aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/mm/context.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2012-12-12 11:30:02 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-12 11:30:02 -0800
commitb1286f4e9ac14c8973140b338b4d3c5691264d3b (patch)
tree5a67788bb2276cd67230d24b5a6994ddafb10707 /arch/arm/mm/context.c
parent6facac1ab68fbf9cbad31a9d521f3a0d6aa9470e (diff)
parent0fa5d3996dbda1ee9653c43d39b7ef159fb57ee7 (diff)
Merge branch 'for-linus' of git://git.linaro.org/people/rmk/linux-arm
Pull ARM updates from Russell King: "Here's the updates for ARM for this merge window, which cover quite a variety of areas. There's a bunch of patch series from Will tackling various bugs like the PROT_NONE handling, ASID allocation, cluster boot protocol and ASID TLB tagging updates. We move to a build-time sorted exception table rather than doing the sorting at run-time, add support for the secure computing filter, and some updates to the perf code. We also have sorted out the placement of some headers, fixed some build warnings, fixed some hotplug problems with the per-cpu TWD code." * 'for-linus' of git://git.linaro.org/people/rmk/linux-arm: (73 commits) ARM: 7594/1: Add .smp entry for REALVIEW_EB ARM: 7599/1: head: Remove boot-time HYP mode check for v5 and below ARM: 7598/1: net: bpf_jit_32: fix sp-relative load/stores offsets. ARM: 7595/1: syscall: rework ordering in syscall_trace_exit ARM: 7596/1: mmci: replace readsl/writesl with ioread32_rep/iowrite32_rep ARM: 7597/1: net: bpf_jit_32: fix kzalloc gfp/size mismatch. ARM: 7593/1: nommu: do not enable DCACHE_WORD_ACCESS when !CONFIG_MMU ARM: 7592/1: nommu: prevent generation of kernel unaligned memory accesses ARM: 7591/1: nommu: Enable the strict alignment (CR_A) bit only if ARCH < v6 ARM: 7590/1: /proc/interrupts: limit the display of IPIs to online CPUs only ARM: 7587/1: implement optimized percpu variable access ARM: 7589/1: integrator: pass the lm resource to amba ARM: 7588/1: amba: create a resource parent registrator ARM: 7582/2: rename kvm_seq to vmalloc_seq so to avoid confusion with KVM ARM: 7585/1: kernel: fix nr_cpu_ids check in DT logical map init ARM: 7584/1: perf: fix link error when CONFIG_HW_PERF_EVENTS is not selected ARM: gic: use a private mapping for CPU target interfaces ARM: kernel: add logical mappings look-up ARM: kernel: add cpu logical map DT init in setup_arch ARM: kernel: add device tree init map function ...
Diffstat (limited to 'arch/arm/mm/context.c')
-rw-r--r--arch/arm/mm/context.c207
1 files changed, 108 insertions, 99 deletions
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index 4e07eec1270..bc4a5e9ebb7 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -2,6 +2,9 @@
* linux/arch/arm/mm/context.c
*
* Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
+ * Copyright (C) 2012 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
@@ -14,14 +17,40 @@
#include <linux/percpu.h>
#include <asm/mmu_context.h>
+#include <asm/smp_plat.h>
#include <asm/thread_notify.h>
#include <asm/tlbflush.h>
+/*
+ * On ARMv6, we have the following structure in the Context ID:
+ *
+ * 31 7 0
+ * +-------------------------+-----------+
+ * | process ID | ASID |
+ * +-------------------------+-----------+
+ * | context ID |
+ * +-------------------------------------+
+ *
+ * The ASID is used to tag entries in the CPU caches and TLBs.
+ * The context ID is used by debuggers and trace logic, and
+ * should be unique within all running processes.
