Re: [PATCH] x86/hugetlb: Use 32/64 mmap bases according to syscall
From: Dmitry Safonov
Date: Tue Mar 14 2017 - 08:07:49 EST
On 03/14/2017 02:41 PM, Dmitry Safonov wrote:
Commit:
1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit
mmap()")
introduced two mmap() bases for 32-bit syscalls and for 64-bit syscalls.
After that commit mm->mmap_base has address to base allocations for
64-bit syscalls, while mm->mmap_compat_base - for 32-bit syscalls.
mmap() code was changed accordingly, but hugetlb code was not changed,
which introduced bogus behavior: 32-bit application which mmaps
file on hugetlbfs uses mm->mmap_base and thou tries to allocate
space with 64-bit mmap() base.
Changed x86 hugetlbfs code to use two bases according to calling
syscall, which also will fix any problems with 32-bit syscalls
in 64-bit ELF and vice-versa.
Fixes: commit 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for
32-bit mmap()").
Reported-by: kernel test robot <xiaolong.ye@xxxxxxxxx>
Cc: 0x7f454c46@xxxxxxxxx
Cc: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: x86@xxxxxxxxxx
Signed-off-by: Dmitry Safonov <dsafonov@xxxxxxxxxxxxx>
---
Note: I've tested it on a simple hand-written test, will reply when
got libhugetlbfs tests running in my environment.
Can confirm: I've tested this on clean fedora-25 with libhugetlbfs
tests, it's fixed.
Sorry for the breaking.
arch/x86/include/asm/elf.h | 1 +
arch/x86/kernel/sys_x86_64.c | 12 ------------
arch/x86/mm/hugetlbpage.c | 9 ++++++---
arch/x86/mm/mmap.c | 13 +++++++++++++
4 files changed, 20 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index ac5be5ba8527..d4d3ed456cb7 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -305,6 +305,7 @@ static inline int mmap_is_ia32(void)
extern unsigned long tasksize_32bit(void);
extern unsigned long tasksize_64bit(void);
+extern unsigned long get_mmap_base(int is_legacy);
#ifdef CONFIG_X86_32
diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 63e89dfc808a..207b8f2582c7 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -100,18 +100,6 @@ SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
return error;
}
-static unsigned long get_mmap_base(int is_legacy)
-{
- struct mm_struct *mm = current->mm;
-
-#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
- if (in_compat_syscall())
- return is_legacy ? mm->mmap_compat_legacy_base
- : mm->mmap_compat_base;
-#endif
- return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
-}
-
static void find_start_end(unsigned long flags, unsigned long *begin,
unsigned long *end)
{
diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index c5066a260803..a50f4600a281 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -16,6 +16,8 @@
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>
+#include <asm/elf.h>
+#include <asm/compat.h>
#if 0 /* This is just for testing */
struct page *
@@ -82,8 +84,9 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
info.flags = 0;
info.length = len;
- info.low_limit = current->mm->mmap_legacy_base;
- info.high_limit = TASK_SIZE;
+ info.low_limit = get_mmap_base(1);
+ info.high_limit = in_compat_syscall() ?
+ tasksize_32bit() : tasksize_64bit();
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
info.align_offset = 0;
return vm_unmapped_area(&info);
@@ -100,7 +103,7 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
info.flags = VM_UNMAPPED_AREA_TOPDOWN;
info.length = len;
info.low_limit = PAGE_SIZE;
- info.high_limit = current->mm->mmap_base;
+ info.high_limit = get_mmap_base(0);
info.align_mask = PAGE_MASK & ~huge_page_mask(h);
info.align_offset = 0;
addr = vm_unmapped_area(&info);
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 529ab79800af..0fbb5a71b826 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -31,6 +31,7 @@
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <asm/elf.h>
+#include <asm/compat.h>
struct va_alignment __read_mostly va_align = {
.flags = -1,
@@ -153,6 +154,18 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
#endif
}
+unsigned long get_mmap_base(int is_legacy)
+{
+ struct mm_struct *mm = current->mm;
+
+#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
+ if (in_compat_syscall())
+ return is_legacy ? mm->mmap_compat_legacy_base
+ : mm->mmap_compat_base;
+#endif
+ return is_legacy ? mm->mmap_legacy_base : mm->mmap_base;
+}
+
const char *arch_vma_name(struct vm_area_struct *vma)
{
if (vma->vm_flags & VM_MPX)
--
Dmitry