2 * xsave/xrstor support.
4 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/bootmem.h>
10 #include <linux/compat.h>
11 #include <linux/cpu.h>
12 #include <asm/fpu/api.h>
13 #include <asm/fpu/internal.h>
14 #include <asm/sigframe.h>
15 #include <asm/tlbflush.h>
19 * Supported feature mask by the CPU and the kernel.
24 * Represents init state for the supported extended state.
26 struct xsave_struct
*init_xstate_buf
;
28 static struct _fpx_sw_bytes fx_sw_reserved
, fx_sw_reserved_ia32
;
29 static unsigned int *xstate_offsets
, *xstate_sizes
;
30 static unsigned int xstate_comp_offsets
[sizeof(pcntxt_mask
)*8];
31 static unsigned int xstate_features
;
34 * If a processor implementation discern that a processor state component is
35 * in its initialized state it may modify the corresponding bit in the
36 * xsave_hdr.xstate_bv as '0', with out modifying the corresponding memory
37 * layout in the case of xsaveopt. While presenting the xstate information to
38 * the user, we always ensure that the memory layout of a feature will be in
39 * the init state if the corresponding header bit is zero. This is to ensure
40 * that the user doesn't see some stale state in the memory layout during
41 * signal handling, debugging etc.
43 void __sanitize_i387_state(struct task_struct
*tsk
)
45 struct i387_fxsave_struct
*fx
= &tsk
->thread
.fpu
.state
->fxsave
;
46 int feature_bit
= 0x2;
52 xstate_bv
= tsk
->thread
.fpu
.state
->xsave
.xsave_hdr
.xstate_bv
;
55 * None of the feature bits are in init state. So nothing else
56 * to do for us, as the memory layout is up to date.
58 if ((xstate_bv
& pcntxt_mask
) == pcntxt_mask
)
64 if (!(xstate_bv
& XSTATE_FP
)) {
71 memset(&fx
->st_space
[0], 0, 128);
75 * SSE is in init state
77 if (!(xstate_bv
& XSTATE_SSE
))
78 memset(&fx
->xmm_space
[0], 0, 256);
80 xstate_bv
= (pcntxt_mask
& ~xstate_bv
) >> 2;
83 * Update all the other memory layouts for which the corresponding
84 * header bit is in the init state.
87 if (xstate_bv
& 0x1) {
88 int offset
= xstate_offsets
[feature_bit
];
89 int size
= xstate_sizes
[feature_bit
];
91 memcpy(((void *) fx
) + offset
,
92 ((void *) init_xstate_buf
) + offset
,
102 * Check for the presence of extended state information in the
103 * user fpstate pointer in the sigcontext.
105 static inline int check_for_xstate(struct i387_fxsave_struct __user
*buf
,
106 void __user
*fpstate
,
107 struct _fpx_sw_bytes
*fx_sw
)
109 int min_xstate_size
= sizeof(struct i387_fxsave_struct
) +
110 sizeof(struct xsave_hdr_struct
);
113 if (__copy_from_user(fx_sw
, &buf
->sw_reserved
[0], sizeof(*fx_sw
)))
116 /* Check for the first magic field and other error scenarios. */
117 if (fx_sw
->magic1
!= FP_XSTATE_MAGIC1
||
118 fx_sw
->xstate_size
< min_xstate_size
||
119 fx_sw
->xstate_size
> xstate_size
||
120 fx_sw
->xstate_size
> fx_sw
->extended_size
)
124 * Check for the presence of second magic word at the end of memory
125 * layout. This detects the case where the user just copied the legacy
126 * fpstate layout with out copying the extended state information
127 * in the memory layout.
129 if (__get_user(magic2
, (__u32 __user
*)(fpstate
+ fx_sw
->xstate_size
))
130 || magic2
!= FP_XSTATE_MAGIC2
)
137 * Signal frame handlers.
