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Implement system call msync

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This commit is contained in:
Zhang Junyang
2025-06-10 20:45:52 +08:00
committed by Tate, Hongliang Tian
parent a2aedcfb3a
commit 525085ab86
9 changed files with 227 additions and 54 deletions
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4
docs/src/kernel/linux-compatibility.md
View File

@ -15,7 +15,7 @@ support the loading of Linux kernel modules.
## System Calls
At the time of writing,
Asterinas implements 204 out of the 336 system calls
Asterinas implements 213 out of the 336 system calls
provided by Linux on x86-64 architecture.
| Numbers | Names | Is Implemented |
@ -46,7 +46,7 @@ provided by Linux on x86-64 architecture.
| 23 | select | ✅ |
| 24 | sched_yield | ✅ |
| 25 | mremap | ❌ |
| 26 | msync | ❌ |
| 26 | msync | ✅ |
| 27 | mincore | ❌ |
| 28 | madvise | ✅ |
| 29 | shmget | ❌ |

48
kernel/src/syscall/mmap.rs
View File

@ -12,11 +12,7 @@ use crate::{
file_table::{get_file_fast, FileDesc},
},
prelude::*,
vm::{
perms::VmPerms,
vmar::is_userspace_vaddr,
vmo::{VmoOptions, VmoRightsOp},
},
vm::{perms::VmPerms, vmar::is_userspace_vaddr, vmo::VmoOptions},
};
pub fn sys_mmap(
@ -124,34 +120,28 @@ fn do_sys_mmap(
options = options.vmo(shared_vmo);
}
} else {
let vmo = {
let mut file_table = ctx.thread_local.borrow_file_table_mut();
let file = get_file_fast!(&mut file_table, fd);
let inode_handle = file.as_inode_or_err()?;
let mut file_table = ctx.thread_local.borrow_file_table_mut();
let file = get_file_fast!(&mut file_table, fd);
let inode_handle = file.as_inode_or_err()?;
let access_mode = inode_handle.access_mode();
if vm_perms.contains(VmPerms::READ) && !access_mode.is_readable() {
return_errno!(Errno::EACCES);
}
if option.typ() == MMapType::Shared
&& vm_perms.contains(VmPerms::WRITE)
&& !access_mode.is_writable()
{
return_errno!(Errno::EACCES);
}
let access_mode = inode_handle.access_mode();
if vm_perms.contains(VmPerms::READ) && !access_mode.is_readable() {
return_errno!(Errno::EACCES);
}
if option.typ() == MMapType::Shared
&& vm_perms.contains(VmPerms::WRITE)
&& !access_mode.is_writable()
{
return_errno!(Errno::EACCES);
}
let inode = inode_handle.dentry().inode();
inode
.page_cache()
.ok_or(Error::with_message(
Errno::EBADF,
"File does not have page cache",
))?
.to_dyn()
};
let inode = inode_handle.dentry().inode();
if inode.page_cache().is_none() {
return_errno_with_message!(Errno::EBADF, "File does not have page cache");
}
options = options
.vmo(vmo)
.inode(inode.clone())
.vmo_offset(offset)
.handle_page_faults_around();
}

