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