rust: Initial Rust-based EFI FAT32 chainloader

This code is gated behind the CHAINLOADING define. To build a
release-style m1n1 with chainloading for use with the installer
or kmutil, use:

make CHAINLOADING=1 RELEASE=1

To tell m1n1 to chainload another binary, use this var payload:

chainload=<ESP partition UUID>;<file path>

e.g.

chainload=a17b7e46-e950-bb4f-bc82-8ab1047a058e;m1n1/m1n1.bin

Closes: #154
Co-authored-by: Finn Behrens <me@kloenk.dev>
Co-authored-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Hector Martin <marcan@marcan.st>

.clang-format

@@ -17,6 +17,8 @@ IncludeIsMainRegex: '(_.*)?$'
 # - 3rd party code headers
 # - build artifact headers (stuff outside of src/)
 IncludeCategories:
+  - Regex:           '^"(\.\./)*build/build_.*\.h"$'
+    Priority:        -3
   - Regex:           '^"(\.\./)*config\.h"$'
     Priority:        -2
   - Regex:           '^<'

.github/workflows/build.yml

@@ -21,12 +21,20 @@ jobs:
       - uses: actions/checkout@v2
         with:
           submodules: recursive
-    - name: install aarch64-linux-gnu- toolchain
+
+      - name: Install aarch64-linux-gnu- toolchain
         run: |
           sudo apt-get update
           sudo apt-get install --no-install-recommends -y device-tree-compiler gcc-aarch64-linux-gnu
-    - name: build
+
-      run: make -k -j2 ARCH=aarch64-linux-gnu-
+      - name: Install nightly rust
+        run: |
+          export RUSTUP_TOOLCHAIN=nightly
+          rustup target install aarch64-unknown-none-softfloat
+
+      - name: Build
+        run: make -k -j2 ARCH=aarch64-linux-gnu- CHAINLOADING=1
+
       - uses: actions/upload-artifact@v2
         with:
           name: m1n1

.github/workflows/main.yml

@@ -21,5 +21,13 @@ jobs:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
       - uses: actions/checkout@v2
 
+      - name: install nightly rust
+        run: |
+          rm -f ~/.cargo/bin/rustfmt
+          rm -f ~/.cargo/bin/cargo-fmt
+          rustup toolchain install nightly --component rustfmt --component clippy --allow-downgrade
+
       - name: Run format-check
-        run: make format-check
+        run: |
+          make format-check
+          make rustfmt-check

.gitmodules

@@ -1,3 +1,27 @@
 [submodule "artwork"]
 	path = artwork
 	url = https://github.com/AsahiLinux/artwork.git
+[submodule "rust/vendor/rust-fatfs"]
+	path = rust/vendor/rust-fatfs
+	url = https://github.com/rafalh/rust-fatfs
+[submodule "rust/vendor/bitflags"]
+	path = rust/vendor/bitflags
+	url = https://github.com/bitflags/bitflags
+[submodule "rust/vendor/cfg-if"]
+	path = rust/vendor/cfg-if
+	url = https://github.com/alexcrichton/cfg-if
+[submodule "rust/vendor/cstr_core"]
+	path = rust/vendor/cstr_core
+	url = https://github.com/Amanieu/cstr_core
+[submodule "rust/vendor/cty"]
+	path = rust/vendor/cty
+	url = https://github.com/japaric/cty
+[submodule "rust/vendor/uuid"]
+	path = rust/vendor/uuid
+	url = https://github.com/uuid-rs/uuid
+[submodule "rust/vendor/log"]
+	path = rust/vendor/log
+	url = https://github.com/rust-lang/log
+[submodule "rust/vendor/memchr"]
+	path = rust/vendor/memchr
+	url = https://github.com/BurntSushi/memchr

Makefile

@@ -1,4 +1,5 @@
 ARCH ?= aarch64-linux-gnu-
+RUSTARCH ?= aarch64-unknown-none-softfloat
 
 ifeq ($(shell uname),Darwin)
 USE_CLANG ?= 1
@@ -35,8 +36,18 @@ CFLAGS := -O2 -Wall -g -Wundef -Werror=strict-prototypes -fno-common -fno-PIE \
 	-fno-stack-protector -mgeneral-regs-only -mstrict-align -march=armv8.2-a \
 	$(EXTRA_CFLAGS)
 
