2 * Copyright (C) 1994 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * General FPU state handling cleanups
6 * Gareth Hughes <gareth@valinux.com>, May 2000
8 #include <linux/module.h>
9 #include <linux/regset.h>
10 #include <linux/sched.h>
11 #include <linux/slab.h>
13 #include <asm/sigcontext.h>
14 #include <asm/processor.h>
15 #include <asm/math_emu.h>
16 #include <asm/uaccess.h>
17 #include <asm/ptrace.h>
19 #include <asm/fpu-internal.h>
23 * Were we in an interrupt that interrupted kernel mode?
25 * For now, with eagerfpu we will return interrupted kernel FPU
26 * state as not-idle. TBD: Ideally we can change the return value
27 * to something like __thread_has_fpu(current). But we need to
28 * be careful of doing __thread_clear_has_fpu() before saving
29 * the FPU etc for supporting nested uses etc. For now, take
32 * On others, we can do a kernel_fpu_begin/end() pair *ONLY* if that
33 * pair does nothing at all: the thread must not have fpu (so
34 * that we don't try to save the FPU state), and TS must
35 * be set (so that the clts/stts pair does nothing that is
36 * visible in the interrupted kernel thread).
38 static inline bool interrupted_kernel_fpu_idle(void)
43 return !__thread_has_fpu(current
) &&
44 (read_cr0() & X86_CR0_TS
);
48 * Were we in user mode (or vm86 mode) when we were
51 * Doing kernel_fpu_begin/end() is ok if we are running
52 * in an interrupt context from user mode - we'll just
53 * save the FPU state as required.
55 static inline bool interrupted_user_mode(void)
57 struct pt_regs
*regs
= get_irq_regs();
58 return regs
&& user_mode_vm(regs
);
62 * Can we use the FPU in kernel mode with the
63 * whole "kernel_fpu_begin/end()" sequence?
65 * It's always ok in process context (ie "not interrupt")
66 * but it is sometimes ok even from an irq.
68 bool irq_fpu_usable(void)
70 return !in_interrupt() ||
71 interrupted_user_mode() ||
72 interrupted_kernel_fpu_idle();
74 EXPORT_SYMBOL(irq_fpu_usable
);
76 void __kernel_fpu_begin(void)
78 struct task_struct
*me
= current
;
80 if (__thread_has_fpu(me
)) {
82 __thread_clear_has_fpu(me
);
83 /* We do 'stts()' in __kernel_fpu_end() */
84 } else if (!use_eager_fpu()) {
85 this_cpu_write(fpu_owner_task
, NULL
);
89 EXPORT_SYMBOL(__kernel_fpu_begin
);
91 void __kernel_fpu_end(void)
98 EXPORT_SYMBOL(__kernel_fpu_end
);
100 void unlazy_fpu(struct task_struct
*tsk
)
103 if (__thread_has_fpu(tsk
)) {
104 __save_init_fpu(tsk
);
105 __thread_fpu_end(tsk
);
107 tsk
->fpu_counter
= 0;
110 EXPORT_SYMBOL(unlazy_fpu
);
112 unsigned int mxcsr_feature_mask __read_mostly
= 0xffffffffu
;
113 unsigned int xstate_size
;
114 EXPORT_SYMBOL_GPL(xstate_size
);
115 static struct i387_fxsave_struct fx_scratch __cpuinitdata
;
117 static void __cpuinit
mxcsr_feature_mask_init(void)
119 unsigned long mask
= 0;
122 memset(&fx_scratch
, 0, sizeof(struct i387_fxsave_struct
));
123 asm volatile("fxsave %0" : : "m" (fx_scratch
));
124 mask
= fx_scratch
.mxcsr_mask
;
128 mxcsr_feature_mask
&= mask
;
131 static void __cpuinit
init_thread_xstate(void)
134 * Note that xstate_size might be overwriten later during
140 * Disable xsave as we do not support it if i387
141 * emulation is enabled.
143 setup_clear_cpu_cap(X86_FEATURE_XSAVE
);
144 setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT
);
145 xstate_size
= sizeof(struct i387_soft_struct
);
150 xstate_size
= sizeof(struct i387_fxsave_struct
);
152 xstate_size
= sizeof(struct i387_fsave_struct
);
156 * Called at bootup to set up the initial FPU state that is later cloned
157 * into all processes.
