~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/x86/kernel/fpu/signal.c

Version: ~ [ linux-5.8 ] ~ [ linux-5.7.12 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.55 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.136 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.191 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.232 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.232 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.85 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  * FPU signal frame handling routines.
  4  */
  5 
  6 #include <linux/compat.h>
  7 #include <linux/cpu.h>
  8 
  9 #include <asm/fpu/internal.h>
 10 #include <asm/fpu/signal.h>
 11 #include <asm/fpu/regset.h>
 12 #include <asm/fpu/xstate.h>
 13 
 14 #include <asm/sigframe.h>
 15 #include <asm/trace/fpu.h>
 16 
 17 static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
 18 
 19 /*
 20  * Check for the presence of extended state information in the
 21  * user fpstate pointer in the sigcontext.
 22  */
 23 static inline int check_for_xstate(struct fxregs_state __user *buf,
 24                                    void __user *fpstate,
 25                                    struct _fpx_sw_bytes *fx_sw)
 26 {
 27         int min_xstate_size = sizeof(struct fxregs_state) +
 28                               sizeof(struct xstate_header);
 29         unsigned int magic2;
 30 
 31         if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
 32                 return -1;
 33 
 34         /* Check for the first magic field and other error scenarios. */
 35         if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
 36             fx_sw->xstate_size < min_xstate_size ||
 37             fx_sw->xstate_size > fpu_user_xstate_size ||
 38             fx_sw->xstate_size > fx_sw->extended_size)
 39                 return -1;
 40 
 41         /*
 42          * Check for the presence of second magic word at the end of memory
 43          * layout. This detects the case where the user just copied the legacy
 44          * fpstate layout with out copying the extended state information
 45          * in the memory layout.
 46          */
 47         if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
 48             || magic2 != FP_XSTATE_MAGIC2)
 49                 return -1;
 50 
 51         return 0;
 52 }
 53 
 54 /*
 55  * Signal frame handlers.
 56  */
 57 static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
 58 {
 59         if (use_fxsr()) {
 60                 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
 61                 struct user_i387_ia32_struct env;
 62                 struct _fpstate_32 __user *fp = buf;
 63 
 64                 convert_from_fxsr(&env, tsk);
 65 
 66                 if (__copy_to_user(buf, &env, sizeof(env)) ||
 67                     __put_user(xsave->i387.swd, &fp->status) ||
 68                     __put_user(X86_FXSR_MAGIC, &fp->magic))
 69                         return -1;
 70         } else {
 71                 struct fregs_state __user *fp = buf;
 72                 u32 swd;
 73                 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
 74                         return -1;
 75         }
 76 
 77         return 0;
 78 }
 79 
 80 static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
 81 {
 82         struct xregs_state __user *x = buf;
 83         struct _fpx_sw_bytes *sw_bytes;
 84         u32 xfeatures;
 85         int err;
 86 
 87         /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
 88         sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
 89         err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
 90 
 91         if (!use_xsave())
 92                 return err;
 93 
 94         err |= __put_user(FP_XSTATE_MAGIC2,
 95                           (__u32 *)(buf + fpu_user_xstate_size));
 96 
 97         /*
 98          * Read the xfeatures which we copied (directly from the cpu or
 99          * from the state in task struct) to the user buffers.
100          */
101         err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
102 
103         /*
104          * For legacy compatible, we always set FP/SSE bits in the bit
105          * vector while saving the state to the user context. This will
106          * enable us capturing any changes(during sigreturn) to
107          * the FP/SSE bits by the legacy applications which don't touch
108          * xfeatures in the xsave header.
109          *
110          * xsave aware apps can change the xfeatures in the xsave
111          * header as well as change any contents in the memory layout.
112          * xrestore as part of sigreturn will capture all the changes.
113          */
114         xfeatures |= XFEATURE_MASK_FPSSE;
115 
116         err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
117 
118         return err;
119 }
120 
121 static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
122 {
123         int err;
124 
125         if (use_xsave())
126                 err = copy_xregs_to_user(buf);
127         else if (use_fxsr())
128                 err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
129         else
130                 err = copy_fregs_to_user((struct fregs_state __user *) buf);
131 
132         if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
133                 err = -EFAULT;
134         return err;
135 }
136 
137 /*
138  * Save the fpu, extended register state to the user signal frame.
139  *
140  * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
141  *  state is copied.
142  *  'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
143  *
144  *      buf == buf_fx for 64-bit frames and 32-bit fsave frame.
145  *      buf != buf_fx for 32-bit frames with fxstate.
