2 * FPU signal frame handling routines.
5 #include <linux/compat.h>
8 #include <asm/fpu/internal.h>
9 #include <asm/fpu/signal.h>
10 #include <asm/fpu/regset.h>
11 #include <asm/fpu/xstate.h>
13 #include <asm/sigframe.h>
14 #include <asm/trace/fpu.h>
16 static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
19 * Check for the presence of extended state information in the
20 * user fpstate pointer in the sigcontext.
22 static inline int check_for_xstate(struct fxregs_state __user *buf,
24 struct _fpx_sw_bytes *fx_sw)
26 int min_xstate_size = sizeof(struct fxregs_state) +
27 sizeof(struct xstate_header);
30 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
33 /* Check for the first magic field and other error scenarios. */
34 if (fx_sw->magic1 != FP_XSTATE_MAGIC1 ||
35 fx_sw->xstate_size < min_xstate_size ||
36 fx_sw->xstate_size > fpu_user_xstate_size ||
37 fx_sw->xstate_size > fx_sw->extended_size)
41 * Check for the presence of second magic word at the end of memory
42 * layout. This detects the case where the user just copied the legacy
43 * fpstate layout with out copying the extended state information
44 * in the memory layout.
46 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
47 || magic2 != FP_XSTATE_MAGIC2)
54 * Signal frame handlers.
56 static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
59 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
60 struct user_i387_ia32_struct env;
61 struct _fpstate_32 __user *fp = buf;
63 convert_from_fxsr(&env, tsk);
65 if (__copy_to_user(buf, &env, sizeof(env)) ||
66 __put_user(xsave->i387.swd, &fp->status) ||
67 __put_user(X86_FXSR_MAGIC, &fp->magic))
70 struct fregs_state __user *fp = buf;
72 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
79 static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
81 struct xregs_state __user *x = buf;
82 struct _fpx_sw_bytes *sw_bytes;
86 /* Setup the bytes not touched by the [f]xsave and reserved for SW. */
87 sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved;
88 err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes));
93 err |= __put_user(FP_XSTATE_MAGIC2,
94 (__u32 *)(buf + fpu_user_xstate_size));
97 * Read the xfeatures which we copied (directly from the cpu or
98 * from the state in task struct) to the user buffers.
100 err |= __get_user(xfeatures, (__u32 *)&x->header.xfeatures);
103 * For legacy compatible, we always set FP/SSE bits in the bit
104 * vector while saving the state to the user context. This will
105 * enable us capturing any changes(during sigreturn) to
106 * the FP/SSE bits by the legacy applications which don't touch
107 * xfeatures in the xsave header.
109 * xsave aware apps can change the xfeatures in the xsave
110 * header as well as change any contents in the memory layout.
111 * xrestore as part of sigreturn will capture all the changes.
113 xfeatures |= XFEATURE_MASK_FPSSE;
115 err |= __put_user(xfeatures, (__u32 *)&x->header.xfeatures);
120 static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
125 err = copy_xregs_to_user(buf);
127 err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
129 err = copy_fregs_to_user((struct fregs_state __user *) buf);
131 if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
137 * Save the fpu, extended register state to the user signal frame.
139 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
141 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
143 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
144 * buf != buf_fx for 32-bit frames with fxstate.
146 * If the fpu, extended register state is live, save the state directly
147 * to the user frame pointed by the aligned pointer 'buf_fx'. Otherwise,
148 * copy the thread's fpu state to the user frame starting at 'buf_fx'.
150 * If this is a 32-bit frame with fxstate, put a fsave header before
151 * the aligned state at 'buf_fx'.
153 * For [f]xsave state, update the SW reserved fields in the [f]xsave frame
154 * indicating the absence/presence of the extended state to the user.
156 int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size)
158 struct fpu *fpu = ¤t->thread.fpu;
159 struct xregs_state *xsave = &fpu->state.xsave;
160 struct task_struct *tsk = current;
161 int ia32_fxstate = (buf != buf_fx);
163 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
164 IS_ENABLED(CONFIG_IA32_EMULATION));
166 if (!access_ok(VERIFY_WRITE, buf, size))
169 if (!static_cpu_has(X86_FEATURE_FPU))
170 return fpregs_soft_get(current, NULL, 0,
171 sizeof(struct user_i387_ia32_struct), NULL,
172 (struct _fpstate_32 __user *) buf) ? -1 : 1;
174 if (fpu->fpstate_active || using_compacted_format()) {
175 /* Save the live register state to the user directly. */
176 if (copy_fpregs_to_sigframe(buf_fx))
178 /* Update the thread's fxstate to save the fsave header. */
180 copy_fxregs_to_kernel(fpu);
183 * It is a *bug* if kernel uses compacted-format for xsave
184 * area and we copy it out directly to a signal frame. It
185 * should have been handled above by saving the registers
188 if (boot_cpu_has(X86_FEATURE_XSAVES)) {
189 WARN_ONCE(1, "x86/fpu: saving compacted-format xsave area to a signal frame!\n");
193 fpstate_sanitize_xstate(fpu);
194 if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
198 /* Save the fsave header for the 32-bit frames. */
199 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
202 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
209 sanitize_restored_xstate(struct task_struct *tsk,
210 struct user_i387_ia32_struct *ia32_env,
211 u64 xfeatures, int fx_only)
213 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
214 struct xstate_header *header = &xsave->header;
217 /* These bits must be zero. */
218 memset(header->reserved, 0, 48);
221 * Init the state that is not present in the memory
222 * layout and not enabled by the OS.
