diff options
Diffstat (limited to 'arch/arm/mm/highmem.c')
| -rw-r--r-- | arch/arm/mm/highmem.c | 87 |
1 files changed, 86 insertions, 1 deletions
diff --git a/arch/arm/mm/highmem.c b/arch/arm/mm/highmem.c index 2be1ec7c1b41..77b030f5ec09 100644 --- a/arch/arm/mm/highmem.c +++ b/arch/arm/mm/highmem.c @@ -79,7 +79,8 @@ void kunmap_atomic(void *kvaddr, enum km_type type) unsigned int idx = type + KM_TYPE_NR * smp_processor_id(); if (kvaddr >= (void *)FIXADDR_START) { - __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE); + if (cache_is_vivt()) + __cpuc_flush_dcache_area((void *)vaddr, PAGE_SIZE); #ifdef CONFIG_DEBUG_HIGHMEM BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx)); set_pte_ext(TOP_PTE(vaddr), __pte(0), 0); @@ -124,3 +125,87 @@ struct page *kmap_atomic_to_page(const void *ptr) pte = TOP_PTE(vaddr); return pte_page(*pte); } + +#ifdef CONFIG_CPU_CACHE_VIPT + +#include <linux/percpu.h> + +/* + * The VIVT cache of a highmem page is always flushed before the page + * is unmapped. Hence unmapped highmem pages need no cache maintenance + * in that case. + * + * However unmapped pages may still be cached with a VIPT cache, and + * it is not possible to perform cache maintenance on them using physical + * addresses unfortunately. So we have no choice but to set up a temporary + * virtual mapping for that purpose. + * + * Yet this VIPT cache maintenance may be triggered from DMA support + * functions which are possibly called from interrupt context. As we don't + * want to keep interrupt disabled all the time when such maintenance is + * taking place, we therefore allow for some reentrancy by preserving and + * restoring the previous fixmap entry before the interrupted context is + * resumed. If the reentrancy depth is 0 then there is no need to restore + * the previous fixmap, and leaving the current one in place allow it to + * be reused the next time without a TLB flush (common with DMA). + */ + +static DEFINE_PER_CPU(int, kmap_high_l1_vipt_depth); + +void *kmap_high_l1_vipt(struct page *page, pte_t *saved_pte) +{ + unsigned int idx, cpu = smp_processor_id(); + int *depth = &per_cpu(kmap_high_l1_vipt_depth, cpu); + unsigned long vaddr, flags; + pte_t pte, *ptep; + + idx = KM_L1_CACHE + KM_TYPE_NR * cpu; + vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + ptep = TOP_PTE(vaddr); + pte = mk_pte(page, kmap_prot); + + if (!in_interrupt()) + preempt_disable(); + + raw_local_irq_save(flags); + (*depth)++; + if (pte_val(*ptep) == pte_val(pte)) { + *saved_pte = pte; + } else { + *saved_pte = *ptep; + set_pte_ext(ptep, pte, 0); + local_flush_tlb_kernel_page(vaddr); + } + raw_local_irq_restore(flags); + + return (void *)vaddr; +} + +void kunmap_high_l1_vipt(struct page *page, pte_t saved_pte) +{ + unsigned int idx, cpu = smp_processor_id(); + int *depth = &per_cpu(kmap_high_l1_vipt_depth, cpu); + unsigned long vaddr, flags; + pte_t pte, *ptep; + + idx = KM_L1_CACHE + KM_TYPE_NR * cpu; + vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); + ptep = TOP_PTE(vaddr); + pte = mk_pte(page, kmap_prot); + + BUG_ON(pte_val(*ptep) != pte_val(pte)); + BUG_ON(*depth <= 0); + + raw_local_irq_save(flags); + (*depth)--; + if (*depth != 0 && pte_val(pte) != pte_val(saved_pte)) { + set_pte_ext(ptep, saved_pte, 0); + local_flush_tlb_kernel_page(vaddr); + } + raw_local_irq_restore(flags); + + if (!in_interrupt()) + preempt_enable(); +} + +#endif /* CONFIG_CPU_CACHE_VIPT */ |