Null pointer deref with hrtimer_try_to_cancel()
[linux-2.6.git] / arch / x86 / include / asm / 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                                                                         \
69                      : /* reloaded segment registers */                 \
70                         "memory");                                      \
71 } while (0)
72
73 /*
74  * disable hlt during certain critical i/o operations
75  */
76 #define HAVE_DISABLE_HLT
77 #else
78 #define __SAVE(reg, offset) "movq %%" #reg ",(14-" #offset ")*8(%%rsp)\n\t"
79 #define __RESTORE(reg, offset) "movq (14-" #offset ")*8(%%rsp),%%" #reg "\n\t"
80
81 /* frame pointer must be last for get_wchan */
82 #define SAVE_CONTEXT    "pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t"
83 #define RESTORE_CONTEXT "movq %%rbp,%%rsi ; popq %%rbp ; popf\t"
84
85 #define __EXTRA_CLOBBER  \
86         , "rcx", "rbx", "rdx", "r8", "r9", "r10", "r11", \
87           "r12", "r13", "r14", "r15"
88
89 /* Save restore flags to clear handle leaking NT */
90 #define switch_to(prev, next, last) \
91         asm volatile(SAVE_CONTEXT                                                   \
92              "movq %%rsp,%P[threadrsp](%[prev])\n\t" /* save RSP */       \
93              "movq %P[threadrsp](%[next]),%%rsp\n\t" /* restore RSP */    \
94              "call __switch_to\n\t"                                       \
95              ".globl thread_return\n"                                     \
96              "thread_return:\n\t"                                         \
97              "movq %%gs:%P[pda_pcurrent],%%rsi\n\t"                       \
98              "movq %P[thread_info](%%rsi),%%r8\n\t"                       \
99              LOCK_PREFIX "btr  %[tif_fork],%P[ti_flags](%%r8)\n\t"        \
100              "movq %%rax,%%rdi\n\t"                                       \
101              "jc   ret_from_fork\n\t"                                     \
102              RESTORE_CONTEXT                                              \
103              : "=a" (last)                                                \
104              : [next] "S" (next), [prev] "D" (prev),                      \
105                [threadrsp] "i" (offsetof(struct task_struct, thread.sp)), \
106                [ti_flags] "i" (offsetof(struct thread_info, flags)),      \
107                [tif_fork] "i" (TIF_FORK),                                 \
108                [thread_info] "i" (offsetof(struct task_struct, stack)),   \
109                [pda_pcurrent] "i" (offsetof(struct x8664_pda, pcurrent))  \
110              : "memory", "cc" __EXTRA_CLOBBER)
111 #endif
112
113 #ifdef __KERNEL__
114 #define _set_base(addr, base) do { unsigned long __pr; \
115 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
116         "rorl $16,%%edx\n\t" \
117         "movb %%dl,%2\n\t" \
118         "movb %%dh,%3" \
119         :"=&d" (__pr) \
120         :"m" (*((addr)+2)), \
121          "m" (*((addr)+4)), \
122          "m" (*((addr)+7)), \
123          "0" (base) \
124         ); } while (0)
125
126 #define _set_limit(addr, limit) do { unsigned long __lr; \
127 __asm__ __volatile__ ("movw %%dx,%1\n\t" \
128         "rorl $16,%%edx\n\t" \
129         "movb %2,%%dh\n\t" \
130         "andb $0xf0,%%dh\n\t" \
131         "orb %%dh,%%dl\n\t" \
132         "movb %%dl,%2" \
133         :"=&d" (__lr) \
134         :"m" (*(addr)), \
135          "m" (*((addr)+6)), \
136          "0" (limit) \
137         ); } while (0)
138
139 #define set_base(ldt, base) _set_base(((char *)&(ldt)) , (base))
140 #define set_limit(ldt, limit) _set_limit(((char *)&(ldt)) , ((limit)-1))
141
142 extern void native_load_gs_index(unsigned);
143
144 /*
145  * Load a segment. Fall back on loading the zero
146  * segment if something goes wrong..
