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
));
44 * First Magic check failed.
46 if (fx_sw_user
->magic1
!= FP_XSTATE_MAGIC1
)
50 * Check for error scenarios.
52 if (fx_sw_user
->xstate_size
< min_xstate_size
||
53 fx_sw_user
->xstate_size
> xstate_size
||
54 fx_sw_user
->xstate_size
> fx_sw_user
->extended_size
)
57 err
= __get_user(magic2
, (__u32
*) (((void *)fpstate
) +
58 fx_sw_user
->extended_size
-
59 FP_XSTATE_MAGIC2_SIZE
));
61 * Check for the presence of second magic word at the end of memory
62 * layout. This detects the case where the user just copied the legacy
63 * fpstate layout with out copying the extended state information
64 * in the memory layout.
66 if (err
|| magic2
!= FP_XSTATE_MAGIC2
)
74 * Signal frame handlers.
77 int save_i387_xstate(void __user
*buf
)
79 struct task_struct
*tsk
= current
;
82 if (!access_ok(VERIFY_WRITE
, buf
, sig_xstate_size
))
85 BUG_ON(sig_xstate_size
< xstate_size
);
87 if ((unsigned long)buf
% 64)
88 printk("save_i387_xstate: bad fpstate %p\n", buf
);
93 if (task_thread_info(tsk
)->status
& TS_USEDFPU
) {
95 * Start with clearing the user buffer. This will present a
96 * clean context for the bytes not touched by the fxsave/xsave.
98 err
= __clear_user(buf
, sig_xstate_size
);
102 if (task_thread_info(tsk
)->status
& TS_XSAVE
)
103 err
= xsave_user(buf
);
105 err
= fxsave_user(buf
);
109 task_thread_info(tsk
)->status
&= ~TS_USEDFPU
;
112 if (__copy_to_user(buf
, &tsk
->thread
.xstate
->fxsave
,
117 clear_used_math(); /* trigger finit */
119 if (task_thread_info(tsk
)->status
& TS_XSAVE
) {
120 struct _fpstate __user
*fx
= buf
;
121 struct _xstate __user
*x
= buf
;
124 err
= __copy_to_user(&fx
->sw_reserved
, &fx_sw_reserved
,
125 sizeof(struct _fpx_sw_bytes
));
127 err
|= __put_user(FP_XSTATE_MAGIC2
,
128 (__u32 __user
*) (buf
+ sig_xstate_size
129 - FP_XSTATE_MAGIC2_SIZE
));
132 * Read the xstate_bv which we copied (directly from the cpu or
133 * from the state in task struct) to the user buffers and
134 * set the FP/SSE bits.
136 err
|= __get_user(xstate_bv
, &x
->xstate_hdr
.xstate_bv
);
139 * For legacy compatible, we always set FP/SSE bits in the bit
140 * vector while saving the state to the user context. This will
141 * enable us capturing any changes(during sigreturn) to
142 * the FP/SSE bits by the legacy applications which don't touch
143 * xstate_bv in the xsave header.
145 * xsave aware apps can change the xstate_bv in the xsave
146 * header as well as change any contents in the memory layout.
147 * xrestore as part of sigreturn will capture all the changes.
149 xstate_bv
|= XSTATE_FPSSE
;
151 err
|= __put_user(xstate_bv
, &x
->xstate_hdr
.xstate_bv
);
161 * Restore the extended state if present. Otherwise, restore the FP/SSE
164 static int restore_user_xstate(void __user
*buf
)
166 struct _fpx_sw_bytes fx_sw_user
;
170 if (((unsigned long)buf
% 64) ||
171 check_for_xstate(buf
, buf
, &fx_sw_user
))
174 mask
= fx_sw_user
.xstate_bv
;
177 * restore the state passed by the user.
179 err
= xrestore_user(buf
, mask
);
184 * init the state skipped by the user.
186 mask
= pcntxt_mask
& ~mask
;
188 xrstor_state(init_xstate_buf
, mask
);
194 * couldn't find the extended state information in the
195 * memory layout. Restore just the FP/SSE and init all
196 * the other extended state.
