| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * FPU signal frame handling routines. |
| */ |
| |
| #include <linux/compat.h> |
| #include <linux/cpu.h> |
| #include <linux/pagemap.h> |
| |
| #include <asm/fpu/internal.h> |
| #include <asm/fpu/signal.h> |
| #include <asm/fpu/regset.h> |
| #include <asm/fpu/xstate.h> |
| |
| #include <asm/sigframe.h> |
| #include <asm/trace/fpu.h> |
| |
| static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32; |
| |
| /* |
| * Check for the presence of extended state information in the |
| * user fpstate pointer in the sigcontext. |
| */ |
| static inline int check_for_xstate(struct fxregs_state __user *buf, |
| void __user *fpstate, |
| struct _fpx_sw_bytes *fx_sw) |
| { |
| int min_xstate_size = sizeof(struct fxregs_state) + |
| sizeof(struct xstate_header); |
| unsigned int magic2; |
| |
| if (__copy_from_user(fx_sw, &buf->sw_reserved[0], sizeof(*fx_sw))) |
| return -1; |
| |
| /* Check for the first magic field and other error scenarios. */ |
| if (fx_sw->magic1 != FP_XSTATE_MAGIC1 || |
| fx_sw->xstate_size < min_xstate_size || |
| fx_sw->xstate_size > fpu_user_xstate_size || |
| fx_sw->xstate_size > fx_sw->extended_size) |
| return -1; |
| |
| /* |
| * Check for the presence of second magic word at the end of memory |
| * layout. This detects the case where the user just copied the legacy |
| * fpstate layout with out copying the extended state information |
| * in the memory layout. |
| */ |
| if (__get_user(magic2, (__u32 __user *)(fpstate + fx_sw->xstate_size)) |
| || magic2 != FP_XSTATE_MAGIC2) |
| return -1; |
| |
| return 0; |
| } |
| |
| /* |
| * Signal frame handlers. |
| */ |
| static inline int save_fsave_header(struct task_struct *tsk, void __user *buf) |
| { |
| if (use_fxsr()) { |
| struct xregs_state *xsave = &tsk->thread.fpu.state.xsave; |
| struct user_i387_ia32_struct env; |
| struct _fpstate_32 __user *fp = buf; |
| |
| fpregs_lock(); |
| if (!test_thread_flag(TIF_NEED_FPU_LOAD)) |
| copy_fxregs_to_kernel(&tsk->thread.fpu); |
| fpregs_unlock(); |
| |
| convert_from_fxsr(&env, tsk); |
| |
| if (__copy_to_user(buf, &env, sizeof(env)) || |
| __put_user(xsave->i387.swd, &fp->status) || |
| __put_user(X86_FXSR_MAGIC, &fp->magic)) |
| return -1; |
| } else { |
| struct fregs_state __user *fp = buf; |
| u32 swd; |
| if (__get_user(swd, &fp->swd) || __put_user(swd, &fp->status)) |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| static inline int save_xstate_epilog(void __user *buf, int ia32_frame) |
| { |
| struct xregs_state __user *x = buf; |
| struct _fpx_sw_bytes *sw_bytes; |
| u32 xfeatures; |
| int err; |
| |
| /* Setup the bytes not touched by the [f]xsave and reserved for SW. */ |
| sw_bytes = ia32_frame ? &fx_sw_reserved_ia32 : &fx_sw_reserved; |
| err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes)); |
| |
| if (!use_xsave()) |
| return err; |
| |
| err |= __put_user(FP_XSTATE_MAGIC2, |
| (__u32 __user *)(buf + fpu_user_xstate_size)); |
| |
| /* |
| * Read the xfeatures which we copied (directly from the cpu or |
| * from the state in task struct) to the user buffers. |
| */ |
| err |= __get_user(xfeatures, (__u32 __user *)&x->header.xfeatures); |
| |
| /* |
| * For legacy compatible, we always set FP/SSE bits in the bit |
| * vector while saving the state to the user context. This will |
| * enable us capturing any changes(during sigreturn) to |
| * the FP/SSE bits by the legacy applications which don't touch |
| * xfeatures in the xsave header. |
| * |
| * xsave aware apps can change the xfeatures in the xsave |
