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ch2: Trap handling

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This commit is contained in:
Tateisi 2025-08-03 08:48:14 +08:00
parent 13e91ed735
commit b4c3326d85
13 changed files with 388 additions and 5 deletions
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12
README.md
View file

@ -2,12 +2,24 @@
## Build
### in dir `user`
``` bash
cargo build --release
rust-objcopy --strip-all target/riscv64gc-unknown-none-elf/release/00_hello_world -O binary target/riscv64gc-unknown-none-elf/release/00_hello_world.bin
...
```
### in dir `os`
``` bash
LOG=TRACE cargo build --release
```
## Run
rustsbi-qemu should be downloaded manually.
``` bash
qemu-system-riscv64 -machine virt -nographic -bios target/riscv64gc-unknown-none-elf/release/rustsbi-qemu.bin -device loader,file=target/riscv64gc-unknown-none-elf/release/os
```

93
os/Cargo.lock generated
View file

@ -2,11 +2,26 @@
# It is not intended for manual editing.
version = 3
[[package]]
name = "critical-section"
version = "1.2.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "790eea4361631c5e7d22598ecd5723ff611904e3344ce8720784c93e3d83d40b"
[[package]]
name = "embedded-hal"
version = "1.0.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "361a90feb7004eca4019fb28352a9465666b24f840f5c3cddf0ff13920590b89"
[[package]]
name = "lazy_static"
version = "1.5.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
dependencies = [
"spin",
]
[[package]]
name = "log"
@ -20,9 +35,64 @@ version = "0.1.0"
dependencies = [
"lazy_static",
"log",
"riscv",
"sbi-rt",
]
[[package]]
name = "paste"
version = "1.0.15"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "57c0d7b74b563b49d38dae00a0c37d4d6de9b432382b2892f0574ddcae73fd0a"
[[package]]
name = "proc-macro2"
version = "1.0.89"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f139b0662de085916d1fb67d2b4169d1addddda1919e696f3252b740b629986e"
dependencies = [
"unicode-ident",
]
[[package]]
name = "quote"
version = "1.0.37"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
dependencies = [
"proc-macro2",
]
[[package]]
name = "riscv"
version = "0.12.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "5ea8ff73d3720bdd0a97925f0bf79ad2744b6da8ff36be3840c48ac81191d7a7"
dependencies = [
"critical-section",
"embedded-hal",
"paste",
"riscv-macros",
"riscv-pac",
]
[[package]]
name = "riscv-macros"
version = "0.1.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "f265be5d634272320a7de94cea15c22a3bfdd4eb42eb43edc528415f066a1f25"
dependencies = [
"proc-macro2",
"quote",
"syn",
]
[[package]]
name = "riscv-pac"
version = "0.2.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "8188909339ccc0c68cfb5a04648313f09621e8b87dc03095454f1a11f6c5d436"
[[package]]
name = "sbi-rt"
version = "0.0.3"
@ -37,3 +107,26 @@ name = "sbi-spec"
version = "0.0.7"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e6e36312fb5ddc10d08ecdc65187402baba4ac34585cb9d1b78522ae2358d890"
[[package]]
name = "spin"
version = "0.9.8"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
[[package]]
name = "syn"
version = "2.0.87"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "25aa4ce346d03a6dcd68dd8b4010bcb74e54e62c90c573f394c46eae99aba32d"
dependencies = [
"proc-macro2",
"quote",
"unicode-ident",
]
[[package]]
name = "unicode-ident"
version = "1.0.13"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "e91b56cd4cadaeb79bbf1a5645f6b4f8dc5bde8834ad5894a8db35fda9efa1fe"

3
os/Cargo.toml
View file

@ -4,6 +4,7 @@ version = "0.1.0"
edition = "2021"
[dependencies]
lazy_static = "1.5.0"
lazy_static = { version = "1.5.0", features = ["spin_no_std"] }
log = "0.4.22"
riscv = "0.12.1"
sbi-rt = "0.0.3"

