diff options
| -rw-r--r-- | arch/arm/mm/mmu.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index aa78de8bfdd..75f9f9d6709 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -783,6 +783,79 @@ void __init iotable_init(struct map_desc *io_desc, int nr) } } +#ifndef CONFIG_ARM_LPAE + +/* + * The Linux PMD is made of two consecutive section entries covering 2MB + * (see definition in include/asm/pgtable-2level.h). However a call to + * create_mapping() may optimize static mappings by using individual + * 1MB section mappings. This leaves the actual PMD potentially half + * initialized if the top or bottom section entry isn't used, leaving it + * open to problems if a subsequent ioremap() or vmalloc() tries to use + * the virtual space left free by that unused section entry. + * + * Let's avoid the issue by inserting dummy vm entries covering the unused + * PMD halves once the static mappings are in place. + */ + +static void __init pmd_empty_section_gap(unsigned long addr) +{ + struct vm_struct *vm; + + vm = early_alloc_aligned(sizeof(*vm), __alignof__(*vm)); + vm->addr = (void *)addr; + vm->size = SECTION_SIZE; + vm->flags = VM_IOREMAP | VM_ARM_STATIC_MAPPING; + vm->caller = pmd_empty_section_gap; + vm_area_add_early(vm); +} + +static void __init fill_pmd_gaps(void) +{ + struct vm_struct *vm; + unsigned long addr, next = 0; + pmd_t *pmd; + + /* we're still single threaded hence no lock needed here */ + for (vm = vmlist; vm; vm = vm->next) { + if (!(vm->flags & VM_ARM_STATIC_MAPPING)) + continue; + addr = (unsigned long)vm->addr; + if (addr < next) + continue; + + /* + * Check if this vm starts on an odd section boundary. + * If so and the first section entry for this PMD is free + * then we block the corresponding virtual address. + */ + if ((addr & ~PMD_MASK) == SECTION_SIZE) { + pmd = pmd_off_k(addr); + if (pmd_none(*pmd)) + pmd_empty_section_gap(addr & PMD_MASK); + } + + /* + * Then check if this vm ends on an odd section boundary. + * If so and the second section entry for this PMD is empty + * then we block the corresponding virtual address. + */ + addr += vm->size; + if ((addr & ~PMD_MASK) == SECTION_SIZE) { + pmd = pmd_off_k(addr) + 1; + if (pmd_none(*pmd)) + pmd_empty_section_gap(addr); + } + + /* no need to look at any vm entry until we hit the next PMD */ + next = (addr + PMD_SIZE - 1) & PMD_MASK; + } +} + +#else +#define fill_pmd_gaps() do { } while (0) +#endif + static void * __initdata vmalloc_min = (void *)(VMALLOC_END - (240 << 20) - VMALLOC_OFFSET); @@ -1064,6 +1137,7 @@ static void __init devicemaps_init(struct machine_desc *mdesc) */ if (mdesc->map_io) mdesc->map_io(); + fill_pmd_gaps(); /* * Finally flush the caches and tlb to ensure that we're in a |