Revert "Revert "ARM: 7169/1: topdown mmap support""
This reverts commit f27e4f0e730b99ca4dabed0b408d96dbf73a8fac.
An alternate fix has been proposed where userspace programs
set ADDR_COMPAT_LAYOUT. Bring back the topdown mmap support.
Change-Id: Ibd6e74d406db3a5ddb609e2d2a7a6e9dc2080eca
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
index 84560dc..7b6f42a 100644
--- a/arch/arm/include/asm/pgtable.h
+++ b/arch/arm/include/asm/pgtable.h
@@ -313,6 +313,7 @@
* We provide our own arch_get_unmapped_area to cope with VIPT caches.
*/
#define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
/*
* remap a physical page `pfn' of size `size' with page protection `prot'
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index 8e2bb29..07209d7 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -126,6 +126,8 @@
#endif
+#define HAVE_ARCH_PICK_MMAP_LAYOUT
+
#endif
#endif /* __ASM_ARM_PROCESSOR_H */
diff --git a/arch/arm/mm/mmap.c b/arch/arm/mm/mmap.c
index 06262c5..ce8cb19 100644
--- a/arch/arm/mm/mmap.c
+++ b/arch/arm/mm/mmap.c
@@ -11,10 +11,49 @@
#include <linux/random.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
@@ -68,13 +107,9 @@
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)
@@ -111,6 +146,134 @@
}
}
+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