __switch_to\n"        /* regparm call  */     \
  48                      "1:\t"                                             \
  49                      "popl %%ebp\n\t"           /* restore EBP   */     \
  50                      "popfl\n"                  /* restore flags */     \
  51                                                                         \
  52                      /* output parameters */                            \
  53                      : [prev_sp] "=m" (prev->thread.sp),                \
  54                        [prev_ip] "=m" (prev->thread.ip),                \
  55                        "=a" (last),                                     \
  56                                                                         \
  57                        /* clobbered output registers: */                \
  58                        "=b" (ebx), "=c" (ecx), "=d" (edx),              \
  59                        "=S" (esi), "=D" (edi)                           \
  60                                                                         \
  61                        /* input parameters: */                          \
  62                      : [next_sp]  "m" (next->thread.sp),                \
  63                        [next_ip]  "m" (next->thread.ip),                \
  64                                                                         \
  65                        /* regparm parameters for __switch_to(): */      \
  66                        [prev]     "a" (prev),                           \
  67                        [next]     "d" (next));                          \
  68 } while (0)
  69
  70 /*
  71  * disable hlt during certain critical i/o operations
  72  */
  73 #define HAVE_DISABLE_HLT
  74 #else
  75 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
  76 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"
  77
  78 /* frame pointer must be last for get_wchan */
  79 #define SAVE_CONTEXT    "pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t"
  80 #define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popf\t"
  81
  82 #define __EXTRA_CLOBBER  \
  83         , "rcx", "rbx", "rdx", "r8", "r9", "r10", "r11", \
  84           "r12", "r13", "r14", "r15"
  85
  86 /* Save restore flags to clear handle leaking NT */
  87 #define switch_to(prev, next, last) \
  88         asm volatile(SAVE_CONTEXT                                                   \
  89              "movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */       \
  90              "movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */    \
  91              "call __switch_to\n\t"                                       \
  92              ".globl thread_return\n"                                     \
  93              "thread_return:\n\t"                                         \
  94              "movq %%gs:%P[pda_pcurrent],%%rsi\n\t"                       \
  95              "movq %P[thread_info](%%rsi),%%r8\n\t"                       \
  96              LOCK_PREFIX "btr  %[tif_fork],%P[ti_flags](%%r8)\n\t"        \
  97              "movq %%rax,%%rdi\n\t"                                       \
  98              "jc   ret_from_fork\n\t"                                     \
  99              RESTORE_CONTEXT                                              \
 100              : "=a" (last)                                                \
 101              : [next] "S" (next), [prev] "D" (prev),                      \
 102                [threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \
 103                [ti_flags] "i" (offsetof(struct thread_info, flags)),      \
 104                [tif_fork] "i" (TIF_FORK),                                 \
 105                [thread_info] "i" (offsetof(struct task_struct, stack)),   \
 106                [pda_pcurrent] "i" (offsetof(struct x8664_pda, pcurrent))  \
 107              : "memory", "cc" __EXTRA_CLOBBER)
 108 #endif
 109
 110 #ifdef __KERNEL__
 111 #define _set_base(addr, base) do { unsigned long __pr; \
 112 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
 113         "rorl $16,%%edx\n\t" \
 114         "movb %%dl,%2\n\t" \
 115         "movb %%dh,%3" \
 116         :"=&d" (__pr) \
 117         :"m" (*((addr)+2)), \
 118          "m" (*((addr)+4)), \
 119          "m" (*((addr)+7)), \
 120          "0" (base) \
 121         ); } while (0)
 122
 123 #define _set_limit(addr, limit) do { unsigned long __lr; \
 124 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
 125         "rorl $16,%%edx\n\t" \
 126         "movb %2,%%dh\n\t" \
 127         "andb $0xf0,%%dh\n\t" \
 128         "orb %%dh,%%dl\n\t" \
 129         "movb %%dl,%2" \
 130         :"=&d" (__lr) \
 131         :"m" (*(addr)), \
 132          "m" (*((addr)+6)), \
 133          "0" (limit) \
 134         ); } while (0)
 135
 136 #define set_base(ldt, base) _set_base(((char *)&(ldt)) , (base))
 137 #define set_limit(ldt, limit) _set_limit(((char *)&(ldt)) , ((limit)-1))
 138
 139 extern void native_load_gs_index(unsigned);
 140
 141 /*
 142  * Load a segment. Fall back on loading the zero
 143  * segment if something goes wrong..
