brk: make sys_brk() honor COMPAT_BRK when computing lower bound

[karo-tx-linux.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index d2b6d44962b7c7b28b89e20cdbf1af0b0c6ada31..96bdd73db08ba3543f716448edeaa0d4bdcc6496 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -36,6 +36,10 @@
 #define arch_mmap_check(addr, len, flags)      (0)
 #endif
 
+#ifndef arch_rebalance_pgtables
+#define arch_rebalance_pgtables(addr, len)             (addr)
+#endif
+
 static void unmap_region(struct mm_struct *mm,
                struct vm_area_struct *vma, struct vm_area_struct *prev,
                unsigned long start, unsigned long end);
@@ -238,10 +242,16 @@ asmlinkage unsigned long sys_brk(unsigned long brk)
        unsigned long rlim, retval;
        unsigned long newbrk, oldbrk;
        struct mm_struct *mm = current->mm;
+       unsigned long min_brk;
 
        down_write(&mm->mmap_sem);
 
-       if (brk < mm->end_code)
+#ifdef CONFIG_COMPAT_BRK
+       min_brk = mm->end_code;
+#else
+       min_brk = mm->start_brk;
+#endif
+       if (brk < min_brk)
                goto out;
 
        /*
@@ -1424,7 +1434,7 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
        if (addr & ~PAGE_MASK)
                return -EINVAL;
 
-       return addr;
+       return arch_rebalance_pgtables(addr, len);
 }
 
 EXPORT_SYMBOL(get_unmapped_area);
@@ -2161,24 +2171,31 @@ int may_expand_vm(struct mm_struct *mm, unsigned long npages)
 }
 
 
-static struct page *special_mapping_nopage(struct vm_area_struct *vma,
-                                          unsigned long address, int *type)
+static int special_mapping_fault(struct vm_area_struct *vma,
+                               struct vm_fault *vmf)
 {
+       pgoff_t pgoff;
        struct page **pages;
 
-       BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+       /*
+        * special mappings have no vm_file, and in that case, the mm
+        * uses vm_pgoff internally. So we have to subtract it from here.
+        * We are allowed to do this because we are the mm; do not copy
+        * this code into drivers!
+        */
+       pgoff = vmf->pgoff - vma->vm_pgoff;
 
-       address -= vma->vm_start;
-       for (pages = vma->vm_private_data; address > 0 && *pages; ++pages)
-               address -= PAGE_SIZE;
+       for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
+               pgoff--;
 
        if (*pages) {
                struct page *page = *pages;
                get_page(page);
-               return page;
+               vmf->page = page;
+               return 0;
        }
 
-       return NOPAGE_SIGBUS;
+       return VM_FAULT_SIGBUS;
 }
 
 /*
@@ -2190,7 +2207,7 @@ static void special_mapping_close(struct vm_area_struct *vma)
 
 static struct vm_operations_struct special_mapping_vmops = {
        .close = special_mapping_close,
-       .nopage = special_mapping_nopage,
+       .fault = special_mapping_fault,
 };
 
 /*
@@ -2216,7 +2233,7 @@ int install_special_mapping(struct mm_struct *mm,
        vma->vm_start = addr;
        vma->vm_end = addr + len;
 
-       vma->vm_flags = vm_flags | mm->def_flags;
+       vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND;
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 
        vma->vm_ops = &special_mapping_vmops;