110 строки
2.6 KiB
C
110 строки
2.6 KiB
C
|
/*
|
||
|
|
* 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;
|
||
|
|
}
|
||
|
|
start_addr = addr = mm->free_area_cache;
|
||
|
|
|
||
|
|
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;
|
||
|
|
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;
|
||
|
|
}
|
||
|
|
addr = vma->vm_end;
|
||
|
|
if (do_align)
|
||
|
|
addr = COLOUR_ALIGN(addr, pgoff);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|