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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (C) 1994 Linus Torvalds
*
* Pentium III FXSR, SSE support
* General FPU state handling cleanups
* Gareth Hughes <gareth@valinux.com>, May 2000
* x86-64 work by Andi Kleen 2002
*/
#ifndef _ASM_X86_FPU_API_H
#define _ASM_X86_FPU_API_H
#include <linux/bottom_half.h>
/*
* Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
* disables preemption so be careful if you intend to use it for long periods
* of time.
* If you intend to use the FPU in irq/softirq you need to check first with
* irq_fpu_usable() if it is possible.
*/
/* Kernel FPU states to initialize in kernel_fpu_begin_mask() */
#define KFPU_387 _BITUL(0) /* 387 state will be initialized */
#define KFPU_MXCSR _BITUL(1) /* MXCSR will be initialized */
extern void kernel_fpu_begin_mask(unsigned int kfpu_mask);
extern void kernel_fpu_end(void);
extern bool irq_fpu_usable(void);
extern void fpregs_mark_activate(void);
/* Code that is unaware of kernel_fpu_begin_mask() can use this */
static inline void kernel_fpu_begin(void)
{
#ifdef CONFIG_X86_64
/*
* Any 64-bit code that uses 387 instructions must explicitly request
* KFPU_387.
*/
kernel_fpu_begin_mask(KFPU_MXCSR);
#else
/*
* 32-bit kernel code may use 387 operations as well as SSE2, etc,
* as long as it checks that the CPU has the required capability.
*/
kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);
#endif
}
/*
* Use fpregs_lock() while editing CPU's FPU registers or fpu->state.
* A context switch will (and softirq might) save CPU's FPU registers to
* fpu->state and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in
* a random state.
*
* local_bh_disable() protects against both preemption and soft interrupts
* on !RT kernels.
*
* On RT kernels local_bh_disable() is not sufficient because it only
* serializes soft interrupt related sections via a local lock, but stays
* preemptible. Disabling preemption is the right choice here as bottom
* half processing is always in thread context on RT kernels so it
* implicitly prevents bottom half processing as well.
*
* Disabling preemption also serializes against kernel_fpu_begin().
*/
static inline void fpregs_lock(void)
{
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
local_bh_disable();
else
preempt_disable();
}
static inline void fpregs_unlock(void)
{
if (!IS_ENABLED(CONFIG_PREEMPT_RT))
local_bh_enable();
else
preempt_enable();
}
#ifdef CONFIG_X86_DEBUG_FPU
extern void fpregs_assert_state_consistent(void);
#else
static inline void fpregs_assert_state_consistent(void) { }
#endif
/*
* Load the task FPU state before returning to userspace.
*/
extern void switch_fpu_return(void);
/*
* Query the presence of one or more xfeatures. Works on any legacy CPU as well.
*
* If 'feature_name' is set then put a human-readable description of
* the feature there as well - this can be used to print error (or success)
* messages.
*/
extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
/*
* Tasks that are not using SVA have mm->pasid set to zero to note that they
* will not have the valid bit set in MSR_IA32_PASID while they are running.
*/
#define PASID_DISABLED 0
static inline void update_pasid(void) { }
#endif /* _ASM_X86_FPU_API_H */
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