139 static inline int save_fsave_header(struct task_struct
*tsk
, void __user
*buf
)
142 struct xsave_struct
*xsave
= &tsk
->thread
.fpu
.state
->xsave
;
143 struct user_i387_ia32_struct env
;
144 struct _fpstate_ia32 __user
*fp
= buf
;
146 convert_from_fxsr(&env
, tsk
);
148 if (__copy_to_user(buf
, &env
, sizeof(env
)) ||
149 __put_user(xsave
->i387
.swd
, &fp
->status
) ||
150 __put_user(X86_FXSR_MAGIC
, &fp
->magic
))
153 struct i387_fsave_struct __user
*fp
= buf
;
155 if (__get_user(swd
, &fp
->swd
) || __put_user(swd
, &fp
->status
))
162 static inline int save_xstate_epilog(void __user
*buf
, int ia32_frame
)
164 struct xsave_struct __user
*x
= buf
;
165 struct _fpx_sw_bytes
*sw_bytes
;
169 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
170 sw_bytes
= ia32_frame
? &fx_sw_reserved_ia32
: &fx_sw_reserved
;
171 err
= __copy_to_user(&x
->i387
.sw_reserved
, sw_bytes
, sizeof(*sw_bytes
));
176 err
|= __put_user(FP_XSTATE_MAGIC2
, (__u32
*)(buf
+ xstate_size
));
179 * Read the xstate_bv which we copied (directly from the cpu or
180 * from the state in task struct) to the user buffers.
182 err
|= __get_user(xstate_bv
, (__u32
*)&x
->xsave_hdr
.xstate_bv
);
185 * For legacy compatible, we always set FP/SSE bits in the bit
186 * vector while saving the state to the user context. This will
187 * enable us capturing any changes(during sigreturn) to
188 * the FP/SSE bits by the legacy applications which don't touch
189 * xstate_bv in the xsave header.
191 * xsave aware apps can change the xstate_bv in the xsave
192 * header as well as change any contents in the memory layout.
193 * xrestore as part of sigreturn will capture all the changes.
195 xstate_bv
|= XSTATE_FPSSE
;
197 err
|= __put_user(xstate_bv
, (__u32
*)&x
->xsave_hdr
.xstate_bv
);
202 static inline int save_user_xstate(struct xsave_struct __user
*buf
)
207 err
= xsave_user(buf
);
209 err
= fxsave_user((struct i387_fxsave_struct __user
*) buf
);
211 err
= fsave_user((struct i387_fsave_struct __user
*) buf
);
213 if (unlikely(err
) && __clear_user(buf
, xstate_size
))
219 * Save the fpu, extended register state to the user signal frame.
221 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
223 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
225 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
226 * buf != buf_fx for 32-bit frames with fxstate.
228 * If the fpu, extended register state is live, save the state directly
229 * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
230 * copy the thread's fpu state to the user frame starting at 'buf_fx'.
232 * If this is a 32-bit frame with fxstate, put a fsave header before
233 * the aligned state at 'buf_fx'.
235 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
236 * indicating the absence/presence of the extended state to the user.
238 int save_xstate_sig(void __user
*buf
, void __user
*buf_fx
, int size
)
240 struct xsave_struct
*xsave
= ¤t
->thread
.fpu
.state
->xsave
;
241 struct task_struct
*tsk
= current
;
242 int ia32_fxstate
= (buf
!= buf_fx
);
244 ia32_fxstate
&= (config_enabled(CONFIG_X86_32
) ||
245 config_enabled(CONFIG_IA32_EMULATION
));
247 if (!access_ok(VERIFY_WRITE
, buf
, size
))
250 if (!static_cpu_has(X86_FEATURE_FPU
))
251 return fpregs_soft_get(current
, NULL
, 0,
252 sizeof(struct user_i387_ia32_struct
), NULL
,
253 (struct _fpstate_ia32 __user
*) buf
) ? -1 : 1;
255 if (user_has_fpu()) {
256 /* Save the live register state to the user directly. */
257 if (save_user_xstate(buf_fx
))
259 /* Update the thread's fxstate to save the fsave header. */
261 fpu_fxsave(&tsk
->thread
.fpu
);
263 sanitize_i387_state(tsk
);
264 if (__copy_to_user(buf_fx
, xsave
, xstate_size
))
268 /* Save the fsave header for the 32-bit frames. */
269 if ((ia32_fxstate
|| !use_fxsr()) && save_fsave_header(tsk
, buf
))
272 if (use_fxsr() && save_xstate_epilog(buf_fx
, ia32_fxstate
))
279 sanitize_restored_xstate(struct task_struct
*tsk
,
280 struct user_i387_ia32_struct
*ia32_env
,
281 u64 xstate_bv
, int fx_only
)
283 struct xsave_struct
*xsave
= &tsk
->thread
.fpu
.state
->xsave
;
284 struct xsave_hdr_struct
*xsave_hdr
= &xsave
->xsave_hdr
;
287 /* These bits must be zero. */
288 memset(xsave_hdr
->reserved
, 0, 48);
291 * Init the state that is not present in the memory
292 * layout and not enabled by the OS.