 144  */
 145 #define loadsegment(seg, value)                 \
 146         asm volatile("\n"                       \
 147                      "1:\t"                     \
 148                      "movl %k0,%%" #seg "\n"    \
 149                      "2:\n"                     \
 150                      ".section .fixup,\"ax\"\n" \
 151                      "3:\t"                     \
 152                      "movl %k1, %%" #seg "\n\t" \
 153                      "jmp 2b\n"                 \
 154                      ".previous\n"              \
 155                      _ASM_EXTABLE(1b,3b)        \
 156                      : :"r" (value), "r" (0) : "memory")
 157
 158
 159 /*
 160  * Save a segment register away
 161  */
 162 #define savesegment(seg, value)                         \
 163         asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
 164
 165 static inline unsigned long get_limit(unsigned long segment)
 166 {
 167         unsigned long __limit;
 168         asm("lsll %1,%0" : "=r" (__limit) : "r" (segment));
 169         return __limit + 1;
 170 }
 171
 172 static inline void native_clts(void)
 173 {
 174         asm volatile("clts");
 175 }
 176
 177 /*
 178  * Volatile isn't enough to prevent the compiler from reordering the
 179  * read/write functions for the control registers and messing everything up.
 180  * A memory clobber would solve the problem, but would prevent reordering of
 181  * all loads stores around it, which can hurt performance. Solution is to
 182  * use a variable and mimic reads and writes to it to enforce serialization
 183  */
 184 static unsigned long __force_order;
 185
 186 static inline unsigned long native_read_cr0(void)
 187 {
 188         unsigned long val;
 189         asm volatile("mov %%cr0,%0\n\t" : "=r" (val), "=m" (__force_order));
 190         return val;
 191 }
 192
 193 static inline void native_write_cr0(unsigned long val)
 194 {
 195         asm volatile("mov %0,%%cr0": : "r" (val), "m" (__force_order));
 196 }
 197
 198 static inline unsigned long native_read_cr2(void)
 199 {
 200         unsigned long val;
 201         asm volatile("mov %%cr2,%0\n\t" : "=r" (val), "=m" (__force_order));
 202         return val;
 203 }
 204
 205 static inline void native_write_cr2(unsigned long val)
 206 {
 207         asm volatile("mov %0,%%cr2": : "r" (val), "m" (__force_order));
 208 }
 209
 210 static inline unsigned long native_read_cr3(void)
 211 {
 212         unsigned long val;
 213         asm volatile("mov %%cr3,%0\n\t" : "=r" (val), "=m" (__force_order));
 214         return val;
 215 }
 216
 217 static inline void native_write_cr3(unsigned long val)
 218 {
 219         asm volatile("mov %0,%%cr3": : "r" (val), "m" (__force_order));
 220 }
 221
 222 static inline unsigned long native_read_cr4(void)
 223 {
 224         unsigned long val;
 225         asm volatile("mov %%cr4,%0\n\t" : "=r" (val), "=m" (__force_order));
 226         return val;
 227 }
 228
 229 static inline unsigned long native_read_cr4_safe(void)
 230 {
 231         unsigned long val;
 232         /* This could fault if %cr4 does not exist. In x86_64, a cr4 always
 233          * exists, so it will never fail. */
 234 #ifdef CONFIG_X86_32
 235         asm volatile("1: mov %%cr4, %0\n"
 236                      "2:\n"
 237                      _ASM_EXTABLE(1b, 2b)
 238                      : "=r" (val), "=m" (__force_order) : "0" (0));
 239 #else
 240         val = native_read_cr4();
 241 #endif
 242         return val;
 243 }
 244
 245 static inline void native_write_cr4(unsigned long val)
 246 {
 247         asm volatile("mov %0,%%cr4": : "r" (val), "m" (__force_order));
 248 }
 249
 250 #ifdef CONFIG_X86_64
 251 static inline unsigned long native_read_cr8(void)
 252 {
 253         unsigned long cr8;
 254         asm volatile("movq %%cr8,%0" : "=r" (cr8));
 255         return cr8;
 256 }
 257
 258 static inline void native_write_cr8(unsigned long val)
 259 {
 260         asm volatile("movq %0,%%cr8" :: "r" (val) : "memory");
 261 }
 262 #endif
 263
 264 static inline void native_wbinvd(void)
 265 {
 266         asm volatile("wbinvd": : :"memory");
 267 }
 268
 269 #ifdef CONFIG_PARAVIRT
 270 #include <asm/paravirt.h>
 271 #else
 272 #define read_cr0()      (native_read_cr0())
 273 #define write_cr0(x)    (native_write_cr0(x))
 274 #define read_cr2()      (native_read_cr2())
 275 #define write_cr2(x)    (native_write_cr2(x))
 276 #define read_cr3()      (native_read_cr3())
 277 #define write_cr3(x)    (native_write_cr3(x))
 278 #define read_cr4()      (native_read_cr4())
 279 #define read_cr4_safe() (native_read_cr4_safe())
 280 #define write_cr4(x)    (native_write_cr4(x))
 281 #define wbinvd()        (native_wbinvd())
 282 #ifdef CONFIG_X86_64
 283 #define read_cr8()      (native_read_cr8())
 284 #define write_cr8(x)    (native_write_cr8(x))
 285 #define load_gs_index   native_load_gs_index
 286 #endif
 287
 288 /* Clear the 'TS' bit */
 289 #define clts()          (native_clts())
 290
 291 #endif/* CONFIG_PARAVIRT */
 292
 293 #define stts() write_cr0(read_cr0() | X86_CR0_TS)
 294
 295 #endif /* __KERNEL__ */
 296
 297 static inline void clflush(volatile void *__p)
 298 {
 299         asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
 300 }
 301
 302 #define nop() asm volatile ("nop")
 303
 304 void disable_hlt(void);
 305 void enable_hlt(void);
 306
 307 void cpu_idle_wait(void);
 308
 309 extern unsigned long arch_align_stack(unsigned long sp);
 310 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
 311
 312 void default_idle(void);
 313
 314 /*
 315  * Force strict CPU ordering.