225 header->xfeatures = XFEATURE_MASK_FPSSE;
227 header->xfeatures &= (xfeatures_mask & xfeatures);
232 * mscsr reserved bits must be masked to zero for security
235 xsave->i387.mxcsr &= mxcsr_feature_mask;
237 convert_to_fxsr(tsk, ia32_env);
242 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
244 static inline int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
247 if ((unsigned long)buf % 64 || fx_only) {
248 u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
249 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
250 return copy_user_to_fxregs(buf);
252 u64 init_bv = xfeatures_mask & ~xbv;
253 if (unlikely(init_bv))
254 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
255 return copy_user_to_xregs(buf, xbv);
257 } else if (use_fxsr()) {
258 return copy_user_to_fxregs(buf);
260 return copy_user_to_fregs(buf);
263 static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
265 int ia32_fxstate = (buf != buf_fx);
266 struct task_struct *tsk = current;
267 struct fpu *fpu = &tsk->thread.fpu;
268 int state_size = fpu_kernel_xstate_size;
272 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
273 IS_ENABLED(CONFIG_IA32_EMULATION));
280 if (!access_ok(VERIFY_READ, buf, size))
283 fpu__activate_curr(fpu);
285 if (!static_cpu_has(X86_FEATURE_FPU))
286 return fpregs_soft_set(current, NULL,
287 0, sizeof(struct user_i387_ia32_struct),
291 struct _fpx_sw_bytes fx_sw_user;
292 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
294 * Couldn't find the extended state information in the
295 * memory layout. Restore just the FP/SSE and init all
296 * the other extended state.
298 state_size = sizeof(struct fxregs_state);
300 trace_x86_fpu_xstate_check_failed(fpu);
302 state_size = fx_sw_user.xstate_size;
303 xfeatures = fx_sw_user.xfeatures;
309 * For 32-bit frames with fxstate, copy the user state to the
310 * thread's fpu state, reconstruct fxstate from the fsave
311 * header. Sanitize the copied state etc.
313 struct fpu *fpu = &tsk->thread.fpu;
314 struct user_i387_ia32_struct env;
318 * Drop the current fpu which clears fpu->fpstate_active. This ensures
319 * that any context-switch during the copy of the new state,
320 * avoids the intermediate state from getting restored/saved.
321 * Thus avoiding the new restored state from getting corrupted.
322 * We will be ready to restore/save the state only after
323 * fpu->fpstate_active is again set.
327 if (using_compacted_format()) {
328 err = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
330 err = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
332 /* xcomp_bv must be 0 when using uncompacted format */
333 if (!err && state_size > offsetof(struct xregs_state, header) && fpu->state.xsave.header.xcomp_bv)
337 if (err || __copy_from_user(&env, buf, sizeof(env))) {
338 fpstate_init(&fpu->state);
339 trace_x86_fpu_init_state(fpu);
342 sanitize_restored_xstate(tsk, &env, xfeatures, fx_only);
345 fpu->fpstate_active = 1;
353 * For 64-bit frames and 32-bit fsave frames, restore the user
354 * state to the registers directly (with exceptions handled).
357 if (copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only)) {
366 static inline int xstate_sigframe_size(void)
368 return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
369 fpu_user_xstate_size;
373 * Restore FPU state from a sigframe:
375 int fpu__restore_sig(void __user *buf, int ia32_frame)
377 void __user *buf_fx = buf;
378 int size = xstate_sigframe_size();
380 if (ia32_frame && use_fxsr()) {
381 buf_fx = buf + sizeof(struct fregs_state);
382 size += sizeof(struct fregs_state);
385 return __fpu__restore_sig(buf, buf_fx, size);
389 fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
390 unsigned long *buf_fx, unsigned long *size)
392 unsigned long frame_size = xstate_sigframe_size();
394 *buf_fx = sp = round_down(sp - frame_size, 64);
395 if (ia32_frame && use_fxsr()) {
396 frame_size += sizeof(struct fregs_state);
397 sp -= sizeof(struct fregs_state);
405 * Prepare the SW reserved portion of the fxsave memory layout, indicating
406 * the presence of the extended state information in the memory layout
407 * pointed by the fpstate pointer in the sigcontext.
408 * This will be saved when ever the FP and extended state context is
409 * saved on the user stack during the signal handler delivery to the user.
411 void fpu__init_prepare_fx_sw_frame(void)
413 int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
415 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
416 fx_sw_reserved.extended_size = size;
417 fx_sw_reserved.xfeatures = xfeatures_mask;
418 fx_sw_reserved.xstate_size = fpu_user_xstate_size;
420 if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
421 IS_ENABLED(CONFIG_X86_32)) {
422 int fsave_header_size = sizeof(struct fregs_state);
424 fx_sw_reserved_ia32 = fx_sw_reserved;
425 fx_sw_reserved_ia32.extended_size = size + fsave_header_size;