146  *
147  * If the fpu, extended register state is live, save the state directly
148  * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
149  * copy the thread's fpu state to the user frame starting at 'buf_fx'.
150  *
151  * If this is a 32-bit frame with fxstate, put a fsave header before
152  * the aligned state at 'buf_fx'.
153  *
154  * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
155  * indicating the absence/presence of the extended state to the user.
156  */
157 int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
158 {
159         struct fpu *fpu = &current->thread.fpu;
160         struct xregs_state *xsave = &fpu->state.xsave;
161         struct task_struct *tsk = current;
162         int ia32_fxstate = (buf != buf_fx);
163 
164         ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
165                          IS_ENABLED(CONFIG_IA32_EMULATION));
166 
167         if (!access_ok(buf, size))
168                 return -EACCES;
169 
170         if (!static_cpu_has(X86_FEATURE_FPU))
171                 return fpregs_soft_get(current, NULL, 0,
172                         sizeof(struct user_i387_ia32_struct), NULL,
173                         (struct _fpstate_32 __user *) buf) ? -1 : 1;
174 
175         if (fpu->initialized || using_compacted_format()) {
176                 /* Save the live register state to the user directly. */
177                 if (copy_fpregs_to_sigframe(buf_fx))
178                         return -1;
179                 /* Update the thread's fxstate to save the fsave header. */
180                 if (ia32_fxstate)
181                         copy_fxregs_to_kernel(fpu);
182         } else {
183                 /*
184                  * It is a *bug* if kernel uses compacted-format for xsave
185                  * area and we copy it out directly to a signal frame. It
186                  * should have been handled above by saving the registers
187                  * directly.
188                  */
189                 if (boot_cpu_has(X86_FEATURE_XSAVES)) {
190                         WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
191                         return -1;
192                 }
193 
194                 fpstate_sanitize_xstate(fpu);
195                 if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
196                         return -1;
197         }
198 
199         /* Save the fsave header for the 32-bit frames. */
200         if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
201                 return -1;
202 
203         if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
204                 return -1;
205 
206         return 0;
207 }
208 
209 static inline void
210 sanitize_restored_xstate(struct task_struct *tsk,
211                          struct user_i387_ia32_struct *ia32_env,
212                          u64 xfeatures, int fx_only)
213 {
214         struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
215         struct xstate_header *header = &xsave->header;
216 
217         if (use_xsave()) {
218                 /*
219                  * Note: we don't need to zero the reserved bits in the
220                  * xstate_header here because we either didn't copy them at all,
221                  * or we checked earlier that they aren't set.
222                  */
223 
224                 /*
225                  * Init the state that is not present in the memory
226                  * layout and not enabled by the OS.
227                  */
228                 if (fx_only)
229                         header->xfeatures = XFEATURE_MASK_FPSSE;
230                 else
231                         header->xfeatures &= xfeatures;
232         }
233 
234         if (use_fxsr()) {
235                 /*
236                  * mscsr reserved bits must be masked to zero for security
237                  * reasons.
238                  */
239                 xsave->i387.mxcsr &= mxcsr_feature_mask;
240 
241                 convert_to_fxsr(tsk, ia32_env);
242         }
243 }
244 
245 /*
246  * Restore the extended state if present. Otherwise, restore the FP/SSE state.
247  */
248 static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
249 {
250         if (use_xsave()) {
251                 if ((unsigned long)buf % 64 || fx_only) {
252                         u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
253                         copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
254                         return copy_user_to_fxregs(buf);
255                 } else {
256                         u64 init_bv = xfeatures_mask & ~xbv;
257                         if (unlikely(init_bv))
258                                 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
259                         return copy_user_to_xregs(buf, xbv);
260                 }
261         } else if (use_fxsr()) {
262                 return copy_user_to_fxregs(buf);
263         } else
264                 return copy_user_to_fregs(buf);
265 }
266 
267 static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
268 {
269         int ia32_fxstate = (buf != buf_fx);
270         struct task_struct *tsk = current;
271         struct fpu *fpu = &tsk->thread.fpu;
272         int state_size = fpu_kernel_xstate_size;
273         u64 xfeatures = 0;
274         int fx_only = 0;
275 
276         ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
277                          IS_ENABLED(CONFIG_IA32_EMULATION));
278 
279         if (!buf) {
280                 fpu__clear(fpu);
281                 return 0;
282         }
283 
284         if (!access_ok(buf, size))
285                 return -EACCES;
286 
287         fpu__initialize(fpu);
288 
289         if (!static_cpu_has(X86_FEATURE_FPU))
290                 return fpregs_soft_set(current, NULL,
291                                        0, sizeof(struct user_i387_ia32_struct),
292                                        NULL, buf) != 0;
293 
294         if (use_xsave()) {
295                 struct _fpx_sw_bytes fx_sw_user;
296                 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
297                         /*
298                          * Couldn't find the extended state information in the
299                          * memory layout. Restore just the FP/SSE and init all
300                          * the other extended state.