+CFG :=
 ifeq ($(RELEASE),1)
-CFLAGS += -DRELEASE
+CFG += \#define RELEASE\\n
+endif
+
+# Required for no_std + alloc for now
+export RUSTUP_TOOLCHAIN=nightly
+RUST_LIB := librust.a
+RUST_LIBS :=
+ifeq ($(CHAINLOADING),1)
+CFG += \#define CHAINLOADING\\n
+RUST_LIBS += $(RUST_LIB)
 endif
 
 LDFLAGS := -EL -maarch64elf --no-undefined -X -Bsymbolic \
@@ -102,7 +113,7 @@ OBJECTS := \
 	utils.o utils_asm.o \
 	vsprintf.o \
 	wdt.o \
-	$(MINILZLIB_OBJECTS) $(TINF_OBJECTS) $(DLMALLOC_OBJECTS) $(LIBFDT_OBJECTS)
+	$(MINILZLIB_OBJECTS) $(TINF_OBJECTS) $(DLMALLOC_OBJECTS) $(LIBFDT_OBJECTS) $(RUST_LIBS)
 
 DTS := t8103-j274.dts
 
@@ -115,14 +126,18 @@ TARGET_RAW := m1n1.bin
 
 DEPDIR := build/.deps
 
-.PHONY: all clean format update_tag
+.PHONY: all clean format update_tag update_cfg
-all: build/$(TARGET) build/$(TARGET_RAW) $(DTBS)
+all: update_tag update_cfg build/$(TARGET) build/$(TARGET_RAW) $(DTBS)
 clean:
 	rm -rf build/*
 format:
 	$(CLANG_FORMAT) -i src/*.c src/*.h sysinc/*.h
 format-check:
 	$(CLANG_FORMAT) --dry-run --Werror src/*.c src/*.h sysinc/*.h
+rustfmt:
+	cd rust && cargo fmt
+rustfmt-check:
+	cd rust && cargo fmt --check
 
 build/dtb/%.dts: dts/%.dts
 	@echo "  DTCPP $@"
@@ -134,6 +149,13 @@ build/dtb/%.dtb: build/dtb/%.dts
 	@mkdir -p "$(dir $@)"
 	@dtc -I dts -i dts $< -o $@
 
+build/$(RUST_LIB): rust/src/* rust/*
+	@echo "  RS    $@"
+	@mkdir -p $(DEPDIR)
+	@mkdir -p "$(dir $@)"
+	@cargo build --target $(RUSTARCH) --lib --release --manifest-path rust/Cargo.toml --target-dir build
+	@cp "build/$(RUSTARCH)/release/${RUST_LIB}" "$@"
+
 build/%.o: src/%.S
 	@echo "  AS    $@"
 	@mkdir -p $(DEPDIR)
@@ -167,7 +189,13 @@ update_tag:
 	@cmp -s build/build_tag.h build/build_tag.tmp 2>/dev/null || \
 	( mv -f build/build_tag.tmp build/build_tag.h && echo "  TAG   build/build_tag.h" )
 
+update_cfg:
+	@echo -ne "$(CFG)" > build/build_cfg.tmp
+	@cmp -s build/build_cfg.h build/build_cfg.tmp 2>/dev/null || \
+	( mv -f build/build_cfg.tmp build/build_cfg.h && echo "  CFG   build/build_cfg.h" )
+
 build/build_tag.h: update_tag
+build/build_cfg.h: update_cfg
 
 build/%.bin: data/%.png
 	@echo "  IMG   $@"
@@ -181,7 +209,8 @@ build/%.bin: font/%.bin
 	@echo "  CP    $@"
 	@cp $< $@
 
-build/main.o: build/build_tag.h src/main.c
+build/main.o: build/build_tag.h build/build_cfg.h src/main.c
 build/usb_dwc3.o: build/build_tag.h src/usb_dwc3.c
+build/chainload.o: build/build_cfg.h src/usb_dwc3.c
 
