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 #include <linux/sched.h>
  14 #include <linux/kernel_stat.h>
  15 #include <linux/regset.h>
  16 #include <linux/hardirq.h>
  17 #include <asm/asm.h>
  18 #include <asm/processor.h>
  19 #include <asm/sigcontext.h>
  20 #include <asm/user.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/xsave.h>
  23
  24 extern unsigned int sig_xstate_size;
  25 extern void fpu_init(void);
  26 extern void mxcsr_feature_mask_init(void);
  27 extern int init_fpu(struct task_struct *child);
  28 extern asmlinkage void math_state_restore(void);
  29 extern void init_thread_xstate(void);
  30 extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
  31
  32 extern user_regset_active_fn fpregs_active, xfpregs_active;
  33 extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get;
  34 extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set;
  35
  36 extern struct _fpx_sw_bytes fx_sw_reserved;
  37 #ifdef CONFIG_IA32_EMULATION
  38 extern unsigned int sig_xstate_ia32_size;
  39 extern struct _fpx_sw_bytes fx_sw_reserved_ia32;
  40 struct _fpstate_ia32;
  41 struct _xstate_ia32;
  42 extern int save_i387_xstate_ia32(void __user *buf);
  43 extern int restore_i387_xstate_ia32(void __user *buf);
  44 #endif
  45
  46 #define X87_FSW_ES (1 << 7)     /* Exception Summary */
  47
  48 #ifdef CONFIG_X86_64
  49
  50 /* Ignore delayed exceptions from user space */
  51 static inline void tolerant_fwait(void)
  52 {
  53         asm volatile("1: fwait\n"
  54                      "2:\n"
  55                      _ASM_EXTABLE(1b, 2b));
  56 }
  57
  58 static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
  59 {
  60         int err;
  61
  62         asm volatile("1:  rex64/fxrstor (%[fx])\n\t"
  63                      "2:\n"
  64                      ".section .fixup,\"ax\"\n"
  65                      "3:  movl $-1,%[err]\n"
  66                      "    jmp  2b\n"
  67                      ".previous\n"
  68                      _ASM_EXTABLE(1b, 3b)
  69                      : [err] "=r" (err)
  70 #if 0 /* See comment in fxsave() below. */
  71                      : [fx] "r" (fx), "m" (*fx), "0" (0));
  72 #else
  73                      : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
  74 #endif
  75         return err;
  76 }
  77
  78 /* AMD CPUs don't save/restore FDP/FIP/FOP unless an exception
  79    is pending. Clear the x87 state here by setting it to fixed
  80    values. The kernel data segment can be sometimes 0 and sometimes
  81    new user value. Both should be ok.
  82    Use the PDA as safe address because it should be already in L1. */
  83 static inline void clear_fpu_state(struct task_struct *tsk)
  84 {
  85         struct xsave_struct *xstate = &tsk->thread.xstate->xsave;
  86         struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
  87
  88         /*
  89          * xsave header may indicate the init state of the FP.
  90          */
  91         if ((task_thread_info(tsk)->status & TS_XSAVE) &&
  92             !(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
  93                 return;
  94
  95         if (unlikely(fx->swd & X87_FSW_ES))
  96                 asm volatile("fnclex");
  97         alternative_input(ASM_NOP8 ASM_NOP2,
  98                           "    emms\n"          /* clear stack tags */
  99                           "    fildl %%gs:0",   /* load to clear state */
 100                           X86_FEATURE_FXSAVE_LEAK);
 101 }
 102
 103 static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
 104 {
 105         int err;
 106
 107         asm volatile("1:  rex64/fxsave (%[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), "=m" (*fx)
 115 #if 0 /* See comment in fxsave() below. */
 116                      : [fx] "r" (fx), "0" (0));
 117 #else
 118                      : [fx] "cdaSDb" (fx), "0" (0));
 119 #endif
 120         if (unlikely(err) &&
 121             __clear_user(fx, sizeof(struct i387_fxsave_struct)))
 122                 err = -EFAULT;
 123         /* No need to clear here because the caller clears USED_MATH */
 124         return err;
 125 }
 126
 127 static inline void fxsave(struct task_struct *tsk)
 128 {
 129         /* Using "rex64; fxsave %0" is broken because, if the memory operand
 130            uses any extended registers for addressing, a second REX prefix
 131            will be generated (to the assembler, rex64 followed by semicolon
 132            is a separate instruction), and hence the 64-bitness is lost. */
 133 #if 0
 134         /* Using "fxsaveq %0" would be the ideal choice, but is only supported
 135            starting with gas 2.16. */
 136         __asm__ __volatile__("fxsaveq %0"
 137                              : "=m" (tsk->thread.xstate->fxsave));
 138 #elif 0
