* gdbstub: fix IsMemoryBreak() returning false while connected to client
As a result, the only existing codepath for a memory watchpoint hit to break into GDB (InterpeterMainLoop, GDB_BP_CHECK, ARMul_State::RecordBreak) is finally taken,
which exposes incorrect logic* in both RecordBreak and ServeBreak.
* a blank BreakpointAddress structure is passed, which sets r15 (PC) to NULL
* gdbstub: DynCom: default-initialize two members/vars used in conditionals
* gdbstub: DynCom: don't record memory watchpoint hits via RecordBreak()
For now, instead check for GDBStub::IsMemoryBreak() in InterpreterMainLoop and ServeBreak.
Fixes PC being set to a stale/unhit breakpoint address (often zero) when a memory watchpoint (rwatch, watch, awatch) is handled in ServeBreak() and generates a GDB trap.
Reasons for removing a call to RecordBreak() for memory watchpoints:
* The``breakpoint_data`` we pass is typed Execute or None. It describes the predicted next code breakpoint hit relative to PC;
* GDBStub::IsMemoryBreak() returns true if a recent Read/Write operation hit a watchpoint. It doesn't specify which in return, nor does it trace it anywhere. Thus, the only data we could give RecordBreak() is a placeholder BreakpointAddress at offset NULL and type Access. I found the idea silly, compared to simply relying on GDBStub::IsMemoryBreak().
There is currently no measure in the code that remembers the addresses (and types) of any watchpoints that were hit by an instruction, in order to send them to GDB as "extended stop information."
I'm considering an implementation for this.
* gdbstub: Change an ASSERT to DEBUG_ASSERT
I have never seen the (Reg[15] == last_bkpt.address) assert fail in practice, even after several weeks of (locally) developping various branches around GDB. Only leave it inside Debug builds.
Many of the member variables of the thread class aren't even used
outside of the class itself, so there's no need to make those variables
public. This change follows in the steps of the previous changes that
made other kernel types' members private.
The main motivation behind this is that the Thread class will likely
change in the future as emulation becomes more accurate, and letting
random bits of the emulator access data members of the Thread class
directly makes it a pain to shuffle around and/or modify internals.
Having all data members public like this also makes it difficult to
reason about certain bits of behavior without first verifying what parts
of the core actually use them.
Everything being public also generally follows the tendency for changes
to be introduced in completely different translation units that would
otherwise be better introduced as an addition to the Thread class'
public interface.
Makes the public interface consistent in terms of how accesses are done
on a process object. It also makes it slightly nicer to reason about the
logic of the process class, as we don't want to expose everything to
external code.
Internally within the kernel, it also includes a member variable for the
floating-point status register, and TPIDR, so we should do the same here to match
it.
While we're at it, also fix up the size of the struct and add a static
assertion to ensure it always stays the correct size.
The locations of these can actually vary depending on the address space
layout, so we shouldn't be using these when determining where to map
memory or be using them as offsets for calculations. This keeps all the
memory ranges flexible and malleable based off of the virtual memory
manager instance state.
This modifies the CPU interface to more accurately match an
AArch64-supporting CPU as opposed to an ARM11 one. Two of the methods
don't even make sense to keep around for this interface, as Adv Simd is
used, rather than the VFP in the primary execution state. This is
essentially a modernization change that should have occurred from the
get-go.
Rather than having to type out the full std::map type signature, we can
just use a straightforward alias. While we're at it, rename
GetBreakpointList to GetBreakpointMap, which makes the name more
accurate. We can also get rid of unnecessary u64 static_casts, since
VAddr is an alias for a u64.
General moving to keep kernel object types separate from the direct
kernel code. Also essentially a preliminary cleanup before eliminating
global kernel state in the kernel code.
* More improvements to GDBStub
- Debugging of threads should work correctly with source and assembly level stepping and modifying registers and memory, meaning threads and callstacks are fully clickable in VS.
- List of modules is available to the client, with assumption that .nro and .nso are backed up by an .elf with symbols, while deconstructed ROMs keep N names.
- Initial support for floating point registers.
* Tidy up as requested in PR feedback
* Tidy up as requested in PR feedback
This gets gdbstub working at least to the point where clients can
communicate with it.
What works:
- Reading/writing GPRegs
- Reading/writing memory
- Interrupting the emulated program and continuing
What does NOT work:
- Breakpoints. Sizes have been updated to u64, but support will need to be
added in the interpreter for them to work.
- VRegs. Mostly because my gdb was having issues with 128-bit regs for
some reason. However, the current u128 representation is a bit
awkward to use and should probably be updated first.
Corrects a few issues with regards to Doxygen documentation, for example:
- Incorrect parameter referencing.
- Missing @param tags.
- Typos in @param tags.
and a few minor other issues.
Currently, this is only ever queried, so adding a function to check if the
server is enabled is more sensible.
If directly modifying this externally is ever desirable, it should be done
by adding a function to the interface, rather than exposing implementation
details directly.
Dimitri A