1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __X86_KERNEL_FPU_CONTEXT_H 3 #define __X86_KERNEL_FPU_CONTEXT_H 4 5 #include <asm/fpu/xstate.h> 6 #include <asm/trace/fpu.h> 7 8 /* Functions related to FPU context tracking */ 9 10 /* 11 * The in-register FPU state for an FPU context on a CPU is assumed to be 12 * valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx 13 * matches the FPU. 14 * 15 * If the FPU register state is valid, the kernel can skip restoring the 16 * FPU state from memory. 17 * 18 * Any code that clobbers the FPU registers or updates the in-memory 19 * FPU state for a task MUST let the rest of the kernel know that the 20 * FPU registers are no longer valid for this task. 21 * 22 * Either one of these invalidation functions is enough. Invalidate 23 * a resource you control: CPU if using the CPU for something else 24 * (with preemption disabled), FPU for the current task, or a task that 25 * is prevented from running by the current task. 26 */ 27 static inline void __cpu_invalidate_fpregs_state(void) 28 { 29 __this_cpu_write(fpu_fpregs_owner_ctx, NULL); 30 } 31 32 static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu) 33 { 34 fpu->last_cpu = -1; 35 } 36 37 static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu) 38 { 39 return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu; 40 } 41 42 static inline void fpregs_deactivate(struct fpu *fpu) 43 { 44 __this_cpu_write(fpu_fpregs_owner_ctx, NULL); 45 trace_x86_fpu_regs_deactivated(fpu); 46 } 47 48 static inline void fpregs_activate(struct fpu *fpu) 49 { 50 __this_cpu_write(fpu_fpregs_owner_ctx, fpu); 51 trace_x86_fpu_regs_activated(fpu); 52 } 53 54 /* Internal helper for switch_fpu_return() and signal frame setup */ 55 static inline void fpregs_restore_userregs(void) 56 { 57 struct fpu *fpu = ¤t->thread.fpu; 58 int cpu = smp_processor_id(); 59 60 if (WARN_ON_ONCE(current->flags & (PF_KTHREAD | PF_IO_WORKER))) 61 return; 62 63 if (!fpregs_state_valid(fpu, cpu)) { 64 /* 65 * This restores _all_ xstate which has not been 66 * established yet. 67 * 68 * If PKRU is enabled, then the PKRU value is already 69 * correct because it was either set in switch_to() or in 70 * flush_thread(). So it is excluded because it might be 71 * not up to date in current->thread.fpu.xsave state. 72 * 73 * XFD state is handled in restore_fpregs_from_fpstate(). 74 */ 75 restore_fpregs_from_fpstate(fpu->fpstate, XFEATURE_MASK_FPSTATE); 76 77 fpregs_activate(fpu); 78 fpu->last_cpu = cpu; 79 } 80 clear_thread_flag(TIF_NEED_FPU_LOAD); 81 } 82 83 #endif 84