 -include $(DEPDIR)/*

README.md

@@ -132,3 +132,5 @@ licensed under the [OFL-1.1](3rdparty_licenses/LICENSE.OFL-1.1) license and copy
 
 m1n1 embeds portions of the [dwc3 usb linux driver](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/dwc3/core.h?id=7bc5a6ba369217e0137833f5955cf0b0f08b0712), which was [BSD-or-GPLv2 dual-licensed](3rdparty_licenses/LICENSE.BSD-3.dwc3) and copyright
 * Copyright (C) 2010-2011 Texas Instruments Incorporated - http://www.ti.com
+
+m1n1 embeds some rust crates. Licenses can be found in the vendor directory for every crate.

m1n1-raw.ld

@@ -45,6 +45,8 @@ SECTIONS {
         *(.rela.text.*)
         *(.rela.data)
         *(.rela.data.*)
+        *(.rela.rodata)
+        *(.rela.rodata*)
         *(.rela.dyn)
         _rela_end = .;
         . = ALIGN(0x4000);

m1n1.ld

@@ -150,6 +150,8 @@ SECTIONS {
         *(.rela.text.*)
         *(.rela.data)
         *(.rela.data.*)
+        *(.rela.rodata)
+        *(.rela.rodata*)
         *(.rela.dyn)
         _rela_end = .;
         . = ALIGN(0x4000);

rust/Cargo.lock

@@ -0,0 +1,56 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+
+[[package]]
+name = "cstr_core"
+version = "0.2.5"
+dependencies = [
+ "cty",
+ "memchr",
+]
+
+[[package]]
+name = "cty"
+version = "0.2.2"
+
+[[package]]
+name = "fatfs"
+version = "0.4.0"
+dependencies = [
+ "bitflags",
+ "log",
+]
+
+[[package]]
+name = "log"
+version = "0.4.14"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "memchr"
+version = "2.4.1"
+
+[[package]]
+name = "rust"
+version = "0.1.0"
+dependencies = [
+ "cstr_core",
+ "cty",
+ "fatfs",
+ "uuid",
+]
+
+[[package]]
+name = "uuid"
+version = "1.0.0-alpha.1"

rust/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "rust"
+version = "0.1.0"
+edition = "2021"
+repository = "https://github.com/AsahiLinux/m1n1"
+license = "MIT"
+publish = false
+
+[lib]
+crate-type = [ "staticlib" ]
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[dependencies]
+fatfs = { path = "vendor/rust-fatfs", default-features = false, features = ["lfn", "alloc"] }
+cstr_core = "0.2.5"
+uuid = { version = "1.0.0-alpha.1", default-features = false }
+cty = "0.2.2"
+
+[patch.crates-io]
+uuid = { path = "vendor/uuid" }
+cty = { path = "vendor/cty" }
+cstr_core = { path = "vendor/cstr_core" }
+memchr = { path = "vendor/memchr" }
+log = { path = "vendor/log" }
+bitflags = { path = "vendor/bitflags" }
+cfg-if = { path = "vendor/cfg-if" }

