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Message-ID: <00a409f0-1e2e-0bd7-83e7-f21a47878916@intel.com>
Date: Fri, 2 Oct 2020 08:58:14 -0700
From: "Yu, Yu-cheng" <yu-cheng.yu@...el.com>
To: Peter Collingbourne <pcc@...gle.com>
Cc: x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
linux-doc@...r.kernel.org, linux-mm@...ck.org,
linux-arch@...r.kernel.org, linux-api@...r.kernel.org,
Arnd Bergmann <arnd@...db.de>,
Andy Lutomirski <luto@...nel.org>,
Balbir Singh <bsingharora@...il.com>,
Borislav Petkov <bp@...en8.de>,
Cyrill Gorcunov <gorcunov@...il.com>,
Dave Hansen <dave.hansen@...ux.intel.com>,
Eugene Syromiatnikov <esyr@...hat.com>,
Florian Weimer <fweimer@...hat.com>,
"H.J. Lu" <hjl.tools@...il.com>, Jann Horn <jannh@...gle.com>,
Jonathan Corbet <corbet@....net>,
Kees Cook <keescook@...omium.org>,
Mike Kravetz <mike.kravetz@...cle.com>,
Nadav Amit <nadav.amit@...il.com>,
Oleg Nesterov <oleg@...hat.com>, Pavel Machek <pavel@....cz>,
Peter Zijlstra <peterz@...radead.org>,
Randy Dunlap <rdunlap@...radead.org>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
Vedvyas Shanbhogue <vedvyas.shanbhogue@...el.com>,
Dave Martin <Dave.Martin@....com>,
Weijiang Yang <weijiang.yang@...el.com>,
Pengfei Xu <pengfei.xu@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v13 19/26] mm: Re-introduce do_mmap_pgoff()
On 10/1/2020 7:06 PM, Peter Collingbourne wrote:
> On Fri, Sep 25, 2020 at 7:57 AM Yu-cheng Yu <yu-cheng.yu@...el.com> wrote:
>>
>> There was no more caller passing vm_flags to do_mmap(), and vm_flags was
>> removed from the function's input by:
>>
>> commit 45e55300f114 ("mm: remove unnecessary wrapper function do_mmap_pgoff()").
>>
>> There is a new user now. Shadow stack allocation passes VM_SHSTK to
>> do_mmap(). Re-introduce the vm_flags and do_mmap_pgoff().
>
> I would prefer to change the callers to pass the additional 0 argument
> instead of bringing the wrapper function back, but if we're going to
> bring it back then we should fix the naming (both functions take a
> pgoff argument, so the previous name do_mmap_pgoff() was just plain
> confusing).
>
> Peter
>
Thanks for your feedback. Here is the updated patch. I will re-send
the whole series later.
Yu-cheng
======
From 6a9f1e6bcdb6e599a44d5f58cf4cebd28c4634a2 Mon Sep 17 00:00:00 2001
From: Yu-cheng Yu <yu-cheng.yu@...el.com>
Date: Wed, 12 Aug 2020 14:01:58 -0700
Subject: [PATCH 19/26] mm: Re-introduce do_mmap_pgoff()
There was no more caller passing vm_flags to do_mmap(), and vm_flags was
removed from the function's input by:
commit 45e55300f114 ("mm: remove unnecessary wrapper function
do_mmap_pgoff()").
There is a new user now. Shadow stack allocation passes VM_SHSTK to
do_mmap(). Re-introduce vm_flags to do_mmap(), but without the old wrapper
do_mmap_pgoff(). Instead, fix all callers of the wrapper by passing a zero
vm_flags to do_mmap().
