2 * xsave/xrstor support.
4 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
6 #include <linux/bootmem.h>
7 #include <linux/compat.h>
9 #ifdef CONFIG_IA32_EMULATION
10 #include <asm/sigcontext32.h>
15 * Supported feature mask by the CPU and the kernel.
19 struct _fpx_sw_bytes fx_sw_reserved
;
20 #ifdef CONFIG_IA32_EMULATION
21 struct _fpx_sw_bytes fx_sw_reserved_ia32
;
25 * Check for the presence of extended state information in the
26 * user fpstate pointer in the sigcontext.
28 int check_for_xstate(struct i387_fxsave_struct __user
*buf
,
30 struct _fpx_sw_bytes
*fx_sw_user
)
32 int min_xstate_size
= sizeof(struct i387_fxsave_struct
) +
33 sizeof(struct xsave_hdr_struct
);
37 err
= __copy_from_user(fx_sw_user
, &buf
->sw_reserved
[0],
38 sizeof(struct _fpx_sw_bytes
));
43 * First Magic check failed.
45 if (fx_sw_user
->magic1
!= FP_XSTATE_MAGIC1
)
49 * Check for error scenarios.
51 if (fx_sw_user
->xstate_size
< min_xstate_size
||
52 fx_sw_user
->xstate_size
> xstate_size
||
53 fx_sw_user
->xstate_size
> fx_sw_user
->extended_size
)
56 err
= __get_user(magic2
, (__u32
*) (((void *)fpstate
) +
57 fx_sw_user
->extended_size
-
58 FP_XSTATE_MAGIC2_SIZE
));
62 * Check for the presence of second magic word at the end of memory
63 * layout. This detects the case where the user just copied the legacy
64 * fpstate layout with out copying the extended state information
65 * in the memory layout.
67 if (magic2
!= FP_XSTATE_MAGIC2
)
75 * Signal frame handlers.
78 int save_i387_xstate(void __user
*buf
)
80 struct task_struct
*tsk
= current
;
83 if (!access_ok(VERIFY_WRITE
, buf
, sig_xstate_size
))
86 BUG_ON(sig_xstate_size
< xstate_size
);
88 if ((unsigned long)buf
% 64)
89 printk("save_i387_xstate: bad fpstate %p\n", buf
);
94 if (task_thread_info(tsk
)->status
& TS_USEDFPU
) {
96 * Start with clearing the user buffer. This will present a
97 * clean context for the bytes not touched by the fxsave/xsave.
99 err
= __clear_user(buf
, sig_xstate_size
);
104 err
= xsave_user(buf
);
106 err
= fxsave_user(buf
);
110 task_thread_info(tsk
)->status
&= ~TS_USEDFPU
;
113 if (__copy_to_user(buf
, &tsk
->thread
.fpu
.state
->fxsave
,
118 clear_used_math(); /* trigger finit */
121 struct _fpstate __user
*fx
= buf
;
122 struct _xstate __user
*x
= buf
;
125 err
= __copy_to_user(&fx
->sw_reserved
, &fx_sw_reserved
,
126 sizeof(struct _fpx_sw_bytes
));
128 err
|= __put_user(FP_XSTATE_MAGIC2
,
129 (__u32 __user
*) (buf
+ sig_xstate_size
130 - FP_XSTATE_MAGIC2_SIZE
));
133 * Read the xstate_bv which we copied (directly from the cpu or
134 * from the state in task struct) to the user buffers and
135 * set the FP/SSE bits.
137 err
|= __get_user(xstate_bv
, &x
->xstate_hdr
.xstate_bv
);
140 * For legacy compatible, we always set FP/SSE bits in the bit
141 * vector while saving the state to the user context. This will
142 * enable us capturing any changes(during sigreturn) to
143 * the FP/SSE bits by the legacy applications which don't touch
144 * xstate_bv in the xsave header.
146 * xsave aware apps can change the xstate_bv in the xsave
147 * header as well as change any contents in the memory layout.
148 * xrestore as part of sigreturn will capture all the changes.
150 xstate_bv
|= XSTATE_FPSSE
;
152 err
|= __put_user(xstate_bv
, &x
->xstate_hdr
.xstate_bv
);
162 * Restore the extended state if present. Otherwise, restore the FP/SSE
165 static int restore_user_xstate(void __user
*buf
)
167 struct _fpx_sw_bytes fx_sw_user
;
171 if (((unsigned long)buf
% 64) ||
172 check_for_xstate(buf
, buf
, &fx_sw_user
))
175 mask
= fx_sw_user
.xstate_bv
;
178 * restore the state passed by the user.