54
os/src/batch.rs
View file

@ -1,14 +1,52 @@
use core::{arch::asm, slice};
use core::{arch::asm, mem, slice};
use lazy_static::*;
use log::info;
use crate::{sbi::shutdown, sync::UPSafeCell};
use crate::{sbi::shutdown, sync::UPSafeCell, trap::TrapContext};
const KERNEL_STACK_SIZE: usize = 4096 * 2;
const USER_STACK_SIZE: usize = 4096 * 2;
const MAX_APP_NUM: usize = 16;
const APP_BASE_ADDRESS: usize = 0x80400000;
const APP_SIZE_LIMIT: usize = 0x20000;
#[repr(align(4096))]
struct KernelStack {
data: [u8; KERNEL_STACK_SIZE],
}
#[repr(align(4096))]
struct UserStack {
data: [u8; USER_STACK_SIZE],
}
static KERNEL_STACK: KernelStack = KernelStack {
data: [0; KERNEL_STACK_SIZE],
};
static USER_STACK: UserStack = UserStack {
data: [0; USER_STACK_SIZE],
};
impl KernelStack {
fn get_sp(&self) -> usize {
self.data.as_ptr() as usize + KERNEL_STACK_SIZE
}
pub fn push_context(&self, cx: TrapContext) -> &'static mut TrapContext {
let cx_ptr = (self.get_sp() - mem::size_of::<TrapContext>()) as *mut TrapContext;
unsafe {
*cx_ptr = cx;
}
unsafe { cx_ptr.as_mut().unwrap() }
}
}
impl UserStack {
fn get_sp(&self) -> usize {
self.data.as_ptr() as usize + USER_STACK_SIZE
}
}
struct AppManager {
num_app: usize,
current_app: usize,
@ -68,6 +106,7 @@ lazy_static! {
}
pub fn init() {
print_app_info();
}
pub fn print_app_info() {
@ -83,5 +122,14 @@ pub fn run_next_app() -> ! {
app_manager.move_to_next_app();
drop(app_manager);
// todo
extern "C" {
fn __restore(cx_addr: usize);
}
unsafe {
__restore(KERNEL_STACK.push_context(TrapContext::app_init_context(
APP_BASE_ADDRESS,
USER_STACK.get_sp(),
)) as *const _ as usize);
}
panic!("Unreachable in batch::run_current_app");
}

47
os/src/link_app.S Normal file
View file

@ -0,0 +1,47 @@
.align 3
.section .data
.global _num_app
_num_app:
.quad 5
.quad app_0_start
.quad app_1_start
.quad app_2_start
.quad app_3_start
.quad app_4_start
.quad app_4_end
.section .data
.global app_0_start
.global app_0_end
app_0_start:
.incbin "../user/target/riscv64gc-unknown-none-elf/release/00_hello_world.bin"
app_0_end:
.section .data
.global app_1_start
.global app_1_end
app_1_start:
.incbin "../user/target/riscv64gc-unknown-none-elf/release/01_store_fault.bin"
app_1_end:
.section .data
.global app_2_start
.global app_2_end
app_2_start:
.incbin "../user/target/riscv64gc-unknown-none-elf/release/02_power.bin"
app_2_end:
.section .data
.global app_3_start
.global app_3_end
app_3_start:
.incbin "../user/target/riscv64gc-unknown-none-elf/release/03_priv_inst.bin"
app_3_end:
.section .data
.global app_4_start
.global app_4_end
app_4_start:
.incbin "../user/target/riscv64gc-unknown-none-elf/release/04_priv_csr.bin"
app_4_end:

7
os/src/main.rs
View file

@ -10,11 +10,14 @@ mod console;
mod batch;
mod sync;
mod trap;
mod syscall;
use core::arch::global_asm;
use log::{debug, error, info, trace, warn};
global_asm!(include_str!("entry.asm"));
global_asm!(include_str!("link_app.S"));
#[no_mangle]
pub fn rust_main() -> ! {
@ -24,7 +27,9 @@ pub fn rust_main() -> ! {
print_system_info();
print_to_console();
panic!("Shutdown machine!");
trap::init();
batch::init();
batch::run_next_app();
}
fn clear_bss() {

17
os/src/syscall/fs.rs Normal file
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@ -0,0 +1,17 @@
use core::{slice, str};
const FD_STDOUT: usize = 1;
pub fn sys_write(fd: usize, buf: *const u8, len: usize) -> isize {
match fd {
FD_STDOUT => {
let slice = unsafe { slice::from_raw_parts(buf, len) };
let str = str::from_utf8(slice).unwrap();
print!("{}", str);
len as isize
}
_ => {
panic!("Unsupported fd in sys_write!");
}
}
}

16
os/src/syscall/mod.rs Normal file
View file

@ -0,0 +1,16 @@
use fs::sys_write;
use process::sys_exit;
const SYSCALL_WRITE: usize = 64;
const SYSCALL_EXIT: usize = 93;
mod fs;
mod process;
pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
match syscall_id {
SYSCALL_WRITE => sys_write(args[0], args[1] as *const u8, args[2]),
SYSCALL_EXIT => sys_exit(args[0] as i32),
_ => panic!("Unsupported syscall_id: {}", syscall_id)
}
}

