From 039f7f5c8391f9638aeddecb1a8ca8db5e8d888c Mon Sep 17 00:00:00 2001
From: jD91mZM2 <me@krake.one>
Date: Tue, 7 Jul 2020 14:16:42 +0200
Subject: [PATCH] Simplify EXEC catching
Instead of having a separate flag, let's reuse STOP_SINGLESTEP :)
I wasn't thinking enough when making this flag!
---
src/arch/x86_64/macros.rs | 19 -------------------
src/arch/x86_64/start.rs | 40 ++++++++-------------------------------
src/context/signal.rs | 11 ++++++++++-
src/syscall/process.rs | 40 +++++++++++++++------------------------
syscall | 2 +-
5 files changed, 34 insertions(+), 78 deletions(-)
diff --git a/src/arch/x86_64/macros.rs b/src/arch/x86_64/macros.rs
index 5e9002f..6271229 100644
--- a/src/arch/x86_64/macros.rs
+++ b/src/arch/x86_64/macros.rs
@@ -1,6 +1,5 @@
use core::mem;
use syscall::data::IntRegisters;
-use super::gdt;
/// Print to console
#[macro_export]
@@ -216,24 +215,6 @@ 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();
diff --git a/src/arch/x86_64/start.rs b/src/arch/x86_64/start.rs
index b2bc4e5..30425f0 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, mem, ptr};
+use core::slice;
use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
use crate::allocator;
@@ -17,7 +17,6 @@ use crate::gdt;
use crate::idt;
use crate::interrupt;
use crate::log;
-use crate::macros::InterruptStack;
use crate::memory;
use crate::paging;
@@ -234,7 +233,12 @@ pub unsafe extern fn kstart_ap(args_ptr: *const KernelArgsAp) -> ! {
}
#[naked]
-pub unsafe fn usermode(ip: usize, sp: usize, arg: usize) -> ! {
+pub unsafe fn usermode(ip: usize, sp: usize, arg: usize, singlestep: bool) -> ! {
+ let mut flags = 1 << 9;
+ if singlestep {
+ flags |= 1 << 8;
+ }
+
asm!("push r10
push r11
push r12
@@ -244,7 +248,7 @@ pub unsafe fn usermode(ip: usize, sp: usize, arg: usize) -> ! {
: // No output
: "{r10}"(gdt::GDT_USER_DATA << 3 | 3), // Data segment
"{r11}"(sp), // Stack pointer
- "{r12}"(1 << 9), // Flags - Set interrupt enable flag
+ "{r12}"(flags), // Flags - Set interrupt enable flag
"{r13}"(gdt::GDT_USER_CODE << 3 | 3), // Code segment
"{r14}"(ip), // IP
"{r15}"(arg) // Argument
@@ -284,31 +288,3 @@ 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/context/signal.rs b/src/context/signal.rs
index 78e165a..05d3ff7 100644
--- a/src/context/signal.rs
+++ b/src/context/signal.rs
@@ -105,6 +105,15 @@ pub extern "C" fn signal_handler(sig: usize) {
} else {
// println!("Call {:X}", handler);
+ let singlestep = {
+ let contexts = contexts();
+ let context = contexts.current().expect("context::signal_handler userspace not inside of context");
+ let context = context.read();
+ unsafe {
+ ptrace::regs_for(&context).map(|s| s.is_singlestep()).unwrap_or(false)
+ }
+ };
+
unsafe {
let mut sp = crate::USER_SIGSTACK_OFFSET + crate::USER_SIGSTACK_SIZE - 256;
@@ -113,7 +122,7 @@ pub extern "C" fn signal_handler(sig: usize) {
sp -= mem::size_of::<usize>();
*(sp as *mut usize) = restorer;
- usermode(handler, sp, sig);
+ usermode(handler, sp, sig, singlestep);
}
}
diff --git a/src/syscall/process.rs b/src/syscall/process.rs
index e27576f..2da33bd 100644
--- a/src/syscall/process.rs
+++ b/src/syscall/process.rs
@@ -6,7 +6,6 @@ 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;
@@ -21,14 +20,14 @@ 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, usermode_interrupt_stack};
+use crate::start::usermode;
use crate::syscall::data::{SigAction, Stat};
use crate::syscall::error::*;
-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::flag::{wifcontinued, wifstopped, CloneFlags, CLONE_FILES,
+ CLONE_FS, CLONE_SIGHAND, CLONE_STACK, CLONE_VFORK, CLONE_VM, MapFlags,
+ 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};
use crate::syscall::ptrace_event;
use crate::syscall::validate::{validate_slice, validate_slice_mut};
@@ -661,6 +660,7 @@ fn fexec_noreturn(
vars: Box<[Box<[u8]>]>
) -> ! {
let entry;
+ let singlestep;
let mut sp = crate::USER_STACK_OFFSET + crate::USER_STACK_SIZE - 256;
{
@@ -669,6 +669,10 @@ fn fexec_noreturn(
let context_lock = contexts.current().ok_or(Error::new(ESRCH)).expect("exec_noreturn pid not found");
let mut context = context_lock.write();
+ singlestep = unsafe {
+ ptrace::regs_for(&context).map(|s| s.is_singlestep()).unwrap_or(false)
+ };
+
context.name = Arc::new(Mutex::new(name));
empty(&mut context, false);
@@ -712,8 +716,8 @@ fn fexec_noreturn(
unsafe {
// Copy file data
intrinsics::copy((elf.data.as_ptr() as usize + segment.p_offset as usize) as *const u8,
- segment.p_vaddr as *mut u8,
- segment.p_filesz as usize);
+ segment.p_vaddr as *mut u8,
+ segment.p_filesz as usize);
}
let mut flags = EntryFlags::NO_EXECUTE | EntryFlags::USER_ACCESSIBLE;
@@ -900,22 +904,8 @@ fn fexec_noreturn(
}
}
- // 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) }
- }
+ // Go to usermode
+ unsafe { usermode(entry, sp, 0, singlestep) }
}
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 fcebe8f..a1af645 160000
--- a/syscall
+++ b/syscall
@@ -1 +1 @@
-Subproject commit fcebe8f225142830fa5880a27d9faa6ed6b2aeb8
+Subproject commit a1af645cbf426c2ff66b3d06d04dd2aceb538128
--
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