x86, mm: get ASLR work for hugetlb mappings

Matthew noticed that hugetlb doesn't participate in ASLR on x86-64.  The
reason is genereic hugetlb_get_unmapped_area() which is used on x86-64.
It doesn't support randomization and use bottom-up unmapped area lookup,
instead of usual top-down on x86-64.

x86 has arch-specific hugetlb_get_unmapped_area(), but it's used only on
x86-32.

Let's use arch-specific hugetlb_get_unmapped_area() on x86-64 too.  It
fixes the issue and make hugetlb use top-down unmapped area lookup.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
index c87892442e53d4081f4ff1276524e0298cf73617..775873d3be55617a49e15c3460ae22a94dabad75 100644 (file)
--- a/arch/x86/include/asm/page.h
+++ b/arch/x86/include/asm/page.h
@@ -71,6 +71,7 @@ extern bool __virt_addr_valid(unsigned long kaddr);
 #include <asm-generic/getorder.h>
 
 #define __HAVE_ARCH_GATE_AREA 1
+#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 
 #endif /* __KERNEL__ */
 #endif /* _ASM_X86_PAGE_H */

diff --git a/arch/x86/include/asm/page_32.h b/arch/x86/include/asm/page_32.h
index 4d550d04b6099bf444e8291ffdfde9538a4e47df..904f528cc8e82ae638e25a2bdeec23fed332eb7a 100644 (file)
--- a/arch/x86/include/asm/page_32.h
+++ b/arch/x86/include/asm/page_32.h
@@ -5,10 +5,6 @@
 
 #ifndef __ASSEMBLY__
 
-#ifdef CONFIG_HUGETLB_PAGE
-#define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
-#endif
-
 #define __phys_addr_nodebug(x) ((x) - PAGE_OFFSET)
 #ifdef CONFIG_DEBUG_VIRTUAL
 extern unsigned long __phys_addr(unsigned long);

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 9d980d88b7477a82f757e75d0efda0c867c76d43..8c9f647ff9e111203af86f894a13b450e4513013 100644 (file)
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -87,9 +87,7 @@ int pmd_huge_support(void)
 }
 #endif
 
-/* x86_64 also uses this file */
-
-#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
+#ifdef CONFIG_HUGETLB_PAGE
 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
                unsigned long addr, unsigned long len,
                unsigned long pgoff, unsigned long flags)
@@ -99,7 +97,7 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 
        info.flags = 0;
        info.length = len;
-       info.low_limit = TASK_UNMAPPED_BASE;
+       info.low_limit = current->mm->mmap_legacy_base;
        info.high_limit = TASK_SIZE;
        info.align_mask = PAGE_MASK & ~huge_page_mask(h);
        info.align_offset = 0;
@@ -172,8 +170,7 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                return hugetlb_get_unmapped_area_topdown(file, addr, len,
                                pgoff, flags);
 }
-
-#endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
+#endif /* CONFIG_HUGETLB_PAGE */
 
 #ifdef CONFIG_X86_64
 static __init int setup_hugepagesz(char *opt)