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Implement a GDBSTUB Server #6

Merged
paoda merged 9 commits from gdbstub into main 2023-02-23 22:18:27 +00:00
Conversation 0 Commits 9 Files Changed 8 +227 -61
8 changed files with 227 additions and 61 deletions
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3
.gitmodules vendored
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@ -13,3 +13,6 @@
[submodule "lib/zig-toml"]
path = lib/zig-toml
url = https://github.com/aeronavery/zig-toml
[submodule "lib/zba-gdbstub"]
path = lib/zba-gdbstub
url = https://git.musuka.dev/paoda/zba-gdbstub

5
build.zig
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@ -1,6 +1,8 @@
const std = @import("std");
const builtin = @import("builtin");
const Sdk = @import("lib/SDL.zig/Sdk.zig");
const Gdbstub = @import("lib/zba-gdbstub/build.zig");
pub fn build(b: *std.build.Builder) void {
// Minimum Zig Version
@ -40,6 +42,9 @@ pub fn build(b: *std.build.Builder) void {
// OpenGL 3.3 Bindings
exe.addAnonymousModule("gl", .{ .source_file = .{ .path = "lib/gl.zig" } });
// gdbstub
Gdbstub.link(exe);
// Zig SDL Bindings: https://github.com/MasterQ32/SDL.zig
const sdk = Sdk.init(b, null);
sdk.link(exe, .dynamic);

