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Refactor mmap and support shared filebacked mmap

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This commit is contained in:
Chen Chengjun
2024-08-12 16:12:47 +08:00
committed by Tate, Hongliang Tian
parent 19184d5c3d
commit 4bf355af50
1 changed files with 52 additions and 49 deletions
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83
kernel/aster-nix/src/syscall/mmap.rs
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@ -7,11 +7,11 @@ use aster_rights::Rights;
use super::SyscallReturn;
use crate::{
fs::file_table::FileDesc,
fs::{file_handle::FileLike, file_table::FileDesc, inode_handle::InodeHandle},
prelude::*,
vm::{
perms::VmPerms,
vmo::{Vmo, VmoChildOptions, VmoOptions, VmoRightsOp},
vmo::{VmoOptions, VmoRightsOp},
},
};
@ -60,18 +60,9 @@ fn do_sys_mmap(
return_errno_with_message!(Errno::EINVAL, "mmap only support page-aligned offset");
}
let vmo = if option.flags.contains(MMapFlags::MAP_ANONYMOUS) {
if offset != 0 {
return_errno_with_message!(Errno::EINVAL, "offset must be zero for anonymous mapping");
}
alloc_anonyous_vmo(len)?
} else {
alloc_filebacked_vmo(fd, len, offset, &option, ctx)?
};
let root_vmar = ctx.process.root_vmar();
let vm_map_options = {
let mut options = root_vmar.new_map(vmo.to_dyn(), vm_perms)?;
let mut options = root_vmar.new_map(len, vm_perms)?;
let flags = option.flags;
if flags.contains(MMapFlags::MAP_FIXED) {
options = options.offset(addr).can_overwrite(true);
@ -84,30 +75,42 @@ fn do_sys_mmap(
options = options.is_shared(true);
}
options
};
let map_addr = vm_map_options.build()?;
trace!("map range = 0x{:x} - 0x{:x}", map_addr, map_addr + len);
if option.flags.contains(MMapFlags::MAP_ANONYMOUS) {
if offset != 0 {
return_errno_with_message!(
Errno::EINVAL,
"offset must be zero for anonymous mapping"
);
}
Ok(map_addr)
}
fn alloc_anonyous_vmo(len: usize) -> Result<Vmo> {
// Anonymous shared mapping should share the same memory pages.
if option.typ() == MMapType::Shared {
let shared_vmo = {
let vmo_options: VmoOptions<Rights> = VmoOptions::new(len);
vmo_options.alloc()
}
vmo_options.alloc()?
};
options = options.vmo(shared_vmo);
}
} else {
let vmo = {
let file_table = ctx.process.file_table().lock();
let file = file_table.get_file(fd)?;
let inode_handle = file
.downcast_ref::<InodeHandle>()
.ok_or(Error::with_message(Errno::EINVAL, "no inode"))?;
fn alloc_filebacked_vmo(
fd: FileDesc,
len: usize,
offset: usize,
option: &MMapOptions,
ctx: &Context,
) -> Result<Vmo> {
let page_cache_vmo = {
let fs_resolver = ctx.process.fs().read();
let dentry = fs_resolver.lookup_from_fd(fd)?;
let inode = dentry.inode();
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(
@ -117,14 +120,14 @@ fn alloc_filebacked_vmo(
.to_dyn()
};
if option.typ() == MMapType::Private {
// map private
VmoChildOptions::new_cow(page_cache_vmo, offset..(offset + len)).alloc()
} else {
// map shared
// FIXME: map shared vmo can exceed parent range, but slice child cannot
VmoChildOptions::new_slice_rights(page_cache_vmo, offset..(offset + len)).alloc()
options = options.vmo(vmo).vmo_offset(offset);
}
options
};
let map_addr = vm_map_options.build()?;
Ok(map_addr)
}
fn check_option(option: &MMapOptions) -> Result<()> {