+ */
+#define ASID_FIRST_VERSION (1ULL << ASID_BITS)
+#define NUM_USER_ASIDS (ASID_FIRST_VERSION - 1)
+
+#define ASID_TO_IDX(asid) ((asid & ~ASID_MASK) - 1)
+#define IDX_TO_ASID(idx) ((idx + 1) & ~ASID_MASK)
+
static DEFINE_RAW_SPINLOCK(cpu_asid_lock);
-unsigned int cpu_last_asid = ASID_FIRST_VERSION;
+static atomic64_t asid_generation = ATOMIC64_INIT(ASID_FIRST_VERSION);
+static DECLARE_BITMAP(asid_map, NUM_USER_ASIDS);
+
+static DEFINE_PER_CPU(atomic64_t, active_asids);
+static DEFINE_PER_CPU(u64, reserved_asids);
+static cpumask_t tlb_flush_pending;
#ifdef CONFIG_ARM_LPAE
-void cpu_set_reserved_ttbr0(void)
+static void cpu_set_reserved_ttbr0(void)
{
unsigned long ttbl = __pa(swapper_pg_dir);
unsigned long ttbh = 0;
@@ -37,7 +66,7 @@ void cpu_set_reserved_ttbr0(void)
isb();
}
#else
-void cpu_set_reserved_ttbr0(void)
+static void cpu_set_reserved_ttbr0(void)
{
u32 ttb;
/* Copy TTBR1 into TTBR0 */
@@ -84,124 +113,104 @@ static int __init contextidr_notifier_init(void)
arch_initcall(contextidr_notifier_init);
#endif
-/*
- * We fork()ed a process, and we need a new context for the child
- * to run in.
- */
-void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+static void flush_context(unsigned int cpu)
{
- mm->context.id = 0;
- raw_spin_lock_init(&mm->context.id_lock);
-}
+ int i;
+ u64 asid;
+
+ /* Update the list of reserved ASIDs and the ASID bitmap. */
+ bitmap_clear(asid_map, 0, NUM_USER_ASIDS);
+ for_each_possible_cpu(i) {
+ if (i == cpu) {
+ asid = 0;
+ } else {
+ asid = atomic64_xchg(&per_cpu(active_asids, i), 0);
+ __set_bit(ASID_TO_IDX(asid), asid_map);
+ }
+ per_cpu(reserved_asids, i) = asid;
+ }
-static void flush_context(void)
-{
- cpu_set_reserved_ttbr0();
- local_flush_tlb_all();
- if (icache_is_vivt_asid_tagged()) {
+ /* Queue a TLB invalidate and flush the I-cache if necessary. */
+ if (!tlb_ops_need_broadcast())
+ cpumask_set_cpu(cpu, &tlb_flush_pending);
+ else
+ cpumask_setall(&tlb_flush_pending);
+
+ if (icache_is_vivt_asid_tagged())
__flush_icache_all();
- dsb();
- }
}
-#ifdef CONFIG_SMP
+static int is_reserved_asid(u64 asid)
+{
+ int cpu;
+ for_each_possible_cpu(cpu)
+ if (per_cpu(reserved_asids, cpu) == asid)
+ return 1;
+ return 0;
+}
-static void set_mm_context(struct mm_struct *mm, unsigned int asid)
+static void new_context(struct mm_struct *mm, unsigned int cpu)
{
- unsigned long flags;
+ u64 asid = mm->context.id;
+ u64 generation = atomic64_read(&asid_generation);
- /*
- * Locking needed for multi-threaded applications where the
- * same mm->context.id could be set from different CPUs during
- * the broadcast. This function is also called via IPI so the
- * mm->context.id_lock has to be IRQ-safe.
- */
- raw_spin_lock_irqsave(&mm->context.id_lock, flags);
- if (likely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) {
+ if (asid != 0 && is_reserved_asid(asid)) {
/*
- * Old version of ASID found. Set the new one and
- * reset mm_cpumask(mm).
+ * Our current ASID was active during a rollover, we can
+ * continue to use it and this was just a false alarm.
*/
- mm->context.id = asid;
+ asid = generation | (asid & ~ASID_MASK);
+ } else {
+ /*
+ * Allocate a free ASID. If we can't find one, take a
+ * note of the currently active ASIDs and mark the TLBs
+ * as requiring flushes.
