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library: the last three protocols speak the envelope

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These were the awkward ones. Each began with an operation packed into a
single byte — two of them with a version wedged in beside it — so there was
no wrapping them: the layouts had to be rebuilt. The device manager's own
enumerate and subscribe become the reserved verbs that mean the same thing
everywhere, its replies lose three status structs the envelope already
carries, and a device id becomes the packet's target. Power drops the
version it repeated on every request, because describe is the handshake,
and stops claiming a 64-byte ceiling it never needed for calls. USB moves a
control transfer's data to the packet tail in both directions, which makes
the status length the transferred length and retires a field that had been
saying the same thing twice.

The danger in this one was not the protocols but their readers. Init
recognised a power button by two bytes at the head of a message, the ACPI
service dispatched on the first byte, the xHCI driver read its operation
with a raw integer load, and the HID drivers reinterpreted a report
wholesale — none of which would have failed to compile once the layouts
moved. They would simply have stopped: no shutdown on the power button, no
reports from the keyboard. Every one of them now reads through the
generated types, and the shutdown gate that answers only a subscriber is
the same code it was.

Two sizes were decided by measuring rather than assuming. The child-added
message is both a request and the event broadcast to subscribers, and
alignment rounds it to 48 bytes, which puts its packet exactly on the
64-byte push floor — a test pins that, because a field added carelessly
would now overflow it. The interrupt report gives up eight bytes of inline
room to make space for the header; the two drivers that produce reports
send eight and four.

Suite 110/110.
This commit is contained in:
Daniel Samson
2026-08-01 07:20:37 +01:00
parent d2dfbcabf8
commit 2719b93530
27 changed files with 1058 additions and 685 deletions
Download Patch File Download Diff File Expand all files Collapse all files
system/drivers/pci-bus/pci-bus.zig
+7 -4
View File
@@ -229,18 +229,21 @@ fn registerAndReport(bus: u64, dev: u64, function: u64, class_triple: u32) void
std.log.info("register refused for {d}:{d}.{d}", .{ bus, dev, function });
return;
};
const report = device_manager_protocol.ChildAdded{
// The registered device id is the packet's target — the manager's object
// addressing — so the report body carries only where on the bus it sits and
// what it is.
var packet: [device_manager_protocol.message_maximum]u8 = undefined;
const framed = device_manager_protocol.Protocol.encodeRequest(.child_added, registered, .{
.bus = @intFromEnum(device_manager_protocol.BusKind.pci),
.parent = bridge_id,
.bus_address = (bus << 8) | (dev << 3) | function,
.identity = class_triple,
.device_id = registered,
.vendor = descriptor.vendor,
.device = descriptor.device,
.subsystem = descriptor.subsystem,
};
}, &.{}, &packet) orelse return;
var reply: [device_manager_protocol.message_maximum]u8 = undefined;
_ = ipc.call(manager_handle, std.mem.asBytes(&report), &reply) catch {
_ = ipc.call(manager_handle, framed, &reply) catch {
std.log.info("child report for {d}:{d}.{d} failed", .{ bus, dev, function });
};
}
system/drivers/usb-hid/keyboard.zig
+4 -3
View File
@@ -112,9 +112,10 @@ pub fn main(init: process.Init) void {
if (signals.has(.terminate)) return;
continue;
}
if (!got.isMessage() or got.len < @sizeOf(usb.InterruptReport)) continue;
const message = std.mem.bytesToValue(usb.InterruptReport, receive[0..@sizeOf(usb.InterruptReport)]);
if (!got.isMessage()) continue;
// An `interrupt_report` event packet: the verb in its folded header, the
// report after it. Anything else on this endpoint is not ours.
const message = usb.reportOf(receive[0..got.len]) orelse continue;
if (message.length < @sizeOf(hid.KeyboardReport)) continue;
const report = std.mem.bytesToValue(hid.KeyboardReport, message.data[0..@sizeOf(hid.KeyboardReport)]);
const transitions = decoder.feed(report);
system/drivers/usb-hid/mouse.zig
+4 -3
View File
@@ -74,9 +74,10 @@ pub fn main(init: process.Init) void {
if (signals.has(.terminate)) return;
continue;
}
if (!got.isMessage() or got.len < @sizeOf(usb.InterruptReport)) continue;
const message = std.mem.bytesToValue(usb.InterruptReport, receive[0..@sizeOf(usb.InterruptReport)]);
if (!got.isMessage()) continue;
// An `interrupt_report` event packet: the verb in its folded header, the
// report after it. Anything else on this endpoint is not ours.