98
kernel/src/syscall/msync.rs
View File

@ -1,9 +1,99 @@
// SPDX-License-Identifier: MPL-2.0
use super::SyscallReturn;
use crate::prelude::*;
use align_ext::AlignExt;
use super::SyscallReturn;
use crate::{prelude::*, thread::kernel_thread::ThreadOptions};
bitflags! {
/// Flags for `msync`.
///
/// See <https://elixir.bootlin.com/linux/v6.15.1/source/include/uapi/asm-generic/mman-common.h#L42>.
pub struct MsyncFlags: i32 {
/// Performs `msync` asynchronously.
const MS_ASYNC = 0x01;
/// Invalidates cache so that other processes mapping the same file
/// will immediately see the changes before this `msync` call.
///
/// Should be a no-op since we use the same page cache for all processes.
const MS_INVALIDATE = 0x02;
/// Performs `msync` synchronously.
const MS_SYNC = 0x04;
}
}
macro_rules! return_partially_mapped {
() => {
return_errno_with_message!(Errno::ENOMEM, "`msync` called on a partially mapped range")
};
}
pub fn sys_msync(start: Vaddr, size: usize, flag: i32, ctx: &Context) -> Result<SyscallReturn> {
let flags = MsyncFlags::from_bits(flag).ok_or_else(|| Error::new(Errno::EINVAL))?;
debug!("msync: start = {start:#x}, size = {size}, flags = {flags:?}");
if start % PAGE_SIZE != 0 || flags.contains(MsyncFlags::MS_ASYNC | MsyncFlags::MS_SYNC) {
return_errno!(Errno::EINVAL);
}
if size == 0 {
return Ok(SyscallReturn::Return(0));
}
let range = {
let end = start
.checked_add(size)
.ok_or(Error::with_message(
Errno::EINVAL,
"`msync` `size` overflows",
))?
.align_up(PAGE_SIZE);
start..end
};
let user_space = ctx.user_space();
let root_vmar = user_space.root_vmar().dup()?;
let guard = root_vmar.query(range.clone());
let mut mappings_iter = guard.iter();
// Check if the range is fully mapped.
let Some(first) = mappings_iter.next() else {
return_errno_with_message!(Errno::ENOMEM, "`msync` called on a not mapped range");
};
if first.map_to_addr() > range.start {
return_partially_mapped!();
}
let mut last_end = first.map_end();
for mapping in mappings_iter {
let start = mapping.map_to_addr();
if start != last_end {
return_partially_mapped!();
}
last_end = mapping.map_end();
}
if last_end < range.end {
return_partially_mapped!();
}
// Do nothing if not file-backed, as <https://pubs.opengroup.org/onlinepubs/9699919799/> says.
let inodes = guard
.iter()
.filter_map(|m| m.inode().cloned())
.collect::<Vec<_>>();
let task_fn = move || {
for inode in inodes {
// TODO: Sync a necessary range instead of syncing the whole inode.
let _ = inode.sync_all();
}
};
if flags.contains(MsyncFlags::MS_ASYNC) {
ThreadOptions::new(task_fn).spawn();
} else {
task_fn();
}
pub fn sys_msync(_start: Vaddr, _size: usize, _flag: i32, _ctx: &Context) -> Result<SyscallReturn> {
// TODO: implement real `msync`.
Ok(SyscallReturn::Return(0))
}