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@...el.com>
Cc: Peter Collingbourne <pcc@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: linux-mm@...ck.org
---
fs/aio.c | 2 +-
include/linux/mm.h | 3 ++-
ipc/shm.c | 2 +-
mm/mmap.c | 10 +++++-----
mm/nommu.c | 4 ++--
mm/util.c | 2 +-
6 files changed, 12 insertions(+), 11 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index d5ec30385566..ca8c11665eea 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -527,7 +527,7 @@ static int aio_setup_ring(struct kioctx *ctx,
unsigned int nr_events)
ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
PROT_READ | PROT_WRITE,
- MAP_SHARED, 0, &unused, NULL);
+ MAP_SHARED, 0, 0, &unused, NULL);
mmap_write_unlock(mm);
if (IS_ERR((void *)ctx->mmap_base)) {
ctx->mmap_size = 0;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index e09d13699bbe..e020eea33138 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2560,7 +2560,8 @@ extern unsigned long mmap_region(struct file
*file, unsigned long addr,
struct list_head *uf);
extern unsigned long do_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot, unsigned long flags,
- unsigned long pgoff, unsigned long *populate, struct list_head *uf);
+ vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
+ struct list_head *uf);
extern int __do_munmap(struct mm_struct *, unsigned long, size_t,
struct list_head *uf, bool downgrade);
extern int do_munmap(struct mm_struct *, unsigned long, size_t,
diff --git a/ipc/shm.c b/ipc/shm.c
index e25c7c6106bc..91474258933d 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1556,7 +1556,7 @@ long do_shmat(int shmid, char __user *shmaddr, int
shmflg,
goto invalid;
}
- addr = do_mmap(file, addr, size, prot, flags, 0, &populate, NULL);
+ addr = do_mmap(file, addr, size, prot, flags, 0, 0, &populate, NULL);
*raddr = addr;
err = 0;
if (IS_ERR_VALUE(addr))
diff --git a/mm/mmap.c b/mm/mmap.c
index 574b3f273462..fc04184d2eae 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1365,11 +1365,11 @@ static inline bool file_mmap_ok(struct file
*file, struct inode *inode,
*/
unsigned long do_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
- unsigned long flags, unsigned long pgoff,
- unsigned long *populate, struct list_head *uf)
+ unsigned long flags, vm_flags_t vm_flags,
+ unsigned long pgoff, unsigned long *populate,
+ struct list_head *uf)
{
struct mm_struct *mm = current->mm;
- vm_flags_t vm_flags;
int pkey = 0;
*populate = 0;
@@ -1431,7 +1431,7 @@ unsigned long do_mmap(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, pkey) | calc_vm_flag_bits(flags) |
+ vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
if (flags & MAP_LOCKED)
@@ -3007,7 +3007,7 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long,
start, unsigned long, size,
file = get_file(vma->vm_file);
ret = do_mmap(vma->vm_file, start, size,
- prot, flags, pgoff, &populate, NULL);
+ prot, flags, 0, pgoff, &populate, NULL);
fput(file);
out:
mmap_write_unlock(mm);
diff --git a/mm/nommu.c b/mm/nommu.c
index 75a327149af1..f67d6bcdfc9f 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1078,6 +1078,7 @@ unsigned long do_mmap(struct file *file,
unsigned long len,
unsigned long prot,
unsigned long flags,
+ vm_flags_t vm_flags,
unsigned long pgoff,
unsigned long *populate,
struct list_head *uf)
@@ -1085,7 +1086,6 @@ unsigned long do_mmap(struct file *file,
struct vm_area_struct *vma;
struct vm_region *region;
struct rb_node *rb;
- vm_flags_t vm_flags;
unsigned long capabilities, result;
int ret;
@@ -1104,7 +1104,7 @@ unsigned long do_mmap(struct file *file,
/* we've determined that we can make the mapping, now translate what we
* now know into VMA flags */
- vm_flags = determine_vm_flags(file, prot, flags, capabilities);
+ vm_flags |= determine_vm_flags(file, prot, flags, capabilities);
/* we're going to need to record the mapping */
region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
diff --git a/mm/util.c b/mm/util.c
index 5ef378a2a038..beb8b881c080 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -503,7 +503,7 @@ unsigned long vm_mmap_pgoff(struct file *file,
unsigned long addr,
if (!ret) {
if (mmap_write_lock_killable(mm))
return -EINTR;
- ret = do_mmap(file, addr, len, prot, flag, pgoff, &populate,
+ ret = do_mmap(file, addr, len, prot, flag, 0, pgoff, &populate,
&uf);
mmap_write_unlock(mm);
userfaultfd_unmap_complete(mm, &uf);
--
2.21.0
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