summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
Diffstat
-rw-r--r--arch/mips/include/asm/pgtable.h1
-rw-r--r--arch/mips/mm/mmap.c193
2 files changed, 171 insertions, 23 deletions
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 7e40f377817..b2202a68cf0 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -414,6 +414,7 @@ int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
* constraints placed on us by the cache architecture.
*/
#define HAVE_ARCH_UNMAPPED_AREA
+#define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
/*
* No page table caches to initialise
diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index ae3c20a9556..9ff5d0fac55 100644
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -10,6 +10,7 @@
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/module.h>
+#include <linux/personality.h>
#include <linux/random.h>
#include <linux/sched.h>
@@ -17,21 +18,65 @@ unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */
EXPORT_SYMBOL(shm_align_mask);
+/* 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);
+}
+
+static inline unsigned long COLOUR_ALIGN_DOWN(unsigned long addr,
+ unsigned long pgoff)
+{
+ unsigned long base = addr & ~shm_align_mask;
+ unsigned long off = (pgoff << PAGE_SHIFT) & shm_align_mask;
+
+ if (base + off <= addr)
+ return base + off;
+
+ return base - off;
+}
+
#define COLOUR_ALIGN(addr,pgoff) \
((((addr) + shm_align_mask) & ~shm_align_mask) + \
(((pgoff) << PAGE_SHIFT) & shm_align_mask))
-unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
- unsigned long len, unsigned long pgoff, unsigned long flags)
+enum mmap_allocation_direction {UP, DOWN};
+
+static unsigned long arch_get_unmapped_area_foo(struct file *filp,
+ unsigned long addr0, unsigned long len, unsigned long pgoff,
+ unsigned long flags, enum mmap_allocation_direction dir)
{
- struct vm_area_struct * vmm;
+ struct mm_struct *mm = current->mm;
+ struct vm_area_struct *vma;
+ unsigned long addr = addr0;
int do_color_align;
- if (len > TASK_SIZE)
+ if (unlikely(len > TASK_SIZE))
return -ENOMEM;
if (flags & MAP_FIXED) {
- /* Even MAP_FIXED mappings must reside within TASK_SIZE. */
+ /* Even MAP_FIXED mappings must reside within TASK_SIZE */
if (TASK_SIZE - len < addr)
return -EINVAL;
@@ -48,34 +93,130 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
do_color_align = 0;
if (filp || (flags & MAP_SHARED))
do_color_align = 1;
+
+ /* requesting a specific address */
if (addr) {
if (do_color_align)
addr = COLOUR_ALIGN(addr, pgoff);
else
addr = PAGE_ALIGN(addr);
- vmm = find_vma(current->mm, addr);
+
+ vma = find_vma(mm, addr);
if (TASK_SIZE - len >= addr &&
- (!vmm || addr + len <= vmm->vm_start))
+ (!vma || addr + len <= vma->vm_start))
return addr;
}
- addr = current->mm->mmap_base;
- if (do_color_align)
- addr = COLOUR_ALIGN(addr, pgoff);
- else
- addr = PAGE_ALIGN(addr);
- for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
- /* At this point: (!vmm || addr < vmm->vm_end). */
- if (TASK_SIZE - len < addr)
- return -ENOMEM;
- if (!vmm || addr + len <= vmm->vm_start)
- return addr;
- addr = vmm->vm_end;
+ if (dir == UP) {
+ addr = mm->mmap_base;
+ if (do_color_align)
+ addr = COLOUR_ALIGN(addr, pgoff);
+ else
+ addr = PAGE_ALIGN(addr);
+
+ for (vma = find_vma(current->mm, addr); ; vma = vma->vm_next) {
+ /* At this point: (!vma || addr < vma->vm_end). */
+ if (TASK_SIZE - len < addr)
+ return -ENOMEM;
+ if (!vma || addr + len <= vma->vm_start)
+ return addr;
+ addr = vma->vm_end;
+ if (do_color_align)
+ addr = COLOUR_ALIGN(addr, pgoff);
+ }
+ } else {
+ /* 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_color_align) {
+ unsigned long base =
+ COLOUR_ALIGN_DOWN(addr - len, pgoff);
+
+ addr = base + len;
+ }
+
+ /* make sure it can fit in the remaining address space */
+ if (likely(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 (unlikely(mm->mmap_base < len))
+ goto bottomup;
+
+ addr = mm->mmap_base-len;
if (do_color_align)
- addr = COLOUR_ALIGN(addr, pgoff);
+ 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 (likely(!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_color_align)
+ addr = COLOUR_ALIGN_DOWN(addr, pgoff);
+ } while (likely(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;
}
}
+unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr0,
+ unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+ return arch_get_unmapped_area_foo(filp,
+ addr0, len, pgoff, flags, UP);
+}
+
+/*
+ * There is no need to export this but sched.h declares the function as
+ * extern so making it static here results in an error.
+ */
+unsigned long arch_get_unmapped_area_topdown(struct file *filp,
+ unsigned long addr0, unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ return arch_get_unmapped_area_foo(filp,
+ addr0, len, pgoff, flags, DOWN);
+}
+
void arch_pick_mmap_layout(struct mm_struct *mm)
{
unsigned long random_factor = 0UL;
@@ -89,9 +230,15 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
random_factor &= 0xffffffful;
}
- mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
- mm->get_unmapped_area = arch_get_unmapped_area;
- mm->unmap_area = arch_unmap_area;
+ 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;
+ }
}
static inline unsigned long brk_rnd(void)
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-30 09:02:44 +0000