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-rw-r--r--include/asm-x86/i387.h400
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diff --git a/include/asm-x86/i387.h b/include/asm-x86/i387.h
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1/*
2 * Copyright (C) 1994 Linus Torvalds
3 *
4 * Pentium III FXSR, SSE support
5 * General FPU state handling cleanups
6 * Gareth Hughes <gareth@valinux.com>, May 2000
7 * x86-64 work by Andi Kleen 2002
8 */
9
10#ifndef ASM_X86__I387_H
11#define ASM_X86__I387_H
12
13#include <linux/sched.h>
14#include <linux/kernel_stat.h>
15#include <linux/regset.h>
16#include <linux/hardirq.h>
17#include <asm/asm.h>
18#include <asm/processor.h>
19#include <asm/sigcontext.h>
20#include <asm/user.h>
21#include <asm/uaccess.h>
22#include <asm/xsave.h>
23
24extern unsigned int sig_xstate_size;
25extern void fpu_init(void);
26extern void mxcsr_feature_mask_init(void);
27extern int init_fpu(struct task_struct *child);
28extern asmlinkage void math_state_restore(void);
29extern void init_thread_xstate(void);
30extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
31
32extern user_regset_active_fn fpregs_active, xfpregs_active;
33extern user_regset_get_fn fpregs_get, xfpregs_get, fpregs_soft_get;
34extern user_regset_set_fn fpregs_set, xfpregs_set, fpregs_soft_set;
35
36extern struct _fpx_sw_bytes fx_sw_reserved;
37#ifdef CONFIG_IA32_EMULATION
38extern unsigned int sig_xstate_ia32_size;
39extern struct _fpx_sw_bytes fx_sw_reserved_ia32;
40struct _fpstate_ia32;
41struct _xstate_ia32;
42extern int save_i387_xstate_ia32(void __user *buf);
43extern int restore_i387_xstate_ia32(void __user *buf);
44#endif
45
46#define X87_FSW_ES (1 << 7) /* Exception Summary */
47
48#ifdef CONFIG_X86_64
49
50/* Ignore delayed exceptions from user space */
51static inline void tolerant_fwait(void)
52{
53 asm volatile("1: fwait\n"
54 "2:\n"
55 _ASM_EXTABLE(1b, 2b));
56}
57
58static inline int fxrstor_checking(struct i387_fxsave_struct *fx)
59{
60 int err;
61
62 asm volatile("1: rex64/fxrstor (%[fx])\n\t"
63 "2:\n"
64 ".section .fixup,\"ax\"\n"
65 "3: movl $-1,%[err]\n"
66 " jmp 2b\n"
67 ".previous\n"
68 _ASM_EXTABLE(1b, 3b)
69 : [err] "=r" (err)
70#if 0 /* See comment in __save_init_fpu() below. */
71 : [fx] "r" (fx), "m" (*fx), "0" (0));
72#else
73 : [fx] "cdaSDb" (fx), "m" (*fx), "0" (0));
74#endif
75 return err;
76}
77
78static inline int restore_fpu_checking(struct task_struct *tsk)
79{
80 if (task_thread_info(tsk)->status & TS_XSAVE)
81 return xrstor_checking(&tsk->thread.xstate->xsave);
82 else
83 return fxrstor_checking(&tsk->thread.xstate->fxsave);
84}
85
86/* AMD CPUs don't save/restore FDP/FIP/FOP unless an exception
87 is pending. Clear the x87 state here by setting it to fixed
88 values. The kernel data segment can be sometimes 0 and sometimes
89 new user value. Both should be ok.
90 Use the PDA as safe address because it should be already in L1. */
91static inline void clear_fpu_state(struct task_struct *tsk)
92{
93 struct xsave_struct *xstate = &tsk->thread.xstate->xsave;
94 struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
95
96 /*
97 * xsave header may indicate the init state of the FP.
