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WIP: Add per-cpu interrupt stack used before mapping kernel heap

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This commit is contained in:
Jeremy Soller
2018-01-09 22:16:14 -07:00
parent 192a8ce793
commit d82ffd16cb
5 changed files with 129 additions and 43 deletions
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8
src/arch/x86_64/gdt.rs
View File

@@ -124,7 +124,13 @@ pub unsafe fn init(tcb_offset: usize, stack_offset: usize) {
GDT[GDT_TSS].set_limit(mem::size_of::<TaskStateSegment>() as u32);
// Set the stack pointer when coming back from userspace
TSS.rsp[0] = stack_offset as u64;
if cfg!(feature = "pti") {
use arch::x86_64::pti::{PTI_CPU_STACK, PTI_CONTEXT_STACK};
TSS.rsp[0] = (PTI_CPU_STACK.as_ptr() as usize + PTI_CPU_STACK.len()) as u64;
PTI_CONTEXT_STACK = stack_offset;
} else {
TSS.rsp[0] = stack_offset as u64;
}
// Load the new GDT, which is correctly located in thread local storage
dtables::lgdt(&GDTR);

60
src/arch/x86_64/macros.rs
View File

@@ -166,22 +166,22 @@ macro_rules! interrupt {
pub unsafe extern fn $name () {
#[inline(never)]
unsafe fn inner() {
// Map kernel
$crate::arch::x86_64::pti::map();
$func
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
}
// Push scratch registers
scratch_push!();
fs_push!();
// Map kernel
$crate::arch::x86_64::pti::map();
// Call inner rust function
inner();
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers and return
fs_pop!();
scratch_pop!();
@@ -213,13 +213,7 @@ macro_rules! interrupt_stack {
pub unsafe extern fn $name () {
#[inline(never)]
unsafe fn inner($stack: &mut $crate::arch::x86_64::macros::InterruptStack) {
// Map kernel
$crate::arch::x86_64::pti::map();
$func
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
}
// Push scratch registers
@@ -230,9 +224,15 @@ macro_rules! interrupt_stack {
let rsp: usize;
asm!("" : "={rsp}"(rsp) : : : "intel", "volatile");
// Map kernel
$crate::arch::x86_64::pti::map();
// Call inner rust function
inner(&mut *(rsp as *mut $crate::arch::x86_64::macros::InterruptStack));
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers and return
fs_pop!();
scratch_pop!();
@@ -266,13 +266,7 @@ macro_rules! interrupt_error {
pub unsafe extern fn $name () {
#[inline(never)]
unsafe fn inner($stack: &$crate::arch::x86_64::macros::InterruptErrorStack) {
// Map kernel
$crate::arch::x86_64::pti::map();
$func
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
}
// Push scratch registers
@@ -283,9 +277,15 @@ macro_rules! interrupt_error {
let rsp: usize;
asm!("" : "={rsp}"(rsp) : : : "intel", "volatile");
// Map kernel
$crate::arch::x86_64::pti::map();
// Call inner rust function
inner(&*(rsp as *const $crate::arch::x86_64::macros::InterruptErrorStack));
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers, error code, and return
fs_pop!();
scratch_pop!();
@@ -320,13 +320,7 @@ macro_rules! interrupt_stack_p {
pub unsafe extern fn $name () {
#[inline(never)]
unsafe fn inner($stack: &mut $crate::arch::x86_64::macros::InterruptStackP) {
// Map kernel
$crate::arch::x86_64::pti::map();
$func
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
}
// Push scratch registers
@@ -338,9 +332,15 @@ macro_rules! interrupt_stack_p {
let rsp: usize;
asm!("" : "={rsp}"(rsp) : : : "intel", "volatile");
// Map kernel
$crate::arch::x86_64::pti::map();
// Call inner rust function
inner(&mut *(rsp as *mut $crate::arch::x86_64::macros::InterruptStackP));
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers and return
fs_pop!();
preserved_pop!();
@@ -377,13 +377,7 @@ macro_rules! interrupt_error_p {
pub unsafe extern fn $name () {
#[inline(never)]
unsafe fn inner($stack: &$crate::arch::x86_64::macros::InterruptErrorStackP) {
// Map kernel
$crate::arch::x86_64::pti::map();
$func
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
}
// Push scratch registers
@@ -395,9 +389,15 @@ macro_rules! interrupt_error_p {
let rsp: usize;
asm!("" : "={rsp}"(rsp) : : : "intel", "volatile");
// Map kernel
$crate::arch::x86_64::pti::map();
// Call inner rust function
inner(&*(rsp as *const $crate::arch::x86_64::macros::InterruptErrorStackP));
// Unmap kernel
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers, error code, and return
fs_pop!();
preserved_pop!();

