[Devel] [PATCH RHEL7 COMMIT] ms/x86/hugetlb: Adjust to the new native/compat mmap bases

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-514.16.1.vz7.32.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-514.16.1.vz7.32.5
------>
commit 97021fe0a6d7eddb9f8e52a400457d439b9c4953
Author: Dmitry Safonov <dsafonov at virtuozzo.com>
Date:   Wed May 31 16:00:01 2017 +0400

    ms/x86/hugetlb: Adjust to the new native/compat mmap bases
    
    Commit 1b028f784e8c introduced two mmap() bases for 32-bit syscalls and for
    64-bit syscalls. The mmap() code in x86 was modified to handle the
    separation, but the patch series missed to update the hugetlb code.
    
    As a consequence a 32bit application mapping a file on hugetlbfs uses the
    64-bit mmap base for address space allocation, which fails.
    
    Adjust the hugetlb mapping code to use the proper bases depending on the
    syscall invocation mode (64-bit or compat).
    
    [ tglx: Massaged changelog and switched from asm/compat.h to linux/compat.h ]
    
    Fixes: commit 1b028f784e8c ("x86/mm: Introduce mmap_compat_base() for 32-bit mmap()")
    Reported-by: kernel test robot <xiaolong.ye at intel.com>
    Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
    
    Cc: 0x7f454c46 at gmail.com
    Cc: linux-mm at kvack.org
    Cc: Andy Lutomirski <luto at kernel.org>
    Cc: Cyrill Gorcunov <gorcunov at openvz.org>
    Cc: Borislav Petkov <bp at suse.de>
    Cc: "Kirill A. Shutemov" <kirill.shutemov at linux.intel.com>
    Link: http://lkml.kernel.org/r/20170314114126.9280-1-dsafonov@virtuozzo.com
    Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
    
    [picked from ms commit e13b73dd9c80]
    Signed-off-by: Dmitry Safonov <dsafonov at virtuozzo.com>
---
 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           | 14 ++++++++++++++
 4 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 6949194..8b0f639 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -289,6 +289,7 @@ 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 ffe8b89..1b9ea4f 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -99,18 +99,6 @@ out:
 	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 9db4999..ad8829b 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -12,10 +12,12 @@
 #include <linux/pagemap.h>
 #include <linux/err.h>
 #include <linux/sysctl.h>
+#include <linux/compat.h>
 #include <asm/mman.h>
 #include <asm/tlb.h>
 #include <asm/tlbflush.h>
 #include <asm/pgalloc.h>
+#include <asm/elf.h>
 
 #if 0	/* This is just for testing */
 struct page *
@@ -84,8 +86,9 @@ static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file,
 
 	info.flags = 0;
 	info.length = len;
-	info.low_limit = TASK_UNMAPPED_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);
@@ -102,7 +105,7 @@ 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 f97dd2d..a1656c8 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -29,6 +29,7 @@
 #include <linux/random.h>
 #include <linux/limits.h>
 #include <linux/sched.h>
+#include <linux/compat.h>
 #include <asm/elf.h>
 
 struct __read_mostly va_alignment va_align = {
@@ -155,3 +156,16 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 			arch_rnd(mmap32_rnd_bits), tasksize_32bit());
 #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;
+}