| * header as well as change any contents in the memory layout. |
| * xrestore as part of sigreturn will capture all the changes. |
| */ |
| xfeatures |= XFEATURE_MASK_FPSSE; |
| |
| err |= __put_user(xfeatures, (__u32 __user *)&x->header.xfeatures); |
| |
| return err; |
| } |
| |
| static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf) |
| { |
| int err; |
| |
| if (use_xsave()) |
| err = copy_xregs_to_user(buf); |
| else if (use_fxsr()) |
| err = copy_fxregs_to_user((struct fxregs_state __user *) buf); |
| else |
| err = copy_fregs_to_user((struct fregs_state __user *) buf); |
| |
| if (unlikely(err) && __clear_user(buf, fpu_user_xstate_size)) |
| err = -EFAULT; |
| return err; |
| } |
| |
| /* |
| * Save the fpu, extended register state to the user signal frame. |
| * |
| * 'buf_fx' is the 64-byte aligned pointer at which the [f|fx|x]save |
| * state is copied. |
| * 'buf' points to the 'buf_fx' or to the fsave header followed by 'buf_fx'. |
| * |
| * buf == buf_fx for 64-bit frames and 32-bit fsave frame. |
| * buf != buf_fx for 32-bit frames with fxstate. |
| * |
| * Try to save it directly to the user frame with disabled page fault handler. |
| * If this fails then do the slow path where the FPU state is first saved to |
| * task's fpu->state and then copy it to the user frame pointed to by the |
| * aligned pointer 'buf_fx'. |
| * |
| * If this is a 32-bit frame with fxstate, put a fsave header before |
| * the aligned state at 'buf_fx'. |
| * |
| * For [f]xsave state, update the SW reserved fields in the [f]xsave frame |
| * indicating the absence/presence of the extended state to the user. |
| */ |
| int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) |
| { |
| struct task_struct *tsk = current; |
| int ia32_fxstate = (buf != buf_fx); |
| int ret; |
| |
| ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) || |
| IS_ENABLED(CONFIG_IA32_EMULATION)); |
| |
| if (!access_ok(buf, size)) |
| return -EACCES; |
| |
| if (!static_cpu_has(X86_FEATURE_FPU)) |
| return fpregs_soft_get(current, NULL, 0, |
| sizeof(struct user_i387_ia32_struct), NULL, |
| (struct _fpstate_32 __user *) buf) ? -1 : 1; |
| |
| retry: |
| /* |
| * Load the FPU registers if they are not valid for the current task. |
| * With a valid FPU state we can attempt to save the state directly to |
| * userland's stack frame which will likely succeed. If it does not, |
| * resolve the fault in the user memory and try again. |
| */ |
| fpregs_lock(); |
| if (test_thread_flag(TIF_NEED_FPU_LOAD)) |
| __fpregs_load_activate(); |
| |
| pagefault_disable(); |
| ret = copy_fpregs_to_sigframe(buf_fx); |
| pagefault_enable(); |
| fpregs_unlock(); |
| |
| if (ret) { |
| if (!fault_in_pages_writeable(buf_fx, fpu_user_xstate_size)) |
| goto retry; |
| return -EFAULT; |
| } |
| |
| /* Save the fsave header for the 32-bit frames. */ |
| if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf)) |
| return -1; |
| |
| if (use_fxsr() && save_xstate_epilog(buf_fx, ia32_fxstate)) |
| return -1; |
| |
| return 0; |
| } |
| |
| static inline void |
| sanitize_restored_xstate(union fpregs_state *state, |
| struct user_i387_ia32_struct *ia32_env, |
| u64 xfeatures, int fx_only) |
| { |
| struct xregs_state *xsave = &state->xsave; |
| struct xstate_header *header = &xsave->header; |
| |
| if (use_xsave()) { |
| /* |
| * Note: we don't need to zero the reserved bits in the |
| * xstate_header here because we either didn't copy them at all, |
| * or we checked earlier that they aren't set. |
| */ |
| |