const message = usb.reportOf(receive[0..got.len]) orelse continue;
const length = @min(message.length, message.data.len);
const report = hid.parseMouse(message.data[0..length]) orelse continue;
const mask = buttonMask(report.buttons);
system/drivers/usb-xhci-bus/build.zig
+4 -4
View File
@@ -10,10 +10,10 @@ pub fn build(b: *std.Build) void {
.name = "usb-xhci-bus",
.root_source_file = b.path("usb-xhci-bus.zig"),
.imports = &.{
"channel", "device-manager-protocol", "driver", "input-client",
"ipc", "logging", "memory", "mmio",
"pci", "process", "service", "time",
"usb-abi", "usb-ids", "usb-transfer-protocol",
"channel", "device-manager-protocol", "driver", "envelope",
"input-client", "ipc", "logging", "memory",
"mmio", "pci", "process", "service",
"time", "usb-abi", "usb-ids", "usb-transfer-protocol",
},
});
b.installArtifact(exe);
system/drivers/usb-xhci-bus/usb-xhci-bus.zig
+124 -102
View File
@@ -25,6 +25,7 @@ const device_manager = @import("driver");
const memory = @import("memory");
const logging = @import("logging");
const device_manager_protocol = @import("device-manager-protocol");
const envelope = @import("envelope");
const usb_ids = @import("usb-ids");
const usb_abi = @import("usb-abi");
const usb_transfer_protocol = @import("usb-transfer-protocol");
@@ -386,6 +387,23 @@ fn bringUpBehindHub(manager: ipc.Handle, engine: *library.Controller, hub: *libr
if (deviceIsHub(usb_device)) _ = engine.setupHub(usb_device);
}
/// Report one interface gone. A removal is addressed by the composite (parent,
/// bus address) — a pair no single `Header.target` can carry — so that stays the
/// packet's body and the target addresses the manager itself. `where` names the
/// port and interface for the log line, or null where the caller stays quiet
/// (a hub subtree collapsing reports a great many at once).
fn reportRemoved(manager: ipc.Handle, bus_address: u64, where: ?struct { port: u32, interface: u8 }) void {
var packet: [device_manager_protocol.message_maximum]u8 = undefined;
const framed = device_manager_protocol.Protocol.encodeRequest(.child_removed, 0, .{
.parent = controller_id,
.bus_address = bus_address,
}, &.{}, &packet) orelse return;
var reply: [device_manager_protocol.message_maximum]u8 = undefined;
_ = ipc.call(manager, framed, &reply) catch {
if (where) |place| std.log.info("child-removed report for port {d} interface {d} failed", .{ place.port, place.interface });
};
}
/// Tear down a device that disconnected from a hub: recursively tear down its
/// own downstream devices first if it is a hub, report each interface removed,
/// then Disable Slot. Mirrors tearDownPort for a hub-attached device.
@@ -398,12 +416,7 @@ fn tearDownHubDevice(manager: ipc.Handle, engine: *library.Controller, dev: *lib
const key = hubPortKey(dev.parent_slot, dev.parent_port);
for (dev.interfaces[0..dev.interface_count]) |*interface| {
if (interface.registered_device_id == 0) continue;
const event = device_manager_protocol.ChildRemoved{
.parent = controller_id,
.bus_address = (@as(u64, key) << 8) | interface.number,
};
var reply: [device_manager_protocol.message_maximum]u8 = undefined;
_ = ipc.call(manager, std.mem.asBytes(&event), &reply) catch {};
reportRemoved(manager, (@as(u64, key) << 8) | interface.number, null);
interface.registered_device_id = 0;
}
engine.tearDownDevice(dev);
@@ -428,14 +441,7 @@ fn tearDownPort(manager: ipc.Handle, engine: *library.Controller, port: u32) voi
std.log.info("port {d} disconnected", .{port});
for (usb_device.interfaces[0..usb_device.interface_count]) |*interface| {
if (interface.registered_device_id == 0) continue;
const event = device_manager_protocol.ChildRemoved{
.parent = controller_id,
.bus_address = (@as(u64, port) << 8) | interface.number,
};
var reply: [device_manager_protocol.message_maximum]u8 = undefined;
_ = ipc.call(manager, std.mem.asBytes(&event), &reply) catch {
std.log.info("child-removed report for port {d} interface {d} failed", .{ port, interface.number });
};
reportRemoved(manager, (@as(u64, port) << 8) | interface.number, .{ .port = port, .interface = interface.number });
interface.registered_device_id = 0;
}
engine.tearDownDevice(usb_device);
@@ -469,15 +475,17 @@ fn reportInterface(manager: ipc.Handle, port: u32, interface: library.InterfaceI
return null;
};
const report = device_manager_protocol.ChildAdded{
// The registered device id is the packet's target — the manager's object
// addressing — so the report body carries only where on the bus it sits.
