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feat: kernel W^X (per-section perms, firmware unmapped, stack guard, boot check), halt on kernel faults, region W^X across processes

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This commit is contained in:
Gabriel Kaszewski
2026-10-27 00:13:00 +01:00
parent bafc18a5f8
commit 55758ae5b2
12 changed files with 285 additions and 17 deletions
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18
crates/adapter-riscv/src/trap/mod.rs
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@@ -123,6 +123,8 @@ const CAUSE_INTERRUPT_BIT: usize = 1 << 63;
const CAUSE_S_TIMER: usize = 5;
const CAUSE_S_EXTERNAL: usize = 9;
const CAUSE_ECALL_U: usize = 8;
/// Set in `sstatus` when the trap came from supervisor mode.
const SSTATUS_SPP: usize = 1 << 8;
pub fn init() {
unsafe extern "C" {
@@ -347,6 +349,22 @@ fn handle_exception(frame: &mut TrapFrame, scause: usize) {
}
}
}
_ if frame.sstatus & SSTATUS_SPP != 0 => {
// The kernel itself faulted (a W^X violation, the stack guard,
// a bad pointer). Its state can no longer be trusted, and no
// user thread is to blame.
let uart = crate::hw::uart::Uart::new();
uart.write_str("KERNEL FAULT: scause=");
uart.write_hex(scause);
let stval: usize;
unsafe { core::arch::asm!("csrr {0}, stval", out(reg) stval) };
uart.write_str(" stval=");
uart.write_hex(stval);
uart.write_str(" sepc=");
uart.write_hex(frame.sepc);
uart.put_char(b'\n');
crate::halt(&uart, "fault in kernel mode");
}
_ => {
let uart = crate::hw::uart::Uart::new();
uart.write_str("FAULT: scause=");