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-rw-r--r--arch/powerpc/mm/mmu_context.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/arch/powerpc/mm/mmu_context.c b/arch/powerpc/mm/mmu_context.c
new file mode 100644
index 0000000000..b24c19078e
--- /dev/null
+++ b/arch/powerpc/mm/mmu_context.c
@@ -0,0 +1,117 @@
+// 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;
+#ifdef CONFIG_PPC_BOOK3S_32
+ tsk->thread.sr0 = mm->context.sr0;
+#endif
+#if defined(CONFIG_BOOKE_OR_40x) && defined(CONFIG_PPC_KUAP)
+ tsk->thread.pid = mm->context.id;
+#endif
+}
+#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;
+#ifdef CONFIG_PPC_KUAP
+ tsk->thread.pid = mm->context.id;
+#endif
+}
+#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)
+{
+ int cpu = smp_processor_id();
+ bool new_on_cpu = false;
+
+ /* Mark this context has been used on the new CPU */
+ if (!cpumask_test_cpu(cpu, mm_cpumask(next))) {
+ VM_WARN_ON_ONCE(next == &init_mm);
+ cpumask_set_cpu(cpu, 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 (PPC_DSSALL);
+
+ if (!new_on_cpu)
+ 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);
+
+ VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, mm_cpumask(prev)));
+}
+
+#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