98 */
99 if ((task_thread_info(tsk)->status & TS_XSAVE) &&
100 !(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
101 return;
102
103 if (unlikely(fx->swd & X87_FSW_ES))
104 asm volatile("fnclex");
105 alternative_input(ASM_NOP8 ASM_NOP2,
106 " emms\n" /* clear stack tags */
107 " fildl %%gs:0", /* load to clear state */
108 X86_FEATURE_FXSAVE_LEAK);
109}
110
111static inline int fxsave_user(struct i387_fxsave_struct __user *fx)
112{
113 int err;
114
115 asm volatile("1: rex64/fxsave (%[fx])\n\t"
116 "2:\n"
117 ".section .fixup,\"ax\"\n"
118 "3: movl $-1,%[err]\n"
119 " jmp 2b\n"
120 ".previous\n"
121 _ASM_EXTABLE(1b, 3b)
122 : [err] "=r" (err), "=m" (*fx)
123#if 0 /* See comment in __fxsave_clear() below. */
124 : [fx] "r" (fx), "0" (0));
125#else
126 : [fx] "cdaSDb" (fx), "0" (0));
127#endif
128 if (unlikely(err) &&
129 __clear_user(fx, sizeof(struct i387_fxsave_struct)))
130 err = -EFAULT;
131 /* No need to clear here because the caller clears USED_MATH */
132 return err;
133}
134
135static inline void fxsave(struct task_struct *tsk)
136{
137 /* Using "rex64; fxsave %0" is broken because, if the memory operand
138 uses any extended registers for addressing, a second REX prefix
139 will be generated (to the assembler, rex64 followed by semicolon
140 is a separate instruction), and hence the 64-bitness is lost. */
141#if 0
142 /* Using "fxsaveq %0" would be the ideal choice, but is only supported
143 starting with gas 2.16. */
144 __asm__ __volatile__("fxsaveq %0"
145 : "=m" (tsk->thread.xstate->fxsave));
146#elif 0
147 /* Using, as a workaround, the properly prefixed form below isn't
148 accepted by any binutils version so far released, complaining that
149 the same type of prefix is used twice if an extended register is
150 needed for addressing (fix submitted to mainline 2005-11-21). */
151 __asm__ __volatile__("rex64/fxsave %0"
152 : "=m" (tsk->thread.xstate->fxsave));
153#else
154 /* This, however, we can work around by forcing the compiler to select
155 an addressing mode that doesn't require extended registers. */
156 __asm__ __volatile__("rex64/fxsave (%1)"
157 : "=m" (tsk->thread.xstate->fxsave)
158 : "cdaSDb" (&tsk->thread.xstate->fxsave));
159#endif
160}
161
162static inline void __save_init_fpu(struct task_struct *tsk)
163{
164 if (task_thread_info(tsk)->status & TS_XSAVE)
165 xsave(tsk);
166 else
167 fxsave(tsk);
168
169 clear_fpu_state(tsk);
170 task_thread_info(tsk)->status &= ~TS_USEDFPU;
171}
172
173#else /* CONFIG_X86_32 */
174
175extern void finit(void);
176
177static inline void tolerant_fwait(void)
178{
179 asm volatile("fnclex ; fwait");
180}
181
182static inline void restore_fpu(struct task_struct *tsk)
183{
184 if (task_thread_info(tsk)->status & TS_XSAVE) {
185 xrstor_checking(&tsk->thread.xstate->xsave);
186 return;
187 }
188 /*
189 * The "nop" is needed to make the instructions the same
190 * length.
191 */
192 alternative_input(
193 "nop ; frstor %1",
194 "fxrstor %1",
195 X86_FEATURE_FXSR,
196 "m" (tsk->thread.xstate->fxsave));
197}
198
199/* We need a safe address that is cheap to find and that is already
200 in L1 during context switch. The best choices are unfortunately
201 different for UP and SMP */
202#ifdef CONFIG_SMP
203#define safe_address (__per_cpu_offset[0])
204#else
205#define safe_address (kstat_cpu(0).cpustat.user)
206#endif
207
208/*
209 * These must be called with preempt disabled
210 */
211static inline void __save_init_fpu(struct task_struct *tsk)
212{
213 if (task_thread_info(tsk)->status & TS_XSAVE) {
214 struct xsave_struct *xstate = &tsk->thread.xstate->xsave;
215 struct i387_fxsave_struct *fx = &tsk->thread.xstate->fxsave;
216
217 xsave(tsk);
218
219 /*
220 * xsave header may indicate the init state of the FP.
221 */
222 if (!(xstate->xsave_hdr.xstate_bv & XSTATE_FP))
223 goto end;
224
225 if (unlikely(fx->swd & X87_FSW_ES))
226 asm volatile("fnclex");
227
228 /*
229 * we can do a simple return here or be paranoid :)
230 */
231 goto clear_state;
232 }
233
234 /* Use more nops than strictly needed in case the compiler
235 varies code */
236 alternative_input(
237 "fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
238 "fxsave %[fx]\n"
239 "bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
240 X86_FEATURE_FXSR,
241 [fx] "m" (tsk->thread.xstate->fxsave),
242 [fsw] "m" (tsk->thread.xstate->fxsave.swd) : "memory");
243clear_state:
244 /* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
245 is pending. Clear the x87 state here by setting it to fixed
246 values. safe_address is a random variable that should be in L1 */
247 alternative_input(
248 GENERIC_NOP8 GENERIC_NOP2,
249 "emms\n\t" /* clear stack tags */
250 "fildl %[addr]", /* set F?P to defined value */
251 X86_FEATURE_FXSAVE_LEAK,
252 [addr] "m" (safe_address));
253end:
254 task_thread_info(tsk)->status &= ~TS_USEDFPU;
255}
256
257#endif /* CONFIG_X86_64 */
258
259/*
260 * Signal frame handlers...
