init: Add init subfolder

Add the initial version of init. Currently it only does exec() on a
dummy file. This is addressed in the future commits.

Introduced "make user" to compile the init process.

Co-developed-by: Vijay Dhanraj <[email protected]>
Signed-off-by: Peter Fang <[email protected]>

.github/workflows/rust.yml

@@ -62,7 +62,7 @@ jobs:
         uses: actions-rs/cargo@v1
         with:
           command: clippy
-          args: --workspace --all-features --exclude svsm --exclude svsm-fuzz --target=x86_64-unknown-linux-gnu -- -D warnings
+          args: --workspace --all-features --exclude svsm --exclude svsm-fuzz --exclude init --target=x86_64-unknown-linux-gnu -- -D warnings
 
       - name: Clippy on svsm-fuzz
         uses: actions-rs/cargo@v1

Cargo.toml

@@ -14,6 +14,8 @@ members = [
     "libmstpm",
     # syscall interface definitions
     "syscall",
+    # init process
+    "init",
 ]
 
 
@@ -46,6 +48,7 @@ tdx-tdcall = "0.2.1"
 uuid = "1.6.1"
 # Add the derive feature by default because all crates use it.
 zerocopy = { version = "0.8.2", features = ["alloc", "derive"] }
+buddy_system_allocator = "0.10.0"
 
 # other repos
 packit = { git = "https://github.com/coconut-svsm/packit", version = "0.1.1" }

Makefile

@@ -44,6 +44,7 @@ IGVMBUILDER = "target/x86_64-unknown-linux-gnu/${TARGET_PATH}/igvmbuilder"
 IGVMBIN = bin/igvmbld
 IGVMMEASURE = "target/x86_64-unknown-linux-gnu/${TARGET_PATH}/igvmmeasure"
 IGVMMEASUREBIN = bin/igvmmeasure
+INITELF = "target/x86_64-unknown-none/${TARGET_PATH}/init"
 
 RUSTDOC_OUTPUT = target/x86_64-unknown-none/doc
 DOC_SITE = target/x86_64-unknown-none/site
@@ -135,6 +136,12 @@ bin/test-kernel.elf: bin
 	LINK_TEST=1 cargo +nightly test ${CARGO_ARGS} ${SVSM_ARGS_TEST} -p svsm --config 'target.x86_64-unknown-none.runner=["sh", "-c", "cp $$0 ../${TEST_KERNEL_ELF}"]'
 	objcopy -O elf64-x86-64 --strip-unneeded ${TEST_KERNEL_ELF} bin/test-kernel.elf
 
+bin/init: bin
+	cargo build --manifest-path init/Cargo.toml ${CARGO_ARGS} --bin init
+	objcopy -O elf64-x86-64 --strip-unneeded ${INITELF} $@
+
+user: bin/init
+
 ${FS_BIN}: bin
 ifneq ($(FS_FILE), none)
 	cp -f $(FS_FILE) ${FS_BIN}
@@ -176,7 +183,7 @@ bin/svsm-test.bin: bin/stage1-test
 
 clippy:
 	cargo clippy --workspace --all-features --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure -- -D warnings
-	cargo clippy --workspace --all-features --exclude svsm-fuzz --exclude svsm --target=x86_64-unknown-linux-gnu -- -D warnings
+	cargo clippy --workspace --all-features --exclude svsm-fuzz --exclude svsm --exclude init --target=x86_64-unknown-linux-gnu -- -D warnings
 	RUSTFLAGS="--cfg fuzzing" cargo clippy --package svsm-fuzz --all-features --target=x86_64-unknown-linux-gnu -- -D warnings
 	cargo clippy --workspace --all-features --tests --target=x86_64-unknown-linux-gnu -- -D warnings
 
