cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sched.h (2079B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef _ASM_X86_FPU_SCHED_H
      3#define _ASM_X86_FPU_SCHED_H
      4
      5#include <linux/sched.h>
      6
      7#include <asm/cpufeature.h>
      8#include <asm/fpu/types.h>
      9
     10#include <asm/trace/fpu.h>
     11
     12extern void save_fpregs_to_fpstate(struct fpu *fpu);
     13extern void fpu__drop(struct fpu *fpu);
     14extern int  fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal);
     15extern void fpu_flush_thread(void);
     16
     17/*
     18 * FPU state switching for scheduling.
     19 *
     20 * This is a two-stage process:
     21 *
     22 *  - switch_fpu_prepare() saves the old state.
     23 *    This is done within the context of the old process.
     24 *
     25 *  - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state
     26 *    will get loaded on return to userspace, or when the kernel needs it.
     27 *
     28 * If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers
     29 * are saved in the current thread's FPU register state.
     30 *
     31 * If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not
     32 * hold current()'s FPU registers. It is required to load the
     33 * registers before returning to userland or using the content
     34 * otherwise.
     35 *
     36 * The FPU context is only stored/restored for a user task and
     37 * PF_KTHREAD is used to distinguish between kernel and user threads.
     38 */
     39static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu)
     40{
     41	if (cpu_feature_enabled(X86_FEATURE_FPU) &&
     42	    !(current->flags & PF_KTHREAD)) {
     43		save_fpregs_to_fpstate(old_fpu);
     44		/*
     45		 * The save operation preserved register state, so the
     46		 * fpu_fpregs_owner_ctx is still @old_fpu. Store the
     47		 * current CPU number in @old_fpu, so the next return
     48		 * to user space can avoid the FPU register restore
     49		 * when is returns on the same CPU and still owns the
     50		 * context.
     51		 */
     52		old_fpu->last_cpu = cpu;
     53
     54		trace_x86_fpu_regs_deactivated(old_fpu);
     55	}
     56}
     57
     58/*
     59 * Delay loading of the complete FPU state until the return to userland.
     60 * PKRU is handled separately.
     61 */
     62static inline void switch_fpu_finish(void)
     63{
     64	if (cpu_feature_enabled(X86_FEATURE_FPU))
     65		set_thread_flag(TIF_NEED_FPU_LOAD);
     66}
     67
     68#endif /* _ASM_X86_FPU_SCHED_H */