 139         /* Using, as a workaround, the properly prefixed form below isn't
 140            accepted by any binutils version so far released, complaining that
 141            the same type of prefix is used twice if an extended register is
 142            needed for addressing (fix submitted to mainline 2005-11-21). */
 143         __asm__ __volatile__("rex64/fxsave %0"
 144                              : "=m" (tsk->thread.xstate->fxsave));
 145 #else
 146         /* This, however, we can work around by forcing the compiler to select
 147            an addressing mode that doesn't require extended registers. */
 148         __asm__ __volatile__("rex64/fxsave (%1)"
 149                              : "=m" (tsk->thread.xstate->fxsave)
 150                              : "cdaSDb" (&tsk->thread.xstate->fxsave));
 151 #endif
 152 }
 153
 154 static inline void __save_init_fpu(struct task_struct *tsk)
 155 {
 156         if (task_thread_info(tsk)->status & TS_XSAVE)
 157                 xsave(tsk);
 158         else
 159                 fxsave(tsk);
 160
 161         clear_fpu_state(tsk);
 162         task_thread_info(tsk)->status &= ~TS_USEDFPU;
 163 }
 164
 165 #else  /* CONFIG_X86_32 */
 166
 167 #ifdef CONFIG_MATH_EMULATION
 168 extern void finit_task(struct task_struct *tsk);
 169 #else
 170 static inline void finit_task(struct task_struct *tsk)
 171 {
 172 }
 173 #endif
 174
 175 static inline void tolerant_fwait(void)
 176 {
 177         asm volatile("fnclex ; fwait");
 178 }
 179
 180 /* perform fxrstor iff the processor has extended states, otherwise frstor */
 181 static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
 182 {
 183         /*
 184          * The "nop" is needed to make the instructions the same
 185          * length.
 186          */
 187         alternative_input(
 188                 "nop ; frstor %1",
 189                 "fxrstor %1",
 190                 X86_FEATURE_FXSR,
 191                 "m" (*fx));
 192
 193         return 0;
 194 }
 195
 196 /* We need a safe address that is cheap to find and that is already
 197    in L1 during context switch. The best choices are unfortunately
 198    different for UP and SMP */
 199 #ifdef CONFIG_SMP
 200 #define safe_address (__per_cpu_offset[0])
 201 #else
 202 #define safe_address (kstat_cpu(0).cpustat.user)
 203 #endif
 204
 205 /*
 206  * These must be called with preempt disabled
 207  */
 208 static inline void __save_init_fpu(struct task_struct *tsk)
 209 {
 210         if (task_thread_info(tsk)->status & TS_XSAVE) {
 211                 struct xsave_struct *xstate = &tsk->thread.xstate->xsave;
 212                 struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
 213
 214                 xsave(tsk);
 215
 216                 /*
 217                  * xsave header may indicate the init state of the FP.
 218                  */
 219                 if (!(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
 220                         goto end;
 221
 222                 if (unlikely(fx->swd & X87_FSW_ES))
 223                         asm volatile("fnclex");
 224
 225                 /*
 226                  * we can do a simple return here or be paranoid :)
 227                  */
 228                 goto clear_state;
 229         }
 230
 231         /* Use more nops than strictly needed in case the compiler
 232            varies code */
 233         alternative_input(
 234                 "fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
 235                 "fxsave %[fx]\n"
 236                 "bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
 237                 X86_FEATURE_FXSR,
 238                 [fx] "m" (tsk->thread.xstate->fxsave),
 239                 [fsw] "m" (tsk->thread.xstate->fxsave.swd) : "memory");
 240 clear_state:
 241         /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
 242            is pending.  Clear the x87 state here by setting it to fixed
 243            values. safe_address is a random variable that should be in L1 */
 244         alternative_input(
 245                 GENERIC_NOP8 GENERIC_NOP2,
 246                 "emms\n\t"              /* clear stack tags */
 247                 "fildl %[addr]",        /* set F?P to defined value */
 248                 X86_FEATURE_FXSAVE_LEAK,
 249                 [addr] "m" (safe_address));
 250 end:
 251         task_thread_info(tsk)->status &= ~TS_USEDFPU;
 252 }
 253
 254 #endif  /* CONFIG_X86_64 */
 255
 256 static inline int restore_fpu_checking(struct task_struct *tsk)
 257 {
 258         if (task_thread_info(tsk)->status & TS_XSAVE)
 259                 return xrstor_checking(&tsk->thread.xstate->xsave);
 260         else
 261                 return fxrstor_checking(&tsk->thread.xstate->fxsave);
 262 }
 263
 264 /*
 265  * Signal frame handlers...