| /* |
| * Init the state that is not present in the memory |
| * layout and not enabled by the OS. |
| */ |
| if (fx_only) |
| header->xfeatures = XFEATURE_MASK_FPSSE; |
| else |
| header->xfeatures &= xfeatures; |
| } |
| |
| if (use_fxsr()) { |
| /* |
| * mscsr reserved bits must be masked to zero for security |
| * reasons. |
| */ |
| xsave->i387.mxcsr &= mxcsr_feature_mask; |
| |
| if (ia32_env) |
| convert_to_fxsr(&state->fxsave, ia32_env); |
| } |
| } |
| |
| /* |
| * Restore the extended state if present. Otherwise, restore the FP/SSE state. |
| */ |
| static int copy_user_to_fpregs_zeroing(void __user *buf, u64 xbv, int fx_only) |
| { |
| if (use_xsave()) { |
| if (fx_only) { |
| u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE; |
| copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); |
| return copy_user_to_fxregs(buf); |
| } else { |
| u64 init_bv = xfeatures_mask & ~xbv; |
| if (unlikely(init_bv)) |
| copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); |
| return copy_user_to_xregs(buf, xbv); |
| } |
| } else if (use_fxsr()) { |
| return copy_user_to_fxregs(buf); |
| } else |
| return copy_user_to_fregs(buf); |
| } |
| |
| static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size) |
| { |
| struct user_i387_ia32_struct *envp = NULL; |
| int state_size = fpu_kernel_xstate_size; |
| int ia32_fxstate = (buf != buf_fx); |
| struct task_struct *tsk = current; |
| struct fpu *fpu = &tsk->thread.fpu; |
| struct user_i387_ia32_struct env; |
| u64 xfeatures = 0; |
| int fx_only = 0; |
| int ret = 0; |
| |
| ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) || |
| IS_ENABLED(CONFIG_IA32_EMULATION)); |
| |
| if (!buf) { |
| fpu__clear(fpu); |
| return 0; |
| } |
| |
| if (!access_ok(buf, size)) |
| return -EACCES; |
| |
| if (!static_cpu_has(X86_FEATURE_FPU)) |
| return fpregs_soft_set(current, NULL, |
| 0, sizeof(struct user_i387_ia32_struct), |
| NULL, buf) != 0; |
| |
| if (use_xsave()) { |
| struct _fpx_sw_bytes fx_sw_user; |
| if (unlikely(check_for_xstate(buf_fx, buf_fx, &fx_sw_user))) { |
| /* |
| * Couldn't find the extended state information in the |
| * memory layout. Restore just the FP/SSE and init all |
| * the other extended state. |
| */ |
| state_size = sizeof(struct fxregs_state); |
| fx_only = 1; |
| trace_x86_fpu_xstate_check_failed(fpu); |
| } else { |
| state_size = fx_sw_user.xstate_size; |
| xfeatures = fx_sw_user.xfeatures; |
| } |
| } |
| |
| /* |
| * The current state of the FPU registers does not matter. By setting |
| * TIF_NEED_FPU_LOAD unconditionally it is ensured that the our xstate |
| * is not modified on context switch and that the xstate is considered |
| * to be loaded again on return to userland (overriding last_cpu avoids |
| * the optimisation). |
| */ |
| set_thread_flag(TIF_NEED_FPU_LOAD); |
| __fpu_invalidate_fpregs_state(fpu); |
| |
| if ((unsigned long)buf_fx % 64) |
| fx_only = 1; |
| /* |
| * For 32-bit frames with fxstate, copy the fxstate so it can be |
| * reconstructed later. |
| */ |
| if (ia32_fxstate) { |
| ret = __copy_from_user(&env, buf, sizeof(env)); |
| if (ret) |
| goto err_out; |
| envp = &env; |
| } else { |
| /* |
| * Attempt to restore the FPU registers directly from user |
| * memory. For that to succeed, the user access cannot cause |
| * page faults. If it does, fall back to the slow path below, |
| * going through the kernel buffer with the enabled pagefault |
| * handler. |
| */ |
| fpregs_lock(); |
| pagefault_disable(); |
| ret = copy_user_to_fpregs_zeroing(buf_fx, xfeatures, fx_only); |
