acpi_pad: build only on X86
[linux-2.6/linux-acpi-2.6.git] / arch / x86 / kernel / xsave.c
blobc5ee17e8c6d95628809825073d7681db6d842943
1 /*
2 * xsave/xrstor support.
4 * Author: Suresh Siddha <suresh.b.siddha@intel.com>
5 */
6 #include <linux/bootmem.h>
7 #include <linux/compat.h>
8 #include <asm/i387.h>
9 #ifdef CONFIG_IA32_EMULATION
10 #include <asm/sigcontext32.h>
11 #endif
12 #include <asm/xcr.h>
15 * Supported feature mask by the CPU and the kernel.
17 u64 pcntxt_mask;
19 struct _fpx_sw_bytes fx_sw_reserved;
20 #ifdef CONFIG_IA32_EMULATION
21 struct _fpx_sw_bytes fx_sw_reserved_ia32;
22 #endif
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,
29 void __user *fpstate,
30 struct _fpx_sw_bytes *fx_sw_user)
32 int min_xstate_size = sizeof(struct i387_fxsave_struct) +
33 sizeof(struct xsave_hdr_struct);
34 unsigned int magic2;
35 int err;
37 err = __copy_from_user(fx_sw_user, &buf->sw_reserved[0],
38 sizeof(struct _fpx_sw_bytes));
40 if (err)
41 return err;
44 * First Magic check failed.
46 if (fx_sw_user->magic1 != FP_XSTATE_MAGIC1)
47 return -1;
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)
55 return -1;
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)
67 return -1;
69 return 0;
72 #ifdef CONFIG_X86_64
74 * Signal frame handlers.
77 int save_i387_xstate(void __user *buf)
79 struct task_struct *tsk = current;
80 int err = 0;
82 if (!access_ok(VERIFY_WRITE, buf, sig_xstate_size))
83 return -EACCES;
85 BUG_ON(sig_xstate_size < xstate_size);
87 if ((unsigned long)buf % 64)
88 printk("save_i387_xstate: bad fpstate %p\n", buf);
90 if (!used_math())
91 return 0;
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);
99 if (err)
100 return err;
102 if (task_thread_info(tsk)->status & TS_XSAVE)
103 err = xsave_user(buf);
104 else
105 err = fxsave_user(buf);
107 if (err)
108 return err;
109 task_thread_info(tsk)->status &= ~TS_USEDFPU;
110 stts();
111 } else {
112 if (__copy_to_user(buf, &tsk->thread.xstate->fxsave,
113 xstate_size))
114 return -1;
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;
122 u64 xstate_bv;
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);
153 if (err)
154 return err;
157 return 1;
161 * Restore the extended state if present. Otherwise, restore the FP/SSE
162 * state.
164 static int restore_user_xstate(void __user *buf)
166 struct _fpx_sw_bytes fx_sw_user;
167 u64 mask;
168 int err;
170 if (((unsigned long)buf % 64) ||
171 check_for_xstate(buf, buf, &fx_sw_user))
172 goto fx_only;
174 mask = fx_sw_user.xstate_bv;
177 * restore the state passed by the user.
179 err = xrestore_user(buf, mask);
180 if (err)
181 return err;
184 * init the state skipped by the user.
186 mask = pcntxt_mask & ~mask;
188 xrstor_state(init_xstate_buf, mask);
190 return 0;
192 fx_only:
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;
208 int err = 0;
210 if (!buf) {
211 if (used_math())
212 goto clear;
213 return 0;
214 } else
215 if (!access_ok(VERIFY_READ, buf, sig_xstate_size))
216 return -EACCES;
218 if (!used_math()) {
219 err = init_fpu(tsk);
220 if (err)
221 return err;
224 if (!(task_thread_info(current)->status & TS_USEDFPU)) {
225 clts();
226 task_thread_info(current)->status |= TS_USEDFPU;
228 if (task_thread_info(tsk)->status & TS_XSAVE)
229 err = restore_user_xstate(buf);
230 else
231 err = fxrstor_checking((__force struct i387_fxsave_struct *)
232 buf);
233 if (unlikely(err)) {
235 * Encountered an error while doing the restore from the
236 * user buffer, clear the fpu state.
238 clear:
239 clear_fpu(tsk);
240 clear_used_math();
242 return err;
244 #endif
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;
262 #endif
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;
274 #endif
278 * Represents init state for the supported extended state.
280 struct xsave_struct *init_xstate_buf;
282 #ifdef CONFIG_X86_64
283 unsigned int sig_xstate_size = sizeof(struct _fpstate);
284 #endif
287 * Enable the extended processor state save/restore feature
289 void __cpuinit xsave_init(void)
291 if (!cpu_has_xsave)
292 return;
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",
324 pcntxt_mask);
325 BUG();
329 * Support only the state known to OS.
331 pcntxt_mask = pcntxt_mask & XCNTXT_MASK;
332 xsave_init();
335 * Recompute the context size for enabled features
337 cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
338 xstate_size = ebx;
340 prepare_fx_sw_frame();
342 setup_xstate_init();
344 printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%llx, "
345 "cntxt size 0x%x\n",
346 pcntxt_mask, xstate_size);