1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (C) 1994 Linus Torvalds 4 * 5 * Pentium III FXSR, SSE support 6 * General FPU state handling cleanups 7 * Gareth Hughes <gareth@valinux.com>, May 2000 8 * x86-64 work by Andi Kleen 2002 9 */ 10 11 #ifndef _ASM_X86_FPU_API_H 12 #define _ASM_X86_FPU_API_H 13 #include <linux/bottom_half.h> 14 15 #include <asm/fpu/types.h> 16 17 /* 18 * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It 19 * disables preemption so be careful if you intend to use it for long periods 20 * of time. 21 * If you intend to use the FPU in irq/softirq you need to check first with 22 * irq_fpu_usable() if it is possible. 23 */ 24 25 /* Kernel FPU states to initialize in kernel_fpu_begin_mask() */ 26 #define KFPU_387 _BITUL(0) /* 387 state will be initialized */ 27 #define KFPU_MXCSR _BITUL(1) /* MXCSR will be initialized */ 28 29 extern void kernel_fpu_begin_mask(unsigned int kfpu_mask); 30 extern void kernel_fpu_end(void); 31 extern bool irq_fpu_usable(void); 32 extern void fpregs_mark_activate(void); 33 34 /* Code that is unaware of kernel_fpu_begin_mask() can use this */ 35 static inline void kernel_fpu_begin(void) 36 { 37 #ifdef CONFIG_X86_64 38 /* 39 * Any 64-bit code that uses 387 instructions must explicitly request 40 * KFPU_387. 41 */ 42 kernel_fpu_begin_mask(KFPU_MXCSR); 43 #else 44 /* 45 * 32-bit kernel code may use 387 operations as well as SSE2, etc, 46 * as long as it checks that the CPU has the required capability. 47 */ 48 kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR); 49 #endif 50 } 51 52 /* 53 * Use fpregs_lock() while editing CPU's FPU registers or fpu->fpstate. 54 * A context switch will (and softirq might) save CPU's FPU registers to 55 * fpu->fpstate.regs and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in 56 * a random state. 57 * 58 * local_bh_disable() protects against both preemption and soft interrupts 59 * on !RT kernels. 60 * 61 * On RT kernels local_bh_disable() is not sufficient because it only 62 * serializes soft interrupt related sections via a local lock, but stays 63 * preemptible. Disabling preemption is the right choice here as bottom 64 * half processing is always in thread context on RT kernels so it 65 * implicitly prevents bottom half processing as well. 66 * 67 * Disabling preemption also serializes against kernel_fpu_begin(). 68 */ 69 static inline void fpregs_lock(void) 70 { 71 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) 72 local_bh_disable(); 73 else 74 preempt_disable(); 75 } 76 77 static inline void fpregs_unlock(void) 78 { 79 if (!IS_ENABLED(CONFIG_PREEMPT_RT)) 80 local_bh_enable(); 81 else 82 preempt_enable(); 83 } 84 85 #ifdef CONFIG_X86_DEBUG_FPU 86 extern void fpregs_assert_state_consistent(void); 87 #else 88 static inline void fpregs_assert_state_consistent(void) { } 89 #endif 90 91 /* 92 * Load the task FPU state before returning to userspace. 93 */ 94 extern void switch_fpu_return(void); 95 96 /* 97 * Query the presence of one or more xfeatures. Works on any legacy CPU as well. 98 * 99 * If 'feature_name' is set then put a human-readable description of 100 * the feature there as well - this can be used to print error (or success) 101 * messages. 102 */ 103 extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name); 104 105 /* 106 * Tasks that are not using SVA have mm->pasid set to zero to note that they 107 * will not have the valid bit set in MSR_IA32_PASID while they are running. 108 */ 109 #define PASID_DISABLED 0 110 111 /* Trap handling */ 112 extern int fpu__exception_code(struct fpu *fpu, int trap_nr); 113 extern void fpu_sync_fpstate(struct fpu *fpu); 114 extern void fpu_reset_from_exception_fixup(void); 115 116 /* Boot, hotplug and resume */ 117 extern void fpu__init_cpu(void); 118 extern void fpu__init_system(struct cpuinfo_x86 *c); 119 extern void fpu__init_check_bugs(void); 120 extern void fpu__resume_cpu(void); 121 122 #ifdef CONFIG_MATH_EMULATION 123 extern void fpstate_init_soft(struct swregs_state *soft); 124 #else 125 static inline void fpstate_init_soft(struct swregs_state *soft) {} 126 #endif 127 128 /* State tracking */ 129 DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx); 130 131 /* Process cleanup */ 132 #ifdef CONFIG_X86_64 133 extern void fpstate_free(struct fpu *fpu); 134 #else 135 static inline void fpstate_free(struct fpu *fpu) { } 136 #endif 137 138 /* fpstate-related functions which are exported to KVM */ 139 extern void fpstate_clear_xstate_component(struct fpstate *fps, unsigned int xfeature); 140 141 /* KVM specific functions */ 142 extern bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu); 143 extern void fpu_free_guest_fpstate(struct fpu_guest *gfpu); 144 extern int fpu_swap_kvm_fpstate(struct fpu_guest *gfpu, bool enter_guest); 145 146 extern void fpu_copy_guest_fpstate_to_uabi(struct fpu_guest *gfpu, void *buf, unsigned int size, u32 pkru); 147 extern int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, u64 xcr0, u32 *vpkru); 148 149 static inline void fpstate_set_confidential(struct fpu_guest *gfpu) 150 { 151 gfpu->fpstate->is_confidential = true; 152 } 153 154 static inline bool fpstate_is_confidential(struct fpu_guest *gfpu) 155 { 156 return gfpu->fpstate->is_confidential; 157 } 158 159 /* prctl */ 160 struct task_struct; 161 extern long fpu_xstate_prctl(struct task_struct *tsk, int option, unsigned long arg2); 162 163 #endif /* _ASM_X86_FPU_API_H */ 164