1 files changed, 113 insertions, 0 deletions
diff --git a/arch/powerpc/mm/mmu_context.c b/arch/powerpc/mm/mmu_context.c
new file mode 100644
index 000000000..1fb9c99f8
--- /dev/null
+++ b/arch/powerpc/mm/mmu_context.c
@@ -0,0 +1,113 @@
+// 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)
+{
+	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 (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);
+}
+
+#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