1
lib/zba-gdbstub Submodule

@ -0,0 +1 @@
Subproject commit acb59994fcfb83d36efef47810a9dc791c6e542e

148
src/core/Bus.zig
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@ -198,55 +198,6 @@ fn fillReadTableExternal(self: *Self, addr: u32) ?*anyopaque {
return &self.pak.buf[masked_addr];
}
pub fn dbgRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const bits = @typeInfo(std.math.IntFittingRange(0, page_size - 1)).Int.bits;
const page = unaligned_address >> bits;
const offset = unaligned_address & (page_size - 1);
// We're doing some serious out-of-bounds open-bus reads
if (page >= table_len) return self.openBus(T, unaligned_address);
if (self.read_table[page]) |some_ptr| {
// We have a pointer to a page, cast the pointer to it's underlying type
const Ptr = [*]const T;
const ptr = @ptrCast(Ptr, @alignCast(@alignOf(std.meta.Child(Ptr)), some_ptr));
// Note: We don't check array length, since we force align the
// lower bits of the address as the GBA would
return ptr[forceAlign(T, offset) / @sizeOf(T)];
}
return self.dbgSlowRead(T, unaligned_address);
}
fn dbgSlowRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const page = @truncate(u8, unaligned_address >> 24);
const address = forceAlign(T, unaligned_address);
return switch (page) {
// General Internal Memory
0x00 => blk: {
if (address < Bios.size)
break :blk self.bios.dbgRead(T, self.cpu.r[15], unaligned_address);
break :blk self.openBus(T, address);
},
0x02 => unreachable, // handled by fastmem
0x03 => unreachable, // handled by fastmem
0x04 => self.readIo(T, address),
// Internal Display Memory
0x05 => unreachable, // handled by fastmem
0x06 => unreachable, // handled by fastmem
0x07 => unreachable, // handled by fastmem
// External Memory (Game Pak)
0x08...0x0D => self.pak.dbgRead(T, address),
0x0E...0x0F => self.readBackup(T, unaligned_address),
else => self.openBus(T, address),
};
}
fn readIo(self: *const Self, comptime T: type, address: u32) T {
return io.read(self, T, address) orelse self.openBus(T, address);
}
@ -336,6 +287,27 @@ pub fn read(self: *Self, comptime T: type, unaligned_address: u32) T {
return self.slowRead(T, unaligned_address);
}
pub fn dbgRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const bits = @typeInfo(std.math.IntFittingRange(0, page_size - 1)).Int.bits;
const page = unaligned_address >> bits;
const offset = unaligned_address & (page_size - 1);
// We're doing some serious out-of-bounds open-bus reads
if (page >= table_len) return self.openBus(T, unaligned_address);
if (self.read_table[page]) |some_ptr| {
// We have a pointer to a page, cast the pointer to it's underlying type
const Ptr = [*]const T;
const ptr = @ptrCast(Ptr, @alignCast(@alignOf(std.meta.Child(Ptr)), some_ptr));
// Note: We don't check array length, since we force align the
// lower bits of the address as the GBA would
return ptr[forceAlign(T, offset) / @sizeOf(T)];
}
return self.dbgSlowRead(T, unaligned_address);
}
fn slowRead(self: *Self, comptime T: type, unaligned_address: u32) T {
@setCold(true);
@ -366,6 +338,34 @@ fn slowRead(self: *Self, comptime T: type, unaligned_address: u32) T {
};
}
fn dbgSlowRead(self: *const Self, comptime T: type, unaligned_address: u32) T {
const page = @truncate(u8, unaligned_address >> 24);
const address = forceAlign(T, unaligned_address);
return switch (page) {
// General Internal Memory
0x00 => blk: {
if (address < Bios.size)
break :blk self.bios.dbgRead(T, self.cpu.r[15], unaligned_address);
break :blk self.openBus(T, address);
},
0x02 => unreachable, // handled by fastmem
0x03 => unreachable, // handled by fastmem
0x04 => self.readIo(T, address),
// Internal Display Memory
0x05 => unreachable, // handled by fastmem
0x06 => unreachable, // handled by fastmem
0x07 => unreachable, // handled by fastmem
// External Memory (Game Pak)
0x08...0x0D => self.pak.dbgRead(T, address),
0x0E...0x0F => self.readBackup(T, unaligned_address),
else => self.openBus(T, address),
};
}
fn readBackup(self: *const Self, comptime T: type, unaligned_address: u32) T {
const value = self.pak.backup.read(unaligned_address);
@ -406,6 +406,31 @@ pub fn write(self: *Self, comptime T: type, unaligned_address: u32, value: T) vo
}
}
/// Mostly Identical to `Bus.write`, slowmeme is handled by `Bus.dbgSlowWrite`
pub fn dbgWrite(self: *Self, comptime T: type, unaligned_address: u32, value: T) void {
const bits = @typeInfo(std.math.IntFittingRange(0, page_size - 1)).Int.bits;
const page = unaligned_address >> bits;
const offset = unaligned_address & (page_size - 1);
// We're doing some serious out-of-bounds open-bus writes, they do nothing though
if (page >= table_len) return;
if (self.write_tables[@boolToInt(T == u8)][page]) |some_ptr| {
// We have a pointer to a page, cast the pointer to it's underlying type
const Ptr = [*]T;
const ptr = @ptrCast(Ptr, @alignCast(@alignOf(std.meta.Child(Ptr)), some_ptr));
// Note: We don't check array length, since we force align the
// lower bits of the address as the GBA would
ptr[forceAlign(T, offset) / @sizeOf(T)] = value;
} else {
// we can return early if this is an 8-bit OAM write
if (T == u8 and @truncate(u8, unaligned_address >> 24) == 0x07) return;
self.dbgSlowWrite(T, unaligned_address, value);
}
}
fn slowWrite(self: *Self, comptime T: type, unaligned_address: u32, value: T) void {
@setCold(true);
@ -431,6 +456,31 @@ fn slowWrite(self: *Self, comptime T: type, unaligned_address: u32, value: T) vo
}
}
fn dbgSlowWrite(self: *Self, comptime T: type, unaligned_address: u32, value: T) void {
@setCold(true);
const page = @truncate(u8, unaligned_address >> 24);
const address = forceAlign(T, unaligned_address);
switch (page) {
// General Internal Memory
0x00 => self.bios.write(T, address, value),
0x02 => unreachable, // completely handled by fastmem
0x03 => unreachable, // completely handled by fastmem
0x04 => return, // FIXME: Let debug writes mess with I/O
// Internal Display Memory
0x05 => self.ppu.palette.write(T, address, value),
0x06 => self.ppu.vram.write(T, self.ppu.dispcnt, address, value),
0x07 => unreachable, // completely handled by fastmem
// External Memory (Game Pak)
0x08...0x0D => return, // FIXME: Debug Write to Backup/GPIO w/out messing with state
0x0E...0x0F => return, // FIXME: Debug Write to Backup w/out messing with state
else => {},
}
}
inline fn rotateBy(comptime T: type, address: u32) u32 {
return switch (T) {
u32 => address & 3,