 316  * And yes, this is required on UP too when we're talking
 317  * to devices.
 318  */
 319 #ifdef CONFIG_X86_32
 320 /*
 321  * Some non-Intel clones support out of order store. wmb() ceases to be a
 322  * nop for these.
 323  */
 324 #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
 325 #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
 326 #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
 327 #else
 328 #define mb()    asm volatile("mfence":::"memory")
 329 #define rmb()   asm volatile("lfence":::"memory")
 330 #define wmb()   asm volatile("sfence" ::: "memory")
 331 #endif
 332
 333 /**
 334  * read_barrier_depends - Flush all pending reads that subsequents reads
 335  * depend on.
 336  *
 337  * No data-dependent reads from memory-like regions are ever reordered
 338  * over this barrier.  All reads preceding this primitive are guaranteed
 339  * to access memory (but not necessarily other CPUs' caches) before any
 340  * reads following this primitive that depend on the data return by
 341  * any of the preceding reads.  This primitive is much lighter weight than
 342  * rmb() on most CPUs, and is never heavier weight than is
 343  * rmb().
 344  *
 345  * These ordering constraints are respected by both the local CPU
 346  * and the compiler.
 347  *
 348  * Ordering is not guaranteed by anything other than these primitives,
 349  * not even by data dependencies.  See the documentation for
 350  * memory_barrier() for examples and URLs to more information.
 351  *
 352  * For example, the following code would force ordering (the initial
 353  * value of "a" is zero, "b" is one, and "p" is "&a"):
 354  *
 355  * <programlisting>
 356  *      CPU 0                           CPU 1
 357  *
 358  *      b = 2;
 359  *      memory_barrier();
 360  *      p = &b;                         q = p;
 361  *                                      read_barrier_depends();
 362  *                                      d = *q;
 363  * </programlisting>
 364  *
 365  * because the read of "*q" depends on the read of "p" and these
 366  * two reads are separated by a read_barrier_depends().  However,
 367  * the following code, with the same initial values for "a" and "b":
 368  *
 369  * <programlisting>
 370  *      CPU 0                           CPU 1
 371  *
 372  *      a = 2;
 373  *      memory_barrier();
 374  *      b = 3;                          y = b;
 375  *                                      read_barrier_depends();
 376  *                                      x = a;
 377  * </programlisting>
 378  *
 379  * does not enforce ordering, since there is no data dependency between
 380  * the read of "a" and the read of "b".  Therefore, on some CPUs, such
 381  * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
 382  * in cases like this where there are no data dependencies.
 383  **/
 384
 385 #define read_barrier_depends()  do { } while (0)
 386
 387 #ifdef CONFIG_SMP
 388 #define smp_mb()        mb()
 389 #ifdef CONFIG_X86_PPRO_FENCE
 390 # define smp_rmb()      rmb()
 391 #else
 392 # define smp_rmb()      barrier()
 393 #endif
 394 #ifdef CONFIG_X86_OOSTORE
 395 # define smp_wmb()      wmb()
 396 #else
 397 # define smp_wmb()      barrier()
 398 #endif
 399 #define smp_read_barrier_depends()      read_barrier_depends()
 400 #define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
 401 #else
 402 #define smp_mb()        barrier()
 403 #define smp_rmb()       barrier()
 404 #define smp_wmb()       barrier()
 405 #define smp_read_barrier_depends()      do { } while (0)
 406 #define set_mb(var, value) do { var = value; barrier(); } while (0)
 407 #endif
 408
 409 /*
 410  * Stop RDTSC speculation. This is needed when you need to use RDTSC
 411  * (or get_cycles or vread that possibly accesses the TSC) in a defined
 412  * code region.
 413  *
 414  * (Could use an alternative three way for this if there was one.)
 415  */
 416 static inline void rdtsc_barrier(void)
 417 {
 418         alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
 419         alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
 420 }
 421
 422 #endif