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Diffstat (limited to 'arch/arm64/include/asm/mmu_context.h')
-rw-r--r--arch/arm64/include/asm/mmu_context.h113
1 files changed, 25 insertions, 88 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 8ec41e5f56f0..c0e87898ba96 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -28,13 +28,6 @@
#include <asm/cputype.h>
#include <asm/pgtable.h>
-#define MAX_ASID_BITS 16
-
-extern unsigned int cpu_last_asid;
-
-void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
-void __new_context(struct mm_struct *mm);
-
#ifdef CONFIG_PID_IN_CONTEXTIDR
static inline void contextidr_thread_switch(struct task_struct *next)
{
@@ -77,96 +70,38 @@ static inline bool __cpu_uses_extended_idmap(void)
unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS)));
}
-static inline void __cpu_set_tcr_t0sz(u64 t0sz)
-{
- unsigned long tcr;
-
- if (__cpu_uses_extended_idmap())
- asm volatile (
- " mrs %0, tcr_el1 ;"
- " bfi %0, %1, %2, %3 ;"
- " msr tcr_el1, %0 ;"
- " isb"
- : "=&r" (tcr)
- : "r"(t0sz), "I"(TCR_T0SZ_OFFSET), "I"(TCR_TxSZ_WIDTH));
-}
-
-/*
- * Set TCR.T0SZ to the value appropriate for activating the identity map.
- */
-static inline void cpu_set_idmap_tcr_t0sz(void)
-{
- __cpu_set_tcr_t0sz(idmap_t0sz);
-}
-
/*
* Set TCR.T0SZ to its default value (based on VA_BITS)
*/
static inline void cpu_set_default_tcr_t0sz(void)
{
- __cpu_set_tcr_t0sz(TCR_T0SZ(VA_BITS));
-}
-
-static inline void switch_new_context(struct mm_struct *mm)
-{
- unsigned long flags;
-
- __new_context(mm);
+ unsigned long tcr;
- local_irq_save(flags);
- cpu_switch_mm(mm->pgd, mm);
- local_irq_restore(flags);
-}
+ if (!__cpu_uses_extended_idmap())
+ return;
-static inline void check_and_switch_context(struct mm_struct *mm,
- struct task_struct *tsk)
-{
- /*
- * Required during context switch to avoid speculative page table
- * walking with the wrong TTBR.
- */
- cpu_set_reserved_ttbr0();
-
- if (!((mm->context.id ^ cpu_last_asid) >> MAX_ASID_BITS))
- /*
- * The ASID is from the current generation, just switch to the
- * new pgd. This condition is only true for calls from
- * context_switch() and interrupts are already disabled.
- */
- cpu_switch_mm(mm->pgd, mm);
- else if (irqs_disabled())
- /*
- * Defer the new ASID allocation until after the context
- * switch critical region since __new_context() cannot be
- * called with interrupts disabled.
- */
- set_ti_thread_flag(task_thread_info(tsk), TIF_SWITCH_MM);
- else
- /*
- * That is a direct call to switch_mm() or activate_mm() with
- * interrupts enabled and a new context.
- */
- switch_new_context(mm);
+ asm volatile (
+ " mrs %0, tcr_el1 ;"
+ " bfi %0, %1, %2, %3 ;"
+ " msr tcr_el1, %0 ;"
+ " isb"
+ : "=&r" (tcr)
+ : "r"(TCR_T0SZ(VA_BITS)), "I"(TCR_T0SZ_OFFSET), "I"(TCR_TxSZ_WIDTH));
}
-#define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0)
+/*
+ * It would be nice to return ASIDs back to the allocator, but unfortunately
+ * that introduces a race with a generation rollover where we could erroneously
+ * free an ASID allocated in a future generation. We could workaround this by
+ * freeing the ASID from the context of the dying mm (e.g. in arch_exit_mmap),
+ * but we'd then need to make sure that we didn't dirty any TLBs afterwards.
+ * Setting a reserved TTBR0 or EPD0 would work, but it all gets ugly when you
+ * take CPU migration into account.
+ */
#define destroy_context(mm) do { } while(0)
+void check_and_switch_context(struct mm_struct *mm, unsigned int cpu);
-#define finish_arch_post_lock_switch \
- finish_arch_post_lock_switch
-static inline void finish_arch_post_lock_switch(void)
-{
- if (test_and_clear_thread_flag(TIF_SWITCH_MM)) {
- struct mm_struct *mm = current->mm;
- unsigned long flags;
-
- __new_context(mm);
-
- local_irq_save(flags);
- cpu_switch_mm(mm->pgd, mm);
- local_irq_restore(flags);
- }
-}
+#define init_new_context(tsk,mm) ({ atomic64_set(&mm->context.id, 0); 0; })
/*
* This is called when "tsk" is about to enter lazy TLB mode.
@@ -194,6 +129,9 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
{
unsigned int cpu = smp_processor_id();
+ if (prev == next)
+ return;
+
/*
* init_mm.pgd does not contain any user mappings and it is always
* active for kernel addresses in TTBR1. Just set the reserved TTBR0.
@@ -203,8 +141,7 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
return;
}
- if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next)
- check_and_switch_context(next, tsk);
+ check_and_switch_context(next, cpu);
}
#define deactivate_mm(tsk,mm) do { } while (0)