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or updates the in-memory 19 * FPU state for a task MUST let the rest of the kernel know that the 20 * FPU registers are no longer valid for this task. 21 * 22 * Invalidate a resource you control: CPU if using the CPU for something else 23 * (with preemption disabled), FPU for the current task, or a task that 24 * is prevented from running by the current task. 25 */ 26 static inline void __cpu_invalidate_fpregs_state(void) 27 { 28 __this_cpu_write(fpu_fpregs_owner_ctx, NULL); 29 } 30 31 static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu) 32 { 33 fpu->last_cpu = -1; 34 } 35 36 static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu) 37 { 38 return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu; 39 } 40 41 static inline void fpregs_deactivate(struct fpu *fpu) 42 { 43 __this_cpu_write(fpu_fpregs_owner_ctx, NULL); 44 trace_x86_fpu_regs_deactivated(fpu); 45 } 46 47 static inline void fpregs_activate(struct fpu *fpu) 48 { 49 __this_cpu_write(fpu_fpregs_owner_ctx, fpu); 50 trace_x86_fpu_regs_activated(fpu); 51 } 52 53 /* Internal helper for switch_fpu_return() and signal frame setup */ 54 static inline void fpregs_restore_userregs(void) 55 { 56 struct fpu *fpu = ¤t->thread.fpu; 57 int cpu = smp_processor_id(); 58 59 if (WARN_ON_ONCE(current->flags & (PF_KTHREAD | PF_USER_WORKER))) 60 return; 61 62 if (!fpregs_state_valid(fpu, cpu)) { 63 /* 64 * This restores _all_ xstate which has not been 65 * established yet. 66 * 67 * If PKRU is enabled, then the PKRU value is already 68 * correct because it was either set in switch_to() or in 69 * flush_thread(). So it is excluded because it might be 70 * not up to date in current->thread.fpu.xsave state. 71 * 72 * XFD state is handled in restore_fpregs_from_fpstate(). 73 */ 74 restore_fpregs_from_fpstate(fpu->fpstate, XFEATURE_MASK_FPSTATE); 75 76 fpregs_activate(fpu); 77 fpu->last_cpu = cpu; 78 } 79 clear_thread_flag(TIF_NEED_FPU_LOAD); 80 } 81 82 #endif 83