var packet: [device_manager_protocol.message_maximum]u8 = undefined;
const framed = device_manager_protocol.Protocol.encodeRequest(.child_added, registered, .{
.bus = @intFromEnum(device_manager_protocol.BusKind.usb),
.parent = controller_id,
.bus_address = (@as(u64, port) << 8) | interface.number,
.identity = identity,
.device_id = registered,
};
}, &.{}, &packet) orelse return null;
var reply: [device_manager_protocol.message_maximum]u8 = undefined;
_ = ipc.call(manager, std.mem.asBytes(&report), &reply) catch {
_ = ipc.call(manager, framed, &reply) catch {
std.log.info("child report for port {d} interface {d} failed", .{ port, interface.number });
return null;
};
@@ -496,59 +504,55 @@ fn reportInterface(manager: ipc.Handle, port: u32, interface: library.InterfaceI
return registered;
}
/// Serve the USB transfer protocol: a class driver opens its device, then issues
/// control / interrupt-subscribe / bulk requests against it.
/// The generated transfer dispatch. One controller per process, so the handler
/// context is empty and the open table stays in this file's globals.
const Serve = usb_transfer_protocol.Protocol.Provider(void);
const Invocation = envelope.Invocation;
const Answer = envelope.Answer;
/// Every refusal here is the same one — this controller does not (or no longer)
/// serve the device the packet addressed — so there is one errno for all of them.
const refused: isize = -envelope.ENOENT;
/// Set by `onOpen` when the open table has taken ownership of the endpoint the
/// call carried, and read by `onMessage`, where the turn's `Arrival` lives. The
/// generated dispatch hands a handler the raw handle rather than the `Arrival`,
/// so the *claim* travels back out this way. One turn, one handler, one thread.
var capability_claimed = false;
fn onMessage(message: []const u8, reply: []u8, sender: u32, arrived: *ipc.Arrival) usize {
_ = sender;
if (message.len < 4) return 0;
const operation = std.mem.readInt(u32, message[0..4], .little);
return switch (operation) {
@intFromEnum(usb_transfer_protocol.Operation.open) => handleOpen(message, reply, arrived),
@intFromEnum(usb_transfer_protocol.Operation.control) => handleControl(message, reply),
@intFromEnum(usb_transfer_protocol.Operation.interrupt_subscribe) => handleSubscribe(message, reply),
@intFromEnum(usb_transfer_protocol.Operation.bulk) => handleBulk(message, reply),
@intFromEnum(usb_transfer_protocol.Operation.dma_attach) => handleDmaAttach(message, reply, arrived),
else => 0,
};
capability_claimed = false;
const written = Serve.dispatch({}, handlers, message, sender, arrived.peek(), reply);
if (capability_claimed) _ = arrived.take();
return written;
}
/// dma_attach: bind the class driver's DMA-region capability into the controller's IOMMU
/// domain, so the controller may DMA to the physical addresses inside that buffer. The
/// binding holds its own kernel reference, so this never claims the arriving handle —
/// the turn's `defer` in the harness is the close, on the failure paths as well as this
/// one.