+ */
+ asid = find_first_zero_bit(asid_map, NUM_USER_ASIDS);
+ if (asid == NUM_USER_ASIDS) {
+ generation = atomic64_add_return(ASID_FIRST_VERSION,
+ &asid_generation);
+ flush_context(cpu);
+ asid = find_first_zero_bit(asid_map, NUM_USER_ASIDS);
+ }
+ __set_bit(asid, asid_map);
+ asid = generation | IDX_TO_ASID(asid);
cpumask_clear(mm_cpumask(mm));
}
- raw_spin_unlock_irqrestore(&mm->context.id_lock, flags);
- /*
- * Set the mm_cpumask(mm) bit for the current CPU.
- */
- cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
+ mm->context.id = asid;
}
-/*
- * Reset the ASID on the current CPU. This function call is broadcast
- * from the CPU handling the ASID rollover and holding cpu_asid_lock.
- */
-static void reset_context(void *info)
+void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk)
{
- unsigned int asid;
+ unsigned long flags;
unsigned int cpu = smp_processor_id();
- struct mm_struct *mm = current->active_mm;
- smp_rmb();
- asid = cpu_last_asid + cpu + 1;
+ if (unlikely(mm->context.vmalloc_seq != init_mm.context.vmalloc_seq))
+ __check_vmalloc_seq(mm);
- flush_context();
- set_mm_context(mm, asid);
-
- /* set the new ASID */
- cpu_switch_mm(mm->pgd, mm);
-}
+ /*
+ * Required during context switch to avoid speculative page table
+ * walking with the wrong TTBR.
+ */
+ cpu_set_reserved_ttbr0();
-#else
+ if (!((mm->context.id ^ atomic64_read(&asid_generation)) >> ASID_BITS)
+ && atomic64_xchg(&per_cpu(active_asids, cpu), mm->context.id))
+ goto switch_mm_fastpath;
-static inline void set_mm_context(struct mm_struct *mm, unsigned int asid)
-{
- mm->context.id = asid;
- cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id()));
-}
+ raw_spin_lock_irqsave(&cpu_asid_lock, flags);
+ /* Check that our ASID belongs to the current generation. */
+ if ((mm->context.id ^ atomic64_read(&asid_generation)) >> ASID_BITS)
+ new_context(mm, cpu);
-#endif
+ atomic64_set(&per_cpu(active_asids, cpu), mm->context.id);
+ cpumask_set_cpu(cpu, mm_cpumask(mm));
-void __new_context(struct mm_struct *mm)
-{
- unsigned int asid;
+ if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending))
+ local_flush_tlb_all();
+ raw_spin_unlock_irqrestore(&cpu_asid_lock, flags);
- raw_spin_lock(&cpu_asid_lock);
-#ifdef CONFIG_SMP
- /*
- * Check the ASID again, in case the change was broadcast from
- * another CPU before we acquired the lock.
- */
- if (unlikely(((mm->context.id ^ cpu_last_asid) >> ASID_BITS) == 0)) {
- cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
- raw_spin_unlock(&cpu_asid_lock);
- return;
- }
-#endif
- /*
- * At this point, it is guaranteed that the current mm (with
- * an old ASID) isn't active on any other CPU since the ASIDs
- * are changed simultaneously via IPI.
- */
- asid = ++cpu_last_asid;
- if (asid == 0)
- asid = cpu_last_asid = ASID_FIRST_VERSION;
-
- /*
- * If we've used up all our ASIDs, we need
- * to start a new version and flush the TLB.
- */
- if (unlikely((asid & ~ASID_MASK) == 0)) {
- asid = cpu_last_asid + smp_processor_id() + 1;
- flush_context();
-#ifdef CONFIG_SMP
- smp_wmb();
- smp_call_function(reset_context, NULL, 1);
-#endif
- cpu_last_asid += NR_CPUS;
- }
-
- set_mm_context(mm, asid);
- raw_spin_unlock(&cpu_asid_lock);
+switch_mm_fastpath:
+ cpu_switch_mm(mm->pgd, mm);
}