eda32f4f93
xfeatures_mask_fpstate() is no longer valid when dynamically enabled features come into play. Rework restore_regs_from_fpstate() so it takes a constant mask which will then be applied against the maximum feature set so that the restore operation brings all features which are not in the xsave buffer xfeature bitmap into init state. This ensures that if the previous task used a dynamically enabled feature that the task which restores has all unused components properly initialized. Cleanup the last user of xfeatures_mask_fpstate() as well and remove it. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20211014230739.461348278@linutronix.de
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* FPU registers are no longer valid for this task.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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* Either one of these invalidation functions is enough. Invalidate
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* 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 = ¤t->thread.fpu;
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int cpu = smp_processor_id();
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if (WARN_ON_ONCE(current->flags & PF_KTHREAD))
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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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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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