160 void __cpuinit
fpu_init(void)
163 unsigned long cr4_mask
= 0;
166 cr4_mask
|= X86_CR4_OSFXSR
;
168 cr4_mask
|= X86_CR4_OSXMMEXCPT
;
170 set_in_cr4(cr4_mask
);
173 cr0
&= ~(X86_CR0_TS
|X86_CR0_EM
); /* clear TS and EM */
178 if (!smp_processor_id())
179 init_thread_xstate();
181 mxcsr_feature_mask_init();
186 void fpu_finit(struct fpu
*fpu
)
189 finit_soft_fpu(&fpu
->state
->soft
);
194 fx_finit(&fpu
->state
->fxsave
);
196 struct i387_fsave_struct
*fp
= &fpu
->state
->fsave
;
197 memset(fp
, 0, xstate_size
);
198 fp
->cwd
= 0xffff037fu
;
199 fp
->swd
= 0xffff0000u
;
200 fp
->twd
= 0xffffffffu
;
201 fp
->fos
= 0xffff0000u
;
204 EXPORT_SYMBOL_GPL(fpu_finit
);
207 * The _current_ task is using the FPU for the first time
208 * so initialize it and set the mxcsr to its default
209 * value at reset if we support XMM instructions and then
210 * remember the current task has used the FPU.
212 int init_fpu(struct task_struct
*tsk
)
216 if (tsk_used_math(tsk
)) {
217 if (HAVE_HWFP
&& tsk
== current
)
219 tsk
->thread
.fpu
.last_cpu
= ~0;
224 * Memory allocation at the first usage of the FPU and other state.
226 ret
= fpu_alloc(&tsk
->thread
.fpu
);
230 fpu_finit(&tsk
->thread
.fpu
);
232 set_stopped_child_used_math(tsk
);
235 EXPORT_SYMBOL_GPL(init_fpu
);
238 * The xstateregs_active() routine is the same as the fpregs_active() routine,
239 * as the "regset->n" for the xstate regset will be updated based on the feature
240 * capabilites supported by the xsave.
242 int fpregs_active(struct task_struct
*target
, const struct user_regset
*regset
)
244 return tsk_used_math(target
) ? regset
->n
: 0;
247 int xfpregs_active(struct task_struct
*target
, const struct user_regset
*regset
)
249 return (cpu_has_fxsr
&& tsk_used_math(target
)) ? regset
->n
: 0;
252 int xfpregs_get(struct task_struct
*target
, const struct user_regset
*regset
,
253 unsigned int pos
, unsigned int count
,
254 void *kbuf
, void __user
*ubuf
)
261 ret
= init_fpu(target
);
265 sanitize_i387_state(target
);
267 return user_regset_copyout(&pos
, &count
, &kbuf
, &ubuf
,
268 &target
->thread
.fpu
.state
->fxsave
, 0, -1);
271 int xfpregs_set(struct task_struct
*target
, const struct user_regset
*regset
,
272 unsigned int pos
, unsigned int count
,
273 const void *kbuf
, const void __user
*ubuf
)
280 ret
= init_fpu(target
);
284 sanitize_i387_state(target
);
286 ret
= user_regset_copyin(&pos
, &count
, &kbuf
, &ubuf
,
287 &target
->thread
.fpu
.state
->fxsave
, 0, -1);
290 * mxcsr reserved bits must be masked to zero for security reasons.
292 target
->thread
.fpu
.state
->fxsave
.mxcsr
&= mxcsr_feature_mask
;
295 * update the header bits in the xsave header, indicating the
296 * presence of FP and SSE state.
299 target
->thread
.fpu
.state
->xsave
.xsave_hdr
.xstate_bv
|= XSTATE_FPSSE
;
304 int xstateregs_get(struct task_struct
*target
, const struct user_regset
*regset
,
305 unsigned int pos
, unsigned int count
,
306 void *kbuf
, void __user
*ubuf
)
313 ret
= init_fpu(target
);
318 * Copy the 48bytes defined by the software first into the xstate
319 * memory layout in the thread struct, so that we can copy the entire
320 * xstateregs to the user using one user_regset_copyout().
322 memcpy(&target
->thread
.fpu
.state
->fxsave
.sw_reserved
,
323 xstate_fx_sw_bytes
, sizeof(xstate_fx_sw_bytes
));
326 * Copy the xstate memory layout.