rust/src/chainload.rs

@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: MIT
+#![deny(unsafe_op_in_unsafe_fn)]
+
+use crate::gpt;
+use crate::nvme;
+use crate::println;
+use alloc::vec::Vec;
+use core::ffi::c_void;
+use cstr_core::CStr;
+use cty::*;
+use fatfs::{FileSystem, FsOptions, Read, Seek, SeekFrom};
+use uuid::Uuid;
+
+#[derive(Debug)]
+pub enum Error {
+    FATError(fatfs::Error<nvme::Error>),
+    GPTError(gpt::Error<nvme::Error>),
+    BadArgs,
+    PartitionNotFound,
+    Unknown,
+}
+
+impl From<fatfs::Error<nvme::Error>> for Error {
+    fn from(err: fatfs::Error<nvme::Error>) -> Error {
+        Error::FATError(err)
+    }
+}
+
+impl From<gpt::Error<nvme::Error>> for Error {
+    fn from(err: gpt::Error<nvme::Error>) -> Error {
+        Error::GPTError(err)
+    }
+}
+
+fn load_image(spec: &str) -> Result<Vec<u8>, Error> {
+    println!("Chainloading {}", spec);
+
+    let mut args = spec.split(';');
+
+    let uuid = Uuid::parse_str(args.next().ok_or(Error::BadArgs)?).or(Err(Error::BadArgs))?;
+    let path = args.next().ok_or(Error::BadArgs)?;
+
+    let part = {
+        let storage = nvme::NVMEStorage::new(1, 0);
+        let mut pt = gpt::GPT::new(storage)?;
+
+        //println!("Partitions:");
+        //pt.dump();
+
+        println!("Searching for partition UUID: {}", uuid);
+        pt.find_by_partuuid(uuid)?.ok_or(Error::PartitionNotFound)?
+    };
+
+    let offset = part.get_starting_lba();
+
+    println!("Partition offset: {}", offset);
+
+    let storage = nvme::NVMEStorage::new(1, offset);
+    let opts = FsOptions::new().update_accessed_date(false);
+
+    let fs = FileSystem::new(storage, opts)?;
+    let mut file = fs.root_dir().open_file(path)?;
+
+    let size = file.seek(SeekFrom::End(0))? as usize;
+    file.seek(SeekFrom::Start(0))?;
+
+    println!("File size: {}", size);
+
+    let mut buf: Vec<u8> = vec![0; size];
+    let mut slice = &mut buf[..];
+    while !slice.is_empty() {
+        let read = file.read(slice)?;
+        slice = &mut slice[read..];
+    }
+    println!("File read successfully");
+
+    Ok(buf)
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn rust_load_image(
+    raw_spec: *const c_char,
+    image: *mut *mut c_void,
+    size: *mut size_t,
+) -> c_int {
+    let spec = unsafe { CStr::from_ptr(raw_spec).to_str().unwrap() };
+
+    match load_image(spec) {
+        Ok(buf) => {
+            unsafe {
+                *size = buf.len();
+                *image = buf.leak().as_mut_ptr() as *mut c_void;
+            }
+            0
+        }
+        Err(err) => {
+            println!("Chainload failed: {:?}", err);
+            -1
+        }
+    }
+}

rust/src/dlmalloc.rs

@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: MIT
+
+use core::alloc::{GlobalAlloc, Layout};
+use core::ffi::c_void;
+use core::ptr;
+use cty::*;
+
+extern "C" {
+    pub fn malloc(size: size_t) -> *mut c_void;
+    pub fn realloc(p: *mut c_void, size: size_t) -> *mut c_void;
+    pub fn free(p: *mut c_void);
+    pub fn posix_memalign(p: *mut *mut c_void, alignment: size_t, size: size_t) -> c_int;
+}
+
+pub struct DLMalloc;
+
+unsafe impl GlobalAlloc for DLMalloc {
+    #[inline]
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        let mut ptr = ptr::null_mut();
+        let ret = unsafe {
+            posix_memalign(
+                &mut ptr,
+                layout.align().max(core::mem::size_of::<usize>()),
+                layout.size(),
+            )
+        };
+        if ret == 0 {
+            ptr as *mut u8
+        } else {
+            ptr::null_mut()
+        }
+    }
+
+    #[inline]
+    unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 {
+        // Unfortunately, calloc doesn't make any alignment guarantees, so the memory
+        // has to be manually zeroed-out.
+        let ptr = unsafe { self.alloc(layout) };
+        if !ptr.is_null() {
+            unsafe { ptr::write_bytes(ptr, 0, layout.size()) };
+        }
+        ptr
+    }
+
+    #[inline]
+    unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+        unsafe {
+            free(ptr as *mut c_void);
+        }
+    }
+
+    #[inline]
+    unsafe fn realloc(&self, ptr: *mut u8, _layout: Layout, new_size: usize) -> *mut u8 {
+        unsafe { realloc(ptr as *mut c_void, new_size) as *mut u8 }
+    }
+}