56
src/core/emu.zig
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@ -162,3 +162,59 @@ fn sleep(timer: *Timer, wake_time: u64) ?u64 {
fn spinLoop(timer: *Timer, wake_time: u64) void {
while (true) if (timer.read() > wake_time) break;
}
pub const EmuThing = struct {
const Self = @This();
const Interface = @import("gdbstub").Emulator;
const Allocator = std.mem.Allocator;
cpu: *Arm7tdmi,
scheduler: *Scheduler,
pub fn init(cpu: *Arm7tdmi, scheduler: *Scheduler) Self {
return .{ .cpu = cpu, .scheduler = scheduler };
}
pub fn interface(self: *Self, allocator: Allocator) Interface {
return Interface.init(allocator, self);
}
pub fn read(self: *const Self, addr: u32) u8 {
return self.cpu.bus.dbgRead(u8, addr);
}
pub fn write(self: *Self, addr: u32, value: u8) void {
self.cpu.bus.dbgWrite(u8, addr, value);
}
pub fn registers(self: *const Self) *[16]u32 {
return &self.cpu.r;
}
pub fn cpsr(self: *const Self) u32 {
return self.cpu.cpsr.raw;
}
pub fn step(self: *Self) void {
const cpu = self.cpu;
const sched = self.scheduler;
// Is true when we have executed one (1) instruction
var did_step: bool = false;
// TODO: How can I make it easier to keep this in lock-step with runFrame?
while (!did_step) {
if (!cpu.stepDmaTransfer()) {
if (cpu.isHalted()) {
// Fast-forward to next Event
sched.tick = sched.queue.peek().?.tick;
} else {
cpu.step();
did_step = true;
}
}
if (sched.tick >= sched.nextTimestamp()) sched.handleEvent(cpu);
}
}
};

3
src/core/ppu.zig
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@ -986,8 +986,7 @@ pub const Ppu = struct {
cpu.handleInterrupt();
}
// See if HBlank DMA is present and not enabled
// If we're not also in VBlank, attempt to run any pending DMA Reqs
if (!self.dispstat.vblank.read())
dma.onBlanking(cpu.bus, .HBlank);

