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Move handling of kernel page table entry copying to RMM

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This way it can ensure those page table entries never get unmapped,
ensuring they are kept in sync between all processes.
This commit is contained in:
bjorn3
2026-03-29 12:06:23 +02:00
parent 604e1729cb
commit abf710b4a2
19 changed files with 83 additions and 154 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/acpi/madt/arch/x86.rs
+1 -1
View File
@@ -144,7 +144,7 @@ pub(super) fn init(madt: Madt) {
// Unmap trampoline
let (_frame, _, flush) = unsafe {
KernelMapper::lock_rw()
.unmap_phys(trampoline_page.start_address(), true)
.unmap_phys(trampoline_page.start_address())
.expect("failed to unmap trampoline page")
};
flush.flush();
src/arch/riscv64/paging/mod.rs
-3
View File
@@ -9,9 +9,6 @@ pub use crate::rmm::KernelMapper;
pub mod entry;
pub mod mapper;
/// Number of entries per page table
pub const ENTRY_COUNT: usize = RmmA::PAGE_ENTRIES;
/// Size of pages
pub const PAGE_SIZE: usize = RmmA::PAGE_SIZE;
pub const PAGE_MASK: usize = RmmA::PAGE_OFFSET_MASK;
src/arch/x86_shared/device/local_apic.rs
+1 -1
View File
@@ -70,7 +70,7 @@ impl LocalApic {
if !self.x2 {
debug!("Detected xAPIC at {:#x}", physaddr.data());
if let Some((_entry, _, flush)) = mapper.unmap_phys(virtaddr, true) {
if let Some((_entry, _, flush)) = mapper.unmap_phys(virtaddr) {
// Unmap xAPIC page if already mapped
flush.flush();
}
src/arch/x86_shared/paging/mod.rs
-2
View File
@@ -23,8 +23,6 @@ pub mod entry {
pub mod mapper;
pub const ENTRY_COUNT: usize = RmmA::PAGE_ENTRIES;
/// Size of pages
pub const PAGE_SIZE: usize = RmmA::PAGE_SIZE;
pub const PAGE_MASK: usize = RmmA::PAGE_OFFSET_MASK;
src/context/arch/aarch64.rs
+2 -13
View File
@@ -1,11 +1,10 @@
use crate::{
arch::{device::cpu::registers::control_regs, interrupt::InterruptStack, paging::PageMapper},
context::{context::Kstack, memory::Table},
arch::{device::cpu::registers::control_regs, interrupt::InterruptStack},
context::context::Kstack,
percpu::PercpuBlock,
syscall::FloatRegisters,
};
use core::{mem, mem::offset_of, ptr, sync::atomic::AtomicBool};
use rmm::TableKind;
use spin::Once;
use syscall::{EnvRegisters, Error, Result, ENOMEM};
@@ -390,13 +389,3 @@ unsafe extern "C" fn switch_to_inner(_prev: &mut Context, _next: &mut Context) {
switch_hook = sym crate::context::switch_finish_hook,
);
}
/// Allocates a new empty utable
pub fn setup_new_utable() -> Result<Table> {
let utable = unsafe {
PageMapper::create(TableKind::User, crate::memory::TheFrameAllocator)
.ok_or(Error::new(ENOMEM))?
};
Ok(Table { utable })
}
src/context/arch/riscv64.rs
+3 -26
View File
@@ -1,15 +1,12 @@
use crate::{
arch::{
interrupt::InterruptStack,
paging::{PageMapper, ENTRY_COUNT},
},
context::{context::Kstack, memory::Table},
arch::interrupt::InterruptStack,
context::context::Kstack,
memory::{KernelMapper, RmmA},
percpu::PercpuBlock,
syscall::FloatRegisters,
};
use core::{mem::offset_of, sync::atomic::AtomicBool};
use rmm::{Arch, TableKind, VirtualAddress};
use rmm::{Arch, VirtualAddress};
use spin::Once;
use syscall::{error::*, EnvRegisters};
@@ -228,23 +225,3 @@ unsafe extern "C" fn switch_to_inner(prev: &mut Context, next: &mut Context) {
switch_hook = sym crate::context::switch_finish_hook,
);
}
/// Allocates a new empty utable
pub fn setup_new_utable() -> Result<Table> {
let utable = unsafe {
PageMapper::create(TableKind::User, crate::memory::TheFrameAllocator)
.ok_or(Error::new(ENOMEM))?
};
// Copy higher half (kernel) mappings
unsafe {
let active_ktable = KernelMapper::lock_ro();
for pde_no in ENTRY_COUNT / 2..ENTRY_COUNT {
if let Some(entry) = active_ktable.table().entry(pde_no) {
utable.table().set_entry(pde_no, entry);
}
}
}
Ok(Table { utable })
}
src/context/arch/x86.rs
+2 -36
View File
@@ -6,13 +6,9 @@ use crate::{
syscall::FloatRegisters,
};
use crate::{
arch::{interrupt::InterruptStack, paging::PageMapper},
context::{context::Kstack, memory::Table},
memory::RmmA,
};
use crate::{arch::interrupt::InterruptStack, context::context::Kstack, memory::RmmA};
use core::mem::offset_of;
use rmm::{Arch, TableKind, VirtualAddress};
use rmm::{Arch, VirtualAddress};
use spin::Once;
use syscall::{error::*, EnvRegisters};
@@ -315,33 +311,3 @@ unsafe extern "cdecl" fn switch_to_inner() {
switch_hook = sym crate::context::switch_finish_hook,
);
}
/// Allocates a new identically mapped ktable and empty utable (same memory on x86)
pub fn setup_new_utable() -> Result<Table> {
use crate::memory::KernelMapper;
let utable = unsafe {
PageMapper::create(TableKind::User, crate::memory::TheFrameAllocator)
.ok_or(Error::new(ENOMEM))?
