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Linux/arch/x86/include/asm/i387.h

  1 /*
  2  * Copyright (C) 1994 Linus Torvalds
  3  *
  4  * Pentium III FXSR, SSE support
  5  * General FPU state handling cleanups
  6  *      Gareth Hughes <gareth@valinux.com>, May 2000
  7  * x86-64 work by Andi Kleen 2002
  8  */
  9 
 10 #ifndef _ASM_X86_I387_H
 11 #define _ASM_X86_I387_H
 12 
 13 #ifndef __ASSEMBLY__
 14 
 15 #include <linux/sched.h>
 16 #include <linux/kernel_stat.h>
 17 #include <linux/regset.h>
 18 #include <linux/hardirq.h>
 19 #include <linux/slab.h>
 20 #include <asm/asm.h>
 21 #include <asm/cpufeature.h>
 22 #include <asm/processor.h>
 23 #include <asm/sigcontext.h>
 24 #include <asm/user.h>
 25 #include <asm/uaccess.h>
 26 #include <asm/xsave.h>
 27 
 28 extern unsigned int sig_xstate_size;
 29 extern void fpu_init(void);
 30 extern void mxcsr_feature_mask_init(void);
 31 extern int init_fpu(struct task_struct *child);
 32 extern asmlinkage void math_state_restore(void);
 33 extern void __math_state_restore(void);
 34 extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
 35 
 36 extern user_regset_active_fn fpregs_active, xfpregs_active;
 37 extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get,
 38                                 xstateregs_get;
 39 extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set,
 40                                  xstateregs_set;
 41 
 42 /*
 43  * xstateregs_active == fpregs_active. Please refer to the comment
 44  * at the definition of fpregs_active.
 45  */
 46 #define xstateregs_active       fpregs_active
 47 
 48 extern struct _fpx_sw_bytes fx_sw_reserved;
 49 #ifdef CONFIG_IA32_EMULATION
 50 extern unsigned int sig_xstate_ia32_size;
 51 extern struct _fpx_sw_bytes fx_sw_reserved_ia32;
 52 struct _fpstate_ia32;
 53 struct _xstate_ia32;
 54 extern int save_i387_xstate_ia32(void __user *buf);
 55 extern int restore_i387_xstate_ia32(void __user *buf);
 56 #endif
 57 
 58 #ifdef CONFIG_MATH_EMULATION
 59 extern void finit_soft_fpu(struct i387_soft_struct *soft);
 60 #else
 61 static inline void finit_soft_fpu(struct i387_soft_struct *soft) {}
 62 #endif
 63 
 64 #define X87_FSW_ES (1 << 7)     /* Exception Summary */
 65 
 66 static __always_inline __pure bool use_xsaveopt(void)
 67 {
 68         return static_cpu_has(X86_FEATURE_XSAVEOPT);
 69 }
 70 
 71 static __always_inline __pure bool use_xsave(void)
 72 {
 73         return static_cpu_has(X86_FEATURE_XSAVE);
 74 }
 75 
 76 static __always_inline __pure bool use_fxsr(void)
 77 {
 78         return static_cpu_has(X86_FEATURE_FXSR);
 79 }
 80 
 81 extern void __sanitize_i387_state(struct task_struct *);
 82 
 83 static inline void sanitize_i387_state(struct task_struct *tsk)
 84 {
 85         if (!use_xsaveopt())
 86                 return;
 87         __sanitize_i387_state(tsk);
 88 }
 89 
 90 #ifdef CONFIG_X86_64
 91 static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
 92 {
 93         int err;
 94 
 95         /* See comment in fxsave() below. */
 96 #ifdef CONFIG_AS_FXSAVEQ
 97         asm volatile("1:  fxrstorq %[fx]\n\t"
 98                      "2:\n"
 99                      ".section .fixup,\"ax\"\n"
100                      "3:  movl $-1,%[err]\n"
101                      "    jmp  2b\n"
102                      ".previous\n"
103                      _ASM_EXTABLE(1b, 3b)
104                      : [err] "=r" (err)
105                      : [fx] "m" (*fx), "" (0));
106 #else
107         asm volatile("1:  rex64/fxrstor (%[fx])\n\t"
108                      "2:\n"
109                      ".section .fixup,\"ax\"\n"
110                      "3:  movl $-1,%[err]\n"
111                      "    jmp  2b\n"
112                      ".previous\n"
113                      _ASM_EXTABLE(1b, 3b)
114                      : [err] "=r" (err)
115                      : [fx] "R" (fx), "m" (*fx), "" (0));
116 #endif
117         return err;
118 }
119 
120 static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
121 {
122         int err;
123 
124         /*
125          * Clear the bytes not touched by the fxsave and reserved
126          * for the SW usage.
