[PATCH v12 19/26] mm: Re-introduce do_mmap_pgoff()

From: Yu-cheng Yu
Date: Fri Sep 18 2020 - 15:23:12 EST

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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().

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
---
fs/aio.c | 6 +++---
fs/hugetlbfs/inode.c | 2 +-
include/linux/fs.h | 2 +-
include/linux/mm.h | 12 +++++++++++-
ipc/shm.c | 2 +-
mm/mmap.c | 16 ++++++++--------
mm/nommu.c | 6 +++---
mm/shmem.c | 2 +-
mm/util.c | 4 ++--
9 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index d5ec30385566..22d19a4ad586 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -525,9 +525,9 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
return -EINTR;
}

- ctx->mmap_base = do_mmap(ctx->aio_ring_file, 0, ctx->mmap_size,
- PROT_READ | PROT_WRITE,
- MAP_SHARED, 0, &unused, NULL);
+ ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED, 0, &unused, NULL);
mmap_write_unlock(mm);
if (IS_ERR((void *)ctx->mmap_base)) {
ctx->mmap_size = 0;
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index b5c109703daa..f936bcf02cce 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -140,7 +140,7 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
* already been checked by prepare_hugepage_range. If you add
* any error returns here, do so after setting VM_HUGETLB, so
* is_vm_hugetlb_page tests below unmap_region go the right
- * way when do_mmap unwinds (may be important on powerpc
+ * way when do_mmap_pgoff unwinds (may be important on powerpc
* and ia64).
*/
vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7519ae003a08..f7df4558f72c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -538,7 +538,7 @@ static inline int mapping_mapped(struct address_space *mapping)

/*
* Might pages of this file have been modified in userspace?
- * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap
+ * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap_pgoff
* marks vma as VM_SHARED if it is shared, and the file was opened for
* writing i.e. vma may be mprotected writable even if now readonly.
*
diff --git a/include/linux/mm.h b/include/linux/mm.h
index de6d1f7bac48..febbba1ece6e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2558,13 +2558,23 @@ 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,
struct list_head *uf);
extern int do_madvise(unsigned long start, size_t len_in, int behavior);

+static inline 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,
+ struct list_head *uf)
+{
+ return do_mmap(file, addr, len, prot, flags, 0, pgoff, populate, uf);
+}
+
#ifdef CONFIG_MMU
extern int __mm_populate(unsigned long addr, unsigned long len,
int ignore_errors);
diff --git a/ipc/shm.c b/ipc/shm.c
index e25c7c6106bc..3131c1de6bba 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_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
*raddr = addr;
err = 0;
if (IS_ERR_VALUE(addr))
diff --git a/mm/mmap.c b/mm/mmap.c
index 574b3f273462..81d4a00092da 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1030,7 +1030,7 @@ static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
* anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
*
* We don't check here for the merged mmap wrapping around the end of pagecache
- * indices (16TB on ia32) because do_mmap() does not permit mmap's which
+ * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which
* wrap, nor mmaps which cover the final page at index -1UL.
*/
static int
@@ -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)
@@ -2233,7 +2233,7 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
/*
* mmap_region() will call shmem_zero_setup() to create a file,
* so use shmem's get_unmapped_area in case it can be huge.
- * do_mmap() will clear pgoff, so match alignment.
+ * do_mmap_pgoff() will clear pgoff, so match alignment.
*/
pgoff = 0;
get_area = shmem_get_unmapped_area;
@@ -3006,7 +3006,7 @@ 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,
+ ret = do_mmap_pgoff(vma->vm_file, start, size,
prot, flags, pgoff, &populate, NULL);
fput(file);
out:
@@ -3226,7 +3226,7 @@ int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
* By setting it to reflect the virtual start address of the
* vma, merges and splits can happen in a seamless way, just
* using the existing file pgoff checks and manipulations.
- * Similarly in do_mmap and in do_brk.
+ * Similarly in do_mmap_pgoff and in do_brk.
*/
if (vma_is_anonymous(vma)) {
BUG_ON(vma->anon_vma);
diff --git a/mm/nommu.c b/mm/nommu.c
index 75a327149af1..71a4ea828f06 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);
@@ -1763,7 +1763,7 @@ EXPORT_SYMBOL_GPL(access_process_vm);
*
* Check the shared mappings on an inode on behalf of a shrinking truncate to
* make sure that any outstanding VMAs aren't broken and then shrink the
- * vm_regions that extend beyond so that do_mmap() doesn't
+ * vm_regions that extend beyond so that do_mmap_pgoff() doesn't
* automatically grant mappings that are too large.
*/
int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
diff --git a/mm/shmem.c b/mm/shmem.c
index 271548ca20f3..dea76ecc849b 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -4246,7 +4246,7 @@ EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);

/**
* shmem_zero_setup - setup a shared anonymous mapping
- * @vma: the vma to be mmapped is prepared by do_mmap
+ * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
*/
int shmem_zero_setup(struct vm_area_struct *vma)
{
diff --git a/mm/util.c b/mm/util.c
index 5ef378a2a038..8d6280c05238 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -503,8 +503,8 @@ 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,
- &uf);
+ ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff,
+ &populate, &uf);
mmap_write_unlock(mm);
userfaultfd_unmap_complete(mm, &uf);
if (populate)
--
2.21.0

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