};
{
let active_ktable = KernelMapper::lock_ro();
let copy_mapping = |p4_no| unsafe {
let entry = active_ktable
.table()
.entry(p4_no)
.unwrap_or_else(|| panic!("expected kernel PML {} to be mapped", p4_no));
utable.table().set_entry(p4_no, entry)
};
// Copy higher half (kernel) mappings
for i in 512..1024 {
copy_mapping(i);
}
}
Ok(Table { utable })
}
src/context/arch/x86_64.rs
+2 -30
View File
@@ -5,16 +5,9 @@ use core::{
use crate::syscall::FloatRegisters;
use crate::{
arch::{
interrupt::InterruptStack,
paging::{PageMapper, ENTRY_COUNT},
},
context::{context::Kstack, memory::Table},
memory::RmmA,
};
use crate::{arch::interrupt::InterruptStack, context::context::Kstack, memory::RmmA};
use core::mem::offset_of;
use rmm::{Arch, TableKind, VirtualAddress};
use rmm::{Arch, VirtualAddress};
use spin::Once;
use syscall::{error::*, EnvRegisters};
use x86::msr;
@@ -394,24 +387,3 @@ unsafe extern "sysv64" fn switch_to_inner(_prev: &mut Context, _next: &mut Conte
switch_hook = sym crate::context::switch_finish_hook,
);
}
/// Allocates a new identically mapped ktable and empty utable (same memory on x86_64).
pub fn setup_new_utable() -> Result<Table> {
use crate::memory::{KernelMapper, TheFrameAllocator};
let utable = unsafe {
PageMapper::create(TableKind::User, TheFrameAllocator).ok_or(Error::new(ENOMEM))?
};
// Copy higher half (kernel) mappings
unsafe {
let active_ktable = KernelMapper::lock_ro();
for pde_no in ENTRY_COUNT / 2..ENTRY_COUNT {
if let Some(entry) = active_ktable.table().entry(pde_no) {
utable.table().set_entry(pde_no, entry);
}
}
}
Ok(Table { utable })
}
src/context/memory.rs
+10 -8
View File
@@ -14,7 +14,7 @@ use syscall::{error::*, flag::MapFlags, GrantFlags, MunmapFlags};
use crate::{
arch::paging::PAGE_SIZE,
context::{arch::setup_new_utable, file::LockedFileDescription},
context::file::LockedFileDescription,
cpu_set::LogicalCpuSet,
memory::{
deallocate_frame, get_page_info, init_frame, the_zeroed_frame, AddRefError, Enomem, Frame,
@@ -566,9 +566,14 @@ impl AddrSpace {
}
pub fn new() -> Result<Self> {
let utable = unsafe {
PageMapper::create(TableKind::User, crate::memory::TheFrameAllocator)
.ok_or(Error::new(ENOMEM))?
};
Ok(Self {
grants: UserGrants::new(),
table: setup_new_utable()?,
table: Table { utable },
mmap_min: MMAP_MIN_DEFAULT,
used_by: LogicalCpuSet::empty(),
})
@@ -1822,11 +1827,9 @@ impl Grant {
for src_page in self.span().pages() {
let dst_page = dst_base.next_by(src_page.offset_from(self.base));
let unmap_parents = true;
// TODO: Validate flags?
let Some((phys, _flags, flush)) =
(unsafe { src_mapper.unmap_phys(src_page.start_address(), unmap_parents) })
(unsafe { src_mapper.unmap_phys(src_page.start_address()) })
else {
continue;
};
@@ -1953,7 +1956,7 @@ impl Grant {
for i in 0..self.info.page_count {
unsafe {
let (phys, _, flush) = mapper
.unmap_phys(self.base.next_by(i).start_address(), true)
.unmap_phys(self.base.next_by(i).start_address())
.expect("all physborrowed grants must be fully Present in the page tables");
flush.ignore();
@@ -1969,8 +1972,7 @@ impl Grant {
} else {
for page in self.span().pages() {
// Lazy mappings do not need to be unmapped.
let Some((phys, _, flush)) =
(unsafe { mapper.unmap_phys(page.start_address(), true) })
let Some((phys, _, flush)) = (unsafe { mapper.unmap_phys(page.start_address()) })
else {
continue;
};
src/startup/memory.rs
-17
View File
@@ -295,23 +295,6 @@ unsafe fn map_memory<A: Arch>(areas: &[MemoryArea], mut bump_allocator: &mut Bum
let mut mapper = PageMapper::<A, _>::create(TableKind::Kernel, &mut bump_allocator)
.expect("failed to create Mapper");
if cfg!(target_arch = "x86") {
// Pre-allocate all kernel PD entries so that when the page table is copied,
// these entries are synced between processes
for i in 512..1024 {
use rmm::{FrameAllocator, PageEntry};
let phys = mapper
.allocator_mut()
.allocate_one()
.expect("failed to map page table");
let flags = A::ENTRY_FLAG_READWRITE | A::ENTRY_FLAG_DEFAULT_TABLE;
mapper
.table()
.set_entry(i, PageEntry::new(phys.data(), flags));
}
}
// Map all physical areas at PHYS_OFFSET
for area in areas.iter() {
for i in 0..area.size / PAGE_SIZE {