 266  */
 267 extern int save_i387_xstate(void __user *buf);
 268 extern int restore_i387_xstate(void __user *buf);
 269
 270 static inline void __unlazy_fpu(struct task_struct *tsk)
 271 {
 272         if (task_thread_info(tsk)->status & TS_USEDFPU) {
 273                 __save_init_fpu(tsk);
 274                 stts();
 275         } else
 276                 tsk->fpu_counter = 0;
 277 }
 278
 279 static inline void __clear_fpu(struct task_struct *tsk)
 280 {
 281         if (task_thread_info(tsk)->status & TS_USEDFPU) {
 282                 tolerant_fwait();
 283                 task_thread_info(tsk)->status &= ~TS_USEDFPU;
 284                 stts();
 285         }
 286 }
 287
 288 static inline void kernel_fpu_begin(void)
 289 {
 290         struct thread_info *me = current_thread_info();
 291         preempt_disable();
 292         if (me->status & TS_USEDFPU)
 293                 __save_init_fpu(me->task);
 294         else
 295                 clts();
 296 }
 297
 298 static inline void kernel_fpu_end(void)
 299 {
 300         stts();
 301         preempt_enable();
 302 }
 303
 304 /*
 305  * Some instructions like VIA's padlock instructions generate a spurious
 306  * DNA fault but don't modify SSE registers. And these instructions
 307  * get used from interrupt context as well. To prevent these kernel instructions
 308  * in interrupt context interacting wrongly with other user/kernel fpu usage, we
 309  * should use them only in the context of irq_ts_save/restore()
 310  */
 311 static inline int irq_ts_save(void)
 312 {
 313         /*
 314          * If in process context and not atomic, we can take a spurious DNA fault.
 315          * Otherwise, doing clts() in process context requires disabling preemption
 316          * or some heavy lifting like kernel_fpu_begin()
 317          */
 318         if (!in_atomic())
 319                 return 0;
 320
 321         if (read_cr0() & X86_CR0_TS) {
 322                 clts();
 323                 return 1;
 324         }
 325
 326         return 0;
 327 }
 328
 329 static inline void irq_ts_restore(int TS_state)
 330 {
 331         if (TS_state)
 332                 stts();
 333 }
 334
 335 #ifdef CONFIG_X86_64
 336
 337 static inline void save_init_fpu(struct task_struct *tsk)
 338 {
 339         __save_init_fpu(tsk);
 340         stts();
 341 }
 342
 343 #define unlazy_fpu      __unlazy_fpu
 344 #define clear_fpu       __clear_fpu
 345
 346 #else  /* CONFIG_X86_32 */
 347
 348 /*
 349  * These disable preemption on their own and are safe
 350  */
 351 static inline void save_init_fpu(struct task_struct *tsk)
 352 {
 353         preempt_disable();
 354         __save_init_fpu(tsk);
 355         stts();
 356         preempt_enable();
 357 }
 358
 359 static inline void unlazy_fpu(struct task_struct *tsk)
 360 {
 361         preempt_disable();
 362         __unlazy_fpu(tsk);
 363         preempt_enable();
 364 }
 365
 366 static inline void clear_fpu(struct task_struct *tsk)
 367 {
 368         preempt_disable();
 369         __clear_fpu(tsk);
 370         preempt_enable();
 371 }
 372
 373 #endif  /* CONFIG_X86_64 */
 374
 375 /*
 376  * i387 state interaction
 377  */
 378 static inline unsigned short get_fpu_cwd(struct task_struct *tsk)
 379 {
 380         if (cpu_has_fxsr) {
 381                 return tsk->thread.xstate->fxsave.cwd;
 382         } else {
 383                 return (unsigned short)tsk->thread.xstate->fsave.cwd;
 384         }
 385 }
 386
 387 static inline unsigned short get_fpu_swd(struct task_struct *tsk)
 388 {
 389         if (cpu_has_fxsr) {
 390                 return tsk->thread.xstate->fxsave.swd;
 391         } else {
 392                 return (unsigned short)tsk->thread.xstate->fsave.swd;
 393         }
 394 }
 395
 396 static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
 397 {
 398         if (cpu_has_xmm) {
 399                 return tsk->thread.xstate->fxsave.mxcsr;
 400         } else {
 401                 return MXCSR_DEFAULT;
 402         }
 403 }
 404
 405 #endif /* _ASM_X86_I387_H */