/* * linux/arch/arm/mm/mmap.c */ #include <linux/config.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/shm.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; #ifdef CONFIG_CPU_V6 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(CPUID_CACHETYPE); if (cache_type != read_cpuid(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 should enforce the MAP_FIXED case. However, currently * the generic kernel code doesn't allow us to handle this. */ if (flags & MAP_FIXED) { if (aliasing && flags & MAP_SHARED && addr & (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; } 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); } }