add draft to support WebAssembly within the kernel

Cargo.toml

@@ -70,6 +70,7 @@ nostd = []
 semihosting = ["dep:semihosting"]
 shell = ["simple-shell"]
 idle-poll = []
+wasm = ["wasmtime"]
 
 [dependencies]
 hermit-macro = { path = "hermit-macro" }
@@ -107,6 +108,7 @@ talc = { version = "4" }
 time = { version = "0.3", default-features = false }
 volatile = { version = "0.6", features = ["unstable"] }
 zerocopy = { version = "0.7", features = ["derive"] }
+wasmtime = { version = "21.0", default-features = false, features = ["runtime", "gc", "component-model"], optional = true }
 
 [dependencies.smoltcp]
 version = "0.11"

src/arch/x86_64/kernel/longjmp.s

@@ -0,0 +1,14 @@
+.section .text
+.global longjmp
+longjmp:
+	xor eax,eax
+	cmp esi, 1              /* CF = val ? 0 : 1 */
+	adc eax, esi            /* eax = val + !val */
+	mov rbx, [rdi]
+	mov rbp, [rdi+8] 
+	mov r12, [rdi+16] 
+	mov r13, [rdi+24] 
+	mov r14, [rdi+32] 
+	mov r15, [rdi+40] 
+	mov rsp, [rdi+48] 
+	jmp [rdi+56]

src/arch/x86_64/kernel/mod.rs

@@ -1,5 +1,6 @@
 #[cfg(feature = "common-os")]
 use core::arch::asm;
+use core::arch::global_asm;
 use core::num::NonZeroU64;
 use core::ptr;
 use core::sync::atomic::{AtomicPtr, AtomicU32, Ordering};
@@ -38,6 +39,9 @@ pub(crate) mod systemtime;
 #[cfg(feature = "vga")]
 mod vga;
 
+global_asm!(include_str!("setjmp.s"));
+global_asm!(include_str!("longjmp.s"));
+
 /// Kernel header to announce machine features
 #[cfg_attr(target_os = "none", link_section = ".data")]
 static mut RAW_BOOT_INFO: Option<&'static RawBootInfo> = None;

src/arch/x86_64/kernel/setjmp.s

@@ -0,0 +1,15 @@
+.section .text
+.global setjmp
+setjmp:
+mov [rdi], rbx
+mov [rdi+8], rbp
+mov [rdi+16], r12
+mov [rdi+24], r13
+mov [rdi+32], r14
+mov [rdi+40], r15
+lea rdx, [rsp+8] # rsp without current ret addr
+mov [rdi+48], rdx
+mov rdi, rsp     # save return addr ptr for new rip
+mov [rdi+56], rdx
+xor rax, rax
+ret

src/arch/x86_64/mm/paging.rs

@@ -106,7 +106,7 @@ pub fn virtual_to_physical(virtual_address: VirtAddr) -> Option<PhysAddr> {
 
 	match translate {
 		TranslateResult::NotMapped | TranslateResult::InvalidFrameAddress(_) => {
-			warn!(
+			trace!(
 				"Uable to determine the physical address of 0x{:X}",
 				virtual_address
 			);

src/lib.rs

@@ -93,6 +93,8 @@ mod shell;
 mod synch;
 pub mod syscalls;
 pub mod time;
+#[cfg(all(target_arch = "x86_64", feature = "wasm"))]
+mod wasm;
 
 #[cfg(target_os = "none")]
 hermit_entry::define_entry_version!();
@@ -156,6 +158,11 @@ extern "C" fn initd(_arg: usize) {
 	#[cfg(not(test))]
 	let (argc, argv, environ) = syscalls::get_application_parameters();
 
+	#[cfg(all(target_arch = "x86_64", feature = "wasm"))]
+	if crate::wasm::init().is_err() {
+		error!("Unable to initialized wasm support")
+	}
+
 	// give the IP thread time to initialize the network interface
 	core_scheduler().reschedule();