fn handleDmaAttach(message: []const u8, reply: []u8, arrived: *ipc.Arrival) usize {
if (message.len < @sizeOf(usb_transfer_protocol.DmaAttachRequest)) return writeReply(reply, usb_transfer_protocol.DmaAttachReply{ .status = -1 });
const handle = arrived.peek() orelse return writeReply(reply, usb_transfer_protocol.DmaAttachReply{ .status = -1 });
const ok = device.dmaBind(controller_id, handle);
return writeReply(reply, usb_transfer_protocol.DmaAttachReply{ .status = if (ok) 0 else -1 });
}
const handlers = Serve.Handlers{
.open = onOpen,
.control = onControl,
.interrupt_subscribe = onInterruptSubscribe,
.bulk = onBulk,
.dma_attach = onDmaAttach,
};
fn writeReply(reply: []u8, value: anytype) usize {
const bytes = std.mem.asBytes(&value);
@memcpy(reply[0..bytes.len], bytes);
return bytes.len;
}
/// open: resolve the assigned device id to an interface, remember the caller's
/// endpoint (for interrupt reports), and answer with a device token + the
/// interface's endpoints so the class driver need not re-read the config.
fn handleOpen(message: []const u8, reply: []u8, arrived: *ipc.Arrival) usize {
if (message.len < @sizeOf(usb_transfer_protocol.OpenRequest)) return writeReply(reply, usb_transfer_protocol.OpenReply{ .status = -1, .endpoint_count = 0, .device_token = 0, .interface_class = 0, .interface_subclass = 0, .interface_protocol = 0, .interface_number = 0 });
const request = std.mem.bytesToValue(usb_transfer_protocol.OpenRequest, message[0..@sizeOf(usb_transfer_protocol.OpenRequest)]);
const engine = if (controller) |*c| c else return writeReply(reply, usb_transfer_protocol.OpenReply{ .status = -1, .endpoint_count = 0, .device_token = 0, .interface_class = 0, .interface_subclass = 0, .interface_protocol = 0, .interface_number = 0 });
const found = engine.findInterface(request.device_id) orelse return writeReply(reply, usb_transfer_protocol.OpenReply{ .status = -1, .endpoint_count = 0, .device_token = 0, .interface_class = 0, .interface_subclass = 0, .interface_protocol = 0, .interface_number = 0 });
/// open: the target is the class driver's assigned device id. Resolve it to an
/// interface, remember the caller's endpoint (for interrupt reports), and answer
/// with a device token — the target of every later packet — plus the interface's
/// endpoints, so the class driver need not re-read the configuration descriptor.
fn onOpen(_: void, invocation: Invocation(void), answer: Answer(usb_transfer_protocol.Opened)) isize {
const engine = if (controller) |*c| c else return refused;
const found = engine.findInterface(invocation.target) orelse return refused;
// The report endpoint is claimed only if the open table actually keeps it;
// a full table leaves it to the turn to close.
if (arrived.peek()) |endpoint| {
if (recordOpen(request.device_id, endpoint)) _ = arrived.take();
if (invocation.capability) |endpoint| {
if (recordOpen(invocation.target, endpoint)) capability_claimed = true;
}
var open_reply = usb_transfer_protocol.OpenReply{
.status = 0,
var opened = usb_transfer_protocol.Opened{
.device_token = invocation.target,
.endpoint_count = found.interface.endpoint_count,
.device_token = request.device_id,
.interface_class = found.interface.class,
.interface_subclass = found.interface.subclass,
.interface_protocol = found.interface.protocol,
@@ -556,57 +560,71 @@ fn handleOpen(message: []const u8, reply: []u8, arrived: *ipc.Arrival) usize {
};
const count = @min(found.interface.endpoint_count, usb_transfer_protocol.max_reported_endpoints);
for (found.interface.endpoints[0..count], 0..) |endpoint, index| {
open_reply.endpoints[index] = .{
opened.endpoints[index] = .{
.address = endpoint.address,
.transfer_type = endpoint.transfer_type,
.max_packet_size = endpoint.max_packet_size,
.interval = endpoint.interval,
};
}
return writeReply(reply, open_reply);
answer.set(opened);
return 0;
}
/// control: one EP0 control transfer, small data inline both ways.