94
kernel/src/vm/vmar/mod.rs
View File

@ -16,6 +16,7 @@ use ostd::{
mm::{
tlb::TlbFlushOp, vm_space::CursorMut, PageFlags, PageProperty, VmSpace, MAX_USERSPACE_VADDR,
},
sync::RwMutexReadGuard,
task::disable_preempt,
};
@ -24,6 +25,7 @@ use self::{
vm_mapping::{MappedVmo, VmMapping},
};
use crate::{
fs::utils::Inode,
prelude::*,
process::{Process, ResourceType},
thread::exception::PageFaultInfo,
@ -164,6 +166,11 @@ impl VmarInner {
Some(vm_mapping)
}
/// Finds a set of [`VmMapping`]s that intersect with the provided range.
fn query(&self, range: &Range<Vaddr>) -> impl Iterator<Item = &VmMapping> {
self.vm_mappings.find(range)
}
/// Calculates the total amount of overlap between `VmMapping`s
/// and the provided range.
fn count_overlap_size(&self, range: Range<Vaddr>) -> usize {
@ -315,6 +322,13 @@ impl Vmar_ {
)
}
fn query(&self, range: Range<usize>) -> VmarQueryGuard<'_> {
VmarQueryGuard {
vmar: self.inner.read(),
range,
}
}
fn protect(&self, perms: VmPerms, range: Range<usize>) -> Result<()> {
assert!(range.start % PAGE_SIZE == 0);
assert!(range.end % PAGE_SIZE == 0);
@ -586,6 +600,7 @@ impl<R> Vmar<R> {
pub struct VmarMapOptions<'a, R1, R2> {
parent: &'a Vmar<R1>,
vmo: Option<Vmo<R2>>,
inode: Option<Arc<dyn Inode>>,
perms: VmPerms,
vmo_offset: usize,
vmo_limit: usize,
@ -610,6 +625,7 @@ impl<'a, R1, R2> VmarMapOptions<'a, R1, R2> {
Self {
parent,
vmo: None,
inode: None,
perms,
vmo_offset: 0,
vmo_limit: usize::MAX,
@ -622,22 +638,30 @@ impl<'a, R1, R2> VmarMapOptions<'a, R1, R2> {
}
}
/// Binds a VMO to the mapping.
/// Binds a [`Vmo`] to the mapping.
///
/// If the mapping is a private mapping, its size may not be equal to that of the VMO.
/// For example, it is ok to create a mapping whose size is larger than
/// that of the VMO, although one cannot read from or write to the
/// part of the mapping that is not backed by the VMO.
/// If the mapping is a private mapping, its size may not be equal to that
/// of the [`Vmo`]. For example, it is OK to create a mapping whose size is
/// larger than that of the [`Vmo`], although one cannot read from or write
/// to the part of the mapping that is not backed by the [`Vmo`].
///
/// So you may wonder: what is the point of supporting such _oversized_
/// mappings? The reason is two-fold.
/// 1. VMOs are resizable. So even if a mapping is backed by a VMO whose
/// size is equal to that of the mapping initially, we cannot prevent
/// the VMO from shrinking.
/// Such _oversized_ mappings are useful for two reasons:
/// 1. [`Vmo`]s are resizable. So even if a mapping is backed by a VMO
/// whose size is equal to that of the mapping initially, we cannot
/// prevent the VMO from shrinking.
/// 2. Mappings are not allowed to overlap by default. As a result,
/// oversized mappings can serve as a placeholder to prevent future
/// mappings from occupying some particular address ranges accidentally.
/// oversized mappings can reserve space for future expansions.
///
/// The [`Vmo`] of a mapping will be implicitly set if [`Self::inode`] is
/// set.
///
/// # Panics
///
/// This function panics if an [`Inode`] is already provided.
pub fn vmo(mut self, vmo: Vmo<R2>) -> Self {
if self.inode.is_some() {
panic!("Cannot set `vmo` when `inode` is already set");
}
self.vmo = Some(vmo);
self
@ -712,6 +736,36 @@ impl<'a, R1, R2> VmarMapOptions<'a, R1, R2> {
}
}
impl<R1> VmarMapOptions<'_, R1, Rights> {
/// Binds an [`Inode`] to the mapping.
///
/// This is used for file-backed mappings. The provided file inode will be
/// mapped. See [`Self::vmo`] for details on the map size.
///
/// If an [`Inode`] is provided, the [`Self::vmo`] must not be provided
/// again. The actually mapped [`Vmo`] will be the [`Inode`]'s page cache.
///
/// # Panics
///
/// This function panics if:
/// - a [`Vmo`] or [`Inode`] is already provided;
/// - the provided [`Inode`] does not have a page cache.
pub fn inode(mut self, inode: Arc<dyn Inode>) -> Self {
if self.vmo.is_some() {
panic!("Cannot set `inode` when `vmo` is already set");
}
self.vmo = Some(
inode
.page_cache()
.expect("Map an inode without page cache")
.to_dyn(),
);
self.inode = Some(inode);
self
}
}
impl<R1, R2> VmarMapOptions<'_, R1, R2>
where
Vmo<R2>: VmoRightsOp,
@ -726,6 +780,7 @@ where
let Self {
parent,
vmo,
inode,
perms,
vmo_offset,
vmo_limit,
@ -784,6 +839,7 @@ where
NonZeroUsize::new(map_size).unwrap(),
map_to_addr,
vmo,
inode,
is_shared,
handle_page_faults_around,
perms,
@ -832,6 +888,20 @@ where
}
}
/// A guard that allows querying a [`Vmar`] for its mappings.
pub struct VmarQueryGuard<'a> {
vmar: RwMutexReadGuard<'a, VmarInner>,
range: Range<usize>,
}
impl VmarQueryGuard<'_> {
/// Returns an iterator over the [`VmMapping`]s that intersect with the
/// provided range when calling [`Vmar::query`].
pub fn iter(&self) -> impl Iterator<Item = &VmMapping> {
self.vmar.query(&self.range)
}
}
/// Determines whether two ranges are intersected.
/// returns false if one of the ranges has a length of 0
pub fn is_intersected(range1: &Range<usize>, range2: &Range<usize>) -> bool {

7
kernel/src/vm/vmar/static_cap.rs
View File

@ -5,7 +5,7 @@ use core::ops::Range;
use aster_rights::{Dup, Read, Rights, TRightSet, TRights, Write};
use aster_rights_proc::require;
use super::{VmPerms, Vmar, VmarMapOptions, VmarRightsOp, Vmar_};
use super::{VmPerms, Vmar, VmarMapOptions, VmarQueryGuard, VmarRightsOp, Vmar_};
use crate::{
prelude::*, thread::exception::PageFaultInfo, vm::page_fault_handler::PageFaultHandler,
};
@ -85,6 +85,11 @@ impl<R: TRights> Vmar<TRightSet<R>> {
self.0.protect(perms, range)
}
/// Finds all the mapped regions that intersect with the specified range.
pub fn query(&self, range: Range<usize>) -> VmarQueryGuard<'_> {
self.0.query(range)
}
/// Clears all mappings.
///
/// After being cleared, this vmar will become an empty vmar

