Files
linux/tools/testing/vma/include/stubs.h
Lorenzo Stoakes (Oracle) 3e4bb27068 mm: various small mmap_prepare cleanups
Patch series "mm: expand mmap_prepare functionality and usage", v4.

This series expands the mmap_prepare functionality, which is intended to
replace the deprecated f_op->mmap hook which has been the source of bugs
and security issues for some time.

This series starts with some cleanup of existing mmap_prepare logic, then
adds documentation for the mmap_prepare call to make it easier for
filesystem and driver writers to understand how it works.

It then importantly adds a vm_ops->mapped hook, a key feature that was
missing from mmap_prepare previously - this is invoked when a driver which
specifies mmap_prepare has successfully been mapped but not merged with
another VMA.

mmap_prepare is invoked prior to a merge being attempted, so you cannot
manipulate state such as reference counts as if it were a new mapping.

The vm_ops->mapped hook allows a driver to perform tasks required at this
stage, and provides symmetry against subsequent vm_ops->open,close calls.

The series uses this to correct the afs implementation which wrongly
manipulated reference count at mmap_prepare time.

It then adds an mmap_prepare equivalent of vm_iomap_memory() -
mmap_action_simple_ioremap(), then uses this to update a number of drivers.

It then splits out the mmap_prepare compatibility layer (which allows for
invocation of mmap_prepare hooks in an mmap() hook) in such a way as to
allow for more incremental implementation of mmap_prepare hooks.

It then uses this to extend mmap_prepare usage in drivers.

Finally it adds an mmap_prepare equivalent of vm_map_pages(), which lays
the foundation for future work which will extend mmap_prepare to DMA
coherent mappings.


This patch (of 21):

Rather than passing arbitrary fields, pass a vm_area_desc pointer to mmap
prepare functions to mmap prepare, and an action and vma pointer to mmap
complete in order to put all the action-specific logic in the function
actually doing the work.

Additionally, allow mmap prepare functions to return an error so we can
error out as soon as possible if there is something logically incorrect in
the input.

Update remap_pfn_range_prepare() to properly check the input range for the
CoW case.

Also remove io_remap_pfn_range_complete(), as we can simply set up the
fields correctly in io_remap_pfn_range_prepare() and use
remap_pfn_range_complete() for this.

While we're here, make remap_pfn_range_prepare_vma() a little neater, and
pass mmap_action directly to call_action_complete().

Then, update compat_vma_mmap() to perform its logic directly, as
__compat_vma_map() is not used by anything so we don't need to export it.

Also update compat_vma_mmap() to use vfs_mmap_prepare() rather than
calling the mmap_prepare op directly.

Finally, update the VMA userland tests to reflect the changes.

Link: https://lkml.kernel.org/r/cover.1774045440.git.ljs@kernel.org
Link: https://lkml.kernel.org/r/99f408e4694f44ab12bdc55fe0bd9685d3bd1117.1774045440.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bodo Stroesser <bostroesser@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Long Li <longli@microsoft.com>
Cc: Marc Dionne <marc.dionne@auristor.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Richard Weinberger <richard@nod.at>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-04-05 13:53:41 -07:00