147  */
148 #define loadsegment(seg, value)                 \
149         asm volatile("\n"                       \
150                      "1:\t"                     \
151                      "movl %k0,%%" #seg "\n"    \
152                      "2:\n"                     \
153                      ".section .fixup,\"ax\"\n" \
154                      "3:\t"                     \
155                      "movl %k1, %%" #seg "\n\t" \
156                      "jmp 2b\n"                 \
157                      ".previous\n"              \
158                      _ASM_EXTABLE(1b,3b)        \
159                      : :"r" (value), "r" (0) : "memory")
160
161
162 /*
163  * Save a segment register away
164  */
165 #define savesegment(seg, value)                         \
166         asm("mov %%" #seg ",%0":"=r" (value) : : "memory")
167
168 static inline unsigned long get_limit(unsigned long segment)
169 {
170         unsigned long __limit;
171         asm("lsll %1,%0" : "=r" (__limit) : "r" (segment));
172         return __limit + 1;
173 }
174
175 static inline void native_clts(void)
176 {
177         asm volatile("clts");
178 }
179
180 /*
181  * Volatile isn't enough to prevent the compiler from reordering the
182  * read/write functions for the control registers and messing everything up.
183  * A memory clobber would solve the problem, but would prevent reordering of
184  * all loads stores around it, which can hurt performance. Solution is to
185  * use a variable and mimic reads and writes to it to enforce serialization
186  */
187 static unsigned long __force_order;
188
189 static inline unsigned long native_read_cr0(void)
190 {
191         unsigned long val;
192         asm volatile("mov %%cr0,%0\n\t" : "=r" (val), "=m" (__force_order));
193         return val;
194 }
195
196 static inline void native_write_cr0(unsigned long val)
197 {
198         asm volatile("mov %0,%%cr0": : "r" (val), "m" (__force_order));
199 }
200
201 static inline unsigned long native_read_cr2(void)
202 {
203         unsigned long val;
204         asm volatile("mov %%cr2,%0\n\t" : "=r" (val), "=m" (__force_order));
205         return val;
206 }
207
208 static inline void native_write_cr2(unsigned long val)
209 {
210         asm volatile("mov %0,%%cr2": : "r" (val), "m" (__force_order));
211 }
212
213 static inline unsigned long native_read_cr3(void)
214 {
215         unsigned long val;
216         asm volatile("mov %%cr3,%0\n\t" : "=r" (val), "=m" (__force_order));
217         return val;
218 }
219
220 static inline void native_write_cr3(unsigned long val)
221 {
222         asm volatile("mov %0,%%cr3": : "r" (val), "m" (__force_order));
223 }
224
225 static inline unsigned long native_read_cr4(void)
226 {
227         unsigned long val;
228         asm volatile("mov %%cr4,%0\n\t" : "=r" (val), "=m" (__force_order));
229         return val;
230 }
231
232 static inline unsigned long native_read_cr4_safe(void)
233 {
234         unsigned long val;
235         /* This could fault if %cr4 does not exist. In x86_64, a cr4 always
236          * exists, so it will never fail. */
237 #ifdef CONFIG_X86_32
238         asm volatile("1: mov %%cr4, %0\n"
239                      "2:\n"
240                      _ASM_EXTABLE(1b, 2b)
241                      : "=r" (val), "=m" (__force_order) : "0" (0));
242 #else
243         val = native_read_cr4();
244 #endif
245         return val;
246 }
247
248 static inline void native_write_cr4(unsigned long val)
249 {
250         asm volatile("mov %0,%%cr4": : "r" (val), "m" (__force_order));
251 }
252
253 #ifdef CONFIG_X86_64
254 static inline unsigned long native_read_cr8(void)
255 {
256         unsigned long cr8;
257         asm volatile("movq %%cr8,%0" : "=r" (cr8));
258         return cr8;
259 }
260
261 static inline void native_write_cr8(unsigned long val)
262 {
263         asm volatile("movq %0,%%cr8" :: "r" (val) : "memory");
264 }
265 #endif
266
267 static inline void native_wbinvd(void)
268 {
269         asm volatile("wbinvd": : :"memory");
270 }
271
272 #ifdef CONFIG_PARAVIRT
273 #include <asm/paravirt.h>
274 #else
275 #define read_cr0()      (native_read_cr0())
276 #define write_cr0(x)    (native_write_cr0(x))
277 #define read_cr2()      (native_read_cr2())
278 #define write_cr2(x)    (native_write_cr2(x))
279 #define read_cr3()      (native_read_cr3())
280 #define write_cr3(x)    (native_write_cr3(x))
281 #define read_cr4()      (native_read_cr4())
282 #define read_cr4_safe() (native_read_cr4_safe())
283 #define write_cr4(x)    (native_write_cr4(x))
284 #define wbinvd()        (native_wbinvd())
285 #ifdef CONFIG_X86_64
286 #define read_cr8()      (native_read_cr8())
287 #define write_cr8(x)    (native_write_cr8(x))
288 #define load_gs_index   native_load_gs_index
289 #endif
290
291 /* Clear the 'TS' bit */
292 #define clts()          (native_clts())
293
294 #endif/* CONFIG_PARAVIRT */
295
296 #define stts() write_cr0(read_cr0() | X86_CR0_TS)
297
298 #endif /* __KERNEL__ */
299
300 static inline void clflush(volatile void *__p)
301 {
302         asm volatile("clflush %0" : "+m" (*(volatile char __force *)__p));
303 }
304
305 #define nop() asm volatile ("nop")
306
307 void disable_hlt(void);
308 void enable_hlt(void);
309
310 void cpu_idle_wait(void);
311
312 extern unsigned long arch_align_stack(unsigned long sp);
313 extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
314
315 void default_idle(void);
316
317 /*
318  * Force strict CPU ordering.