| pagefault_enable(); |
| if (!ret) { |
| fpregs_mark_activate(); |
| fpregs_unlock(); |
| return 0; |
| } |
| fpregs_unlock(); |
| } |
| |
| |
| if (use_xsave() && !fx_only) { |
| u64 init_bv = xfeatures_mask & ~xfeatures; |
| |
| if (using_compacted_format()) { |
| ret = copy_user_to_xstate(&fpu->state.xsave, buf_fx); |
| } else { |
| ret = __copy_from_user(&fpu->state.xsave, buf_fx, state_size); |
| |
| if (!ret && state_size > offsetof(struct xregs_state, header)) |
| ret = validate_xstate_header(&fpu->state.xsave.header); |
| } |
| if (ret) |
| goto err_out; |
| |
| sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only); |
| |
| fpregs_lock(); |
| if (unlikely(init_bv)) |
| copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); |
| ret = copy_kernel_to_xregs_err(&fpu->state.xsave, xfeatures); |
| |
| } else if (use_fxsr()) { |
| ret = __copy_from_user(&fpu->state.fxsave, buf_fx, state_size); |
| if (ret) { |
| ret = -EFAULT; |
| goto err_out; |
| } |
| |
| sanitize_restored_xstate(&fpu->state, envp, xfeatures, fx_only); |
| |
| fpregs_lock(); |
| if (use_xsave()) { |
| u64 init_bv = xfeatures_mask & ~XFEATURE_MASK_FPSSE; |
| copy_kernel_to_xregs(&init_fpstate.xsave, init_bv); |
| } |
| |
| ret = copy_kernel_to_fxregs_err(&fpu->state.fxsave); |
| } else { |
| ret = __copy_from_user(&fpu->state.fsave, buf_fx, state_size); |
| if (ret) |
| goto err_out; |
| |
| fpregs_lock(); |
| ret = copy_kernel_to_fregs_err(&fpu->state.fsave); |
| } |
| if (!ret) |
| fpregs_mark_activate(); |
| fpregs_unlock(); |
| |
| err_out: |
| if (ret) |
| fpu__clear(fpu); |
| return ret; |
| } |
| |
| static inline int xstate_sigframe_size(void) |
| { |
| return use_xsave() ? fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE : |
| fpu_user_xstate_size; |
| } |
| |
| /* |
| * Restore FPU state from a sigframe: |
| */ |
| int fpu__restore_sig(void __user *buf, int ia32_frame) |
| { |
| void __user *buf_fx = buf; |
| int size = xstate_sigframe_size(); |
| |
| if (ia32_frame && use_fxsr()) { |
| buf_fx = buf + sizeof(struct fregs_state); |
| size += sizeof(struct fregs_state); |
| } |
| |
| return __fpu__restore_sig(buf, buf_fx, size); |
| } |
| |
| unsigned long |
| fpu__alloc_mathframe(unsigned long sp, int ia32_frame, |
| unsigned long *buf_fx, unsigned long *size) |
| { |
| unsigned long frame_size = xstate_sigframe_size(); |
| |
| *buf_fx = sp = round_down(sp - frame_size, 64); |
| if (ia32_frame && use_fxsr()) { |
| frame_size += sizeof(struct fregs_state); |
| sp -= sizeof(struct fregs_state); |
| } |
| |
| *size = frame_size; |
| |
| return sp; |
| } |
| /* |
| * Prepare the SW reserved portion of the fxsave memory layout, indicating |
| * the presence of the extended state information in the memory layout |
| * pointed by the fpstate pointer in the sigcontext. |
| * This will be saved when ever the FP and extended state context is |
| * saved on the user stack during the signal handler delivery to the user. |
| */ |
| void fpu__init_prepare_fx_sw_frame(void) |
| { |
| int size = fpu_user_xstate_size + FP_XSTATE_MAGIC2_SIZE; |
| |
| fx_sw_reserved.magic1 = FP_XSTATE_MAGIC1; |
| fx_sw_reserved.extended_size = size; |
| fx_sw_reserved.xfeatures = xfeatures_mask; |
| fx_sw_reserved.xstate_size = fpu_user_xstate_size; |
| |
| if (IS_ENABLED(CONFIG_IA32_EMULATION) || |
| IS_ENABLED(CONFIG_X86_32)) { |
| int fsave_header_size = sizeof(struct fregs_state); |
| |
| fx_sw_reserved_ia32 = fx_sw_reserved; |
| fx_sw_reserved_ia32.extended_size = size + fsave_header_size; |
| } |
| } |
| |