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firmware: More explicit panic message if stack guard is tripped 

This should give even only mildly technical users a
chance to figure out what's going on, which empirically
is not the case for a plain Exception(LoadFault) without
further context.
This commit is contained in:
David Nadlinger 2022-11-24 16:54:49 +00:00
parent 6c47aac760
commit 950b9ac4d6
2 changed files with 16 additions and 1 deletions
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15
artiq/firmware/ksupport/lib.rs
View File

@ -471,6 +471,8 @@ unsafe fn attribute_writeback(typeinfo: *const ()) {
} }
} }
static mut STACK_GUARD_BASE: usize = 0x0;
#[no_mangle] #[no_mangle]
pub unsafe fn main() { pub unsafe fn main() {
eh_artiq::reset_exception_buffer(KERNELCPU_PAYLOAD_ADDRESS); eh_artiq::reset_exception_buffer(KERNELCPU_PAYLOAD_ADDRESS);
@ -502,6 +504,7 @@ pub unsafe fn main() {
ptr::write_bytes(__bss_start as *mut u8, 0, (_end - __bss_start) as usize); ptr::write_bytes(__bss_start as *mut u8, 0, (_end - __bss_start) as usize);
board_misoc::pmp::init_stack_guard(_sstack_guard as usize); board_misoc::pmp::init_stack_guard(_sstack_guard as usize);
STACK_GUARD_BASE = _sstack_guard as usize;
board_misoc::cache::flush_cpu_dcache(); board_misoc::cache::flush_cpu_dcache();
board_misoc::cache::flush_cpu_icache(); board_misoc::cache::flush_cpu_icache();
@ -531,10 +534,20 @@ pub unsafe fn main() {
#[no_mangle] #[no_mangle]
#[unwind(allowed)] #[unwind(allowed)]
pub extern fn exception(_regs: *const u32) { pub unsafe extern fn exception(_regs: *const u32) {
let pc = mepc::read(); let pc = mepc::read();
let cause = mcause::read().cause(); let cause = mcause::read().cause();
let mtval = mtval::read(); let mtval = mtval::read();
if let mcause::Trap::Exception(mcause::Exception::LoadFault)
| mcause::Trap::Exception(mcause::Exception::StoreFault) = cause
{
if mtval >= STACK_GUARD_BASE
&& mtval < (STACK_GUARD_BASE + board_misoc::pmp::STACK_GUARD_SIZE)
{
panic!("{:?} at PC {:#08x} in stack guard page ({:#08x}); stack overflow in user kernel code?",
cause, u32::try_from(pc).unwrap(), mtval);
}
}
panic!("{:?} at PC {:#08x}, trap value {:#08x}", cause, u32::try_from(pc).unwrap(), mtval); panic!("{:?} at PC {:#08x}, trap value {:#08x}", cause, u32::try_from(pc).unwrap(), mtval);
} }

2
artiq/firmware/libboard_misoc/riscv32/pmp.rs
View File

@ -9,6 +9,8 @@ const PMP_W : usize = 0b00000010;
const PMP_R : usize = 0b00000001; const PMP_R : usize = 0b00000001;
const PMP_OFF : usize = 0b00000000; const PMP_OFF : usize = 0b00000000;
pub const STACK_GUARD_SIZE: usize = 0x1000;
#[inline(always)] #[inline(always)]
pub unsafe fn init_stack_guard(guard_base: usize) { pub unsafe fn init_stack_guard(guard_base: usize) {
pmpaddr2::write((guard_base >> 2) | ((0x1000 - 1) >> 3)); pmpaddr2::write((guard_base >> 2) | ((0x1000 - 1) >> 3));