diff --git a/src/arch/x86_64/interrupt/syscall.rs b/src/arch/x86_64/interrupt/syscall.rs
index 9ddd3c79aef35b745b7113c531d4208467c676b8..9f5ed74b253032f23342867e5e5bb6126220c6f1 100644
--- a/src/arch/x86_64/interrupt/syscall.rs
+++ b/src/arch/x86_64/interrupt/syscall.rs
@@ -67,12 +67,7 @@ pub unsafe extern fn syscall_instruction() {
: "intel", "volatile");
// Push scratch registers
- scratch_push!();
- preserved_push!();
- asm!("push fs
- mov r11, 0x18
- mov fs, r11"
- : : : : "intel", "volatile");
+ interrupt_push!();
// Get reference to stack variables
let rsp: usize;
@@ -87,10 +82,8 @@ pub unsafe extern fn syscall_instruction() {
pti::unmap();
// Interrupt return
- asm!("pop fs" : : : : "intel", "volatile");
- preserved_pop!();
- scratch_pop!();
- asm!("iretq" : : : : "intel", "volatile");
+ interrupt_pop!();
+ iret!()
}
#[naked]
@@ -106,12 +99,7 @@ pub unsafe extern fn syscall() {
}
// Push scratch registers
- scratch_push!();
- preserved_push!();
- asm!("push fs
- mov r11, 0x18
- mov fs, r11"
- : : : : "intel", "volatile");
+ interrupt_push!();
// Get reference to stack variables
let rsp: usize;
@@ -126,10 +114,8 @@ pub unsafe extern fn syscall() {
pti::unmap();
// Interrupt return
- asm!("pop fs" : : : : "intel", "volatile");
- preserved_pop!();
- scratch_pop!();
- asm!("iretq" : : : : "intel", "volatile");
+ interrupt_pop!();
+ iret!();
}
#[naked]
diff --git a/src/arch/x86_64/macros.rs b/src/arch/x86_64/macros.rs
index 84021f6b6c755f403f476b23d2f91d8a13166584..22fe5a3cf649ade69d1cb04180acdb1d5738cd5d 100644
--- a/src/arch/x86_64/macros.rs
+++ b/src/arch/x86_64/macros.rs
@@ -1,5 +1,6 @@
use core::mem;
use syscall::data::IntRegisters;
+use super::gdt;
/// Print to console
#[macro_export]
@@ -19,6 +20,7 @@ macro_rules! println {
}
#[allow(dead_code)]
+#[derive(Default)]
#[repr(packed)]
pub struct ScratchRegisters {
pub r11: usize,
@@ -77,6 +79,7 @@ macro_rules! scratch_pop {
}
#[allow(dead_code)]
+#[derive(Default)]
#[repr(packed)]
pub struct PreservedRegisters {
pub r15: usize,
@@ -124,9 +127,13 @@ macro_rules! preserved_pop {
macro_rules! fs_push {
() => (asm!(
- "push fs
+ "
+ push fs
+
+ // Load kernel tls
mov rax, 0x18
- mov fs, ax"
+ mov fs, ax // can't load value directly into `fs`
+ "
: : : : "intel", "volatile"
));
}
@@ -139,6 +146,7 @@ macro_rules! fs_pop {
}
#[allow(dead_code)]
+#[derive(Default)]
#[repr(packed)]
pub struct IretRegisters {
pub rip: usize,
@@ -198,6 +206,7 @@ macro_rules! interrupt {
}
#[allow(dead_code)]
+#[derive(Default)]
#[repr(packed)]
pub struct InterruptStack {
pub fs: usize,
@@ -207,6 +216,24 @@ pub struct InterruptStack {
}
impl InterruptStack {
+ pub fn new_usermode(ip: usize, sp: usize, arg: usize) -> Self {
+ // See which registers are set in start.rs, function `usermode`
+ Self {
+ fs: gdt::GDT_USER_TLS << 3 | 3,
+ preserved: PreservedRegisters::default(),
+ scratch: ScratchRegisters {
+ rdi: arg,
+ ..ScratchRegisters::default()
+ },
+ iret: IretRegisters {
