diff options
| -rw-r--r-- | arch/arm/include/asm/highmem.h | 29 | ||||
| -rw-r--r-- | arch/arm/mm/mmu.c | 10 |
2 files changed, 27 insertions, 12 deletions
diff --git a/arch/arm/include/asm/highmem.h b/arch/arm/include/asm/highmem.h index 7080e2c8fa62..a4edd19dd3d6 100644 --- a/arch/arm/include/asm/highmem.h +++ b/arch/arm/include/asm/highmem.h @@ -19,11 +19,36 @@ extern pte_t *pkmap_page_table; +extern void *kmap_high(struct page *page); +extern void kunmap_high(struct page *page); + +/* + * The reason for kmap_high_get() is to ensure that the currently kmap'd + * page usage count does not decrease to zero while we're using its + * existing virtual mapping in an atomic context. With a VIVT cache this + * is essential to do, but with a VIPT cache this is only an optimization + * so not to pay the price of establishing a second mapping if an existing + * one can be used. However, on platforms without hardware TLB maintenance + * broadcast, we simply cannot use ARCH_NEEDS_KMAP_HIGH_GET at all since + * the locking involved must also disable IRQs which is incompatible with + * the IPI mechanism used by global TLB operations. + */ #define ARCH_NEEDS_KMAP_HIGH_GET +#if defined(CONFIG_SMP) && defined(CONFIG_CPU_TLB_V6) +#undef ARCH_NEEDS_KMAP_HIGH_GET +#if defined(CONFIG_HIGHMEM) && defined(CONFIG_CPU_CACHE_VIVT) +#error "The sum of features in your kernel config cannot be supported together" +#endif +#endif -extern void *kmap_high(struct page *page); +#ifdef ARCH_NEEDS_KMAP_HIGH_GET extern void *kmap_high_get(struct page *page); -extern void kunmap_high(struct page *page); +#else +static inline void *kmap_high_get(struct page *page) +{ + return NULL; +} +#endif /* * The following functions are already defined by <linux/highmem.h> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 3c67e92f7d59..ff7b43b5885a 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -827,16 +827,6 @@ static void __init sanity_check_meminfo(void) * rather difficult. */ reason = "with VIPT aliasing cache"; - } else if (is_smp() && tlb_ops_need_broadcast()) { - /* - * kmap_high needs to occasionally flush TLB entries, - * however, if the TLB entries need to be broadcast - * we may deadlock: - * kmap_high(irqs off)->flush_all_zero_pkmaps-> - * flush_tlb_kernel_range->smp_call_function_many - * (must not be called with irqs off) - */ - reason = "without hardware TLB ops broadcasting"; } if (reason) { printk(KERN_CRIT "HIGHMEM is not supported %s, ignoring high memory\n", |