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@xxxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> --- arch/x86/include/asm/page.h | 1 + arch/x86/include/asm/page_32.h | 4 ---- arch/x86/mm/hugetlbpage.c | 9 +++------ 3 files changed, 4 insertions(+), 10 deletions(-) diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h index c87892442e..775873d3be 100644 --- 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 4d550d04b6..904f528cc8 100644 --- 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 9d980d88b7..8c9f647ff9 100644 --- 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) -- 1.8.4.rc3 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>