SUpport debugging when interrupt handlers go awry, such as when they
blow out their own stack.
Do this by creating a dummy sentinal of 255 for interrupt handlers.
Signed-off-by: Sean Cross <sean@xobs.io>
When an interrupt handler panics, restore the system and allow it to
continue. This will help to debug IRQ handlers that panic for one reason
or another, such as infinite recursion.
Signed-off-by: Sean Cross <sean@xobs.io>
- make the "base" field no longer public. It is accessible, but only
through an `unsafe` method, because, it is unsafe.
- add accessors to offest/mask fields. Because, it's not at all
unsafe to access these, and it can be useful for bit-ops that are
not part of the generic set of UTRA.
- add Arc to AtomicCSR, and require `std` for AtomicCSR types.
This should not break anything, I checked inside @foundation-devices
keyOS and they don't seem to be using AtomicCSR anywhere.
The Arc makes it a bit safer to clone the AtomicCSR base pointer
and share it between threads, but it will have an impact on performance.
The USB stack (which requires AtomicCSR) was regression testing and the
impact seems minimal.
Recall that the main purpose of AtomicCSR is to provide a CSR accessor
that does not require a mutable reference to the base object. This
can make certain Rust idioms a bit cleaner. We wrap the base accessor
in Arc+Atomic to try and improve the safety of throwing the borrow
checker under the bus, but it's still not perfect because hardware
mutable state can have side-effects within hardware itself that cannot
be modeled or checked by Rust's borrow checker.
Instead of remapping the page to allow the kernel to access a process'
memory, simply set the SUM bit. This makes it no longer an error for the
kernel to access userspace.
Keep setting the `W` bit when we poke, to allow for updating program
memory with breakpoints.
Signed-off-by: Sean Cross <sean@xobs.io>
Previously, we were creating a fake interrupt that was a "user software
interrupt". Update this to be a "supervisor external interrupt" to fix
hardware resume.
Signed-off-by: Sean Cross <sean@xobs.io>
Debug handling was not correct, and didn't work at all. Additionally,
interrupt masking didn't work.
Fix these problems.
Signed-off-by: Sean Cross <sean@xobs.io>
This adds a basic gdb server. Currently, it is possible to list
processes and inspect memory and threads. It is not yet possible to
actually interact with code (e.g. no breakpoints and no single
stepping).
Signed-off-by: Sean Cross <sean@xobs.io>
Previously, `disable_irq()` would unconditionally mask an interrupt in
the `sim` register. However, when interrupts are disabled this register
is zero, and we really should be updating `SIM_BACKING`.
Consult the state of the interrupt handler and update the appropriate
field as necessary.
Signed-off-by: Sean Cross <sean@xobs.io>
This function never failed. Make it infallible so that it matches the
same calling convention as `enable_irq()`
Signed-off-by: Sean Cross <sean@xobs.io>
- we don't need a general memset call -- just a zero page call
- use native rust semantics to embody the call. some alignment checking is
done on the arguments on the way in and out that seem worth it
- the unrolled loop doesn't pay off because we're at the limit of
write bandwidth on the CPU at this point. we would need write-back
caches to gain more performance through unrolling.
Fix a segfault that occurred when using ReplyAndReceiveNext on hosted
mode. This now properly passes memory messages back to the client.
Signed-off-by: Sean Cross <sean@xobs.io>
- strip out gdb-stub. Per xobs, the feature never worked, and it
depends upon a branch of a git repo which is not allowed by crates.io
Since the feature hasn't been developed, and crates.io will not
allow even an optional feature that points to a git repo, the feature
was stripped out.
- rename "kernel" to "xous-kernel", so that we can live in a crates.io
package namespace that is specific to Xous.
still have to figure out the riscv package issue.
Instead of passing a constructed mutable ref from the pagetable entry,
pass a raw pointer and use `read_volatile()` / `write_volatile(x)` on
this pointer.
This should remove a little bit of UB from the kernel.
Signed-off-by: Sean Cross <sean@xobs.io>
Previously, the kernel would dutifully try to map memory that was in the
kernel space. It did this by investigating the kernel memory offset,
which immediately causes a double-fault.
Check to make sure a userspace process is not trying to map kernel
memory before checking the valid page.
Signed-off-by: Sean Cross <sean@xobs.io>
Hosted mode spawns processes very differently, and this difference was
not reflected after changes were made to native mode.
Signed-off-by: Sean Cross <sean@xobs.io>
Unmap the pages from the child process after we're done setting them up.
This ensures they're not still aliased by our process, despite being
marked as "owned" by the other process.
Signed-off-by: Sean Cross <sean@xobs.io>
Implement a functioning CreateProcess syscall on riscv. This call
creates a server in the child process, and connects the server to the
parent. The parent can communicate with the child process using this
server.
The Server ID is passed as four `u32` values to the entrypoint function.
This can be reassembled into something that can then be passed to the
`ReceiveMessage` syscall.
Signed-off-by: Sean Cross <sean@xobs.io>
We now us `ProcessStartup` as the return type. This builds in tset
mode, hosted mode, and RISC-V mode.
Process Startup is still not implemented for RISC-V mode.
Signed-off-by: Sean Cross <sean@xobs.io>
If a process fails for some reason (e.g. by performing a fault) and
there is no exception handler, either terminate the process or (if
gdbserver is enabled) have it suspend the process.
Signed-off-by: Sean Cross <sean@xobs.io>
