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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __X86_KERNEL_FPU_CONTEXT_H
#define __X86_KERNEL_FPU_CONTEXT_H
#include <asm/fpu/xstate.h>
#include <asm/trace/fpu.h>
/* Functions related to FPU context tracking */
/*
* The in-register FPU state for an FPU context on a CPU is assumed to be
* valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx
* matches the FPU.
*
* If the FPU register state is valid, the kernel can skip restoring the
* FPU state from memory.
*
* Any code that clobbers the FPU registers or updates the in-memory
* FPU state for a task MUST let the rest of the kernel know that the
* FPU registers are no longer valid for this task.
*
* Either one of these invalidation functions is enough. Invalidate
* a resource you control: CPU if using the CPU for something else
* (with preemption disabled), FPU for the current task, or a task that
* is prevented from running by the current task.
*/
static inline void __cpu_invalidate_fpregs_state(void)
{
__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
}
static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu)
{
fpu->last_cpu = -1;
}
static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
{
return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
}
static inline void fpregs_deactivate(struct fpu *fpu)
{
__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
trace_x86_fpu_regs_deactivated(fpu);
}
static inline void fpregs_activate(struct fpu *fpu)
{
__this_cpu_write(fpu_fpregs_owner_ctx, fpu);
trace_x86_fpu_regs_activated(fpu);
}
/* Internal helper for switch_fpu_return() and signal frame setup */
static inline void fpregs_restore_userregs(void)
{
struct fpu *fpu = ¤t->thread.fpu;
int cpu = smp_processor_id();
if (WARN_ON_ONCE(current->flags & (PF_KTHREAD | PF_IO_WORKER)))
return;
if (!fpregs_state_valid(fpu, cpu)) {
/*
* This restores _all_ xstate which has not been
* established yet.
*
* If PKRU is enabled, then the PKRU value is already
* correct because it was either set in switch_to() or in
* flush_thread(). So it is excluded because it might be
* not up to date in current->thread.fpu.xsave state.
*
* XFD state is handled in restore_fpregs_from_fpstate().
*/
restore_fpregs_from_fpstate(fpu->fpstate, XFEATURE_MASK_FPSTATE);
fpregs_activate(fpu);
fpu->last_cpu = cpu;
}
clear_thread_flag(TIF_NEED_FPU_LOAD);
}
#endif
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