301                          */
302                         state_size = sizeof(struct fxregs_state);
303                         fx_only = 1;
304                         trace_x86_fpu_xstate_check_failed(fpu);
305                 } else {
306                         state_size = fx_sw_user.xstate_size;
307                         xfeatures = fx_sw_user.xfeatures;
308                 }
309         }
310 
311         if (ia32_fxstate) {
312                 /*
313                  * For 32-bit frames with fxstate, copy the user state to the
314                  * thread's fpu state, reconstruct fxstate from the fsave
315                  * header. Validate and sanitize the copied state.
316                  */
317                 struct user_i387_ia32_struct env;
318                 int err = 0;
319 
320                 /*
321                  * Drop the current fpu which clears fpu->initialized. This ensures
322                  * that any context-switch during the copy of the new state,
323                  * avoids the intermediate state from getting restored/saved.
324                  * Thus avoiding the new restored state from getting corrupted.
325                  * We will be ready to restore/save the state only after
326                  * fpu->initialized is again set.
327                  */
328                 fpu__drop(fpu);
329 
330                 if (using_compacted_format()) {
331                         err = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
332                 } else {
333                         err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
334 
335                         if (!err && state_size > offsetof(struct xregs_state, header))
336                                 err = validate_xstate_header(&fpu->state.xsave.header);
337                 }
338 
339                 if (err || __copy_from_user(&env, buf, sizeof(env))) {
340                         fpstate_init(&fpu->state);
341                         trace_x86_fpu_init_state(fpu);
342                         err = -1;
343                 } else {
344                         sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
345                 }
346 
347                 local_bh_disable();
348                 fpu->initialized = 1;
349                 fpu__restore(fpu);
350                 local_bh_enable();
351 
352                 return err;
353         } else {
354                 /*
355                  * For 64-bit frames and 32-bit fsave frames, restore the user
356                  * state to the registers directly (with exceptions handled).
357                  */
358                 user_fpu_begin();
359                 if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
360                         fpu__clear(fpu);
361                         return -1;
362                 }
363         }
364 
365         return 0;
366 }
367 
368 static inline int xstate_sigframe_size(void)
369 {
370         return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
371                         fpu_user_xstate_size;
372 }
373 
374 /*
375  * Restore FPU state from a sigframe:
376  */
377 int fpu__restore_sig(void __user *buf, int ia32_frame)
378 {
379         void __user *buf_fx = buf;
380         int size = xstate_sigframe_size();
381 
382         if (ia32_frame && use_fxsr()) {
383                 buf_fx = buf + sizeof(struct fregs_state);
384                 size += sizeof(struct fregs_state);
385         }
386 
387         return __fpu__restore_sig(buf, buf_fx, size);
388 }
389 
390 unsigned long
391 fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
392                      unsigned long *buf_fx, unsigned long *size)
393 {
394         unsigned long frame_size = xstate_sigframe_size();
395 
396         *buf_fx = sp = round_down(sp - frame_size, 64);
397         if (ia32_frame && use_fxsr()) {
398                 frame_size += sizeof(struct fregs_state);
399                 sp -= sizeof(struct fregs_state);
400         }
401 
402         *size = frame_size;
403 
404         return sp;
405 }
406 /*
407  * Prepare the SW reserved portion of the fxsave memory layout, indicating
408  * the presence of the extended state information in the memory layout
409  * pointed by the fpstate pointer in the sigcontext.
410  * This will be saved when ever the FP and extended state context is
411  * saved on the user stack during the signal handler delivery to the user.
412  */
413 void fpu__init_prepare_fx_sw_frame(void)
414 {
415         int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
416 
417         fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
418         fx_sw_reserved.extended_size = size;
419         fx_sw_reserved.xfeatures = xfeatures_mask;
420         fx_sw_reserved.xstate_size = fpu_user_xstate_size;
421 
422         if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
423             IS_ENABLED(CONFIG_X86_32)) {
424                 int fsave_header_size = sizeof(struct fregs_state);
425 
426                 fx_sw_reserved_ia32 = fx_sw_reserved;
427                 fx_sw_reserved_ia32.extended_size = size + fsave_header_size;
428         }
429 }
430 
431 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp