1 // SPDX-License-Identifier: GPL-2.0
3 * FPU signal frame handling routines.
6 #include <linux/compat.h>
9 #include <asm/fpu/internal.h>
10 #include <asm/fpu/signal.h>
11 #include <asm/fpu/regset.h>
12 #include <asm/fpu/xstate.h>
14 #include <asm/sigframe.h>
15 #include <asm/trace/fpu.h>
17 static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
20 * Check for the presence of extended state information in the
21 * user fpstate pointer in the sigcontext.
23 static inline int check_for_xstate(struct fxregs_state __user *buf,
25 struct _fpx_sw_bytes *fx_sw)
27 int min_xstate_size = sizeof(struct fxregs_state) +
28 sizeof(struct xstate_header);
31 if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw)))
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)
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.
47 if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size))
48 || magic2 != FP_XSTATE_MAGIC2)
55 * Signal frame handlers.
57 static inline int save_fsave_header(struct task_struct *tsk, void __user *buf)
60 struct xregs_state *xsave = &tsk->thread.fpu.state.xsave;
61 struct user_i387_ia32_struct env;
62 struct _fpstate_32 __user *fp = buf;
64 convert_from_fxsr(&env, tsk);
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))
71 struct fregs_state __user *fp = buf;
73 if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status))
80 static inline int save_xstate_epilog(void __user *buf, int ia32_frame)
82 struct xregs_state __user *x = buf;
83 struct _fpx_sw_bytes *sw_bytes;
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));
94 err |= __put_user(FP_XSTATE_MAGIC2,
95 (__u32 __user *)(buf + fpu_user_xstate_size));
98 * Read the xfeatures which we copied (directly from the cpu or
99 * from the state in task struct) to the user buffers.
101 err |= __get_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
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.
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.
114 xfeatures |= XFEATURE_MASK_FPSSE;
116 err |= __put_user(xfeatures, (__u32 __user *)&x->header.xfeatures);
121 static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf)
126 err = copy_xregs_to_user(buf);
128 err = copy_fxregs_to_user((struct fxregs_state __user *) buf);
130 err = copy_fregs_to_user((struct fregs_state __user *) buf);
132 if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size))
138 * Save the fpu, extended register state to the user signal frame.
140 * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save
142 * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'.
144 * buf == buf_fx for 64-bit frames and 32-bit fsave frame.
145 * buf != buf_fx for 32-bit frames with fxstate.
147 * Save the state to task's fpu->state and then copy it to the user frame
148 * pointed to by the aligned pointer '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(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;
175 * If we do not need to load the FPU registers at return to userspace
176 * then the CPU has the current state and we need to save it. Otherwise,
177 * it has already been done and we can skip it.
180 if (!test_thread_flag(TIF_NEED_FPU_LOAD)) {
181 copy_fpregs_to_fpstate(fpu);
182 set_thread_flag(TIF_NEED_FPU_LOAD);
186 if (using_compacted_format()) {
187 if (copy_xstate_to_user(buf_fx, xsave, 0, size))
190 fpstate_sanitize_xstate(fpu);
191 if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size))
195 /* Save the fsave header for the 32-bit frames. */
196 if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf))
199 if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate))
206 sanitize_restored_xstate(union fpregs_state *state,
207 struct user_i387_ia32_struct *ia32_env,
208 u64 xfeatures, int fx_only)
210 struct xregs_state *xsave = &state->xsave;
211 struct xstate_header *header = &xsave->header;
215 * Note: we don't need to zero the reserved bits in the
216 * xstate_header here because we either didn't copy them at all,
217 * or we checked earlier that they aren't set.
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;
232 * mscsr reserved bits must be masked to zero for security
235 xsave->i387.mxcsr &= mxcsr_feature_mask;
238 convert_to_fxsr(&state->fxsave, ia32_env);
243 * Restore the extended state if present. Otherwise, restore the FP/SSE state.
245 static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only)
249 u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
250 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
251 return copy_user_to_fxregs(buf);
253 u64 init_bv = xfeatures_mask & ~xbv;
254 if (unlikely(init_bv))
255 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
256 return copy_user_to_xregs(buf, xbv);
258 } else if (use_fxsr()) {
259 return copy_user_to_fxregs(buf);
261 return copy_user_to_fregs(buf);
264 static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
266 struct user_i387_ia32_struct *envp = NULL;
267 int state_size = fpu_kernel_xstate_size;
268 int ia32_fxstate = (buf != buf_fx);
269 struct task_struct *tsk = current;
270 struct fpu *fpu = &tsk->thread.fpu;
271 struct user_i387_ia32_struct env;
276 ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) ||
277 IS_ENABLED(CONFIG_IA32_EMULATION));
284 if (!access_ok(buf, size))
287 if (!static_cpu_has(X86_FEATURE_FPU))
288 return fpregs_soft_set(current, NULL,
289 0, sizeof(struct user_i387_ia32_struct),
293 struct _fpx_sw_bytes fx_sw_user;
294 if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) {
296 * Couldn't find the extended state information in the
297 * memory layout. Restore just the FP/SSE and init all
298 * the other extended state.
300 state_size = sizeof(struct fxregs_state);
302 trace_x86_fpu_xstate_check_failed(fpu);
304 state_size = fx_sw_user.xstate_size;
305 xfeatures = fx_sw_user.xfeatures;
310 * The current state of the FPU registers does not matter. By setting
311 * TIF_NEED_FPU_LOAD unconditionally it is ensured that the our xstate
312 * is not modified on context switch and that the xstate is considered
313 * to be loaded again on return to userland (overriding last_cpu avoids
316 set_thread_flag(TIF_NEED_FPU_LOAD);
317 __fpu_invalidate_fpregs_state(fpu);
319 if ((unsigned long)buf_fx % 64)
322 * For 32-bit frames with fxstate, copy the fxstate so it can be
323 * reconstructed later.
326 ret = __copy_from_user(&env, buf, sizeof(env));
332 * Attempt to restore the FPU registers directly from user
333 * memory. For that to succeed, the user access cannot cause
334 * page faults. If it does, fall back to the slow path below,
335 * going through the kernel buffer with the enabled pagefault
340 ret = copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only);
343 fpregs_mark_activate();
351 if (use_xsave() && !fx_only) {
352 u64 init_bv = xfeatures_mask & ~xfeatures;
354 if (using_compacted_format()) {
355 ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx);
357 ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size);
359 if (!ret && state_size > offsetof(struct xregs_state, header))
360 ret = validate_xstate_header(&fpu->state.xsave.header);
365 sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
368 if (unlikely(init_bv))
369 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
370 ret = copy_kernel_to_xregs_err(&fpu->state.xsave, xfeatures);
372 } else if (use_fxsr()) {
373 ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size);
379 sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only);
383 u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE;
384 copy_kernel_to_xregs(&init_fpstate.xsave, init_bv);
387 ret = copy_kernel_to_fxregs_err(&fpu->state.fxsave);
389 ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size);
394 ret = copy_kernel_to_fregs_err(&fpu->state.fsave);
397 fpregs_mark_activate();
406 static inline int xstate_sigframe_size(void)
408 return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE :
409 fpu_user_xstate_size;
413 * Restore FPU state from a sigframe:
415 int fpu__restore_sig(void __user *buf, int ia32_frame)
417 void __user *buf_fx = buf;
418 int size = xstate_sigframe_size();
420 if (ia32_frame && use_fxsr()) {
421 buf_fx = buf + sizeof(struct fregs_state);
422 size += sizeof(struct fregs_state);
425 return __fpu__restore_sig(buf, buf_fx, size);
429 fpu__alloc_mathframe(unsigned long sp, int ia32_frame,
430 unsigned long *buf_fx, unsigned long *size)
432 unsigned long frame_size = xstate_sigframe_size();
434 *buf_fx = sp = round_down(sp - frame_size, 64);
435 if (ia32_frame && use_fxsr()) {
436 frame_size += sizeof(struct fregs_state);
437 sp -= sizeof(struct fregs_state);
445 * Prepare the SW reserved portion of the fxsave memory layout, indicating
446 * the presence of the extended state information in the memory layout
447 * pointed by the fpstate pointer in the sigcontext.
448 * This will be saved when ever the FP and extended state context is
449 * saved on the user stack during the signal handler delivery to the user.
451 void fpu__init_prepare_fx_sw_frame(void)
453 int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE;
455 fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1;
456 fx_sw_reserved.extended_size = size;
457 fx_sw_reserved.xfeatures = xfeatures_mask;
458 fx_sw_reserved.xstate_size = fpu_user_xstate_size;
460 if (IS_ENABLED(CONFIG_IA32_EMULATION) ||
461 IS_ENABLED(CONFIG_X86_32)) {
462 int fsave_header_size = sizeof(struct fregs_state);
464 fx_sw_reserved_ia32 = fx_sw_reserved;
465 fx_sw_reserved_ia32.extended_size = size + fsave_header_size;