rust/src/gpt.rs

@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: MIT
+
+use crate::println;
+use core::convert::TryInto;
+use core::result::Result;
+use fatfs::{Read, Seek};
+use uuid::Uuid;
+
+const EFI_SIGNATURE: u64 = 0x5452415020494645;
+
+const SECTOR_SIZE: usize = 4096;
+
+#[derive(Debug)]
+pub enum Error<T> {
+    Io(T),
+    InvalidGPTHeader,
+}
+
+impl<T> From<T> for Error<T> {
+    fn from(err: T) -> Error<T> {
+        Error::Io(err)
+    }
+}
+
+struct TableHeader {
+    bytes: [u8; Self::SIZE],
+    my_lba: u64,
+}
+
+impl TableHeader {
+    const SIZE: usize = 0x5C;
+
+    fn read<R: Read + Seek>(rdr: &mut R, lba: u64) -> Result<Self, Error<R::Error>> {
+        let mut hdr = Self {
+            bytes: [0; Self::SIZE],
+            my_lba: lba,
+        };
+        let off = SECTOR_SIZE * (lba as usize);
+        rdr.seek(fatfs::SeekFrom::Start(off as u64))?;
+        rdr.read_exact(&mut hdr.bytes)?;
+        match hdr.is_valid() {
+            true => Ok(hdr),
+            false => Err(Error::InvalidGPTHeader),
+        }
+    }
+
+    fn get_signature(&self) -> u64 {
+        u64::from_le_bytes(self.bytes[0..8].try_into().unwrap())
+    }
+    fn get_my_lba(&self) -> u64 {
+        u64::from_le_bytes(self.bytes[24..32].try_into().unwrap())
+    }
+    fn get_partition_entry_lba(&self) -> u64 {
+        u64::from_le_bytes(self.bytes[72..80].try_into().unwrap())
+    }
+    fn get_partition_entry_count(&self) -> usize {
+        u32::from_le_bytes(self.bytes[80..84].try_into().unwrap()) as usize
+    }
+    fn get_partition_entry_size(&self) -> usize {
+        u32::from_le_bytes(self.bytes[84..88].try_into().unwrap()) as usize
+    }
+    fn is_valid(&self) -> bool {
+        self.get_signature() == EFI_SIGNATURE && self.get_my_lba() == self.my_lba
+    }
+}
+
+pub struct PartitionEntry {
+    bytes: [u8; Self::SIZE],
+}
+
+impl PartitionEntry {
+    const SIZE: usize = 0x80;
+
+    fn read<R: Read + Seek>(rdr: &mut R, off: usize) -> Result<Self, Error<R::Error>> {
+        let mut part = Self {
+            bytes: [0; Self::SIZE],
+        };
+        rdr.seek(fatfs::SeekFrom::Start(off as u64))?;
+        rdr.read_exact(&mut part.bytes)?;
+        Ok(part)
+    }
+
+    #[allow(dead_code)]
+    pub fn get_type_guid(&self) -> Uuid {
+        Uuid::from_bytes_le(self.bytes[0..16].try_into().unwrap())
+    }
+    pub fn get_partition_guid(&self) -> Uuid {
+        Uuid::from_bytes_le(self.bytes[16..32].try_into().unwrap())
+    }
+    pub fn get_starting_lba(&self) -> u64 {
+        u64::from_le_bytes(self.bytes[32..40].try_into().unwrap())
+    }
+    pub fn get_ending_lba(&self) -> u64 {
+        u64::from_le_bytes(self.bytes[40..48].try_into().unwrap())
+    }
+    pub fn get_attributes(&self) -> u64 {
+        u64::from_le_bytes(self.bytes[48..56].try_into().unwrap())
+    }
+    pub fn get_name(&self) -> &[u8] {
+        &self.bytes[56..72]
+    }
+}
+
+pub struct GPT<T: fatfs::ReadWriteSeek> {
+    disk: T,
+    hdr: TableHeader,
+}
+
+impl<IO: fatfs::ReadWriteSeek> GPT<IO> {
+    pub fn new<T: fatfs::IntoStorage<IO>>(storage: T) -> Result<Self, Error<IO::Error>> {
+        let mut disk = storage.into_storage();
+
+        let hdr = TableHeader::read(&mut disk, 1)?;
+
+        let gpt = Self { disk, hdr };
+        Ok(gpt)
+    }
+
+    pub fn count(&self) -> usize {
+        self.hdr.get_partition_entry_count()
+    }
+
+    pub fn index(&mut self, index: usize) -> Result<PartitionEntry, Error<IO::Error>> {
+        let off = (self.hdr.get_partition_entry_lba() as usize * SECTOR_SIZE)
+            + index * self.hdr.get_partition_entry_size();
+        PartitionEntry::read(&mut self.disk, off)
+    }
+
+    pub fn find_by_partuuid(
+        &mut self,
+        uuid: Uuid,
+    ) -> Result<Option<PartitionEntry>, Error<IO::Error>> {
+        for i in 0..self.count() {
+            let part = self.index(i)?;
+            if part.get_type_guid().is_nil() {
+                continue;
+            }
+            if part.get_partition_guid() == uuid {
+                return Ok(Some(part));
+            }
+        }
+        Ok(None)
+    }
+
+    pub fn dump(&mut self) {
+        for i in 0..self.count() {
+            let part = self.index(i).unwrap();
+            let guid = part.get_type_guid();
+            if guid.is_nil() {
+                continue;
+            }
+            println!(
+                "{}: {}..{} {:x} {:x}",
+                i,
+                part.get_starting_lba(),
+                part.get_ending_lba(),
+                guid,
+                part.get_partition_guid()
+            );
+        }
+    }
+}