295 xsave_hdr
->xstate_bv
= XSTATE_FPSSE
;
297 xsave_hdr
->xstate_bv
&= (pcntxt_mask
& xstate_bv
);
302 * mscsr reserved bits must be masked to zero for security
305 xsave
->i387
.mxcsr
&= mxcsr_feature_mask
;
307 convert_to_fxsr(tsk
, ia32_env
);
312 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
314 static inline int restore_user_xstate(void __user
*buf
, u64 xbv
, int fx_only
)
317 if ((unsigned long)buf
% 64 || fx_only
) {
318 u64 init_bv
= pcntxt_mask
& ~XSTATE_FPSSE
;
319 xrstor_state(init_xstate_buf
, init_bv
);
320 return fxrstor_user(buf
);
322 u64 init_bv
= pcntxt_mask
& ~xbv
;
323 if (unlikely(init_bv
))
324 xrstor_state(init_xstate_buf
, init_bv
);
325 return xrestore_user(buf
, xbv
);
327 } else if (use_fxsr()) {
328 return fxrstor_user(buf
);
330 return frstor_user(buf
);
333 int __restore_xstate_sig(void __user
*buf
, void __user
*buf_fx
, int size
)
335 int ia32_fxstate
= (buf
!= buf_fx
);
336 struct task_struct
*tsk
= current
;
337 struct fpu
*fpu
= &tsk
->thread
.fpu
;
338 int state_size
= xstate_size
;
342 ia32_fxstate
&= (config_enabled(CONFIG_X86_32
) ||
343 config_enabled(CONFIG_IA32_EMULATION
));
346 fpu_reset_state(fpu
);
350 if (!access_ok(VERIFY_READ
, buf
, size
))
353 if (!fpu
->fpstate_active
&& fpstate_alloc_init(fpu
))
356 if (!static_cpu_has(X86_FEATURE_FPU
))
357 return fpregs_soft_set(current
, NULL
,
358 0, sizeof(struct user_i387_ia32_struct
),
362 struct _fpx_sw_bytes fx_sw_user
;
363 if (unlikely(check_for_xstate(buf_fx
, buf_fx
, &fx_sw_user
))) {
365 * Couldn't find the extended state information in the
366 * memory layout. Restore just the FP/SSE and init all
367 * the other extended state.
369 state_size
= sizeof(struct i387_fxsave_struct
);
372 state_size
= fx_sw_user
.xstate_size
;
373 xstate_bv
= fx_sw_user
.xstate_bv
;
379 * For 32-bit frames with fxstate, copy the user state to the
380 * thread's fpu state, reconstruct fxstate from the fsave
381 * header. Sanitize the copied state etc.
383 struct fpu
*fpu
= &tsk
->thread
.fpu
;
384 struct user_i387_ia32_struct env
;
388 * Drop the current fpu which clears fpu->fpstate_active. This ensures
389 * that any context-switch during the copy of the new state,
390 * avoids the intermediate state from getting restored/saved.
391 * Thus avoiding the new restored state from getting corrupted.
392 * We will be ready to restore/save the state only after
393 * fpu->fpstate_active is again set.
397 if (__copy_from_user(&fpu
->state
->xsave
, buf_fx
, state_size
) ||
398 __copy_from_user(&env
, buf
, sizeof(env
))) {
402 sanitize_restored_xstate(tsk
, &env
, xstate_bv
, fx_only
);
405 fpu
->fpstate_active
= 1;
406 if (use_eager_fpu()) {
415 * For 64-bit frames and 32-bit fsave frames, restore the user
416 * state to the registers directly (with exceptions handled).
419 if (restore_user_xstate(buf_fx
, xstate_bv
, fx_only
)) {
420 fpu_reset_state(fpu
);
429 * Prepare the SW reserved portion of the fxsave memory layout, indicating
430 * the presence of the extended state information in the memory layout
431 * pointed by the fpstate pointer in the sigcontext.
432 * This will be saved when ever the FP and extended state context is
433 * saved on the user stack during the signal handler delivery to the user.