127          */
128         err = __clear_user(&fx->sw_reserved,
129                            sizeof(struct _fpx_sw_bytes));
130         if (unlikely(err))
131                 return -EFAULT;
132 
133         /* See comment in fxsave() below. */
134 #ifdef CONFIG_AS_FXSAVEQ
135         asm volatile("1:  fxsaveq %[fx]\n\t"
136                      "2:\n"
137                      ".section .fixup,\"ax\"\n"
138                      "3:  movl $-1,%[err]\n"
139                      "    jmp  2b\n"
140                      ".previous\n"
141                      _ASM_EXTABLE(1b, 3b)
142                      : [err] "=r" (err), [fx] "=m" (*fx)
143                      : "" (0));
144 #else
145         asm volatile("1:  rex64/fxsave (%[fx])\n\t"
146                      "2:\n"
147                      ".section .fixup,\"ax\"\n"
148                      "3:  movl $-1,%[err]\n"
149                      "    jmp  2b\n"
150                      ".previous\n"
151                      _ASM_EXTABLE(1b, 3b)
152                      : [err] "=r" (err), "=m" (*fx)
153                      : [fx] "R" (fx), "" (0));
154 #endif
155         if (unlikely(err) &&
156             __clear_user(fx, sizeof(struct i387_fxsave_struct)))
157                 err = -EFAULT;
158         /* No need to clear here because the caller clears USED_MATH */
159         return err;
160 }
161 
162 static inline void fpu_fxsave(struct fpu *fpu)
163 {
164         /* Using "rex64; fxsave %0" is broken because, if the memory operand
165            uses any extended registers for addressing, a second REX prefix
166            will be generated (to the assembler, rex64 followed by semicolon
167            is a separate instruction), and hence the 64-bitness is lost. */
168 
169 #ifdef CONFIG_AS_FXSAVEQ
170         /* Using "fxsaveq %0" would be the ideal choice, but is only supported
171            starting with gas 2.16. */
172         __asm__ __volatile__("fxsaveq %0"
173                              : "=m" (fpu->state->fxsave));
174 #else
175         /* Using, as a workaround, the properly prefixed form below isn't
176            accepted by any binutils version so far released, complaining that
177            the same type of prefix is used twice if an extended register is
178            needed for addressing (fix submitted to mainline 2005-11-21).
179         asm volatile("rex64/fxsave %0"
180                      : "=m" (fpu->state->fxsave));
181            This, however, we can work around by forcing the compiler to select
182            an addressing mode that doesn't require extended registers. */
183         asm volatile("rex64/fxsave (%[fx])"
184                      : "=m" (fpu->state->fxsave)
185                      : [fx] "R" (&fpu->state->fxsave));
186 #endif
187 }
188 
189 #else  /* CONFIG_X86_32 */
190 
191 /* perform fxrstor iff the processor has extended states, otherwise frstor */
192 static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
193 {
194         /*
195          * The "nop" is needed to make the instructions the same
196          * length.