+ rip: ip,
+ cs: gdt::GDT_USER_CODE << 3 | 3,
+ rflags: 1 << 9,
+ rsp: sp,
+ ss: gdt::GDT_USER_DATA << 3 | 3,
+ },
+ }
+ }
pub fn dump(&self) {
self.iret.dump();
self.scratch.dump();
@@ -298,9 +325,24 @@ impl InterruptStack {
}
}
+macro_rules! interrupt_push {
+ () => {
+ scratch_push!();
+ preserved_push!();
+ fs_push!();
+ };
+}
+macro_rules! interrupt_pop {
+ () => {
+ fs_pop!();
+ preserved_pop!();
+ scratch_pop!();
+ };
+}
+
#[macro_export]
macro_rules! interrupt_stack {
- ($name:ident, $stack: ident, $func:block) => {
+ ($name:ident, $stack:ident, $func:block) => {
#[naked]
pub unsafe extern fn $name () {
#[inline(never)]
@@ -309,9 +351,7 @@ macro_rules! interrupt_stack {
}
// Push scratch registers
- scratch_push!();
- preserved_push!();
- fs_push!();
+ interrupt_push!();
// Get reference to stack variables
let rsp: usize;
@@ -327,15 +367,14 @@ macro_rules! interrupt_stack {
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers and return
- fs_pop!();
- preserved_pop!();
- scratch_pop!();
+ interrupt_pop!();
iret!();
}
};
}
#[allow(dead_code)]
+#[derive(Default)]
#[repr(packed)]
pub struct InterruptErrorStack {
pub fs: usize,
@@ -366,9 +405,7 @@ macro_rules! interrupt_error {
}
// Push scratch registers
- scratch_push!();
- preserved_push!();
- fs_push!();
+ interrupt_push!();
// Get reference to stack variables
let rsp: usize;
@@ -384,10 +421,8 @@ macro_rules! interrupt_error {
$crate::arch::x86_64::pti::unmap();
// Pop scratch registers, error code, and return
- fs_pop!();
- preserved_pop!();
- scratch_pop!();
- asm!("add rsp, 8" : : : : "intel", "volatile");
+ interrupt_pop!();
+ asm!("add rsp, 8" : : : : "intel", "volatile"); // pop error code
iret!();
}
};
diff --git a/src/arch/x86_64/start.rs b/src/arch/x86_64/start.rs
index ab7fc39629f4a7b2f69a4a2d92adcb227a4104b7..b2bc4e5fc1efc093626ed521fe285b5239b7117a 100644
--- a/src/arch/x86_64/start.rs
+++ b/src/arch/x86_64/start.rs
@@ -3,7 +3,7 @@
/// It must create the IDT with the correct entries, those entries are
/// defined in other files inside of the `arch` module
-use core::slice;
+use core::{slice, mem, ptr};
use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
use crate::allocator;
@@ -17,6 +17,7 @@ use crate::gdt;
use crate::idt;
use crate::interrupt;
use crate::log;
+use crate::macros::InterruptStack;
use crate::memory;
use crate::paging;
@@ -283,3 +284,31 @@ pub unsafe fn usermode(ip: usize, sp: usize, arg: usize) -> ! {
: "intel", "volatile");
unreachable!();
}
+
+#[naked]
+pub unsafe fn usermode_interrupt_stack(stack: InterruptStack) -> ! {
+ // Push fake stack to the actual stack
+ let rsp: usize;
+ asm!("sub rsp, $1" : "={rsp}"(rsp) : "r"(mem::size_of::<InterruptStack>()) : : "intel", "volatile");
+ ptr::write(rsp as *mut InterruptStack, stack);
+
+ // Unmap kernel
+ pti::unmap();
+
+ // Set up floating point and TLS
+ asm!("mov ds, r14d
+ mov es, r14d
+ mov fs, r15d
+ mov gs, r14d
+ fninit"