261 */
262extern int save_i387_xstate(void __user *buf);
263extern int restore_i387_xstate(void __user *buf);
264
265static inline void __unlazy_fpu(struct task_struct *tsk)
266{
267 if (task_thread_info(tsk)->status & TS_USEDFPU) {
268 __save_init_fpu(tsk);
269 stts();
270 } else
271 tsk->fpu_counter = 0;
272}
273
274static inline void __clear_fpu(struct task_struct *tsk)
275{
276 if (task_thread_info(tsk)->status & TS_USEDFPU) {
277 tolerant_fwait();
278 task_thread_info(tsk)->status &= ~TS_USEDFPU;
279 stts();
280 }
281}
282
283static inline void kernel_fpu_begin(void)
284{
285 struct thread_info *me = current_thread_info();
286 preempt_disable();
287 if (me->status & TS_USEDFPU)
288 __save_init_fpu(me->task);
289 else
290 clts();
291}
292
293static inline void kernel_fpu_end(void)
294{
295 stts();
296 preempt_enable();
297}
298
299/*
300 * Some instructions like VIA's padlock instructions generate a spurious
301 * DNA fault but don't modify SSE registers. And these instructions
302 * get used from interrupt context aswell. To prevent these kernel instructions
303 * in interrupt context interact wrongly with other user/kernel fpu usage, we
304 * should use them only in the context of irq_ts_save/restore()
305 */
306static inline int irq_ts_save(void)
307{
308 /*
309 * If we are in process context, we are ok to take a spurious DNA fault.
310 * Otherwise, doing clts() in process context require pre-emption to
311 * be disabled or some heavy lifting like kernel_fpu_begin()
312 */
313 if (!in_interrupt())
314 return 0;
315
316 if (read_cr0() & X86_CR0_TS) {
317 clts();
318 return 1;
319 }
320
321 return 0;
322}
323
324static inline void irq_ts_restore(int TS_state)
325{
326 if (TS_state)
327 stts();
328}
329
330#ifdef CONFIG_X86_64
331
332static inline void save_init_fpu(struct task_struct *tsk)
333{
334 __save_init_fpu(tsk);
335 stts();
336}
337
338#define unlazy_fpu __unlazy_fpu
339#define clear_fpu __clear_fpu
340
341#else /* CONFIG_X86_32 */
342
343/*
344 * These disable preemption on their own and are safe
345 */
346static inline void save_init_fpu(struct task_struct *tsk)
347{
348 preempt_disable();
349 __save_init_fpu(tsk);
350 stts();
351 preempt_enable();
352}
353
354static inline void unlazy_fpu(struct task_struct *tsk)
355{
356 preempt_disable();
357 __unlazy_fpu(tsk);
358 preempt_enable();
359}
360
361static inline void clear_fpu(struct task_struct *tsk)
362{
363 preempt_disable();
364 __clear_fpu(tsk);
365 preempt_enable();
366}
367
368#endif /* CONFIG_X86_64 */
369
370/*
371 * i387 state interaction
372 */
373static inline unsigned short get_fpu_cwd(struct task_struct *tsk)
374{
375 if (cpu_has_fxsr) {
376 return tsk->thread.xstate->fxsave.cwd;
377 } else {
378 return (unsigned short)tsk->thread.xstate->fsave.cwd;
379 }
380}
381
382static inline unsigned short get_fpu_swd(struct task_struct *tsk)
383{
384 if (cpu_has_fxsr) {
385 return tsk->thread.xstate->fxsave.swd;
386 } else {
387 return (unsigned short)tsk->thread.xstate->fsave.swd;
388 }
389}
390
391static inline unsigned short get_fpu_mxcsr(struct task_struct *tsk)
392{
393 if (cpu_has_xmm) {
394 return tsk->thread.xstate->fxsave.mxcsr;
395 } else {
396 return MXCSR_DEFAULT;
397 }
398}
399
400#endif /* ASM_X86__I387_H */
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