diff options
Diffstat (limited to 'arch/arm/mm/mmap.c')
| -rw-r--r-- | arch/arm/mm/mmap.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c new file mode 100644 index 00000000..74be05f3 --- /dev/null +++ b/arch/arm/mm/mmap.c @@ -0,0 +1,170 @@ +/* + * linux/arch/arm/mm/mmap.c + */ +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/shm.h> +#include <linux/sched.h> +#include <linux/io.h> +#include <linux/personality.h> +#include <linux/random.h> +#include <asm/cputype.h> +#include <asm/system.h> + +#define COLOUR_ALIGN(addr,pgoff) \ + ((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \ + (((pgoff)<<PAGE_SHIFT) & (SHMLBA-1))) + +/* + * We need to ensure that shared mappings are correctly aligned to + * avoid aliasing issues with VIPT caches. We need to ensure that + * a specific page of an object is always mapped at a multiple of + * SHMLBA bytes. + * + * We unconditionally provide this function for all cases, however + * in the VIVT case, we optimise out the alignment rules. + */ +unsigned long +arch_get_unmapped_area(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, unsigned long flags) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + unsigned long start_addr; +#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_V6K) + unsigned int cache_type; + int do_align = 0, aliasing = 0; + + /* + * We only need to do colour alignment if either the I or D + * caches alias. This is indicated by bits 9 and 21 of the + * cache type register. + */ + cache_type = read_cpuid_cachetype(); + if (cache_type != read_cpuid_id()) { + aliasing = (cache_type | cache_type >> 12) & (1 << 11); + if (aliasing) + do_align = filp || flags & MAP_SHARED; + } +#else +#define do_align 0 +#define aliasing 0 +#endif + + /* + * We enforce the MAP_FIXED case. + */ + if (flags & MAP_FIXED) { + if (aliasing && flags & MAP_SHARED && + (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) + return -EINVAL; + return addr; + } + + if (len > TASK_SIZE) + return -ENOMEM; + + if (addr) { + if (do_align) + addr = COLOUR_ALIGN(addr, pgoff); + else + addr = PAGE_ALIGN(addr); + + vma = find_vma(mm, addr); + if (TASK_SIZE - len >= addr && + (!vma || addr + len <= vma->vm_start)) + return addr; + } + if (len > mm->cached_hole_size) { + start_addr = addr = mm->free_area_cache; + } else { + start_addr = addr = TASK_UNMAPPED_BASE; + mm->cached_hole_size = 0; + } + /* 8 bits of randomness in 20 address space bits */ + if ((current->flags & PF_RANDOMIZE) && + !(current->personality & ADDR_NO_RANDOMIZE)) + addr += (get_random_int() % (1 << 8)) << PAGE_SHIFT; + +full_search: + if (do_align) + addr = COLOUR_ALIGN(addr, pgoff); + else + addr = PAGE_ALIGN(addr); + + for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { + /* At this point: (!vma || addr < vma->vm_end). */ + if (TASK_SIZE - len < addr) { + /* + * Start a new search - just in case we missed + * some holes. + */ + if (start_addr != TASK_UNMAPPED_BASE) { + start_addr = addr = TASK_UNMAPPED_BASE; + mm->cached_hole_size = 0; + goto full_search; + } + return -ENOMEM; + } + if (!vma || addr + len <= vma->vm_start) { + /* + * Remember the place where we stopped the search: + */ + mm->free_area_cache = addr + len; + return addr; + } + if (addr + mm->cached_hole_size < vma->vm_start) + mm->cached_hole_size = vma->vm_start - addr; + addr = vma->vm_end; + if (do_align) + addr = COLOUR_ALIGN(addr, pgoff); + } +} + + +/* + * You really shouldn't be using read() or write() on /dev/mem. This + * might go away in the future. + */ +int valid_phys_addr_range(unsigned long addr, size_t size) +{ + if (addr < PHYS_OFFSET) + return 0; + if (addr + size > __pa(high_memory - 1) + 1) + return 0; + + return 1; +} + +/* + * We don't use supersection mappings for mmap() on /dev/mem, which + * means that we can't map the memory area above the 4G barrier into + * userspace. + */ +int valid_mmap_phys_addr_range(unsigned long pfn, size_t size) +{ + return !(pfn + (size >> PAGE_SHIFT) > 0x00100000); +} + +#ifdef CONFIG_STRICT_DEVMEM + +#include <linux/ioport.h> + +/* + * devmem_is_allowed() checks to see if /dev/mem access to a certain + * address is valid. The argument is a physical page number. + * We mimic x86 here by disallowing access to system RAM as well as + * device-exclusive MMIO regions. This effectively disable read()/write() + * on /dev/mem. + */ +int devmem_is_allowed(unsigned long pfn) +{ + if (iomem_is_exclusive(pfn << PAGE_SHIFT)) + return 0; + if (!page_is_ram(pfn)) + return 1; + return 0; +} + +#endif |