22
kernel/src/vm/vmar/vm_mapping.rs
View File

@ -16,6 +16,7 @@ use ostd::{
use super::{interval_set::Interval, RssType};
use crate::{
fs::utils::Inode,
prelude::*,
thread::exception::PageFaultInfo,
vm::{
@ -42,7 +43,7 @@ use crate::{
/// This type controls the actual mapping in the [`VmSpace`]. It is a linear
/// type and cannot be [`Drop`]. To remove a mapping, use [`Self::unmap`].
#[derive(Debug)]
pub(super) struct VmMapping {
pub struct VmMapping {
/// The size of mapping, in bytes. The map size can even be larger than the
/// size of VMO. Those pages outside VMO range cannot be read or write.
///
@ -56,6 +57,11 @@ pub(super) struct VmMapping {
/// The start of the virtual address maps to the start of the range
/// specified in [`MappedVmo`].
vmo: Option<MappedVmo>,
/// The inode of the file that backs the mapping.
///
/// If the inode is `Some`, it means that the mapping is file-backed.
/// And the `vmo` field must be the page cache of the inode.
inode: Option<Arc<dyn Inode>>,
/// Whether the mapping is shared.
///
/// The updates to a shared mapping are visible among processes, or carried
@ -83,6 +89,7 @@ impl VmMapping {
map_size: NonZeroUsize,
map_to_addr: Vaddr,
vmo: Option<MappedVmo>,
inode: Option<Arc<dyn Inode>>,
is_shared: bool,
handle_page_faults_around: bool,
perms: VmPerms,
@ -91,6 +98,7 @@ impl VmMapping {
map_size,
map_to_addr,
vmo,
inode,
is_shared,
handle_page_faults_around,
perms,
@ -100,6 +108,7 @@ impl VmMapping {
pub(super) fn new_fork(&self) -> Result<VmMapping> {
Ok(VmMapping {
vmo: self.vmo.as_ref().map(|vmo| vmo.dup()).transpose()?,
inode: self.inode.clone(),
..*self
})
}
@ -119,12 +128,17 @@ impl VmMapping {
self.map_size.get()
}
// Returns the permissions of pages in the mapping.
/// Returns the permissions of pages in the mapping.
pub fn perms(&self) -> VmPerms {
self.perms
}
// Returns the mapping's RSS type.
/// Returns the inode of the file that backs the mapping.
pub fn inode(&self) -> Option<&Arc<dyn Inode>> {
self.inode.as_ref()
}
/// Returns the mapping's RSS type.
pub fn rss_type(&self) -> RssType {
if self.vmo.is_none() {
RssType::RSS_ANONPAGES
@ -407,12 +421,14 @@ impl VmMapping {
map_to_addr: self.map_to_addr,
map_size: NonZeroUsize::new(left_size).unwrap(),
vmo: l_vmo,
inode: self.inode.clone(),
..self
};
let right = Self {
map_to_addr: at,
map_size: NonZeroUsize::new(right_size).unwrap(),
vmo: r_vmo,
inode: self.inode,
..self
};

3
test/syscall_test/gvisor/Makefile
View File

@ -25,6 +25,7 @@ TESTS ?= \
mknod_test \
mmap_test \
mount_test \
msync_test \
open_create_test \
open_test \
ppoll_test \
@ -33,9 +34,9 @@ TESTS ?= \
preadv2_test \
proc_test \
pselect_test \
pty_test \
pwrite64_test \
pwritev2_test \
pty_test \
read_test \
readv_test \
rename_test \

1
test/syscall_test/gvisor/blocklists.exfat/msync_test Normal file
View File

@ -0,0 +1 @@
All/MsyncFullParamTest.InvalidateUnlockedSucceeds/*

4
test/syscall_test/ltp/testcases/all.txt
View File

@ -924,8 +924,8 @@ mprotect05
msync01
msync02
# msync03
# msync04
# msync03 # FIXME: This fails because the heap place holder is treated as mapped. Fix after https://github.com/asterinas/asterinas/pull/1999.
# msync04 # TODO: support `/proc/self/pagemap` and `/proc/kpageflags`.
# munlock01
# munlock02