can run entrypoint on user elf

syscalls via call_abi are still not working

Cargo.lock

@@ -422,17 +422,6 @@ dependencies = [
  "defmt 0.3.100",
 ]
 
-[[package]]
-name = "delegate"
-version = "0.13.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6178a82cf56c836a3ba61a7935cdb1c49bfaa6fa4327cd5bf554a503087de26b"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn 2.0.104",
-]
-
 [[package]]
 name = "diff"
 version = "0.1.13"
@@ -485,26 +474,6 @@ version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
-[[package]]
-name = "elf"
-version = "0.7.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4445909572dbd556c457c849c4ca58623d84b27c8fff1e74b0b4227d8b90d17b"
-
-[[package]]
-name = "elf_loader"
-version = "0.12.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "30a0da8db95cff71e500b3d7015c2441a4eb628e0df788b23d1b8d1243314342"
-dependencies = [
- "bitflags 2.9.1",
- "cfg-if",
- "delegate",
- "elf",
- "portable-atomic",
- "portable-atomic-util",
-]
-
 [[package]]
 name = "embassy-embedded-hal"
 version = "0.3.1"
@@ -662,7 +631,6 @@ dependencies = [
  "nb 1.1.0",
  "pio 0.3.0",
  "rand_core",
- "rp-binary-info",
  "rp-pac",
  "rp2040-boot2",
  "sha2-const-stable",
@@ -1065,6 +1033,17 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "goblin"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e961b33649994dcf69303af6b3a332c1228549e604d455d61ec5d2ab5e68d3a"
+dependencies = [
+ "log",
+ "plain",
+ "scroll",
+]
+
 [[package]]
 name = "half"
 version = "2.6.0"
@@ -1456,13 +1435,13 @@ dependencies = [
  "abi",
  "bitflags 2.9.1",
  "bt-hci",
+ "bumpalo",
  "cortex-m",
  "cortex-m-rt",
  "cyw43",
  "cyw43-pio",
  "defmt 0.3.100",
  "defmt-rtt",
- "elf_loader",
  "embassy-embedded-hal",
  "embassy-executor",
  "embassy-futures",
@@ -1476,6 +1455,7 @@ dependencies = [
  "embedded-hal-bus",
  "embedded-layout",
  "embedded-sdmmc",
+ "goblin",
  "heapless",
  "num_enum 0.7.4",
  "panic-probe",
@@ -1588,6 +1568,12 @@ dependencies = [
  "syn 2.0.104",
 ]
 
+[[package]]
+name = "plain"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
+
 [[package]]
 name = "portable-atomic"
 version = "1.11.1"
@@ -1597,15 +1583,6 @@ dependencies = [
  "critical-section",
 ]
 
-[[package]]
-name = "portable-atomic-util"
-version = "0.2.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d8a2f0d8d040d7848a709caf78912debcc3f33ee4b3cac47d73d1e1069e83507"
-dependencies = [
- "portable-atomic",
-]
-
 [[package]]
 name = "precomputed-hash"
 version = "0.1.1"
@@ -1752,12 +1729,6 @@ dependencies = [
  "bytemuck",
 ]
 
-[[package]]
-name = "rp-binary-info"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88ed2051a0bf2c726df01cfce378ed8a367be2a6e402fc183857f429a346d429"
-
 [[package]]
 name = "rp-pac"
 version = "7.0.0"
@@ -1807,6 +1778,26 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
+[[package]]
+name = "scroll"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1257cd4248b4132760d6524d6dda4e053bc648c9070b960929bf50cfb1e7add"
+dependencies = [
+ "scroll_derive",
+]
+
+[[package]]
+name = "scroll_derive"
+version = "0.13.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22fc4f90c27b57691bbaf11d8ecc7cfbfe98a4da6dbe60226115d322aa80c06e"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.104",
+]
+
 [[package]]
 name = "semver"
 version = "0.9.0"

abi/src/lib.rs

@@ -3,9 +3,8 @@
 use core::ffi::c_void;
 use shared::keyboard::{KeyCode, KeyEvent, KeyState, Modifiers};
 
-unsafe extern "C" {
-    fn call_abi(call: *const Syscall);
-}
+#[unsafe(no_mangle)]
+pub unsafe fn call_abi(_call: *const Syscall) {}
 
