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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/arm/mm/mmap.c
downloadconfigs-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/arm/mm/mmap.c')
-rw-r--r--arch/arm/mm/mmap.c109
1 files changed, 109 insertions, 0 deletions
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
new file mode 100644
index 00000000000..32c4b0e35b3
--- /dev/null
+++ b/arch/arm/mm/mmap.c
@@ -0,0 +1,109 @@
+/*
+ * 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);
+ }
+}
+