Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 174 insertions, 0 deletions

diff --git a/arch/arc/include/asm/mmu_context.h b/arch/arc/include/asm/mmu_context.h
new file mode 100644
index 000000000..dda471f5f
--- /dev/null
+++ b/arch/arc/include/asm/mmu_context.h
@@ -0,0 +1,174 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * vineetg: May 2011
+ *  -Refactored get_new_mmu_context( ) to only handle live-mm.
+ *   retiring-mm handled in other hooks
+ *
+ * Vineetg: March 25th, 2008: Bug #92690
+ *  -Major rewrite of Core ASID allocation routine get_new_mmu_context
+ *
+ * Amit Bhor, Sameer Dhavale: Codito Technologies 2004
+ */
+
+#ifndef _ASM_ARC_MMU_CONTEXT_H
+#define _ASM_ARC_MMU_CONTEXT_H
+
+#include <linux/sched/mm.h>
+
+#include <asm/tlb.h>
+#include <asm-generic/mm_hooks.h>
+
+/*		ARC ASID Management
+ *
+ * MMU tags TLBs with an 8-bit ASID, avoiding need to flush the TLB on
+ * context-switch.
+ *
+ * ASID is managed per cpu, so task threads across CPUs can have different
+ * ASID. Global ASID management is needed if hardware supports TLB shootdown
+ * and/or shared TLB across cores, which ARC doesn't.
+ *
+ * Each task is assigned unique ASID, with a simple round-robin allocator
+ * tracked in @asid_cpu. When 8-bit value rolls over,a new cycle is started
+ * over from 0, and TLB is flushed
+ *
+ * A new allocation cycle, post rollover, could potentially reassign an ASID
+ * to a different task. Thus the rule is to refresh the ASID in a new cycle.
+ * The 32 bit @asid_cpu (and mm->asid) have 8 bits MMU PID and rest 24 bits
+ * serve as cycle/generation indicator and natural 32 bit unsigned math
+ * automagically increments the generation when lower 8 bits rollover.
+ */
+
+#define MM_CTXT_ASID_MASK	0x000000ff /* MMU PID reg :8 bit PID */
+#define MM_CTXT_CYCLE_MASK	(~MM_CTXT_ASID_MASK)
+
+#define MM_CTXT_FIRST_CYCLE	(MM_CTXT_ASID_MASK + 1)
+#define MM_CTXT_NO_ASID		0UL
+
+#define asid_mm(mm, cpu)	mm->context.asid[cpu]
+#define hw_pid(mm, cpu)		(asid_mm(mm, cpu) & MM_CTXT_ASID_MASK)
+
+DECLARE_PER_CPU(unsigned int, asid_cache);
+#define asid_cpu(cpu)		per_cpu(asid_cache, cpu)
+
+/*
+ * Get a new ASID if task doesn't have a valid one (unalloc or from prev cycle)
+ * Also set the MMU PID register to existing/updated ASID
+ */
+static inline void get_new_mmu_context(struct mm_struct *mm)
+{
+	const unsigned int cpu = smp_processor_id();
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	/*
+	 * Move to new ASID if it was not from current alloc-cycle/generation.
+	 * This is done by ensuring that the generation bits in both mm->ASID
+	 * and cpu's ASID counter are exactly same.
+	 *
+	 * Note: Callers needing new ASID unconditionally, independent of
+	 * 	 generation, e.g. local_flush_tlb_mm() for forking  parent,
+	 * 	 first need to destroy the context, setting it to invalid
+	 * 	 value.
+	 */
+	if (!((asid_mm(mm, cpu) ^ asid_cpu(cpu)) & MM_CTXT_CYCLE_MASK))
+		goto set_hw;
+
+	/* move to new ASID and handle rollover */
+	if (unlikely(!(++asid_cpu(cpu) & MM_CTXT_ASID_MASK))) {
+
+		local_flush_tlb_all();
+
+		/*
+		 * Above check for rollover of 8 bit ASID in 32 bit container.
+		 * If the container itself wrapped around, set it to a non zero
+		 * "generation" to distinguish from no context
+		 */
+		if (!asid_cpu(cpu))
+			asid_cpu(cpu) = MM_CTXT_FIRST_CYCLE;
+	}
+
+	/* Assign new ASID to tsk */
+	asid_mm(mm, cpu) = asid_cpu(cpu);
+
+set_hw:
+	mmu_setup_asid(mm, hw_pid(mm, cpu));
+
+	local_irq_restore(flags);
+}
+
+/*
+ * Initialize the context related info for a new mm_struct
+ * instance.
+ */
+#define init_new_context init_new_context
+static inline int
+init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+	int i;
+
+	for_each_possible_cpu(i)
+		asid_mm(mm, i) = MM_CTXT_NO_ASID;
+
+	return 0;
+}
+
+#define destroy_context destroy_context
+static inline void destroy_context(struct mm_struct *mm)
+{
+	unsigned long flags;
+
+	/* Needed to elide CONFIG_DEBUG_PREEMPT warning */
+	local_irq_save(flags);
+	asid_mm(mm, smp_processor_id()) = MM_CTXT_NO_ASID;
+	local_irq_restore(flags);
+}
+
+/* Prepare the MMU for task: setup PID reg with allocated ASID
+    If task doesn't have an ASID (never alloc or stolen, get a new ASID)
+*/
+static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+			     struct task_struct *tsk)
+{
+	const int cpu = smp_processor_id();
+
+	/*
+	 * Note that the mm_cpumask is "aggregating" only, we don't clear it
+	 * for the switched-out task, unlike some other arches.
+	 * It is used to enlist cpus for sending TLB flush IPIs and not sending
+	 * it to CPUs where a task once ran-on, could cause stale TLB entry
+	 * re-use, specially for a multi-threaded task.
+	 * e.g. T1 runs on C1, migrates to C3. T2 running on C2 munmaps.
+	 *      For a non-aggregating mm_cpumask, IPI not sent C1, and if T1
+	 *      were to re-migrate to C1, it could access the unmapped region
+	 *      via any existing stale TLB entries.
+	 */
+	cpumask_set_cpu(cpu, mm_cpumask(next));
+
+	mmu_setup_pgd(next, next->pgd);
+
+	get_new_mmu_context(next);
+}
+
+/*
+ * activate_mm defaults (in asm-generic) to switch_mm and is called at the
+ * time of execve() to get a new ASID Note the subtlety here:
+ * get_new_mmu_context() behaves differently here vs. in switch_mm(). Here
+ * it always returns a new ASID, because mm has an unallocated "initial"
+ * value, while in latter, it moves to a new ASID, only if it was
+ * unallocated
+ */
+
+/* it seemed that deactivate_mm( ) is a reasonable place to do book-keeping
+ * for retiring-mm. However destroy_context( ) still needs to do that because
+ * between mm_release( ) = >deactive_mm( ) and
+ * mmput => .. => __mmdrop( ) => destroy_context( )
+ * there is a good chance that task gets sched-out/in, making it's ASID valid
+ * again (this teased me for a whole day).
+ */
+
+#include <asm-generic/mmu_context.h>
+
+#endif /* __ASM_ARC_MMU_CONTEXT_H */