197          */
198         alternative_input(
199                 "nop ; frstor %1",
200                 "fxrstor %1",
201                 X86_FEATURE_FXSR,
202                 "m" (*fx));
203 
204         return 0;
205 }
206 
207 static inline void fpu_fxsave(struct fpu *fpu)
208 {
209         asm volatile("fxsave %[fx]"
210                      : [fx] "=m" (fpu->state->fxsave));
211 }
212 
213 #endif  /* CONFIG_X86_64 */
214 
215 /* We need a safe address that is cheap to find and that is already
216    in L1 during context switch. The best choices are unfortunately
217    different for UP and SMP */
218 #ifdef CONFIG_SMP
219 #define safe_address (__per_cpu_offset[0])
220 #else
221 #define safe_address (kstat_cpu(0).cpustat.user)
222 #endif
223 
224 /*
225  * These must be called with preempt disabled
226  */
227 static inline void fpu_save_init(struct fpu *fpu)
228 {
229         if (use_xsave()) {
230                 fpu_xsave(fpu);
231 
232                 /*
233                  * xsave header may indicate the init state of the FP.
234                  */
235                 if (!(fpu->state->xsave.xsave_hdr.xstate_bv & XSTATE_FP))
236                         return;
237         } else if (use_fxsr()) {
238                 fpu_fxsave(fpu);
239         } else {
240                 asm volatile("fnsave %[fx]; fwait"
241                              : [fx] "=m" (fpu->state->fsave));
242                 return;
243         }
244 
245         if (unlikely(fpu->state->fxsave.swd & X87_FSW_ES))
246                 asm volatile("fnclex");
247 
248         /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
249            is pending.  Clear the x87 state here by setting it to fixed
250            values. safe_address is a random variable that should be in L1 */
251         alternative_input(
252                 ASM_NOP8 ASM_NOP2,
253                 "emms\n\t"              /* clear stack tags */
254                 "fildl %P[addr]",       /* set F?P to defined value */
255                 X86_FEATURE_FXSAVE_LEAK,
256                 [addr] "m" (safe_address));
257 }
258 
259 static inline void __save_init_fpu(struct task_struct *tsk)
260 {
261         fpu_save_init(&tsk->thread.fpu);
262         task_thread_info(tsk)->status &= ~TS_USEDFPU;
263 }
264 
265 static inline int fpu_fxrstor_checking(struct fpu *fpu)
266 {
267         return fxrstor_checking(&fpu->state->fxsave);
268 }
269 
270 static inline int fpu_restore_checking(struct fpu *fpu)
271 {
272         if (use_xsave())
273                 return fpu_xrstor_checking(fpu);
274         else
275                 return fpu_fxrstor_checking(fpu);
276 }
277 
278 static inline int restore_fpu_checking(struct task_struct *tsk)
279 {
280         return fpu_restore_checking(&tsk->thread.fpu);
281 }
282 
283 /*
284  * Signal frame handlers...
285  */
286 extern int save_i387_xstate(void __user *buf);
287 extern int restore_i387_xstate(void __user *buf);
288 
289 static inline void __unlazy_fpu(struct task_struct *tsk)
290 {
291         if (task_thread_info(tsk)->status & TS_USEDFPU) {
292                 __save_init_fpu(tsk);
293                 stts();
294         } else
295                 tsk->fpu_counter = 0;
296 }
297 
298 static inline void __clear_fpu(struct task_struct *tsk)
299 {
300         if (task_thread_info(tsk)->status & TS_USEDFPU) {
301                 /* Ignore delayed exceptions from user space */
302                 asm volatile("1: fwait\n"
303                              "2:\n"
304                              _ASM_EXTABLE(1b, 2b));
305                 task_thread_info(tsk)->status &= ~TS_USEDFPU;
306                 stts();
307         }
308 }
309 
310 static inline void kernel_fpu_begin(void)
311 {
312         struct thread_info *me = current_thread_info();
313         preempt_disable();
314         if (me->status & TS_USEDFPU)
315                 __save_init_fpu(me->task);
316         else
317                 clts();
318 }
319 
320 static inline void kernel_fpu_end(void)
321 {
322         stts();
323         preempt_enable();
324 }
325 
326 static inline bool irq_fpu_usable(void)
327 {
328         struct pt_regs *regs;
329 
330         return !in_interrupt() || !(regs = get_irq_regs()) || \
331                 user_mode(regs) || (read_cr0() & X86_CR0_TS);
332 }
333 
334 /*
335  * Some instructions like VIA's padlock instructions generate a spurious
336  * DNA fault but don't modify SSE registers. And these instructions
337  * get used from interrupt context as well. To prevent these kernel instructions
338  * in interrupt context interacting wrongly with other user/kernel fpu usage, we
339  * should use them only in the context of irq_ts_save/restore()
340  */
341 static inline int irq_ts_save(void)
342 {
343         /*
344          * If in process context and not atomic, we can take a spurious DNA fault.
