118 lines
3.1 KiB
C
118 lines
3.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Common implementation of switch_mm_irqs_off
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*
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* Copyright IBM Corp. 2017
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*/
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#include <linux/mm.h>
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#include <linux/cpu.h>
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#include <linux/sched/mm.h>
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#include <asm/mmu_context.h>
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#include <asm/pgalloc.h>
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#if defined(CONFIG_PPC32)
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static inline void switch_mm_pgdir(struct task_struct *tsk,
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struct mm_struct *mm)
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{
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/* 32-bit keeps track of the current PGDIR in the thread struct */
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tsk->thread.pgdir = mm->pgd;
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#ifdef CONFIG_PPC_BOOK3S_32
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tsk->thread.sr0 = mm->context.sr0;
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#endif
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#if defined(CONFIG_BOOKE_OR_40x) && defined(CONFIG_PPC_KUAP)
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tsk->thread.pid = mm->context.id;
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#endif
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}
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#elif defined(CONFIG_PPC_BOOK3E_64)
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static inline void switch_mm_pgdir(struct task_struct *tsk,
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struct mm_struct *mm)
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{
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/* 64-bit Book3E keeps track of current PGD in the PACA */
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get_paca()->pgd = mm->pgd;
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#ifdef CONFIG_PPC_KUAP
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tsk->thread.pid = mm->context.id;
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#endif
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}
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#else
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static inline void switch_mm_pgdir(struct task_struct *tsk,
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struct mm_struct *mm) { }
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#endif
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void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
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struct task_struct *tsk)
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{
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int cpu = smp_processor_id();
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bool new_on_cpu = false;
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/* Mark this context has been used on the new CPU */
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if (!cpumask_test_cpu(cpu, mm_cpumask(next))) {
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VM_WARN_ON_ONCE(next == &init_mm);
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cpumask_set_cpu(cpu, mm_cpumask(next));
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inc_mm_active_cpus(next);
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/*
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* This full barrier orders the store to the cpumask above vs
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* a subsequent load which allows this CPU/MMU to begin loading
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* translations for 'next' from page table PTEs into the TLB.
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*
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* When using the radix MMU, that operation is the load of the
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* MMU context id, which is then moved to SPRN_PID.
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*
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* For the hash MMU it is either the first load from slb_cache
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* in switch_slb() to preload the SLBs, or the load of
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* get_user_context which loads the context for the VSID hash
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* to insert a new SLB, in the SLB fault handler.
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*
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* On the other side, the barrier is in mm/tlb-radix.c for
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* radix which orders earlier stores to clear the PTEs before
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* the load of mm_cpumask to check which CPU TLBs should be
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* flushed. For hash, pte_xchg to clear the PTE includes the
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* barrier.
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*
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* This full barrier is also needed by membarrier when
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* switching between processes after store to rq->curr, before
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* user-space memory accesses.
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*/
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smp_mb();
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new_on_cpu = true;
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}
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/* Some subarchs need to track the PGD elsewhere */
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switch_mm_pgdir(tsk, next);
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/* Nothing else to do if we aren't actually switching */
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if (prev == next)
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return;
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/*
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* We must stop all altivec streams before changing the HW
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* context
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*/
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if (cpu_has_feature(CPU_FTR_ALTIVEC))
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asm volatile (PPC_DSSALL);
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if (!new_on_cpu)
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membarrier_arch_switch_mm(prev, next, tsk);
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/*
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* The actual HW switching method differs between the various
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* sub architectures. Out of line for now
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*/
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switch_mmu_context(prev, next, tsk);
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VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, mm_cpumask(prev)));
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}
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#ifndef CONFIG_PPC_BOOK3S_64
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void arch_exit_mmap(struct mm_struct *mm)
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{
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void *frag = pte_frag_get(&mm->context);
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if (frag)
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pte_frag_destroy(frag);
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}
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#endif
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