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e3bfa38599
This will make the removal of the task_struct::thread.fpu array easier. No change in functionality - code generated before and after this commit is identical on x86-defconfig: kepler:~/tip> diff -up vmlinux.before.asm vmlinux.after.asm kepler:~/tip> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Chang S. Bae <chang.seok.bae@intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20250409211127.3544993-3-mingo@kernel.org
82 lines
2.3 KiB
C
82 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __X86_KERNEL_FPU_CONTEXT_H
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#define __X86_KERNEL_FPU_CONTEXT_H
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#include <asm/fpu/xstate.h>
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#include <asm/trace/fpu.h>
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/* Functions related to FPU context tracking */
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/*
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* The in-register FPU state for an FPU context on a CPU is assumed to be
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* valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx
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* matches the FPU.
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*
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* If the FPU register state is valid, the kernel can skip restoring the
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* FPU state from memory.
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*
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* Any code that clobbers the FPU registers or updates the in-memory
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* FPU state for a task MUST let the rest of the kernel know that the
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* FPU registers are no longer valid for this task.
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*
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* Invalidate a resource you control: CPU if using the CPU for something else
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* (with preemption disabled), FPU for the current task, or a task that
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* is prevented from running by the current task.
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*/
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static inline void __cpu_invalidate_fpregs_state(void)
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{
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__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
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}
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static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu)
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{
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fpu->last_cpu = -1;
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}
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static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
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{
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return fpu == this_cpu_read(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
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}
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static inline void fpregs_deactivate(struct fpu *fpu)
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{
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__this_cpu_write(fpu_fpregs_owner_ctx, NULL);
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trace_x86_fpu_regs_deactivated(fpu);
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}
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static inline void fpregs_activate(struct fpu *fpu)
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{
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__this_cpu_write(fpu_fpregs_owner_ctx, fpu);
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trace_x86_fpu_regs_activated(fpu);
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}
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/* Internal helper for switch_fpu_return() and signal frame setup */
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static inline void fpregs_restore_userregs(void)
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{
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struct fpu *fpu = x86_task_fpu(current);
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int cpu = smp_processor_id();
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if (WARN_ON_ONCE(current->flags & (PF_KTHREAD | PF_USER_WORKER)))
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return;
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if (!fpregs_state_valid(fpu, cpu)) {
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/*
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* This restores _all_ xstate which has not been
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* established yet.
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*
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* If PKRU is enabled, then the PKRU value is already
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* correct because it was either set in switch_to() or in
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* flush_thread(). So it is excluded because it might be
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* not up to date in current->thread.fpu->xsave state.
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*
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* XFD state is handled in restore_fpregs_from_fpstate().
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*/
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restore_fpregs_from_fpstate(fpu->fpstate, XFEATURE_MASK_FPSTATE);
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fpregs_activate(fpu);
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fpu->last_cpu = cpu;
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}
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clear_thread_flag(TIF_NEED_FPU_LOAD);
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}
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#endif
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