diff options
Diffstat (limited to 'arch/arm64/mm/context.c')
| -rw-r--r-- | arch/arm64/mm/context.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c new file mode 100644 index 000000000..76c1e6cd3 --- /dev/null +++ b/arch/arm64/mm/context.c @@ -0,0 +1,167 @@ +/* + * Based on arch/arm/mm/context.c + * + * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved. + * Copyright (C) 2012 ARM Ltd. + * + * 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 + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/init.h> +#include <linux/sched.h> +#include <linux/mm.h> +#include <linux/smp.h> +#include <linux/percpu.h> + +#include <asm/mmu_context.h> +#include <asm/tlbflush.h> +#include <asm/cachetype.h> + +#define asid_bits(reg) \ + (((read_cpuid(ID_AA64MMFR0_EL1) & 0xf0) >> 2) + 8) + +#define ASID_FIRST_VERSION (1 << MAX_ASID_BITS) + +static DEFINE_RAW_SPINLOCK(cpu_asid_lock); +unsigned int cpu_last_asid = ASID_FIRST_VERSION; + +/* + * 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) +{ + mm->context.id = 0; + raw_spin_lock_init(&mm->context.id_lock); +} + +static void flush_context(void) +{ + /* set the reserved TTBR0 before flushing the TLB */ + cpu_set_reserved_ttbr0(); + flush_tlb_all(); + if (icache_is_aivivt()) + __flush_icache_all(); +} + +#ifdef CONFIG_SMP + +static void set_mm_context(struct mm_struct *mm, unsigned int asid) +{ + unsigned long flags; + + /* + * 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) >> MAX_ASID_BITS)) { + /* + * Old version of ASID found. Set the new one and reset + * mm_cpumask(mm). + */ + mm->context.id = 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)); +} + +/* + * 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) +{ + unsigned int asid; + unsigned int cpu = smp_processor_id(); + struct mm_struct *mm = current->active_mm; + + /* + * current->active_mm could be init_mm for the idle thread immediately + * after secondary CPU boot or hotplug. TTBR0_EL1 is already set to + * the reserved value, so no need to reset any context. + */ + if (mm == &init_mm) + return; + + smp_rmb(); + asid = cpu_last_asid + cpu; + + flush_context(); + set_mm_context(mm, asid); + + /* set the new ASID */ + cpu_switch_mm(mm->pgd, mm); +} + +#else + +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())); +} + +#endif + +void __new_context(struct mm_struct *mm) +{ + unsigned int asid; + unsigned int bits = asid_bits(); + + 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) >> MAX_ASID_BITS)) { + 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 we've used up all our ASIDs, we need to start a new version and + * flush the TLB. + */ + if (unlikely((asid & ((1 << bits) - 1)) == 0)) { + /* increment the ASID version */ + cpu_last_asid += (1 << MAX_ASID_BITS) - (1 << bits); + if (cpu_last_asid == 0) + cpu_last_asid = ASID_FIRST_VERSION; + asid = cpu_last_asid + smp_processor_id(); + flush_context(); +#ifdef CONFIG_SMP + smp_wmb(); + smp_call_function(reset_context, NULL, 1); +#endif + cpu_last_asid += NR_CPUS - 1; + } + + set_mm_context(mm, asid); + raw_spin_unlock(&cpu_asid_lock); +} |