rust/src/lib.rs

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: MIT
+#![no_std]
+#![deny(unsafe_op_in_unsafe_fn)]
+#![feature(alloc_error_handler)]
+#![feature(mixed_integer_ops)]
+#![feature(new_uninit)]
+
+#[macro_use]
+extern crate alloc;
+
+pub mod chainload;
+pub mod dlmalloc;
+pub mod gpt;
+pub mod nvme;
+pub mod print;
+
+use crate::dlmalloc::DLMalloc;
+
+#[global_allocator]
+static GLOBAL: DLMalloc = dlmalloc::DLMalloc;
+
+extern "C" {
+    fn flush_and_reboot();
+}
+
+#[panic_handler]
+fn panic(info: &::core::panic::PanicInfo) -> ! {
+    println!("{}", info);
+    unsafe { flush_and_reboot() };
+    loop {}
+}
+
+#[alloc_error_handler]
+fn alloc_error(layout: core::alloc::Layout) -> ! {
+    panic!("memory allocation of {} bytes failed", layout.size())
+}

rust/src/nvme.rs

@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: MIT
+use crate::println;
+use alloc::boxed::Box;
+use core::cmp::min;
+use core::ffi::c_void;
+use fatfs::SeekFrom;
+
+extern "C" {
+    fn nvme_read(nsid: u32, lba: u64, buffer: *mut c_void) -> bool;
+}
+
+const SECTOR_SIZE: usize = 4096;
+
+pub type Error = ();
+
+#[repr(C, align(4096))]
+struct SectorBuffer([u8; SECTOR_SIZE]);
+
+fn alloc_sector_buf() -> Box<SectorBuffer> {
+    let p: Box<SectorBuffer> = unsafe { Box::new_zeroed().assume_init() };
+    debug_assert_eq!(0, p.0.as_ptr().align_offset(4096));
+    p
+}
+
+pub struct NVMEStorage {
+    nsid: u32,
+    offset: u64,
+    lba: Option<u64>,
+    buf: Box<SectorBuffer>,
+    pos: u64,
+}
+
+impl NVMEStorage {
+    pub fn new(nsid: u32, offset: u64) -> NVMEStorage {
+        NVMEStorage {
+            nsid: nsid,
+            offset: offset,
+            lba: None,
+            buf: alloc_sector_buf(),
+            pos: 0,
+        }
+    }
+}
+
+impl fatfs::IoBase for NVMEStorage {
+    type Error = Error;
+}
+
+impl fatfs::Read for NVMEStorage {
+    fn read(&mut self, mut buf: &mut [u8]) -> Result<usize, Self::Error> {
+        let mut read = 0;
+
+        while !buf.is_empty() {
+            let lba = self.pos / SECTOR_SIZE as u64;
+            let off = self.pos as usize % SECTOR_SIZE;
+
+            if Some(lba) != self.lba {
+                self.lba = Some(lba);
+                let lba = lba + self.offset;
+                if !unsafe { nvme_read(self.nsid, lba, self.buf.0.as_mut_ptr() as *mut c_void) } {
+                    println!("nvme_read({}, {}) failed", self.nsid, lba);
+                    return Err(());
+                }
+            }
+            let copy_len = min(SECTOR_SIZE - off, buf.len());
+            buf[..copy_len].copy_from_slice(&self.buf.0[off..off + copy_len]);
+            buf = &mut buf[copy_len..];
+            read += copy_len;
+            self.pos += copy_len as u64;
+        }
+        Ok(read)
+    }
+}
+
+impl fatfs::Write for NVMEStorage {
+    fn write(&mut self, _buf: &[u8]) -> Result<usize, Self::Error> {
+        Err(())
+    }
+    fn flush(&mut self) -> Result<(), Self::Error> {
+        Err(())
+    }
+}
+
+impl fatfs::Seek for NVMEStorage {
+    fn seek(&mut self, from: SeekFrom) -> Result<u64, Self::Error> {
+        self.pos = match from {
+            SeekFrom::Start(n) => n,
+            SeekFrom::End(_n) => panic!("SeekFrom::End not supported"),
+            SeekFrom::Current(n) => self.pos.checked_add_signed(n).ok_or(())?,
+        };
+        Ok(self.pos)
+    }
+}

