pie elf

src/backend/arch/x86_64.rs

@@ -13,6 +13,7 @@ pub struct Asm {
 pub enum Instr {
     Mov { dst: RegMode, src: RegImm },
     Int { code: u8 },
+    Syscall,
     Lea { dst: RegMode, sym: Symbol },
 }
 
@@ -85,6 +86,7 @@ impl super::super::program::Instr for Instr {
                 };
                 data.extend(addr_offset(data.len(), addr));
             }
+            Instr::Syscall => data.extend([0x0f, 0x05]),
         }
         Ok(None)
     }

src/backend/elf.rs

@@ -64,9 +64,19 @@ impl Arch {
     }
 }
 
+#[repr(u8)]
+pub enum EType {
+    None = 0,
+    Rel = 1,
+    Exec = 2,
+    Dyn = 3,
+    Core = 4,
+}
+
 // this is currently specialized for riscv64; obviously add params later
 pub fn create(program: &[u8], start_offset: Addr) -> Vec<u8> {
-    let addr_start = 0x400000;
+    let pie = true;
+    let addr_start = if pie { 0 } else { 0x400000 };
     let page_size = 0x1000;
     // I don't know if I have to add addr_start here, idk how it maps the memory
     let program_size = std::mem::size_of_val(program) as u64;
@@ -90,7 +100,7 @@ pub fn create(program: &[u8], start_offset: Addr) -> Vec<u8> {
         os_abi: 0x0, // system-v
         os_abi_ver: 0x0,
         pad: [0x0; 7],
-        ty: 0x2, // executable
+        ty: if pie { EType::Dyn } else { EType::Exec } as u16,
         machine: Arch::X86_64.machine(),
         e_version: 0x1,
         entry: addr_start + program_pos + start_offset.val(),

src/backend/test.rs

@@ -1,7 +1,7 @@
 use crate::backend::{
     program::{UnlinkedFunction, UnlinkedProgram},
     symbol::Symbol,
-    x86_64::{instr::*, reg::*},
+    x86_64::{Instr, instr::*, reg::*},
 };
 use std::{fs::OpenOptions, io::Write, os::unix::fs::OpenOptionsExt, process::Command};
 
@@ -10,20 +10,20 @@ pub fn test_x86_64() {
     let program = UnlinkedProgram {
         fns: vec![UnlinkedFunction {
             instrs: vec![
-                mov(eax, 4),
-                mov(ebx, 1),
-                lea(ecx, Symbol::raw(1)),
-                mov(edx, s.len() as u64),
-                int(0x80),
-                mov(eax, 1),
-                mov(ebx, 39),
-                int(0x80),
+                mov(rax, 1),
+                mov(rdi, 1),
+                lea(rsi, Symbol::raw(1)),
+                mov(rdx, s.len() as u64),
+                Instr::Syscall,
+                mov(rax, 0x3c),
+                mov(rdi, 39),
+                Instr::Syscall,
             ],
             sym: Symbol::raw(0),
             locations: Default::default(),
         }],
         ro_data: vec![(s.to_vec(), Symbol::raw(1))],
-        sym_count: 3,
+        sym_count: 2,
         start: Some(Symbol::raw(0)),
     };
     let Ok(linked) = program.link() else {
@@ -42,7 +42,23 @@ pub fn test_x86_64() {
     file.sync_all().expect("Failed to sync file");
     drop(file);
     println!("running...");
-    let mut proc = Command::new(path).spawn().expect("failed to run");
+    let gdb = false;
+    let mut proc = if gdb {
+        let mut cmd = Command::new("gdb");
+        #[rustfmt::skip]
+        cmd.args([
+            "-q",
+            "-ex", "starti",
+            "-ex", "layout asm",
+            "-ex", "focus next",
+            "x86_64_test",
+        ]);
+        cmd
+    } else {
+        Command::new(path)
+    }
+    .spawn()
+    .expect("failed to run");
     let status = proc.wait().expect("failed to wait");
     if let Some(code) = status.code() {
         std::process::exit(code);