@@ -189,4 +196,4 @@ clean:
 distclean: clean
 	$(MAKE) -C libmstpm $@
 
-.PHONY: test clean clippy bin/stage2.bin bin/svsm-kernel.elf bin/test-kernel.elf distclean
+.PHONY: test clean clippy bin/stage2.bin bin/svsm-kernel.elf bin/test-kernel.elf distclean user

elf/src/program_header.rs

@@ -116,6 +116,9 @@ impl Elf64Phdr {
             if !self.p_align.is_power_of_two() {
                 return Err(ElfError::InvalidAddressAlignment);
             }
+            // TODO: Due to a bug in the ELF parser, this function returns an error when p_vaddr is not
+            // aligned. But since spec doesn't guarantee that p_vaddr must be aligned, our ELF parser
+            // needs to be fixed. Current WA is to use a custom linker script to align p_vaddr.
             if self.p_vaddr & (self.p_align - 1) != 0 {
                 return Err(ElfError::UnalignedSegmentAddress);
             }

init/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "init"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "init"
+path = "src/main.rs"
+test = false
+
+[dependencies]
+syscall = { path = "../syscall" }
+buddy_system_allocator = { workspace = true }
+
+[lints]
+workspace = true

init/build.rs

@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+fn main() {
+    println!("cargo:rustc-link-arg-bin=init=-nostdlib");
+    println!("cargo:rustc-link-arg-bin=init=-no-pie");
+    println!("cargo:rustc-link-arg-bin=init=-Tinit/init.lds");
+}

init/init.lds

@@ -0,0 +1,37 @@
+/* Temporary WA until p_vaddr alignment issue is fixed in our ELF parser */
+
+OUTPUT_ARCH(i386:x86-64)
+
+PHDRS
+{
+	text PT_LOAD FLAGS(5);		/* Read + Execute */
+	rodata PT_LOAD FLAGS(4);	/* Read-only */
+	data PT_LOAD FLAGS(6);		/* Read + Write */
+	bss PT_LOAD FLAGS(6);		/* Read + Write */
+}
+
+SECTIONS
+{
+	.text : {
+		*(.text)
+		*(.text.*)
+	} :text
+	. = ALIGN(4096);
+	.rodata : {
+		*(.rodata)
+		*(.rodata.*)
+	} : rodata
+	. = ALIGN(4096);
+	.data : {
+		*(.data)
+		*(.data.*)
+	} :data
+	. = ALIGN(4096);
+	.bss : {
+		*(.bss) *(.bss.*)
+		. = ALIGN(4096);
+	} :bss
+	. = ALIGN(4096);
+}
+
+ENTRY(init_start)

init/src/main.rs

@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+//
+// Copyright (c) 2024 Intel Corporation.
+//
+// Author: Peter Fang <[email protected]>
+
+#![no_std]
+#![no_main]
+
+extern crate alloc;
+use alloc::ffi::CString;
+use buddy_system_allocator::*;
+use core::panic::PanicInfo;
+use syscall::{exec, exit, SysCallError};
+
+const HEAP_SIZE: usize = 64 * 1024;
+static mut HEAP: [u8; HEAP_SIZE] = [0; HEAP_SIZE];
+
+#[global_allocator]
+static HEAP_ALLOCATOR: LockedHeap<32> = LockedHeap::<32>::empty();
+
+#[no_mangle]
+pub extern "C" fn init_start() -> ! {
+    unsafe {
+        HEAP_ALLOCATOR
+            .lock()
+            .init(core::ptr::addr_of!(HEAP) as usize, HEAP_SIZE);
+    }
+
+    let file = CString::new("/dummy").expect("Failed to create new string");
+    let root = CString::new("/").expect("Failed to create new string");
+
+    match exec(&file, &root, 0) {
+        Ok(_) => exit(0),
+        Err(SysCallError::ENOTFOUND) => exit(1),
+        _ => panic!("exec launch failed"),
+    };
+}
+
+#[panic_handler]
+fn panic(_info: &PanicInfo<'_>) -> ! {
+    exit(u32::MAX);
+}