 #[repr(C)]
 pub enum Syscall {

kernel/Cargo.toml

@@ -41,7 +41,6 @@ embassy-rp = { version = "0.4.0", features = [
   "critical-section-impl",
   "unstable-pac",
   "time-driver",
-  "binary-info",
 ] }
 embassy-usb = "0.4.0"
 embassy-futures = "0.1.1"
@@ -77,11 +76,12 @@ embedded-layout = "0.4.2"
 
 static_cell = "2.1.1"
 bitflags = "2.9.1"
-talc = "4.4.3"
-spin = "0.10.0"
 heapless = "0.8.0"
 num_enum = { version = "0.7.4", default-features = false }
-elf_loader = {version ="0.12.0", default-features = false, features = ["portable-atomic"]}
+goblin = { version = "0.10.0", default-features = false, features = ["elf32", "elf64", "alloc", "endian_fd"] }
+bumpalo = "3.19.0"
+talc = "4.4.3"
+spin = "0.10.0"
 
 shared = { path = "../shared" }
 abi = { path = "../abi" }

kernel/build.rs

@@ -19,7 +19,7 @@ fn main() {
     let out = &PathBuf::from(env::var_os("OUT_DIR").unwrap());
     File::create(out.join("memory.x"))
         .unwrap()
-        .write_all(include_bytes!("../memory.x"))
+        .write_all(include_bytes!("memory.x"))
         .unwrap();
     println!("cargo:rustc-link-search={}", out.display());
 

kernel/src/abi.rs

@@ -1,4 +1,5 @@
 use abi::Syscall;
+use defmt::info;
 use embassy_futures::block_on;
 use embedded_graphics::{
     Drawable,
@@ -9,8 +10,9 @@ use embedded_graphics::{
 
 use crate::display::FRAMEBUFFER;
 
-#[unsafe(no_mangle)]
-pub extern "C" fn call_abi(call: *const Syscall) {
+#[allow(unused)]
+pub fn call_abi(call: *const Syscall) {
+    info!("called abi");
     let call = unsafe { &*call };
     match call {
         Syscall::DrawPixel { x, y, color } => {
@@ -20,6 +22,7 @@ pub extern "C" fn call_abi(call: *const Syscall) {
 }
 
 fn draw_pixel(x: u32, y: u32, color: u16) {
+    info!("draw pixel abi called");
     let framebuffer = block_on(FRAMEBUFFER.lock());
     Rectangle::new(Point::new(x as i32, y as i32), Size::new(1, 1))
         .draw_styled(

kernel/src/elf.rs

@@ -0,0 +1,85 @@
+#![allow(static_mut_refs)]
+use abi::Syscall;
+use bumpalo::Bump;
+use core::{alloc::Layout, ffi::c_void, ptr::NonNull, slice::from_raw_parts_mut};
+use goblin::{
+    elf::{Elf, header::ET_DYN, program_header::PT_LOAD, sym},
+    elf32,
+};
+
+use crate::abi::call_abi;
+
+pub fn load_elf(elf_bytes: &[u8], bump: &mut Bump) -> Result<extern "C" fn() -> !, ()> {
+    let elf = Elf::parse(elf_bytes).map_err(|_| ())?;
+
+    if elf.is_64
+        || elf.is_lib
+        || elf.is_object_file()
+        || !elf.little_endian
+        || elf.header.e_type != ET_DYN
+        || elf.interpreter.is_some()
+    {
+        return Err(());
+    }
+
+    // Find base address (lowest virtual address of PT_LOAD segments)
+    let base_vaddr = elf
+        .program_headers
+        .iter()
+        .filter(|ph| ph.p_type == PT_LOAD)
+        .map(|ph| ph.p_vaddr)
+        .min()
+        .ok_or(())?;
+
+    // Determine total memory needed for all PT_LOAD segments
+    let total_size = elf
+        .program_headers
+        .iter()
+        .filter(|ph| ph.p_type == PT_LOAD)
+        .map(|ph| {
+            let start = ph.p_vaddr;
+            let end = ph.p_vaddr + ph.p_memsz;
+            end - base_vaddr
+        })
+        .max()
+        .unwrap_or(0) as usize;
+
+    // Allocate one big block from the bump heap
+    let layout = Layout::from_size_align(total_size, 0x1000).map_err(|_| ())?;
+    let base_ptr = bump.alloc_layout(layout).as_ptr();
+
+    for ph in &elf.program_headers {
+        if ph.p_type != PT_LOAD {
+            continue;
+        }
+
+        let file_offset = ph.p_offset as usize;
+        let file_size = ph.p_filesz as usize;
+        let mem_size = ph.p_memsz as usize;
+        let virt_offset = (ph.p_vaddr - base_vaddr) as usize;
+
+        let src = &elf_bytes[file_offset..file_offset + file_size];
+        let dst = unsafe { base_ptr.add(virt_offset) };
+
+        unsafe {
+            core::ptr::copy_nonoverlapping(src.as_ptr(), dst, file_size);
+            if mem_size > file_size {
+                core::ptr::write_bytes(dst.add(file_size), 0, mem_size - file_size);
+            }
+        }
+    }
+
+    // Patch `call_abi` symbol
+    for sym in elf.syms.iter() {
+        let name = elf.strtab.get_at(sym.st_name).ok_or(())?;
+        if name == "call_abi" && sym.st_bind() == sym::STB_GLOBAL {
+            let offset = (sym.st_value - base_vaddr) as usize;
+            let ptr = unsafe { base_ptr.add(offset) as *mut usize };
+            unsafe { *ptr = call_abi as usize };
+        }
+    }
+
+    // Compute relocated entry point
+    let relocated_entry = unsafe { base_ptr.add((elf.entry - base_vaddr) as usize) };
+    Ok(unsafe { core::mem::transmute(relocated_entry) })
+}

kernel/src/main.rs

@@ -5,6 +5,7 @@
 
 mod abi;
 mod display;
+mod elf;
 mod peripherals;
 mod scsi;
 mod storage;
@@ -14,6 +15,7 @@ mod utils;
 
 use crate::{
     display::{display_handler, init_display},
+    elf::load_elf,
     peripherals::{
         conf_peripherals,
         keyboard::{KeyCode, KeyState, read_keyboard_fifo},
@@ -22,24 +24,10 @@ use crate::{
     usb::{ENABLE_SCSI, usb_handler},
 };
 