+ : // No output because it never returns
+ : "{r14}"(gdt::GDT_USER_DATA << 3 | 3), // Data segment
+ "{r15}"(gdt::GDT_USER_TLS << 3 | 3) // TLS segment
+ : "ds", "es", "fs", "gs"
+ : "intel", "volatile");
+
+ // Go to usermode
+ interrupt_pop!();
+ iret!();
+ unreachable!();
+}
diff --git a/src/syscall/process.rs b/src/syscall/process.rs
index 18de7f27ada9cb30b08e8151e55ce65f0fc38022..e27576fd3e248ec542b0b40df67034f97ec23686 100644
--- a/src/syscall/process.rs
+++ b/src/syscall/process.rs
@@ -6,6 +6,7 @@ use core::{intrinsics, mem};
use core::ops::DerefMut;
use spin::Mutex;
+use crate::arch::macros::InterruptStack;
use crate::context::file::FileDescriptor;
use crate::context::{ContextId, WaitpidKey};
use crate::context;
@@ -20,14 +21,14 @@ use crate::paging::temporary_page::TemporaryPage;
use crate::paging::{ActivePageTable, InactivePageTable, Page, VirtualAddress, PAGE_SIZE};
use crate::{ptrace, syscall};
use crate::scheme::FileHandle;
-use crate::start::usermode;
+use crate::start::{usermode, usermode_interrupt_stack};
use crate::syscall::data::{SigAction, Stat};
use crate::syscall::error::*;
-use crate::syscall::flag::{CloneFlags, CLONE_VFORK, CLONE_VM, CLONE_FS, CLONE_FILES, CLONE_SIGHAND,
- CLONE_STACK, MapFlags, PROT_EXEC, PROT_READ, PROT_WRITE, PTRACE_EVENT_CLONE,
- PTRACE_STOP_EXIT, SigActionFlags, SIG_DFL, SIG_BLOCK, SIG_UNBLOCK, SIG_SETMASK,
- SIGCONT, SIGTERM, WaitFlags, WCONTINUED, WNOHANG, WUNTRACED, wifcontinued,
- wifstopped};
+use crate::syscall::flag::{CloneFlags, CLONE_FILES, CLONE_FS, CLONE_SIGHAND,
+ CLONE_STACK, CLONE_VFORK, CLONE_VM, MapFlags, PtraceFlags, PROT_EXEC,
+ PROT_READ, PROT_WRITE, PTRACE_EVENT_CLONE, PTRACE_STOP_EXIT, SigActionFlags,
+ SIG_BLOCK, SIG_DFL, SIG_SETMASK, SIG_UNBLOCK, SIGCONT, SIGTERM, WaitFlags,
+ WCONTINUED, WNOHANG,WUNTRACED, wifcontinued, wifstopped};
use crate::syscall::ptrace_event;
use crate::syscall::validate::{validate_slice, validate_slice_mut};
@@ -899,8 +900,22 @@ fn fexec_noreturn(
}
}
- // Go to usermode
- unsafe { usermode(entry, sp, 0); }
+ // Create dummy stack for ptrace to read from
+ let mut regs = InterruptStack::new_usermode(entry, sp, 0);
+
+ // ptrace breakpoint
+ let was_traced = {
+ let _guard = ptrace::set_process_regs(&mut regs);
+ ptrace::breakpoint_callback(PtraceFlags::PTRACE_STOP_EXEC, None).is_some()
+ };
+
+ if !was_traced {
+ // Go to usermode, fast route
+ unsafe { usermode(entry, sp, 0) }
+ } else {
+ // Go to usermode, take ptrace-modified stack into account
+ unsafe { usermode_interrupt_stack(regs) }
+ }
}
pub fn fexec_kernel(fd: FileHandle, args: Box<[Box<[u8]>]>, vars: Box<[Box<[u8]>]>, name_override_opt: Option<Box<[u8]>>) -> Result<usize> {
diff --git a/syscall b/syscall
index 9ecdc11d73677477b37567a47af1633478093cbb..c23d36e8923b8087039c26fcde3c359b5e0accc7 160000
--- a/syscall
+++ b/syscall
@@ -1 +1 @@
-Subproject commit 9ecdc11d73677477b37567a47af1633478093cbb
+Subproject commit c23d36e8923b8087039c26fcde3c359b5e0accc7