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Date: Mon, 13 Jul 2015 18:53:23 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Dave Hansen <dave.hansen@...ux.intel.com>,
Andy Lutomirski <luto@...capital.net>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 2/5] x86, mpx: do not set ->vm_ops on mpx VMAs
On 07/13, Kirill A. Shutemov wrote:
>
> We don't really need ->vm_ops here: MPX VMA can be detected with VM_MPX
> flag. And vma_merge() will not merge MPX VMA with non-MPX VMA, because
> ->vm_flags won't match.
Agreed.
I am wondering if something like the patch below (on top of yours) makes
sense... Not sure, but mpx_mmap() doesn't look nice too, and with this
change we can unexport mmap_region().
Oleg.
arch/x86/mm/mpx.c | 51 +++++++--------------------------------------------
include/linux/mm.h | 3 +++
mm/mmap.c | 16 +++++++++++-----
3 files changed, 21 insertions(+), 49 deletions(-)
diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
index 4d1c11c..da8b713 100644
--- a/arch/x86/mm/mpx.c
+++ b/arch/x86/mm/mpx.c
@@ -24,58 +24,21 @@
*/
static unsigned long mpx_mmap(unsigned long len)
{
- unsigned long ret;
- unsigned long addr, pgoff;
+ unsigned long addr, populate;
struct mm_struct *mm = current->mm;
- vm_flags_t vm_flags;
- struct vm_area_struct *vma;
/* Only bounds table and bounds directory can be allocated here */
if (len != MPX_BD_SIZE_BYTES && len != MPX_BT_SIZE_BYTES)
return -EINVAL;
down_write(&mm->mmap_sem);
-
- /* Too many mappings? */
- if (mm->map_count > sysctl_max_map_count) {
- ret = -ENOMEM;
- goto out;
- }
-
- /* Obtain the address to map to. we verify (or select) it and ensure
- * that it represents a valid section of the address space.
- */
- addr = get_unmapped_area(NULL, 0, len, 0, MAP_ANONYMOUS | MAP_PRIVATE);
- if (addr & ~PAGE_MASK) {
- ret = addr;
- goto out;
- }
-
- vm_flags = VM_READ | VM_WRITE | VM_MPX |
- mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
-
- /* Set pgoff according to addr for anon_vma */
- pgoff = addr >> PAGE_SHIFT;
-
- ret = mmap_region(NULL, addr, len, vm_flags, pgoff);
- if (IS_ERR_VALUE(ret))
- goto out;
-
- vma = find_vma(mm, ret);
- if (!vma) {
- ret = -ENOMEM;
- goto out;
- }
-
- if (vm_flags & VM_LOCKED) {
- up_write(&mm->mmap_sem);
- mm_populate(ret, len);
- return ret;
- }
-
-out:
+ addr = __do_mmap_pgoff(NULL, 0, len, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, 0, &populate, VM_MPX);
up_write(&mm->mmap_sem);
- return ret;
+ if (populate)
+ mm_populate(addr, populate);
+
+ return addr;
}
enum reg_type {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0207ffa..910d475 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1849,6 +1849,9 @@ extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned lo
extern unsigned long mmap_region(struct file *file, unsigned long addr,
unsigned long len, vm_flags_t vm_flags, unsigned long pgoff);
+extern unsigned long __do_mmap_pgoff(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long prot, unsigned long flags,
+ unsigned long pgoff, unsigned long *populate, vm_flags_t vm_flags);
extern unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot, unsigned long flags,
unsigned long pgoff, unsigned long *populate);
diff --git a/mm/mmap.c b/mm/mmap.c
index 2185cd9..88bc961 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1247,14 +1247,12 @@ static inline int mlock_future_check(struct mm_struct *mm,
/*
* The caller must hold down_write(¤t->mm->mmap_sem).
*/
-
-unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
+unsigned long __do_mmap_pgoff(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
unsigned long flags, unsigned long pgoff,
- unsigned long *populate)
+ unsigned long *populate, vm_flags_t vm_flags)
{
struct mm_struct *mm = current->mm;
- vm_flags_t vm_flags;
*populate = 0;
@@ -1298,7 +1296,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
* to. we assume access permissions have been handled by the open
* of the memory object, so we don't do any here.
*/
- vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
+ vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
if (flags & MAP_LOCKED)
@@ -1396,6 +1394,14 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
return addr;
}
+unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
+ unsigned long len, unsigned long prot,
+ unsigned long flags, unsigned long pgoff,
+ unsigned long *populate)
+{
+ return __do_mmap_pgoff(file, addr, len, prot, flags, pgoff, populate, 0);
+}
+
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
unsigned long, prot, unsigned long, flags,
unsigned long, fd, unsigned long, pgoff)
--
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