ADD ELF SUPPORT

2 files changed, 70 insertions, 21 deletions

diff --git a/src/execload.rs b/src/execload.rs
new file mode 100644
index 0000000..12fe90d
--- /dev/null
+++ b/src/execload.rs
@@ -0,0 +1,67 @@
+// Copyright (c) 2025 taitep
+// SPDX-License-Identifier: MIT
+//
+// This file is part of TRVE (https://gitea.taitep.se/taitep/trve)
+// See LICENSE file in the project root for full license text.
+
+use std::{fs, path::Path};
+
+use anyhow::{Result, bail};
+use goblin::{
+    Object,
+    elf::{
+        header::{EM_RISCV, ET_EXEC},
+        program_header::PT_LOAD,
+    },
+};
+use trve::consts::Addr;
+
+pub fn load<P: AsRef<Path>>(path: P, ram: &mut [u8], ram_start: Addr) -> Result<Addr> {
+    let buf = fs::read(path)?;
+
+    match Object::parse(&buf)? {
+        Object::Elf(elf) => {
+            if elf.header.e_type != ET_EXEC {
+                bail!("Executable type incorrect, may not be an executable or may be dynamic");
+            }
+            if elf.header.e_machine != EM_RISCV {
+                bail!("Executable architecture is not RISC-V");
+            }
+            if !elf.is_64 {
+                bail!("Executable is not 64-bit");
+            }
+            if !elf.little_endian {
+                bail!("Executable is not little-endian");
+            }
+
+            for ph in elf.program_headers {
+                if ph.p_type == PT_LOAD {
+                    let start = (ph.p_vaddr - ram_start) as usize;
+                    let end = start + ph.p_memsz as usize;
+                    let file_end = start + ph.p_filesz as usize;
+
+                    if end > ram_start as usize + ram.len() {
+                        bail!("Segment at 0x{:x} does not fit in RAM", ph.p_vaddr);
+                    }
+
+                    ram[start..file_end].copy_from_slice(
+                        &buf[ph.p_offset as usize..(ph.p_offset + ph.p_filesz) as usize],
+                    );
+
+                    ram[file_end..end].fill(0);
+                }
+            }
+
+            Ok(elf.entry)
+        }
+        Object::Unknown(_) => {
+            eprintln!("Unrecognized executable format identifier, assuming raw binary");
+            if buf.len() > ram.len() {
+                bail!("Program too large for RAM");
+            }
+            ram[..buf.len()].copy_from_slice(&buf);
+            Ok(ram_start)
+        }
+        _ => bail!("Unsupported executable format"),
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index aeedcb2..26b6a2e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -22,25 +22,7 @@ use anyhow::{Result, bail};
 
 use crate::basic_uart::BasicUart;
 
-fn read_file_to_buffer(path: &str, buffer: &mut [u8]) -> io::Result<usize> {
-    let mut file = File::open(path)?;
-    let mut total_read = 0;
-
-    while total_read < buffer.len() {
-        let n = file.read(&mut buffer[total_read..])?;
-        if n == 0 {
-            return Ok(total_read);
-        }
-        total_read += n;
-    }
-
-    let mut tmp = [0u8; 1];
-    if file.read(&mut tmp)? != 0 {
-        return Err(io::Error::other("RAM too small for file"));
-    }
-
-    Ok(total_read)
-}
+mod execload;
 
 fn main() -> Result<()> {
     let mut ram = Ram::try_new(16 * 1024 * 1024 / 4096)?;
@@ -53,7 +35,7 @@ fn main() -> Result<()> {
         bail!("Wrong number of arguments");
     }
 
-    read_file_to_buffer(&args[1], buf)?;
+    let entry_point = execload::load(&args[1], buf, 0x8000_0000)?;
 
     let uart = BasicUart::new();
     let uart = uart.spawn_poller(Duration::from_millis(10));
@@ -76,7 +58,7 @@ fn main() -> Result<()> {
     };
 
     let mut core = Core::new(mem_cfg);
-    core.reset(0x8000_0000);
+    core.reset(entry_point);
     core.run();
 
     Ok(())