198 xrstor_state(init_xstate_buf
, pcntxt_mask
& ~XSTATE_FPSSE
);
199 return fxrstor_checking((__force
struct i387_fxsave_struct
*)buf
);
203 * This restores directly out of user space. Exceptions are handled.
205 int restore_i387_xstate(void __user
*buf
)
207 struct task_struct
*tsk
= current
;
215 if (!access_ok(VERIFY_READ
, buf
, sig_xstate_size
))
224 if (!(task_thread_info(current
)->status
& TS_USEDFPU
)) {
226 task_thread_info(current
)->status
|= TS_USEDFPU
;
228 if (task_thread_info(tsk
)->status
& TS_XSAVE
)
229 err
= restore_user_xstate(buf
);
231 err
= fxrstor_checking((__force
struct i387_fxsave_struct
*)
235 * Encountered an error while doing the restore from the
236 * user buffer, clear the fpu state.
247 * Prepare the SW reserved portion of the fxsave memory layout, indicating
248 * the presence of the extended state information in the memory layout
249 * pointed by the fpstate pointer in the sigcontext.
250 * This will be saved when ever the FP and extended state context is
251 * saved on the user stack during the signal handler delivery to the user.
253 static void prepare_fx_sw_frame(void)
255 int size_extended
= (xstate_size
- sizeof(struct i387_fxsave_struct
)) +
256 FP_XSTATE_MAGIC2_SIZE
;
258 sig_xstate_size
= sizeof(struct _fpstate
) + size_extended
;
260 #ifdef CONFIG_IA32_EMULATION
261 sig_xstate_ia32_size
= sizeof(struct _fpstate_ia32
) + size_extended
;
264 memset(&fx_sw_reserved
, 0, sizeof(fx_sw_reserved
));
266 fx_sw_reserved
.magic1
= FP_XSTATE_MAGIC1
;
267 fx_sw_reserved
.extended_size
= sig_xstate_size
;
268 fx_sw_reserved
.xstate_bv
= pcntxt_mask
;
269 fx_sw_reserved
.xstate_size
= xstate_size
;
270 #ifdef CONFIG_IA32_EMULATION
271 memcpy(&fx_sw_reserved_ia32
, &fx_sw_reserved
,
272 sizeof(struct _fpx_sw_bytes
));
273 fx_sw_reserved_ia32
.extended_size
= sig_xstate_ia32_size
;
278 * Represents init state for the supported extended state.
280 struct xsave_struct
*init_xstate_buf
;
283 unsigned int sig_xstate_size
= sizeof(struct _fpstate
);
287 * Enable the extended processor state save/restore feature
289 void __cpuinit
xsave_init(void)
294 set_in_cr4(X86_CR4_OSXSAVE
);
297 * Enable all the features that the HW is capable of
298 * and the Linux kernel is aware of.
300 xsetbv(XCR_XFEATURE_ENABLED_MASK
, pcntxt_mask
);
304 * setup the xstate image representing the init state
306 static void __init
setup_xstate_init(void)
308 init_xstate_buf
= alloc_bootmem(xstate_size
);
309 init_xstate_buf
->i387
.mxcsr
= MXCSR_DEFAULT
;
313 * Enable and initialize the xsave feature.
315 void __ref
xsave_cntxt_init(void)
317 unsigned int eax
, ebx
, ecx
, edx
;
319 cpuid_count(0xd, 0, &eax
, &ebx
, &ecx
, &edx
);
320 pcntxt_mask
= eax
+ ((u64
)edx
<< 32);
322 if ((pcntxt_mask
& XSTATE_FPSSE
) != XSTATE_FPSSE
) {
323 printk(KERN_ERR
"FP/SSE not shown under xsave features 0x%llx\n",
329 * Support only the state known to OS.
331 pcntxt_mask
= pcntxt_mask
& XCNTXT_MASK
;
335 * Recompute the context size for enabled features
337 cpuid_count(0xd, 0, &eax
, &ebx
, &ecx
, &edx
);
340 prepare_fx_sw_frame();
344 printk(KERN_INFO
"xsave/xrstor: enabled xstate_bv 0x%llx, "
346 pcntxt_mask
, xstate_size
);