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Relocations are working

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This commit is contained in:
Julien THILLARD
2026-02-27 09:11:57 +01:00
parent 79b75dc75b
commit c3eb93e701
6 changed files with 84 additions and 25 deletions
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2
Cargo.toml
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@@ -14,3 +14,5 @@ log = "0.4"
critical-section = { version = "1", features = ["restore-state-bool"] }
bffs = { path = "../../../code/bffs", features = ["alloc"] }
shared = { path = "crates/shared" }
# ELF parsing helper
goblin = { version = "0.7", default-features = false, features = ["elf32", "elf64", "endian_fd"] }

7
crates/os-std/src/lib.rs
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@@ -20,7 +20,6 @@ macro_rules! custom_std_setup {
unsafe impl core::alloc::GlobalAlloc for GlobalAllocator {
unsafe fn alloc(&self, layout: core::alloc::Layout) -> *mut u8 {
syscall::write_string_temp("Alloc user called");
$crate::syscall::alloc(layout)
}
@@ -51,11 +50,11 @@ macro_rules! print {
#[macro_export]
macro_rules! println {
() => {
// $crate::print!("");
$crate::print!("\n\r");
$crate::print!("");
// $crate::print!("\n\r");
};
($($args:expr),*) => {
$crate::print!($($args),*);
$crate::println!();
// $crate::println!();
};
}

10
justfile
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@@ -12,11 +12,11 @@ sync_filesystem:
sync
build_user_prog prog:
RUSTFLAGS="-C relocation-model=pic -C link-arg=-Tuser.ld" cargo b {{ cargo_flags }} --package {{ prog }}
# cp {{ bin_path / prog }} {{ "mnt/usr/bin" / prog }}
riscv64-elf-objcopy -O binary {{ bin_path / prog }} {{ "mnt/usr/bin" / prog }}
RUSTFLAGS="-C relocation-model=pic -C link-arg=-Tuser.ld -C link-arg=-pie" cargo b {{ cargo_flags }} --package {{ prog }}
cp {{ bin_path / prog }} {{ "mnt/usr/bin" / prog }}
# riscv64-elf-objcopy -O binary {{ bin_path / prog }} {{ "mnt/usr/bin" / prog }}
build: mount_filesystem (map_dir "user" "build_user_prog")
build: mount_filesystem (map_dir "user" f"just cargo_flags=\"{{cargo_flags}}\" build_user_prog")
cargo b {{ cargo_flags }}
just sync_filesystem
@@ -25,7 +25,7 @@ run: build
map_dir dir recipe:
@for file in `ls {{ dir }}`; do \
just cargo_flags="{{ cargo_flags }}" {{ recipe }} $file ; \
{{ recipe }} $file ; \
done
qemu := "qemu-system-riscv64 -machine virt -device bochs-display -bios none -m 512M -device loader,file=disk.img,addr=0x90000000"

1
src/main.rs
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@@ -15,7 +15,6 @@
ptr_metadata
)]
use alloc::string::String;
use embedded_alloc::LlffHeap as Heap;
use log::info;

73
src/process.rs
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@@ -11,6 +11,7 @@ use core::time::Duration;
use alloc::{boxed::Box, format, string::String, vec::Vec};
use bffs::{io::Read, path::Path};
use goblin::elf::reloc::R_RISCV_RELATIVE;
use shared::syscall::exit;
use crate::{
@@ -134,6 +135,78 @@ pub fn create_process_from_file<'a, T: Into<Path<'a>>>(path: T) -> i64 {
println!("Loading binary at address: {:x?}", content.as_ptr());
// If ELF, use goblin to load PT_LOAD segments and apply relocations
if let Ok(gelf) = goblin::elf::Elf::parse(&content) {
// Determine memory bounds from program headers
let mut min_vaddr = u64::MAX;
let mut max_vaddr = 0u64;
for ph in gelf.program_headers.iter() {
if ph.p_type == goblin::elf::program_header::PT_LOAD && ph.p_memsz > 0 {
min_vaddr = core::cmp::min(min_vaddr, ph.p_vaddr);
max_vaddr = core::cmp::max(max_vaddr, ph.p_vaddr + ph.p_memsz);
}
}
if min_vaddr != u64::MAX {
let size = (max_vaddr - min_vaddr) as usize;
use alloc::alloc::{alloc_zeroed, Layout};
let layout = Layout::from_size_align(size, 0x1000).unwrap();
let base = unsafe { alloc_zeroed(layout) };
// Copy segments
for ph in gelf.program_headers.iter() {
if ph.p_type == goblin::elf::program_header::PT_LOAD {
let dst = unsafe { base.add((ph.p_vaddr - min_vaddr) as usize) };
let src_off = ph.p_offset as usize;
let copy_len = ph.p_filesz as usize;
if copy_len > 0 {
unsafe {
core::ptr::copy_nonoverlapping(
content.as_ptr().add(src_off),
dst,
copy_len,
)
}
}
if ph.p_memsz as usize > copy_len {
unsafe {
core::slice::from_raw_parts_mut(
dst.add(copy_len),
ph.p_memsz as usize - copy_len,
)
.fill(0)
}
}
}
}
// Apply relocations using our parser (handles RELA entries)
for rela in gelf.dynrelas.iter() {
let r_type = rela.r_type;
match r_type {
x if x == R_RISCV_RELATIVE => {
let where_off = (rela.r_offset - min_vaddr) as usize;
let where_ptr = unsafe { base.add(where_off) } as *mut u64;
let val = (base as u64).wrapping_add(rela.r_addend.unwrap() as u64);
unsafe { core::ptr::write_unaligned(where_ptr, val) };
}
_ => {}
}
}
// Entry point
let entry_va = gelf.entry;
let entry_addr = unsafe { base.add((entry_va - min_vaddr) as usize) } as *const u8;
let entry_fn =
unsafe { core::mem::transmute::<*const u8, extern "C" fn()>(entry_addr) };
let wrapper = Box::leak(Box::new(move || {
entry_fn();
}));
println!("Program loaded at : {:x?}", entry_addr);
return create_process(wrapper, name);
}
}
// Fallback: treat the file as a raw binary blob and execute in-place
let entry_point =
unsafe { core::mem::transmute::<*const u8, extern "C" fn()>(Vec::leak(content).as_ptr()) };

16
user/test_pic/src/main.rs
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@@ -1,10 +1,5 @@
#![no_std]
#![no_main]
#![feature(fmt_internals)]
use core::fmt::{write, Arguments, Write};
use os_std::syscall;
os_std::custom_std_setup! {}
fn main() {
@@ -14,14 +9,5 @@ fn main() {
for _ in 0..50 {
test.push('C');
}
let mut b = String::from("test");
b.write_str("string: uaeuieuei");
// (&mut b as &mut dyn Write).write_str("string: uaeuieuei");
syscall::write_string_temp(&b);
// write(&mut b, Arguments::from_str_nonconst("string: uaeuieuei"));
// write(&mut b, format_args!("string: uaeuie{}", "uei"));
// syscall::write_int_temp(b.capacity() as u64);
// syscall::write_string_temp(&b);
// println!("{}", test);
// println!("Hello from PIC program loaded dynamically with custom std and a better justfile, and syscalls !");
println!("Hello from PIC program loaded dynamically with custom std and a better justfile, and syscalls !");
}