fn handleControl(message: []const u8, reply: []u8) usize {
if (message.len < @sizeOf(usb_transfer_protocol.ControlRequest)) return writeReply(reply, usb_transfer_protocol.ControlReply{ .status = -1, .actual_length = 0 });
const request = std.mem.bytesToValue(usb_transfer_protocol.ControlRequest, message[0..@sizeOf(usb_transfer_protocol.ControlRequest)]);
const engine = if (controller) |*c| c else return writeReply(reply, usb_transfer_protocol.ControlReply{ .status = -1, .actual_length = 0 });
const found = engine.findInterface(request.device_token) orelse return writeReply(reply, usb_transfer_protocol.ControlReply{ .status = -1, .actual_length = 0 });
/// control: one EP0 control transfer. The data stage rides the tail in both
/// directions, so an IN transfer's answer is simply however many bytes were
/// written into `answer.tail()` — which is what `Status.len` then reports.
fn onControl(_: void, invocation: Invocation(usb_transfer_protocol.Control), answer: Answer(void)) isize {
const engine = if (controller) |*c| c else return refused;
const found = engine.findInterface(invocation.target) orelse return refused;
const setup = std.mem.bytesToValue(usb_abi.Request, &invocation.request.setup);
const direction_in = invocation.request.direction_in != 0;
const room = @min(usb_transfer_protocol.max_inline_data, answer.tail().len);
const data_length = @min(@as(usize, invocation.request.data_length), room);
const setup = std.mem.bytesToValue(usb_abi.Request, &request.setup);
const direction_in = request.direction_in != 0;
const data_length = @min(request.data_length, usb_transfer_protocol.max_inline_data);
var data: [usb_transfer_protocol.max_inline_data]u8 = undefined;
if (!direction_in) @memcpy(data[0..data_length], request.data[0..data_length]);
if (!direction_in) {
const supplied = @min(data_length, invocation.tail.len);
@memcpy(data[0..supplied], invocation.tail[0..supplied]);
if (supplied < data_length) @memset(data[supplied..data_length], 0);
}
const ok = engine.controlTransfer(found.device, setup, data[0..data_length], direction_in);
var control_reply = usb_transfer_protocol.ControlReply{ .status = if (ok) 0 else -1, .actual_length = if (ok) data_length else 0 };
if (ok and direction_in) @memcpy(control_reply.data[0..data_length], data[0..data_length]);
return writeReply(reply, control_reply);
if (!engine.controlTransfer(found.device, setup, data[0..data_length], direction_in)) return refused;
if (!direction_in) return 0; // nothing follows an OUT: the status is the whole answer
@memcpy(answer.tail()[0..data_length], data[0..data_length]);
return @intCast(data_length);
}
/// interrupt_subscribe: arm periodic IN polling; reports flow back asynchronously.
fn handleSubscribe(message: []const u8, reply: []u8) usize {
if (message.len < @sizeOf(usb_transfer_protocol.InterruptSubscribeRequest)) return writeReply(reply, usb_transfer_protocol.InterruptSubscribeReply{ .status = -1 });
const request = std.mem.bytesToValue(usb_transfer_protocol.InterruptSubscribeRequest, message[0..@sizeOf(usb_transfer_protocol.InterruptSubscribeRequest)]);
const engine = if (controller) |*c| c else return writeReply(reply, usb_transfer_protocol.InterruptSubscribeReply{ .status = -1 });
const found = engine.findInterface(request.device_token) orelse return writeReply(reply, usb_transfer_protocol.InterruptSubscribeReply{ .status = -1 });
const endpoint = library.Controller.endpointForAddress(found.interface, request.endpoint_address) orelse return writeReply(reply, usb_transfer_protocol.InterruptSubscribeReply{ .status = -1 });
const report_endpoint = reportEndpointFor(request.device_token) orelse return writeReply(reply, usb_transfer_protocol.InterruptSubscribeReply{ .status = -1 });
const ok = engine.subscribeInterrupt(found.device, endpoint, request.device_token, report_endpoint);
return writeReply(reply, usb_transfer_protocol.InterruptSubscribeReply{ .status = if (ok) 0 else -1 });
/// interrupt_subscribe: arm periodic IN polling; reports flow back asynchronously
/// to the endpoint this device's `open` handed over.