435 static void prepare_fx_sw_frame(void)
437 int fsave_header_size
= sizeof(struct i387_fsave_struct
);
438 int size
= xstate_size
+ FP_XSTATE_MAGIC2_SIZE
;
440 if (config_enabled(CONFIG_X86_32
))
441 size
+= fsave_header_size
;
443 fx_sw_reserved
.magic1
= FP_XSTATE_MAGIC1
;
444 fx_sw_reserved
.extended_size
= size
;
445 fx_sw_reserved
.xstate_bv
= pcntxt_mask
;
446 fx_sw_reserved
.xstate_size
= xstate_size
;
448 if (config_enabled(CONFIG_IA32_EMULATION
)) {
449 fx_sw_reserved_ia32
= fx_sw_reserved
;
450 fx_sw_reserved_ia32
.extended_size
+= fsave_header_size
;
455 * Enable the extended processor state save/restore feature
457 static inline void xstate_enable(void)
459 cr4_set_bits(X86_CR4_OSXSAVE
);
460 xsetbv(XCR_XFEATURE_ENABLED_MASK
, pcntxt_mask
);
464 * Record the offsets and sizes of different state managed by the xsave
467 static void __init
setup_xstate_features(void)
469 int eax
, ebx
, ecx
, edx
, leaf
= 0x2;
471 xstate_features
= fls64(pcntxt_mask
);
472 xstate_offsets
= alloc_bootmem(xstate_features
* sizeof(int));
473 xstate_sizes
= alloc_bootmem(xstate_features
* sizeof(int));
476 cpuid_count(XSTATE_CPUID
, leaf
, &eax
, &ebx
, &ecx
, &edx
);
481 xstate_offsets
[leaf
] = ebx
;
482 xstate_sizes
[leaf
] = eax
;
489 * This function sets up offsets and sizes of all extended states in
490 * xsave area. This supports both standard format and compacted format
491 * of the xsave aread.
496 void setup_xstate_comp(void)
498 unsigned int xstate_comp_sizes
[sizeof(pcntxt_mask
)*8];
502 * The FP xstates and SSE xstates are legacy states. They are always
503 * in the fixed offsets in the xsave area in either compacted form
506 xstate_comp_offsets
[0] = 0;
507 xstate_comp_offsets
[1] = offsetof(struct i387_fxsave_struct
, xmm_space
);
509 if (!cpu_has_xsaves
) {
510 for (i
= 2; i
< xstate_features
; i
++) {
511 if (test_bit(i
, (unsigned long *)&pcntxt_mask
)) {
512 xstate_comp_offsets
[i
] = xstate_offsets
[i
];
513 xstate_comp_sizes
[i
] = xstate_sizes
[i
];
519 xstate_comp_offsets
[2] = FXSAVE_SIZE
+ XSAVE_HDR_SIZE
;
521 for (i
= 2; i
< xstate_features
; i
++) {
522 if (test_bit(i
, (unsigned long *)&pcntxt_mask
))
523 xstate_comp_sizes
[i
] = xstate_sizes
[i
];
525 xstate_comp_sizes
[i
] = 0;
528 xstate_comp_offsets
[i
] = xstate_comp_offsets
[i
-1]
529 + xstate_comp_sizes
[i
-1];
535 * setup the xstate image representing the init state
537 static void __init
setup_init_fpu_buf(void)
540 * Setup init_xstate_buf to represent the init state of
541 * all the features managed by the xsave
543 init_xstate_buf
= alloc_bootmem_align(xstate_size
,
544 __alignof__(struct xsave_struct
));
545 fx_finit(&init_xstate_buf
->i387
);
550 setup_xstate_features();
552 if (cpu_has_xsaves
) {
553 init_xstate_buf
->xsave_hdr
.xcomp_bv
=
554 (u64
)1 << 63 | pcntxt_mask
;
555 init_xstate_buf
->xsave_hdr
.xstate_bv
= pcntxt_mask
;
559 * Init all the features state with header_bv being 0x0
561 xrstor_state_booting(init_xstate_buf
, -1);
564 * Dump the init state again. This is to identify the init state
565 * of any feature which is not represented by all zero's.
567 xsave_state_booting(init_xstate_buf
);
570 static enum { AUTO
, ENABLE
, DISABLE
} eagerfpu
= AUTO
;
571 static int __init
eager_fpu_setup(char *s
)
573 if (!strcmp(s
, "on"))
575 else if (!strcmp(s
, "off"))
577 else if (!strcmp(s
, "auto"))
581 __setup("eagerfpu=", eager_fpu_setup
);
585 * Calculate total size of enabled xstates in XCR0/pcntxt_mask.