-use defmt::unwrap;
-use elf_loader::{
-    Loader, load_exec,
-    mmap::MmapImpl,
-    object::{ElfBinary, ElfObject},
-};
-use static_cell::StaticCell;
-use talc::*;
-
-static mut ARENA: [u8; 10000] = [0; 10000];
-
-#[global_allocator]
-static ALLOCATOR: Talck<spin::Mutex<()>, ClaimOnOom> =
-    Talc::new(unsafe { ClaimOnOom::new(Span::from_array(core::ptr::addr_of!(ARENA).cast_mut())) })
-        .lock();
-
 use {defmt_rtt as _, panic_probe as _};
 
+use bumpalo::Bump;
+use defmt::unwrap;
 use embassy_executor::{Executor, Spawner};
 use embassy_futures::join::join;
 use embassy_rp::{
@@ -56,16 +44,25 @@ use embassy_rp::{
 use embassy_time::{Delay, Timer};
 use embedded_hal_bus::spi::ExclusiveDevice;
 use embedded_sdmmc::SdCard as SdmmcSdCard;
+use static_cell::StaticCell;
+use talc::*;
 
 embassy_rp::bind_interrupts!(struct Irqs {
     I2C1_IRQ => i2c::InterruptHandler<I2C1>;
     USBCTRL_IRQ => embassy_rp_usb::InterruptHandler<USB>;
 });
 
-static mut CORE1_STACK: Stack<4096> = Stack::new();
+static mut CORE1_STACK: Stack<16384> = Stack::new();
 static EXECUTOR0: StaticCell<Executor> = StaticCell::new();
 static EXECUTOR1: StaticCell<Executor> = StaticCell::new();
 
+static mut ARENA: [u8; 50_000] = [0; 50_000];
+
+#[global_allocator]
+static ALLOCATOR: Talck<spin::Mutex<()>, ClaimOnOom> =
+    Talc::new(unsafe { ClaimOnOom::new(Span::from_array(core::ptr::addr_of!(ARENA).cast_mut())) })
+        .lock();
+
 #[embassy_executor::main]
 async fn main(_spawner: Spawner) {
     let p = embassy_rp::init(Default::default());
@@ -110,12 +107,14 @@ async fn main(_spawner: Spawner) {
 // runs dynamically loaded elf files
 #[embassy_executor::task]
 async fn userland_task() {
-    let binary_data: &[u8] = include_bytes!("../../example.bin");
-    let bin = load_exec!("example", binary_data).unwrap();
-    let entry = bin.entry();
+    let mut bump = Bump::with_capacity(25_000);
 
-    let entry_fn: extern "C" fn() = unsafe { core::mem::transmute(entry) };
-    entry_fn(); // jump into user code
+    let binary_data: &[u8] =
+        include_bytes!("../../target/thumbv8m.main-none-eabihf/debug/calculator");
+    let entry = load_elf(binary_data, &mut bump).unwrap();
+
+    entry();
+    bump.reset(); // clear heap arena
 }
 
 struct Display {

user-apps/calculator/src/main.rs

@@ -1,14 +1,26 @@
 #![no_std]
 #![no_main]
 
+use abi::{Syscall, call_abi};
 use core::panic::PanicInfo;
 
 #[panic_handler]
 fn panic(_info: &PanicInfo) -> ! {
-    loop {} // or call your ABI trap, or `abort()`
+    loop {}
 }
 
 #[unsafe(no_mangle)]
-fn main() {
-    loop {}
+pub extern "C" fn _start() -> ! {
+    loop {
+        for i in 0..300 {
+            for o in 0..300 {
+                let call = Syscall::DrawPixel {
+                    x: i,
+                    y: o,
+                    color: 0,
+                };
+                unsafe { call_abi(&call) };
+            }
+        }
+    }
 }

user-apps/link.x

@@ -0,0 +1,21 @@
+MEMORY
+{
+  RAM : ORIGIN = 0x00000000, LENGTH = 256K
+}
+
+SECTIONS
+{
+  .text : {
+    *(.text .text.*);
+    *(.rodata .rodata.*);
+  } > RAM
+
+  .data : {
+    *(.data .data.*);
+  } > RAM
+
+  .bss : {
+    *(.bss .bss.*);
+    *(COMMON);
+  } > RAM
+}