diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index a1a70134e1fe5e1b89180be946629a92b4196909..aa268d9cf22845dbd2cea897711c4178c7ea6474 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -250,10 +250,8 @@ sanitize_restored_user_xstate(union fpregs_state *state, } } -/* - * Restore the FPU state directly from the userspace signal frame. - */ -static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only) +static int __restore_fpregs_from_user(void __user *buf, u64 xrestore, + bool fx_only) { if (use_xsave()) { u64 init_bv = xfeatures_mask_uabi() & ~xrestore; @@ -274,6 +272,57 @@ static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only } } +static int restore_fpregs_from_user(void __user *buf, u64 xrestore, bool fx_only) +{ + struct fpu *fpu = ¤t->thread.fpu; + int ret; + + fpregs_lock(); + pagefault_disable(); + ret = __restore_fpregs_from_user(buf, xrestore, fx_only); + pagefault_enable(); + + if (unlikely(ret)) { + /* + * The above did an FPU restore operation, restricted to + * the user portion of the registers, and failed, but the + * microcode might have modified the FPU registers + * nevertheless. + * + * If the FPU registers do not belong to current, then + * invalidate the FPU register state otherwise the task + * might preempt current and return to user space with + * corrupted FPU registers. + * + * In case current owns the FPU registers then no further + * action is required. The fixup in the slow path will + * handle it correctly. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD)) + __cpu_invalidate_fpregs_state(); + fpregs_unlock(); + return ret; + } + + /* + * Restore supervisor states: previous context switch etc has done + * XSAVES and saved the supervisor states in the kernel buffer from + * which they can be restored now. + * + * It would be optimal to handle this with a single XRSTORS, but + * this does not work because the rest of the FPU registers have + * been restored from a user buffer directly. The single XRSTORS + * happens below, when the user buffer has been copied to the + * kernel one. + */ + if (test_thread_flag(TIF_NEED_FPU_LOAD) && xfeatures_mask_supervisor()) + os_xrstor(&fpu->state.xsave, xfeatures_mask_supervisor()); + + fpregs_mark_activate(); + fpregs_unlock(); + return 0; +} + static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, bool ia32_fxstate) { @@ -298,61 +347,16 @@ static int __fpu_restore_sig(void __user *buf, void __user *buf_fx, user_xfeatures = fx_sw_user.xfeatures; } - if (!ia32_fxstate) { + if (likely(!ia32_fxstate)) { /* * 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. + * 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 = restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only); - pagefault_enable(); - if (!ret) { - - /* - * Restore supervisor states: previous context switch - * etc has done XSAVES and saved the supervisor states - * in the kernel buffer from which they can be restored - * now. - * - * We cannot do a single XRSTORS here - which would - * be nice - because the rest of the FPU registers are - * being restored from a user buffer directly. The - * single XRSTORS happens below, when the user buffer - * has been copied to the kernel one. - */ - if (test_thread_flag(TIF_NEED_FPU_LOAD) && - xfeatures_mask_supervisor()) { - os_xrstor(&fpu->state.xsave, - xfeatures_mask_supervisor()); - } - fpregs_mark_activate(); - fpregs_unlock(); + if (likely(!ret)) return 0; - } - - /* - * The above did an FPU restore operation, restricted to - * the user portion of the registers, and failed, but the - * microcode might have modified the FPU registers - * nevertheless. - * - * If the FPU registers do not belong to current, then - * invalidate the FPU register state otherwise the task might - * preempt current and return to user space with corrupted - * FPU registers. - * - * In case current owns the FPU registers then no further - * action is required. The fixup below will handle it - * correctly. - */ - if (test_thread_flag(TIF_NEED_FPU_LOAD)) - __cpu_invalidate_fpregs_state(); - - fpregs_unlock(); } else { /* * For 32-bit frames with fxstate, copy the fxstate so it can