93
src/arch/x86_64/pti.rs
View File

@@ -1,19 +1,90 @@
use core::ptr;
use memory::Frame;
use paging::ActivePageTable;
use paging::entry::EntryFlags;
#[cfg(feature = "pti")]
#[inline(always)]
pub unsafe fn map() {
let _cr3: usize;
asm!("mov $0, cr3
mov cr3, $0"
: "=r"(_cr3) : : "memory" : "intel", "volatile");
#[thread_local]
pub static mut PTI_CPU_STACK: [u8; 256] = [0; 256];
#[cfg(feature = "pti")]
#[thread_local]
pub static mut PTI_CONTEXT_STACK: usize = 0;
#[cfg(feature = "pti")]
#[inline(never)]
#[naked]
unsafe fn switch_stack(old: usize, new: usize) {
asm!("xchg bx, bx" : : : : "intel", "volatile");
let old_rsp: usize;
let old_rbp: usize;
asm!("" : "={rsp}"(old_rsp), "={rbp}"(old_rbp) : : : "intel", "volatile");
let offset_rsp = old - old_rsp;
let offset_rbp = old - old_rbp;
let new_rsp = new - offset_rsp;
let new_rbp = new - offset_rbp;
ptr::copy_nonoverlapping(
old_rsp as *const u8,
new_rsp as *mut u8,
offset_rsp
);
asm!("xchg bx, bx" : : : : "intel", "volatile");
asm!("" : : "{rsp}"(new_rsp), "{rbp}"(new_rbp) : : "intel", "volatile");
}
#[cfg(feature = "pti")]
#[inline(always)]
#[inline(never)]
#[naked]
pub unsafe fn map() {
asm!("xchg bx, bx" : : : : "intel", "volatile");
// {
// let mut active_table = unsafe { ActivePageTable::new() };
//
// // Map kernel heap
// let address = active_table.p4()[::KERNEL_HEAP_PML4].address();
// let frame = Frame::containing_address(address);
// let mut flags = active_table.p4()[::KERNEL_HEAP_PML4].flags();
// flags.remove(EntryFlags::PRESENT);
// active_table.p4_mut()[::KERNEL_HEAP_PML4].set(frame, flags);
//
// // Reload page tables
// active_table.flush_all();
// }
// Switch to per-context stack
switch_stack(PTI_CPU_STACK.as_ptr() as usize + PTI_CPU_STACK.len(), PTI_CONTEXT_STACK);
}
#[cfg(feature = "pti")]
#[inline(never)]
#[naked]
pub unsafe fn unmap() {
let _cr3: usize;
asm!("mov $0, cr3
mov cr3, $0"
: "=r"(_cr3) : : "memory" : "intel", "volatile");
asm!("xchg bx, bx" : : : : "intel", "volatile");
// Switch to per-CPU stack
switch_stack(PTI_CONTEXT_STACK, PTI_CPU_STACK.as_ptr() as usize + PTI_CPU_STACK.len());
// {
// let mut active_table = unsafe { ActivePageTable::new() };
//
// // Unmap kernel heap
// let address = active_table.p4()[::KERNEL_HEAP_PML4].address();
// let frame = Frame::containing_address(address);
// let mut flags = active_table.p4()[::KERNEL_HEAP_PML4].flags();
// flags.insert(EntryFlags::PRESENT);
// active_table.p4_mut()[::KERNEL_HEAP_PML4].set(frame, flags);
//
// // Reload page tables
// active_table.flush_all();
// }
}
#[cfg(not(feature = "pti"))]

3
src/arch/x86_64/start.rs
View File

@@ -190,7 +190,10 @@ pub unsafe extern fn kstart_ap(args_ptr: *const KernelArgsAp) -> ! {
::kmain_ap(cpu_id);
}
#[naked]
pub unsafe fn usermode(ip: usize, sp: usize, arg: usize) -> ! {
asm!("xchg bx, bx" : : : : "intel", "volatile");
// Unmap kernel
pti::unmap();

8
src/context/switch.rs
View File

@@ -118,7 +118,13 @@ pub unsafe fn switch() -> bool {
(&mut *from_ptr).running = false;
(&mut *to_ptr).running = true;
if let Some(ref stack) = (*to_ptr).kstack {
gdt::TSS.rsp[0] = (stack.as_ptr() as usize + stack.len() - 256) as u64;
if cfg!(feature = "pti") {
use arch::x86_64::pti::{PTI_CPU_STACK, PTI_CONTEXT_STACK};
gdt::TSS.rsp[0] = (PTI_CPU_STACK.as_ptr() as usize + PTI_CPU_STACK.len()) as u64;
PTI_CONTEXT_STACK = stack.as_ptr() as usize + stack.len();
} else {
gdt::TSS.rsp[0] = (stack.as_ptr() as usize + stack.len()) as u64;
}
}
CONTEXT_ID.store((&mut *to_ptr).id, Ordering::SeqCst);
}