diff --git a/src/arch/x86_64/gdt.rs b/src/arch/x86_64/gdt.rs
index f162bb57d445ea02966c9d91feb775670dee8dcb..ca846074fefc917d339e1a6845569b86b389eef2 100644
--- a/src/arch/x86_64/gdt.rs
+++ b/src/arch/x86_64/gdt.rs
@@ -88,6 +88,18 @@ pub static mut TSS: TaskStateSegment = TaskStateSegment {
iomap_base: 0xFFFF
};
+#[cfg(feature = "pti")]
+pub unsafe fn set_tss_stack(stack: usize) {
+ 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;
+}
+
+#[cfg(not(feature = "pti"))]
+pub unsafe fn set_tss_stack(stack: usize) {
+ TSS.rsp[0] = stack as u64;
+}
+
/// Initialize GDT
pub unsafe fn init(tcb_offset: usize, stack_offset: usize) {
// Setup the initial GDT with TLS, so we can setup the TLS GDT (a little confusing)
@@ -124,13 +136,7 @@ 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
- 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;
- }
+ set_tss_stack(stack_offset);
// Load the new GDT, which is correctly located in thread local storage
dtables::lgdt(&GDTR);
diff --git a/src/arch/x86_64/interrupt/syscall.rs b/src/arch/x86_64/interrupt/syscall.rs
index 89a867db27f423f10b954d0f7b9e53e87a974594..359b33b12843ff8e5cbbcc45d4b9fa7fd8da1855 100644
--- a/src/arch/x86_64/interrupt/syscall.rs
+++ b/src/arch/x86_64/interrupt/syscall.rs
@@ -4,64 +4,65 @@ use syscall;
#[naked]
pub unsafe extern fn syscall() {
#[inline(never)]
- unsafe fn inner(stack: &mut SyscallStack) {
- let mut a;
+ unsafe fn inner(stack: &mut SyscallStack) -> usize {
let rbp;
- asm!("" : "={rax}"(a), "={rbp}"(rbp)
- : : : "intel", "volatile");
+ asm!("" : "={rbp}"(rbp) : : : "intel", "volatile");
- // Map kernel
- pti::map();
+ println!("{:X}, {:X}", stack.rax, stack.rbx);
- a = syscall::syscall(a, stack.rbx, stack.rcx, stack.rdx, stack.rsi, stack.rdi, rbp, stack);
-
- // Unmap kernel
- pti::unmap();
-
- asm!("" : : "{rax}"(a) : : "intel", "volatile");
+ syscall::syscall(stack.rax, stack.rbx, stack.rcx, stack.rdx, stack.rsi, stack.rdi, rbp, stack)
}
- // Push scratch registers, minus rax for the return value
- asm!("push rcx
- push rdx
- push rdi
- push rsi
- push r8
- push r9
- push r10
- push r11
- push rbx
- push fs
- mov r11, 0x18
- mov fs, r11"
- : : : : "intel", "volatile");
+ // Push scratch registers
+ asm!("push rax
+ push rbx
+ push rcx
+ push rdx
+ push rdi
+ push rsi
+ push r8
+ push r9
+ push r10
+ push r11
+ push fs
+ mov r11, 0x18
+ mov fs, r11"
+ : : : : "intel", "volatile");
// Get reference to stack variables
let rsp: usize;
asm!("" : "={rsp}"(rsp) : : : "intel", "volatile");
- inner(&mut *(rsp as *mut SyscallStack));
+ // Map kernel
+ pti::map();
+
+ let a = inner(&mut *(rsp as *mut SyscallStack));
+
+ // Unmap kernel
+ pti::unmap();
+
+ asm!("" : : "{rax}"(a) : : "intel", "volatile");
// Interrupt return
asm!("pop fs
- pop rbx
- pop r11
- pop r10
- pop r9
- pop r8
- pop rsi
- pop rdi
- pop rdx
- pop rcx
- iretq"
- : : : : "intel", "volatile");
+ pop r11
+ pop r10
+ pop r9
+ pop r8
+ pop rsi
+ pop rdi
+ pop rdx
+ pop rcx
+ pop rbx
+ add rsp, 8
+ iretq"
+ : : : : "intel", "volatile");
}
#[allow(dead_code)]
#[repr(packed)]
pub struct SyscallStack {
pub fs: usize,
- pub rbx: usize,
pub r11: usize,
pub r10: usize,
pub r9: usize,
@@ -70,6 +71,8 @@ pub struct SyscallStack {
pub rdi: usize,
pub rdx: usize,
pub rcx: usize,
+ pub rbx: usize,
+ pub rax: usize,
pub rip: usize,
pub cs: usize,
pub rflags: usize,
diff --git a/src/arch/x86_64/pti.rs b/src/arch/x86_64/pti.rs
index bb38ea5e65e75333a63d65ecd5b346e33e9b736b..9124c92f1b95089b7cf88294cd4d9b119ee43417 100644
--- a/src/arch/x86_64/pti.rs
+++ b/src/arch/x86_64/pti.rs