180 err
= xrestore_user(buf
, mask
);
185 * init the state skipped by the user.
187 mask
= pcntxt_mask
& ~mask
;
189 xrstor_state(init_xstate_buf
, mask
);
195 * couldn't find the extended state information in the
196 * memory layout. Restore just the FP/SSE and init all
197 * the other extended state.
199 xrstor_state(init_xstate_buf
, pcntxt_mask
& ~XSTATE_FPSSE
);
200 return fxrstor_checking((__force
struct i387_fxsave_struct
*)buf
);
204 * This restores directly out of user space. Exceptions are handled.
206 int restore_i387_xstate(void __user
*buf
)
208 struct task_struct
*tsk
= current
;
216 if (!access_ok(VERIFY_READ
, buf
, sig_xstate_size
))
225 if (!(task_thread_info(current
)->status
& TS_USEDFPU
)) {
227 task_thread_info(current
)->status
|= TS_USEDFPU
;
230 err
= restore_user_xstate(buf
);
232 err
= fxrstor_checking((__force
struct i387_fxsave_struct
*)
236 * Encountered an error while doing the restore from the
237 * user buffer, clear the fpu state.
248 * Prepare the SW reserved portion of the fxsave memory layout, indicating
249 * the presence of the extended state information in the memory layout
250 * pointed by the fpstate pointer in the sigcontext.
251 * This will be saved when ever the FP and extended state context is
252 * saved on the user stack during the signal handler delivery to the user.
254 static void prepare_fx_sw_frame(void)
256 int size_extended
= (xstate_size
- sizeof(struct i387_fxsave_struct
)) +
257 FP_XSTATE_MAGIC2_SIZE
;
259 sig_xstate_size
= sizeof(struct _fpstate
) + size_extended
;
261 #ifdef CONFIG_IA32_EMULATION
262 sig_xstate_ia32_size
= sizeof(struct _fpstate_ia32
) + size_extended
;
265 memset(&fx_sw_reserved
, 0, sizeof(fx_sw_reserved
));
267 fx_sw_reserved
.magic1
= FP_XSTATE_MAGIC1
;
268 fx_sw_reserved
.extended_size
= sig_xstate_size
;
269 fx_sw_reserved
.xstate_bv
= pcntxt_mask
;
270 fx_sw_reserved
.xstate_size
= xstate_size
;
271 #ifdef CONFIG_IA32_EMULATION
272 memcpy(&fx_sw_reserved_ia32
, &fx_sw_reserved
,
273 sizeof(struct _fpx_sw_bytes
));
274 fx_sw_reserved_ia32
.extended_size
= sig_xstate_ia32_size
;
279 * Represents init state for the supported extended state.
281 struct xsave_struct
*init_xstate_buf
;
284 unsigned int sig_xstate_size
= sizeof(struct _fpstate
);
288 * Enable the extended processor state save/restore feature
290 void __cpuinit
xsave_init(void)
295 set_in_cr4(X86_CR4_OSXSAVE
);
298 * Enable all the features that the HW is capable of
299 * and the Linux kernel is aware of.
301 xsetbv(XCR_XFEATURE_ENABLED_MASK
, pcntxt_mask
);
305 * setup the xstate image representing the init state
307 static void __init
setup_xstate_init(void)
309 init_xstate_buf
= alloc_bootmem(xstate_size
);
310 init_xstate_buf
->i387
.mxcsr
= MXCSR_DEFAULT
;
314 * Enable and initialize the xsave feature.
316 void __ref
xsave_cntxt_init(void)
318 unsigned int eax
, ebx
, ecx
, edx
;
320 cpuid_count(0xd, 0, &eax
, &ebx
, &ecx
, &edx
);
321 pcntxt_mask
= eax
+ ((u64
)edx
<< 32);
323 if ((pcntxt_mask
& XSTATE_FPSSE
) != XSTATE_FPSSE
) {
324 printk(KERN_ERR
"FP/SSE not shown under xsave features 0x%llx\n",
330 * Support only the state known to OS.
332 pcntxt_mask
= pcntxt_mask
& XCNTXT_MASK
;
336 * Recompute the context size for enabled features
338 cpuid_count(0xd, 0, &eax
, &ebx
, &ecx
, &edx
);
341 update_regset_xstate_info(xstate_size
, pcntxt_mask
);
342 prepare_fx_sw_frame();
346 printk(KERN_INFO
"xsave/xrstor: enabled xstate_bv 0x%llx, "
348 pcntxt_mask
, xstate_size
);