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);