fn onInterruptSubscribe(_: void, invocation: Invocation(usb_transfer_protocol.InterruptSubscribe), _: Answer(void)) isize {
const engine = if (controller) |*c| c else return refused;
const found = engine.findInterface(invocation.target) orelse return refused;
const endpoint = library.Controller.endpointForAddress(found.interface, invocation.request.endpoint_address) orelse return refused;
const report_endpoint = reportEndpointFor(invocation.target) orelse return refused;
return if (engine.subscribeInterrupt(found.device, endpoint, invocation.target, report_endpoint)) 0 else refused;
}
/// bulk: one bulk transfer to/from the class driver's own DMA buffer (by physical
/// address), so sector-sized data never crosses IPC.
fn handleBulk(message: []const u8, reply: []u8) usize {
if (message.len < @sizeOf(usb_transfer_protocol.BulkRequest)) return writeReply(reply, usb_transfer_protocol.BulkReply{ .status = -1, .actual_length = 0 });
const request = std.mem.bytesToValue(usb_transfer_protocol.BulkRequest, message[0..@sizeOf(usb_transfer_protocol.BulkRequest)]);
const engine = if (controller) |*c| c else return writeReply(reply, usb_transfer_protocol.BulkReply{ .status = -1, .actual_length = 0 });
const found = engine.findInterface(request.device_token) orelse return writeReply(reply, usb_transfer_protocol.BulkReply{ .status = -1, .actual_length = 0 });
const endpoint = library.Controller.endpointForAddress(found.interface, request.endpoint_address) orelse return writeReply(reply, usb_transfer_protocol.BulkReply{ .status = -1, .actual_length = 0 });
const transferred = engine.bulkTransfer(found.device, endpoint, request.physical_address, request.length);
return writeReply(reply, usb_transfer_protocol.BulkReply{ .status = if (transferred != null) 0 else -1, .actual_length = transferred orelse 0 });
fn onBulk(_: void, invocation: Invocation(usb_transfer_protocol.Bulk), answer: Answer(usb_transfer_protocol.Transferred)) isize {
const engine = if (controller) |*c| c else return refused;
const found = engine.findInterface(invocation.target) orelse return refused;
const endpoint = library.Controller.endpointForAddress(found.interface, invocation.request.endpoint_address) orelse return refused;
const transferred = engine.bulkTransfer(found.device, endpoint, invocation.request.physical_address, invocation.request.length) orelse return refused;
answer.set(.{ .actual_length = transferred });
return 0;
}
/// dma_attach: bind the class driver's DMA-region capability into the controller's IOMMU
/// domain, so the controller may DMA to the physical addresses inside that buffer. The
/// binding holds its own kernel reference, so this never claims the arriving handle —
/// the turn's `defer` in the harness is the close, on the failure paths as well as this
/// one.
fn onDmaAttach(_: void, invocation: Invocation(void), _: Answer(void)) isize {
const handle = invocation.capability orelse return -envelope.EPROTO;
return if (device.dmaBind(controller_id, handle)) 0 else refused;
}
/// A timer tick or an MSI landed: drain the event ring, reconcile ports, and fan out.
@@ -679,14 +697,18 @@ fn serviceController() void {
if (serviced >= 32) break;
}
while (engine.takeReport()) |report| {
var message = usb_transfer_protocol.InterruptReport{
.device_token = report.device_token,
.endpoint_address = report.endpoint_address,
.length = @intCast(@min(report.length, usb_transfer_protocol.max_report_data)),
};
// One `interrupt_report` event packet: the device token in the folded
// header, the report after it. A device that produced more than the
// push floor admits has its report truncated here, never split.
const n = @min(report.length, usb_transfer_protocol.max_report_data);
@memcpy(message.data[0..n], report.data[0..n]);
_ = ipc.send(report.report_endpoint, std.mem.asBytes(&message));
var payload = usb_transfer_protocol.InterruptReport{
.endpoint_address = report.endpoint_address,
.length = @intCast(n),
};
@memcpy(payload.data[0..n], report.data[0..n]);
var packet: [envelope.post_maximum]u8 = undefined;
const framed = usb_transfer_protocol.Protocol.encodeEvent(.interrupt_report, report.device_token, payload, &packet) orelse continue;
_ = ipc.send(report.report_endpoint, framed);
}
}
}