rust/src/print.rs

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: MIT
+use core::ffi::c_void;
+
+extern "C" {
+    fn iodev_console_write(buf: *const c_void, len: u64);
+}
+
+pub struct IODevConsoleWriter;
+
+impl core::fmt::Write for IODevConsoleWriter {
+    #[inline]
+    fn write_str(&mut self, msg: &str) -> core::fmt::Result {
+        write(msg)
+    }
+}
+
+impl IODevConsoleWriter {
+    #[inline]
+    pub fn write_fmt(args: core::fmt::Arguments) -> core::fmt::Result {
+        core::fmt::Write::write_fmt(&mut Self, args)
+    }
+
+    #[inline]
+    pub fn write_str(msg: &str) -> core::fmt::Result {
+        write(msg)
+    }
+
+    #[inline]
+    pub fn write_nl() -> core::fmt::Result {
+        write("\n")
+    }
+}
+
+#[inline]
+fn write(msg: &str) -> core::fmt::Result {
+    unsafe { iodev_console_write(msg.as_ptr() as _, msg.len() as u64) };
+    Ok(())
+}
+
+#[macro_export]
+macro_rules! println {
+    () => { $crate::println!("") };
+    ($($arg:tt)*) => {
+        #[allow(unused_must_use)]
+        {
+            $crate::print::IODevConsoleWriter::write_fmt(format_args!($($arg)*));
+            $crate::print::IODevConsoleWriter::write_nl();
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => {
+        #[allow(unused_must_use)]
+        {
+            $crate::print::IODevConsoleWriter::write_fmt(format_args!($($arg)*));
+        }
+    };
+}

rust/vendor/bitflags

@@ -0,0 +1 @@
+Subproject commit ed185cfb1c447c1b4bd6ac021c9ec3bb02c9e2f2

rust/vendor/cfg-if

@@ -0,0 +1 @@
+Subproject commit e60fa1efeab0ec6e90c50d93ec526e1410459c23

rust/vendor/cstr_core

@@ -0,0 +1 @@
+Subproject commit 35e44d2a128f29a52ac0a43baa2d9238bd7239dd

rust/vendor/cty

@@ -0,0 +1 @@
+Subproject commit dcc347dc8afb74906719e68e2f48e3ff38dcc76f

rust/vendor/log

@@ -0,0 +1 @@
+Subproject commit 9d4206770dd93f07cb27c3e1f41dc21c45031302

rust/vendor/memchr

@@ -0,0 +1 @@
+Subproject commit 8e1da98fee06d66c13e66c330e3a3dd6ccf0e3a0

rust/vendor/rust-fatfs

@@ -0,0 +1 @@
+Subproject commit 87fc1ed5074a32b4e0344fcdde77359ef9e75432

rust/vendor/uuid

@@ -0,0 +1 @@
+Subproject commit b98c9586c1359a5cc354defe20d8ea31e58f29f0

src/chainload.c

@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: MIT */
 
+#include "../build/build_cfg.h"
+
 #include "chainload.h"
 #include "adt.h"
 #include "malloc.h"
@@ -10,6 +12,10 @@
 #include "utils.h"
 #include "xnuboot.h"
 