587 static void __init
init_xstate_size(void)
589 unsigned int eax
, ebx
, ecx
, edx
;
592 if (!cpu_has_xsaves
) {
593 cpuid_count(XSTATE_CPUID
, 0, &eax
, &ebx
, &ecx
, &edx
);
598 xstate_size
= FXSAVE_SIZE
+ XSAVE_HDR_SIZE
;
599 for (i
= 2; i
< 64; i
++) {
600 if (test_bit(i
, (unsigned long *)&pcntxt_mask
)) {
601 cpuid_count(XSTATE_CPUID
, i
, &eax
, &ebx
, &ecx
, &edx
);
608 * Enable and initialize the xsave feature.
610 static void __init
xstate_enable_boot_cpu(void)
612 unsigned int eax
, ebx
, ecx
, edx
;
614 if (boot_cpu_data
.cpuid_level
< XSTATE_CPUID
) {
615 WARN(1, KERN_ERR
"XSTATE_CPUID missing\n");
619 cpuid_count(XSTATE_CPUID
, 0, &eax
, &ebx
, &ecx
, &edx
);
620 pcntxt_mask
= eax
+ ((u64
)edx
<< 32);
622 if ((pcntxt_mask
& XSTATE_FPSSE
) != XSTATE_FPSSE
) {
623 pr_err("FP/SSE not shown under xsave features 0x%llx\n",
629 * Support only the state known to OS.
631 pcntxt_mask
= pcntxt_mask
& XCNTXT_MASK
;
636 * Recompute the context size for enabled features
640 update_regset_xstate_info(xstate_size
, pcntxt_mask
);
641 prepare_fx_sw_frame();
642 setup_init_fpu_buf();
644 /* Auto enable eagerfpu for xsaveopt */
645 if (cpu_has_xsaveopt
&& eagerfpu
!= DISABLE
)
648 if (pcntxt_mask
& XSTATE_EAGER
) {
649 if (eagerfpu
== DISABLE
) {
650 pr_err("eagerfpu not present, disabling some xstate features: 0x%llx\n",
651 pcntxt_mask
& XSTATE_EAGER
);
652 pcntxt_mask
&= ~XSTATE_EAGER
;
658 pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x using %s\n",
659 pcntxt_mask
, xstate_size
,
660 cpu_has_xsaves
? "compacted form" : "standard form");
664 * For the very first instance, this calls xstate_enable_boot_cpu();
665 * for all subsequent instances, this calls xstate_enable().
667 * This is somewhat obfuscated due to the lack of powerful enough
668 * overrides for the section checks.
670 void xsave_init(void)
672 static __refdata
void (*next_func
)(void) = xstate_enable_boot_cpu
;
673 void (*this_func
)(void);
678 this_func
= next_func
;
679 next_func
= xstate_enable
;
684 * setup_init_fpu_buf() is __init and it is OK to call it here because
685 * init_xstate_buf will be unset only once during boot.
687 void __init_refok
eager_fpu_init(void)
689 WARN_ON(current
->thread
.fpu
.fpstate_active
);
690 current_thread_info()->status
= 0;
692 if (eagerfpu
== ENABLE
)
693 setup_force_cpu_cap(X86_FEATURE_EAGER_FPU
);
695 printk_once(KERN_INFO
"x86/fpu: Using '%s' FPU context switches.\n", eagerfpu
== ENABLE
? "eager" : "lazy");
697 if (!cpu_has_eager_fpu
) {
702 if (!init_xstate_buf
)
703 setup_init_fpu_buf();
707 * Given the xsave area and a state inside, this function returns the
708 * address of the state.
710 * This is the API that is called to get xstate address in either
711 * standard format or compacted format of xsave area.
714 * xsave: base address of the xsave area;
715 * xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE,
718 * address of the state in the xsave area.
720 void *get_xsave_addr(struct xsave_struct
*xsave
, int xstate
)
722 int feature
= fls64(xstate
) - 1;
723 if (!test_bit(feature
, (unsigned long *)&pcntxt_mask
))
726 return (void *)xsave
+ xstate_comp_offsets
[feature
];
728 EXPORT_SYMBOL_GPL(get_xsave_addr
);