44
src/main.zig
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@ -4,14 +4,17 @@ const known_folders = @import("known_folders");
const clap = @import("clap");
const config = @import("config.zig");
const emu = @import("core/emu.zig");
const Gui = @import("platform.zig").Gui;
const Bus = @import("core/Bus.zig");
const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
const Scheduler = @import("core/scheduler.zig").Scheduler;
const FilePaths = @import("util.zig").FilePaths;
const FpsTracker = @import("util.zig").FpsTracker;
const Allocator = std.mem.Allocator;
const Atomic = std.atomic.Atomic;
const log = std.log.scoped(.Cli);
const width = @import("core/ppu.zig").width;
const height = @import("core/ppu.zig").height;
@ -22,6 +25,7 @@ const params = clap.parseParamsComptime(
\\-h, --help Display this help and exit.
\\-s, --skip Skip BIOS.
\\-b, --bios <str> Optional path to a GBA BIOS ROM.
\\ --gdb Run ZBA from the context of a GDB Server
\\<str> Path to the GBA GamePak ROM.
\\
);
@ -87,10 +91,46 @@ pub fn main() void {
cpu.fastBoot();
}
var quit = Atomic(bool).init(false);
var gui = Gui.init(&bus.pak.title, &bus.apu, width, height) catch |e| exitln("failed to init gui: {}", .{e});
defer gui.deinit();
gui.run(&cpu, &scheduler) catch |e| exitln("failed to run gui thread: {}", .{e});
if (result.args.gdb) {
const Server = @import("gdbstub").Server;
const EmuThing = @import("core/emu.zig").EmuThing;
var wrapper = EmuThing.init(&cpu, &scheduler);
var emulator = wrapper.interface(allocator);
defer emulator.deinit();
log.info("Ready to connect", .{});
var server = Server.init(emulator) catch |e| exitln("failed to init gdb server: {}", .{e});
defer server.deinit(allocator);
log.info("Starting GDB Server Thread", .{});
const thread = std.Thread.spawn(.{}, Server.run, .{ &server, allocator, &quit }) catch |e| exitln("gdb server thread crashed: {}", .{e});
defer thread.join();
gui.run(.{
.cpu = &cpu,
.scheduler = &scheduler,
.quit = &quit,
}) catch |e| exitln("main thread panicked: {}", .{e});
} else {
var tracker = FpsTracker.init();
const thread = std.Thread.spawn(.{}, emu.run, .{ &quit, &scheduler, &cpu, &tracker }) catch |e| exitln("emu thread panicked: {}", .{e});
defer thread.join();
gui.run(.{
.cpu = &cpu,
.scheduler = &scheduler,
.tracker = &tracker,
.quit = &quit,
}) catch |e| exitln("main thread panicked: {}", .{e});
}
}
fn handleArguments(allocator: Allocator, data_path: []const u8, result: *const clap.Result(clap.Help, &params, clap.parsers.default)) !FilePaths {

28
src/platform.zig
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@ -154,9 +154,17 @@ pub const Gui = struct {
return tex_id;
}
pub fn run(self: *Self, cpu: *Arm7tdmi, scheduler: *Scheduler) !void {
var quit = std.atomic.Atomic(bool).init(false);
var tracker = FpsTracker.init();
const RunOptions = struct {
quit: *std.atomic.Atomic(bool),
tracker: ?*FpsTracker = null,
cpu: *Arm7tdmi,
scheduler: *Scheduler,
};
pub fn run(self: *Self, opt: RunOptions) !void {
const cpu = opt.cpu;
const tracker = opt.tracker;
const quit = opt.quit;
var buffer_ids = Self.generateBuffers();
defer {
@ -169,13 +177,15 @@ pub const Gui = struct {
const tex_id = Self.generateTexture(cpu.bus.ppu.framebuf.get(.Renderer));
defer gl.deleteTextures(1, &tex_id);
const thread = try std.Thread.spawn(.{}, emu.run, .{ &quit, scheduler, cpu, &tracker });
defer thread.join();
var title_buf: [0x100]u8 = undefined;
emu_loop: while (true) {
var event: SDL.SDL_Event = undefined;
// This might be true if the emu is running via a gdbstub server
// and the gdb stub exits first
if (quit.load(.Monotonic)) break :emu_loop;
while (SDL.SDL_PollEvent(&event) != 0) {
switch (event.type) {
SDL.SDL_QUIT => break :emu_loop,
@ -238,8 +248,10 @@ pub const Gui = struct {
gl.drawElements(gl.TRIANGLES, 6, gl.UNSIGNED_INT, null);
SDL.SDL_GL_SwapWindow(self.window);
const dyn_title = std.fmt.bufPrintZ(&title_buf, "ZBA | {s} [Emu: {}fps] ", .{ self.title, tracker.value() }) catch unreachable;
SDL.SDL_SetWindowTitle(self.window, dyn_title.ptr);
if (tracker) |t| {
const dyn_title = std.fmt.bufPrintZ(&title_buf, "ZBA | {s} [Emu: {}fps] ", .{ self.title, t.value() }) catch unreachable;
SDL.SDL_SetWindowTitle(self.window, dyn_title.ptr);
}
}
quit.store(true, .Monotonic); // Terminate Emulator Thread