328 ret
= user_regset_copyout(&pos
, &count
, &kbuf
, &ubuf
,
329 &target
->thread
.fpu
.state
->xsave
, 0, -1);
333 int xstateregs_set(struct task_struct
*target
, const struct user_regset
*regset
,
334 unsigned int pos
, unsigned int count
,
335 const void *kbuf
, const void __user
*ubuf
)
338 struct xsave_hdr_struct
*xsave_hdr
;
343 ret
= init_fpu(target
);
347 ret
= user_regset_copyin(&pos
, &count
, &kbuf
, &ubuf
,
348 &target
->thread
.fpu
.state
->xsave
, 0, -1);
351 * mxcsr reserved bits must be masked to zero for security reasons.
353 target
->thread
.fpu
.state
->fxsave
.mxcsr
&= mxcsr_feature_mask
;
355 xsave_hdr
= &target
->thread
.fpu
.state
->xsave
.xsave_hdr
;
357 xsave_hdr
->xstate_bv
&= pcntxt_mask
;
359 * These bits must be zero.
361 xsave_hdr
->reserved1
[0] = xsave_hdr
->reserved1
[1] = 0;
366 #if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
369 * FPU tag word conversions.
372 static inline unsigned short twd_i387_to_fxsr(unsigned short twd
)
374 unsigned int tmp
; /* to avoid 16 bit prefixes in the code */
376 /* Transform each pair of bits into 01 (valid) or 00 (empty) */
378 tmp
= (tmp
| (tmp
>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
379 /* and move the valid bits to the lower byte. */
380 tmp
= (tmp
| (tmp
>> 1)) & 0x3333; /* 00VV00VV00VV00VV */
381 tmp
= (tmp
| (tmp
>> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
382 tmp
= (tmp
| (tmp
>> 4)) & 0x00ff; /* 00000000VVVVVVVV */
387 #define FPREG_ADDR(f, n) ((void *)&(f)->st_space + (n) * 16)
388 #define FP_EXP_TAG_VALID 0
389 #define FP_EXP_TAG_ZERO 1
390 #define FP_EXP_TAG_SPECIAL 2
391 #define FP_EXP_TAG_EMPTY 3
393 static inline u32
twd_fxsr_to_i387(struct i387_fxsave_struct
*fxsave
)
396 u32 tos
= (fxsave
->swd
>> 11) & 7;
397 u32 twd
= (unsigned long) fxsave
->twd
;
399 u32 ret
= 0xffff0000u
;
402 for (i
= 0; i
< 8; i
++, twd
>>= 1) {
404 st
= FPREG_ADDR(fxsave
, (i
- tos
) & 7);
406 switch (st
->exponent
& 0x7fff) {
408 tag
= FP_EXP_TAG_SPECIAL
;
411 if (!st
->significand
[0] &&
412 !st
->significand
[1] &&
413 !st
->significand
[2] &&
415 tag
= FP_EXP_TAG_ZERO
;
417 tag
= FP_EXP_TAG_SPECIAL
;
420 if (st
->significand
[3] & 0x8000)
421 tag
= FP_EXP_TAG_VALID
;
423 tag
= FP_EXP_TAG_SPECIAL
;
427 tag
= FP_EXP_TAG_EMPTY
;
429 ret
|= tag
<< (2 * i
);
435 * FXSR floating point environment conversions.
439 convert_from_fxsr(struct user_i387_ia32_struct
*env
, struct task_struct
*tsk
)
441 struct i387_fxsave_struct
*fxsave
= &tsk
->thread
.fpu
.state
->fxsave
;
442 struct _fpreg
*to
= (struct _fpreg
*) &env
->st_space
[0];
443 struct _fpxreg
*from
= (struct _fpxreg
*) &fxsave
->st_space
[0];
446 env
->cwd
= fxsave
->cwd
| 0xffff0000u
;
447 env
->swd
= fxsave
->swd
| 0xffff0000u
;
448 env
->twd
= twd_fxsr_to_i387(fxsave
);
451 env
->fip
= fxsave
->rip
;
452 env
->foo
= fxsave
->rdp
;
454 * should be actually ds/cs at fpu exception time, but
455 * that information is not available in 64bit mode.