435 lines
7.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0+ */
#pragma once
/*
* Contains declarations that are STUBBED, that is that are rendered no-ops, in
* order to faciliate userland VMA testing.
*/
/* Forward declarations. */
struct mm_struct;
struct vm_area_struct;
struct vm_area_desc;
struct pagetable_move_control;
struct mmap_action;
struct file;
struct anon_vma;
struct anon_vma_chain;
struct address_space;
struct unmap_desc;
#define __bitwise
#define __randomize_layout
#define FIRST_USER_ADDRESS 0UL
#define USER_PGTABLES_CEILING 0UL
#define vma_policy(vma) NULL
#define down_write_nest_lock(sem, nest_lock)
#define data_race(expr) expr
#define ASSERT_EXCLUSIVE_WRITER(x)
struct vm_userfaultfd_ctx {};
struct mempolicy {};
struct mmu_gather {};
struct mutex {};
struct vm_fault {};
static inline void userfaultfd_unmap_complete(struct mm_struct *mm,
struct list_head *uf)
{
}
static inline unsigned long move_page_tables(struct pagetable_move_control *pmc)
{
return 0;
}
static inline void free_pgd_range(struct mmu_gather *tlb,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
}
static inline int ksm_execve(struct mm_struct *mm)
{
return 0;
}
static inline void ksm_exit(struct mm_struct *mm)
{
}
static inline void vma_numab_state_init(struct vm_area_struct *vma)
{
}
static inline void vma_numab_state_free(struct vm_area_struct *vma)
{
}
static inline void dup_anon_vma_name(struct vm_area_struct *orig_vma,
struct vm_area_struct *new_vma)
{
}
static inline void free_anon_vma_name(struct vm_area_struct *vma)
{
}
static inline int mmap_action_prepare(struct vm_area_desc *desc)
{
return 0;
}
static inline int mmap_action_complete(struct vm_area_struct *vma,
struct mmap_action *action)
{
return 0;
}
static inline void fixup_hugetlb_reservations(struct vm_area_struct *vma)
{
}
static inline bool shmem_file(struct file *file)
{
return false;
}
static inline vma_flags_t ksm_vma_flags(struct mm_struct *mm,
const struct file *file, vma_flags_t vma_flags)
{
return vma_flags;
}
static inline void remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn)
{
}
static inline int remap_pfn_range_complete(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t pgprot)
{
return 0;
}
static inline int do_munmap(struct mm_struct *, unsigned long, size_t,
struct list_head *uf)
{
return 0;
}
/* Currently stubbed but we may later wish to un-stub. */
static inline void vm_acct_memory(long pages);
static inline void mmap_assert_locked(struct mm_struct *mm)
{
}
static inline void anon_vma_unlock_write(struct anon_vma *anon_vma)
{
}
static inline void i_mmap_unlock_write(struct address_space *mapping)
{
}
static inline int userfaultfd_unmap_prep(struct vm_area_struct *vma,
unsigned long start,
unsigned long end,
struct list_head *unmaps)
{
return 0;
}
static inline void mmap_write_downgrade(struct mm_struct *mm)
{
}
static inline void mmap_read_unlock(struct mm_struct *mm)
{
}
static inline void mmap_write_unlock(struct mm_struct *mm)
{
}
static inline int mmap_write_lock_killable(struct mm_struct *mm)
{
return 0;
}
static inline bool can_modify_mm(struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
return true;
}
static inline void arch_unmap(struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
}
static inline bool mpol_equal(struct mempolicy *a, struct mempolicy *b)
{
return true;
}
static inline void khugepaged_enter_vma(struct vm_area_struct *vma,
vm_flags_t vm_flags)
{
}
static inline bool mapping_can_writeback(struct address_space *mapping)
{
return true;
}
static inline bool is_vm_hugetlb_page(struct vm_area_struct *vma)
{
return false;
}
static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
{
return false;
}
static inline bool userfaultfd_wp(struct vm_area_struct *vma)
{
return false;
}
static inline void mmap_assert_write_locked(struct mm_struct *mm)
{
}
static inline void mutex_lock(struct mutex *lock)
{
}
static inline void mutex_unlock(struct mutex *lock)
{
}
static inline bool mutex_is_locked(struct mutex *lock)
{
return true;
}
static inline bool signal_pending(void *p)
{
return false;
}
static inline bool is_file_hugepages(const struct file *file)
{
return false;
}
static inline int security_vm_enough_memory_mm(struct mm_struct *mm, long pages)
{
return 0;
}
static inline bool may_expand_vm(struct mm_struct *mm,
const vma_flags_t *vma_flags,
unsigned long npages)
{
return true;
}
static inline int shmem_zero_setup(struct vm_area_struct *vma)
{
return 0;
}
static inline void vm_acct_memory(long pages)
{
}
static inline void vma_interval_tree_insert(struct vm_area_struct *vma,
struct rb_root_cached *rb)
{
}
static inline void vma_interval_tree_remove(struct vm_area_struct *vma,
struct rb_root_cached *rb)
{
}
static inline void flush_dcache_mmap_unlock(struct address_space *mapping)
{
}
static inline void anon_vma_interval_tree_insert(struct anon_vma_chain *avc,
struct rb_root_cached *rb)
{
}
static inline void anon_vma_interval_tree_remove(struct anon_vma_chain *avc,
struct rb_root_cached *rb)
{
}
static inline void uprobe_mmap(struct vm_area_struct *vma)
{
}
static inline void uprobe_munmap(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
}
static inline void i_mmap_lock_write(struct address_space *mapping)
{
}
static inline void anon_vma_lock_write(struct anon_vma *anon_vma)
{
}
static inline void vma_assert_write_locked(struct vm_area_struct *vma)
{
}
static inline void ksm_add_vma(struct vm_area_struct *vma)
{
}
static inline void perf_event_mmap(struct vm_area_struct *vma)
{
}
static inline bool vma_is_dax(struct vm_area_struct *vma)
{
return false;
}
static inline struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
{
return NULL;
}
static inline bool arch_validate_flags(vm_flags_t flags)
{
return true;
}
static inline void vma_close(struct vm_area_struct *vma)
{
}
static inline int mmap_file(struct file *file, struct vm_area_struct *vma)
{
return 0;
}
static inline int is_hugepage_only_range(struct mm_struct *mm,
unsigned long addr, unsigned long len)
{
return 0;
}
static inline bool capable(int cap)
{
return true;
}
static inline struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
{
return NULL;
}
static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma,
struct vm_userfaultfd_ctx vm_ctx)
{
return true;
}
static inline bool anon_vma_name_eq(struct anon_vma_name *anon_name1,
struct anon_vma_name *anon_name2)
{
return true;
}
static inline void might_sleep(void)
{
}
static inline void fput(struct file *file)
{
}
static inline void mpol_put(struct mempolicy *pol)
{
}
static inline void lru_add_drain(void)
{
}
static inline void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm)
{
}
static inline void update_hiwater_rss(struct mm_struct *mm)
{
}
static inline void update_hiwater_vm(struct mm_struct *mm)
{
}
static inline void unmap_vmas(struct mmu_gather *tlb, struct unmap_desc *unmap)
{
}
static inline void free_pgtables(struct mmu_gather *tlb, struct unmap_desc *unmap)
{
}
static inline void mapping_unmap_writable(struct address_space *mapping)
{
}
static inline void flush_dcache_mmap_lock(struct address_space *mapping)
{
}
static inline void tlb_finish_mmu(struct mmu_gather *tlb)
{
}
static inline struct file *get_file(struct file *f)
{
return f;
}
static inline int vma_dup_policy(struct vm_area_struct *src, struct vm_area_struct *dst)
{
return 0;
}
static inline void vma_adjust_trans_huge(struct vm_area_struct *vma,
unsigned long start,
unsigned long end,
struct vm_area_struct *next)
{
}
static inline void hugetlb_split(struct vm_area_struct *, unsigned long) {}
static inline bool vma_supports_mlock(const struct vm_area_struct *vma)
{
return false;
}