+#ifdef CHAINLOADING
+int rust_load_image(const char *spec, void **image, size_t *size);
+#endif
+
 extern u8 _chainload_stub_start[];
 extern u8 _chainload_stub_end[];
 
@@ -107,6 +113,29 @@ int chainload_image(void *image, size_t size, char **vars, size_t var_cnt)
     return 0;
 }
 
+#ifdef CHAINLOADING
+
+int chainload_load(const char *spec, char **vars, size_t var_cnt)
+{
+    void *image;
+    size_t size;
+    int ret;
+
+    if (!nvme_init()) {
+        printf("chainload: NVME init failed\n");
+        return -1;
+    }
+
+    ret = rust_load_image(spec, &image, &size);
+    nvme_shutdown();
+    if (ret < 0)
+        return ret;
+
+    return chainload_image(image, size, vars, var_cnt);
+}
+
+#else
+
 int chainload_load(const char *spec, char **vars, size_t var_cnt)
 {
     UNUSED(spec);
@@ -116,3 +145,5 @@ int chainload_load(const char *spec, char **vars, size_t var_cnt)
     printf("Chainloading files not supported in this build!\n");
     return -1;
 }
+
+#endif

src/main.c

@@ -1,5 +1,8 @@
 /* SPDX-License-Identifier: MIT */
 
+#include "../build/build_cfg.h"
+#include "../build/build_tag.h"
+
 #include "../config.h"
 
 #include "adt.h"
@@ -26,8 +29,6 @@
 #include "wdt.h"
 #include "xnuboot.h"
 
-#include "../build/build_tag.h"
-
 struct vector_args next_stage;
 
 const char version_tag[] = "##m1n1_ver##" BUILD_TAG;

src/payload.c

@@ -3,6 +3,7 @@
 #include "payload.h"
 #include "adt.h"
 #include "assert.h"
+#include "chainload.h"
 #include "heapblock.h"
 #include "kboot.h"
 #include "smp.h"
@@ -27,6 +28,7 @@ static const u8 empty[] = {0, 0, 0, 0};
 static char expect_compatible[256];
 static struct kernel_header *kernel = NULL;
 static void *fdt = NULL;
+static char *chainload_spec = NULL;
 
 static void *load_one_payload(void *start, size_t size);
 
@@ -172,6 +174,9 @@ static bool check_var(u8 **p)
             printf("Too many chosen vars, ignoring %s='%s'\n", *p, val);
         else
             chosen[chosen_cnt++] = (char *)*p;
+    } else if (IS_VAR("chainload=")) {
+        *end = 0;
+        chainload_spec = val;
     } else {
         printf("Unknown variable %s\n", *p);
     }
@@ -242,6 +247,10 @@ int payload_run(void)
     while (p)
         p = load_one_payload(p, 0);
 
+    if (chainload_spec) {
+        return chainload_load(chainload_spec, chosen, chosen_cnt);
+    }
+
     if (kernel && fdt) {
         smp_start_secondaries();
 

src/usb_dwc3.c

@@ -7,6 +7,8 @@
  * - https://www.beyondlogic.org/usbnutshell/usb1.shtml
  */
 
+#include "../build/build_tag.h"
+
 #include "usb_dwc3.h"
 #include "dart.h"
 #include "malloc.h"
@@ -18,8 +20,6 @@
 #include "usb_types.h"
 #include "utils.h"
 
-#include "../build/build_tag.h"
-
 #define MAX_ENDPOINTS   16
 #define CDC_BUFFER_SIZE SZ_1M