319  * And yes, this is required on UP too when we're talking
320  * to devices.
321  */
322 #ifdef CONFIG_X86_32
323 /*
324  * Some non-Intel clones support out of order store. wmb() ceases to be a
325  * nop for these.
326  */
327 #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
328 #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
329 #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
330 #else
331 #define mb()    asm volatile("mfence":::"memory")
332 #define rmb()   asm volatile("lfence":::"memory")
333 #define wmb()   asm volatile("sfence" ::: "memory")
334 #endif
335
336 /**
337  * read_barrier_depends - Flush all pending reads that subsequents reads
338  * depend on.
339  *
340  * No data-dependent reads from memory-like regions are ever reordered
341  * over this barrier.  All reads preceding this primitive are guaranteed
342  * to access memory (but not necessarily other CPUs' caches) before any
343  * reads following this primitive that depend on the data return by
344  * any of the preceding reads.  This primitive is much lighter weight than
345  * rmb() on most CPUs, and is never heavier weight than is
346  * rmb().
347  *
348  * These ordering constraints are respected by both the local CPU
349  * and the compiler.
350  *
351  * Ordering is not guaranteed by anything other than these primitives,
352  * not even by data dependencies.  See the documentation for
353  * memory_barrier() for examples and URLs to more information.
354  *
355  * For example, the following code would force ordering (the initial
356  * value of "a" is zero, "b" is one, and "p" is "&a"):
357  *
358  * <programlisting>
359  *      CPU 0                           CPU 1
360  *
361  *      b = 2;
362  *      memory_barrier();
363  *      p = &b;                         q = p;
364  *                                      read_barrier_depends();
365  *                                      d = *q;
366  * </programlisting>
367  *
368  * because the read of "*q" depends on the read of "p" and these
369  * two reads are separated by a read_barrier_depends().  However,
370  * the following code, with the same initial values for "a" and "b":
371  *
372  * <programlisting>
373  *      CPU 0                           CPU 1
374  *
375  *      a = 2;
376  *      memory_barrier();
377  *      b = 3;                          y = b;
378  *                                      read_barrier_depends();
379  *                                      x = a;
380  * </programlisting>
381  *
382  * does not enforce ordering, since there is no data dependency between
383  * the read of "a" and the read of "b".  Therefore, on some CPUs, such
384  * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
385  * in cases like this where there are no data dependencies.
386  **/
387
388 #define read_barrier_depends()  do { } while (0)
389
390 #ifdef CONFIG_SMP
391 #define smp_mb()        mb()
392 #ifdef CONFIG_X86_PPRO_FENCE
393 # define smp_rmb()      rmb()
394 #else
395 # define smp_rmb()      barrier()
396 #endif
397 #ifdef CONFIG_X86_OOSTORE
398 # define smp_wmb()      wmb()
399 #else
400 # define smp_wmb()      barrier()
401 #endif
402 #define smp_read_barrier_depends()      read_barrier_depends()
403 #define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
404 #else
405 #define smp_mb()        barrier()
406 #define smp_rmb()       barrier()
407 #define smp_wmb()       barrier()
408 #define smp_read_barrier_depends()      do { } while (0)
409 #define set_mb(var, value) do { var = value; barrier(); } while (0)
410 #endif
411
412 /*
413  * Stop RDTSC speculation. This is needed when you need to use RDTSC
414  * (or get_cycles or vread that possibly accesses the TSC) in a defined
415  * code region.
416  *
417  * (Could use an alternative three way for this if there was one.)
418  */
419 static inline void rdtsc_barrier(void)
420 {
421         alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
422         alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
423 }
424
425 #endif /* _ASM_X86_SYSTEM_H */