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-rw-r--r--arch/arm/mm/mmap.c196
1 files changed, 174 insertions, 22 deletions
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 74be05f3e03..ce8cb1970d7 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -9,13 +9,51 @@
#include <linux/io.h>
#include <linux/personality.h>
#include <linux/random.h>
-#include <asm/cputype.h>
-#include <asm/system.h>
+#include <asm/cachetype.h>
+
+static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
+ unsigned long pgoff)
+{
+ unsigned long base = addr & ~(SHMLBA-1);
+ unsigned long off = (pgoff << PAGE_SHIFT) & (SHMLBA-1);
+
+ if (base + off <= addr)
+ return base + off;
+
+ return base - off;
+}
#define COLOUR_ALIGN(addr,pgoff) \
((((addr)+SHMLBA-1)&~(SHMLBA-1)) + \
(((pgoff)<<PAGE_SHIFT) & (SHMLBA-1)))
+/* gap between mmap and stack */
+#define MIN_GAP (128*1024*1024UL)
+#define MAX_GAP ((TASK_SIZE)/6*5)
+
+static int mmap_is_legacy(void)
+{
+ if (current->personality & ADDR_COMPAT_LAYOUT)
+ return 1;
+
+ if (rlimit(RLIMIT_STACK) == RLIM_INFINITY)
+ return 1;
+
+ return sysctl_legacy_va_layout;
+}
+
+static unsigned long mmap_base(unsigned long rnd)
+{
+ unsigned long gap = rlimit(RLIMIT_STACK);
+
+ if (gap < MIN_GAP)
+ gap = MIN_GAP;
+ else if (gap > MAX_GAP)
+ gap = MAX_GAP;
+
+ return PAGE_ALIGN(TASK_SIZE - gap - rnd);
+}
+
/*
* We need to ensure that shared mappings are correctly aligned to
* avoid aliasing issues with VIPT caches. We need to ensure that
@@ -32,25 +70,15 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
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;
+ int do_align = 0;
+ int aliasing = cache_is_vipt_aliasing();
/*
* 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.
+ * caches alias.
*/
- 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
+ if (aliasing)
+ do_align = filp || (flags & MAP_SHARED);
/*
* We enforce the MAP_FIXED case.
@@ -79,13 +107,9 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
if (len > mm->cached_hole_size) {
start_addr = addr = mm->free_area_cache;
} else {
- start_addr = addr = TASK_UNMAPPED_BASE;
+ start_addr = addr = mm->mmap_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)
@@ -122,6 +146,134 @@ full_search:
}
}
+unsigned long
+arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
+ const unsigned long len, const unsigned long pgoff,
+ const unsigned long flags)
+{
+ struct vm_area_struct *vma;
+ struct mm_struct *mm = current->mm;
+ unsigned long addr = addr0;
+ int do_align = 0;
+ int aliasing = cache_is_vipt_aliasing();
+
+ /*
+ * We only need to do colour alignment if either the I or D
+ * caches alias.
+ */
+ if (aliasing)
+ do_align = filp || (flags & MAP_SHARED);
+
+ /* requested length too big for entire address space */
+ if (len > TASK_SIZE)
+ return -ENOMEM;
+
+ if (flags & MAP_FIXED) {
+ if (aliasing && flags & MAP_SHARED &&
+ (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1))
+ return -EINVAL;
+ return addr;
+ }
+
+ /* requesting a specific address */
+ 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;
+ }
+
+ /* check if free_area_cache is useful for us */
+ if (len <= mm->cached_hole_size) {
+ mm->cached_hole_size = 0;
+ mm->free_area_cache = mm->mmap_base;
+ }
+
+ /* either no address requested or can't fit in requested address hole */
+ addr = mm->free_area_cache;
+ if (do_align) {
+ unsigned long base = COLOUR_ALIGN_DOWN(addr - len, pgoff);
+ addr = base + len;
+ }
+
+ /* make sure it can fit in the remaining address space */
+ if (addr > len) {
+ vma = find_vma(mm, addr-len);
+ if (!vma || addr <= vma->vm_start)
+ /* remember the address as a hint for next time */
+ return (mm->free_area_cache = addr-len);
+ }
+
+ if (mm->mmap_base < len)
+ goto bottomup;
+
+ addr = mm->mmap_base - len;
+ if (do_align)
+ addr = COLOUR_ALIGN_DOWN(addr, pgoff);
+
+ do {
+ /*
+ * Lookup failure means no vma is above this address,
+ * else if new region fits below vma->vm_start,
+ * return with success:
+ */
+ vma = find_vma(mm, addr);
+ if (!vma || addr+len <= vma->vm_start)
+ /* remember the address as a hint for next time */
+ return (mm->free_area_cache = addr);
+
+ /* remember the largest hole we saw so far */
+ if (addr + mm->cached_hole_size < vma->vm_start)
+ mm->cached_hole_size = vma->vm_start - addr;
+
+ /* try just below the current vma->vm_start */
+ addr = vma->vm_start - len;
+ if (do_align)
+ addr = COLOUR_ALIGN_DOWN(addr, pgoff);
+ } while (len < vma->vm_start);
+
+bottomup:
+ /*
+ * A failed mmap() very likely causes application failure,
+ * so fall back to the bottom-up function here. This scenario
+ * can happen with large stack limits and large mmap()
+ * allocations.
+ */
+ mm->cached_hole_size = ~0UL;
+ mm->free_area_cache = TASK_UNMAPPED_BASE;
+ addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
+ /*
+ * Restore the topdown base:
+ */
+ mm->free_area_cache = mm->mmap_base;
+ mm->cached_hole_size = ~0UL;
+
+ return addr;
+}
+
+void arch_pick_mmap_layout(struct mm_struct *mm)
+{
+ unsigned long random_factor = 0UL;
+
+ /* 8 bits of randomness in 20 address space bits */
+ if ((current->flags & PF_RANDOMIZE) &&
+ !(current->personality & ADDR_NO_RANDOMIZE))
+ random_factor = (get_random_int() % (1 << 8)) << PAGE_SHIFT;
+
+ if (mmap_is_legacy()) {
+ mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
+ mm->get_unmapped_area = arch_get_unmapped_area;
+ mm->unmap_area = arch_unmap_area;
+ } else {
+ mm->mmap_base = mmap_base(random_factor);
+ mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+ mm->unmap_area = arch_unmap_area_topdown;
+ }
+}
/*
* You really shouldn't be using read() or write() on /dev/mem. This