8
os/src/syscall/process.rs Normal file
View file

@ -0,0 +1,8 @@
use log::info;
use crate::batch::run_next_app;
pub fn sys_exit(exit_code: i32) -> ! {
info!(target: "kernel", "Application exited with code {}", exit_code);
run_next_app()
}

28
os/src/trap/context.rs Normal file
View file

@ -0,0 +1,28 @@
use riscv::register::sstatus::{self, Sstatus, SPP};
#[repr(C)]
pub struct TrapContext {
pub x: [usize; 32],
pub sstatus: Sstatus,
pub sepc: usize,
}
impl TrapContext {
pub fn set_sp(&mut self, sp: usize) {
self.x[2] = sp;
}
pub fn app_init_context(entry: usize, sp: usize) -> Self {
let cur_sstatus = sstatus::read();
unsafe {
sstatus::set_spp(SPP::User);
}
let mut cx = Self {
x: [0; 32],
sstatus: cur_sstatus,
sepc: entry,
};
cx.set_sp(sp);
cx
}
}

44
os/src/trap/mod.rs Normal file
View file

@ -0,0 +1,44 @@
mod context;
pub use context::TrapContext;
use log::error;
use core::arch::global_asm;
use riscv::{interrupt::{Exception, Trap}, register::{scause, stval, stvec::{self, TrapMode}}};
use crate::{batch::run_next_app, syscall};
global_asm!(include_str!("trap.S"));
pub fn init() {
extern "C" {
fn __alltraps();
}
unsafe {
stvec::write(__alltraps as usize, TrapMode::Direct);
}
}
#[no_mangle]
pub fn trap_handler(cx: &mut TrapContext) -> &mut TrapContext {
let scause = scause::read();
let stval = stval::read();
match scause.cause() {
Trap::Exception(e) if e == Exception::UserEnvCall as usize => {
cx.sepc += 4;
cx.x[10] = syscall::syscall(cx.x[17], [cx.x[10], cx.x[11], cx.x[12]]) as usize;
}
Trap::Exception(e) if e == Exception::StoreFault as usize || e == Exception::StorePageFault as usize => {
error!(target: "kernel", "PageFault in application, kernel killed it.");
run_next_app();
}
Trap::Exception(e) if e == Exception::IllegalInstruction as usize => {
error!(target: "kernel", "IllegalInstruction in application, kernel killed it.");
run_next_app();
}
_ => {
panic!("un supported strp {:?}, stval = {:#x}!", scause.cause(), stval);
}
}
cx
}

64
os/src/trap/trap.S Normal file
View file

@ -0,0 +1,64 @@
.altmacro
.macro SAVE_GP n
sd x\n, \n*8(sp)
.endm
.macro LOAD_GP n
ld x\n, \n*8(sp)
.endm
.section .text
.globl __alltraps
.globl __restore
.align 2
__alltraps:
csrrw sp, sscratch, sp
# now sp->kernel stack, sscratch->user stack
# allocate a TrapContext on kernel stack
addi sp, sp, -34*8
# save general-purpose registers
sd x1, 1*8(sp)
# skip sp(x2), we will save it later
sd x3, 3*8(sp)
# skip tp(x4), application does not use it
# save x5~x31
.set n, 5
.rept 27
SAVE_GP %n
.set n, n+1
.endr
# we can use t0/t1/t2 freely, because they were saved on kernel stack
csrr t0, sstatus
csrr t1, sepc
sd t0, 32*8(sp)
sd t1, 33*8(sp)
# read user stack from sscratch and save it on the kernel stack
csrr t2, sscratch
sd t2, 2*8(sp)
# set input argument of trap_handler(cx: &mut TrapContext)
mv a0, sp
call trap_handler
__restore:
# case1: start running app by __restore
# case2: back to U after handling trap
mv sp, a0
# now sp->kernel stack(after allocated), sscratch->user stack
# restore sstatus/sepc
ld t0, 32*8(sp)
ld t1, 33*8(sp)
ld t2, 2*8(sp)
csrw sstatus, t0
csrw sepc, t1
csrw sscratch, t2
# restore general-purpuse registers except sp/tp
ld x1, 1*8(sp)
ld x3, 3*8(sp)
.set n, 5
.rept 27
LOAD_GP %n
.set n, n+1
.endr
# release TrapContext on kernel stack
addi sp, sp, 34*8
# now sp->kernel stack, sscratch->user stack
csrrw sp, sscratch, sp
sret

0
user/src/bin/02_powers.rs → user/src/bin/02_power.rs
View file