@@ -13,20 +13,14 @@ pub static mut PTI_CPU_STACK: [u8; 256] = [0; 256];
pub static mut PTI_CONTEXT_STACK: usize = 0;
#[cfg(feature = "pti")]
-#[inline(never)]
-#[naked]
+#[inline(always)]
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");
+ asm!("" : "={rsp}"(old_rsp) : : : "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,
@@ -34,17 +28,12 @@ unsafe fn switch_stack(old: usize, new: usize) {
offset_rsp
);
- asm!("xchg bx, bx" : : : : "intel", "volatile");
-
- asm!("" : : "{rsp}"(new_rsp), "{rbp}"(new_rbp) : : "intel", "volatile");
+ asm!("" : : "{rsp}"(new_rsp) : : "intel", "volatile");
}
#[cfg(feature = "pti")]
-#[inline(never)]
-#[naked]
+#[inline(always)]
pub unsafe fn map() {
- asm!("xchg bx, bx" : : : : "intel", "volatile");
-
// {
// let mut active_table = unsafe { ActivePageTable::new() };
//
@@ -64,11 +53,8 @@ pub unsafe fn map() {
}
#[cfg(feature = "pti")]
-#[inline(never)]
-#[naked]
+#[inline(always)]
pub unsafe fn unmap() {
- 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());
diff --git a/src/arch/x86_64/start.rs b/src/arch/x86_64/start.rs
index c98135aeeabd609c508c2388db21f9098c68ee2b..4f6c730090a1fcea85259280fee50fd119233743 100644
--- a/src/arch/x86_64/start.rs
+++ b/src/arch/x86_64/start.rs
@@ -192,31 +192,52 @@ pub unsafe extern fn kstart_ap(args_ptr: *const KernelArgsAp) -> ! {
#[naked]
pub unsafe fn usermode(ip: usize, sp: usize, arg: usize) -> ! {
- asm!("xchg bx, bx" : : : : "intel", "volatile");
+ asm!("push r10
+ push r11
+ push r12
+ push r13
+ push r14
+ push r15"
+ : // No output
+ : "{r10}"(gdt::GDT_USER_DATA << 3 | 3), // Data segment
+ "{r11}"(sp), // Stack pointer
+ "{r12}"(1 << 9), // Flags - Set interrupt enable flag
+ "{r13}"(gdt::GDT_USER_CODE << 3 | 3), // Code segment
+ "{r14}"(ip), // IP
+ "{r15}"(arg) // Argument
+ : // No clobbers
+ : "intel", "volatile");
// Unmap kernel
pti::unmap();
// Go to usermode
- asm!("mov ds, r10d
- mov es, r10d
- mov fs, r11d
- mov gs, r10d
- push r10
- push r12
- push r13
- push r14
- push r15
- iretq"
- : // No output because it never returns
- : "{r10}"(gdt::GDT_USER_DATA << 3 | 3), // Data segment
- "{r11}"(gdt::GDT_USER_TLS << 3 | 3), // TLS segment
- "{r12}"(sp), // Stack pointer
- "{r13}"(1 << 9), // Flags - Set interrupt enable flag
- "{r14}"(gdt::GDT_USER_CODE << 3 | 3), // Code segment
- "{r15}"(ip) // IP
- "{rdi}"(arg) // Argument
- : // No clobers because it never returns
- : "intel", "volatile");
+ asm!("mov ds, r14d
+ mov es, r14d
+ mov fs, r15d
+ mov gs, r14d
+ xor rax, rax
+ xor rbx, rbx
+ xor rcx, rcx
+ xor rdx, rdx
+ xor rsi, rsi
+ xor rdi, rdi
+ xor rbp, rbp
+ xor r8, r8
+ xor r9, r9
+ xor r10, r10
+ xor r11, r11
+ xor r12, r12
+ xor r13, r13
+ xor r14, r14
+ xor r15, r15
+ finit
+ pop rdi
+ iretq"
+ : // No output because it never returns
+ : "{r14}"(gdt::GDT_USER_DATA << 3 | 3), // Data segment
+ "{r15}"(gdt::GDT_USER_TLS << 3 | 3) // TLS segment
+ : // No clobbers because it never returns
+ : "intel", "volatile");
unreachable!();
}
diff --git a/src/context/switch.rs b/src/context/switch.rs
index 3cc89fcf311f4eb1a1601a90a4fd31d65139b57b..4c0e91109fb428ca0e10e7cd74803b0b51f913d3 100644
--- a/src/context/switch.rs
+++ b/src/context/switch.rs
@@ -118,13 +118,7 @@ pub unsafe fn switch() -> bool {
(&mut *from_ptr).running = false;
(&mut *to_ptr).running = true;
if let Some(ref stack) = (*to_ptr).kstack {
- 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;
- }
+ gdt::set_tss_stack(stack.as_ptr() as usize + stack.len());
}
CONTEXT_ID.store((&mut *to_ptr).id, Ordering::SeqCst);
}