345          * Otherwise, doing clts() in process context requires disabling preemption
346          * or some heavy lifting like kernel_fpu_begin()
347          */
348         if (!in_atomic())
349                 return 0;
350 
351         if (read_cr0() & X86_CR0_TS) {
352                 clts();
353                 return 1;
354         }
355 
356         return 0;
357 }
358 
359 static inline void irq_ts_restore(int TS_state)
360 {
361         if (TS_state)
362                 stts();
363 }
364 
365 /*
366  * These disable preemption on their own and are safe
367  */
368 static inline void save_init_fpu(struct task_struct *tsk)
369 {
370         preempt_disable();
371         __save_init_fpu(tsk);
372         stts();
373         preempt_enable();
374 }
375 
376 static inline void unlazy_fpu(struct task_struct *tsk)
377 {
378         preempt_disable();
379         __unlazy_fpu(tsk);
380         preempt_enable();
381 }
382 
383 static inline void clear_fpu(struct task_struct *tsk)
384 {
385         preempt_disable();
386         __clear_fpu(tsk);
387         preempt_enable();
388 }
389 
390 /*
391  * i387 state interaction
392  */
393 static inline unsigned short get_fpu_cwd(struct task_struct *tsk)
394 {
395         if (cpu_has_fxsr) {
396                 return tsk->thread.fpu.state->fxsave.cwd;
397         } else {
398                 return (unsigned short)tsk->thread.fpu.state->fsave.cwd;
399         }
400 }
401 
402 static inline unsigned short get_fpu_swd(struct task_struct *tsk)
403 {
404         if (cpu_has_fxsr) {
405                 return tsk->thread.fpu.state->fxsave.swd;
406         } else {
407                 return (unsigned short)tsk->thread.fpu.state->fsave.swd;
408         }
409 }
410 
411 static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
412 {
413         if (cpu_has_xmm) {
414                 return tsk->thread.fpu.state->fxsave.mxcsr;
415         } else {
416                 return MXCSR_DEFAULT;
417         }
418 }
419 
420 static bool fpu_allocated(struct fpu *fpu)
421 {
422         return fpu->state != NULL;
423 }
424 
425 static inline int fpu_alloc(struct fpu *fpu)
426 {
427         if (fpu_allocated(fpu))
428                 return 0;
429         fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
430         if (!fpu->state)
431                 return -ENOMEM;
432         WARN_ON((unsigned long)fpu->state & 15);
433         return 0;
434 }
435 
436 static inline void fpu_free(struct fpu *fpu)
437 {
438         if (fpu->state) {
439                 kmem_cache_free(task_xstate_cachep, fpu->state);
440                 fpu->state = NULL;
441         }
442 }
443 
444 static inline void fpu_copy(struct fpu *dst, struct fpu *src)
445 {
446         memcpy(dst->state, src->state, xstate_size);
447 }
448 
449 extern void fpu_finit(struct fpu *fpu);
450 
451 #endif /* __ASSEMBLY__ */
452 
453 #endif /* _ASM_X86_I387_H */
454 

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