457 env
->fcs
= task_pt_regs(tsk
)->cs
;
458 if (tsk
== current
) {
459 savesegment(ds
, env
->fos
);
461 env
->fos
= tsk
->thread
.ds
;
463 env
->fos
|= 0xffff0000;
465 env
->fip
= fxsave
->fip
;
466 env
->fcs
= (u16
) fxsave
->fcs
| ((u32
) fxsave
->fop
<< 16);
467 env
->foo
= fxsave
->foo
;
468 env
->fos
= fxsave
->fos
;
471 for (i
= 0; i
< 8; ++i
)
472 memcpy(&to
[i
], &from
[i
], sizeof(to
[0]));
475 void convert_to_fxsr(struct task_struct
*tsk
,
476 const struct user_i387_ia32_struct
*env
)
479 struct i387_fxsave_struct
*fxsave
= &tsk
->thread
.fpu
.state
->fxsave
;
480 struct _fpreg
*from
= (struct _fpreg
*) &env
->st_space
[0];
481 struct _fpxreg
*to
= (struct _fpxreg
*) &fxsave
->st_space
[0];
484 fxsave
->cwd
= env
->cwd
;
485 fxsave
->swd
= env
->swd
;
486 fxsave
->twd
= twd_i387_to_fxsr(env
->twd
);
487 fxsave
->fop
= (u16
) ((u32
) env
->fcs
>> 16);
489 fxsave
->rip
= env
->fip
;
490 fxsave
->rdp
= env
->foo
;
491 /* cs and ds ignored */
493 fxsave
->fip
= env
->fip
;
494 fxsave
->fcs
= (env
->fcs
& 0xffff);
495 fxsave
->foo
= env
->foo
;
496 fxsave
->fos
= env
->fos
;
499 for (i
= 0; i
< 8; ++i
)
500 memcpy(&to
[i
], &from
[i
], sizeof(from
[0]));
503 int fpregs_get(struct task_struct
*target
, const struct user_regset
*regset
,
504 unsigned int pos
, unsigned int count
,
505 void *kbuf
, void __user
*ubuf
)
507 struct user_i387_ia32_struct env
;
510 ret
= init_fpu(target
);
515 return fpregs_soft_get(target
, regset
, pos
, count
, kbuf
, ubuf
);
518 return user_regset_copyout(&pos
, &count
, &kbuf
, &ubuf
,
519 &target
->thread
.fpu
.state
->fsave
, 0,
523 sanitize_i387_state(target
);
525 if (kbuf
&& pos
== 0 && count
== sizeof(env
)) {
526 convert_from_fxsr(kbuf
, target
);
530 convert_from_fxsr(&env
, target
);
532 return user_regset_copyout(&pos
, &count
, &kbuf
, &ubuf
, &env
, 0, -1);
535 int fpregs_set(struct task_struct
*target
, const struct user_regset
*regset
,
536 unsigned int pos
, unsigned int count
,
537 const void *kbuf
, const void __user
*ubuf
)
539 struct user_i387_ia32_struct env
;
542 ret
= init_fpu(target
);
546 sanitize_i387_state(target
);
549 return fpregs_soft_set(target
, regset
, pos
, count
, kbuf
, ubuf
);
552 return user_regset_copyin(&pos
, &count
, &kbuf
, &ubuf
,
553 &target
->thread
.fpu
.state
->fsave
, 0, -1);
556 if (pos
> 0 || count
< sizeof(env
))
557 convert_from_fxsr(&env
, target
);
559 ret
= user_regset_copyin(&pos
, &count
, &kbuf
, &ubuf
, &env
, 0, -1);
561 convert_to_fxsr(target
, &env
);
564 * update the header bit in the xsave header, indicating the
568 target
->thread
.fpu
.state
->xsave
.xsave_hdr
.xstate_bv
|= XSTATE_FP
;
573 * FPU state for core dumps.
574 * This is only used for a.out dumps now.
575 * It is declared generically using elf_fpregset_t (which is
576 * struct user_i387_struct) but is in fact only used for 32-bit
577 * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
579 int dump_fpu(struct pt_regs
*regs
, struct user_i387_struct
*fpu
)
581 struct task_struct
*tsk
= current
;
584 fpvalid
= !!used_math();
586 fpvalid
= !fpregs_get(tsk
, NULL
,
587 0, sizeof(struct user_i387_ia32_struct
),
592 EXPORT_SYMBOL(dump_fpu
);
594 #endif /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */