sys_util: add acpi event support

The acpi events are netlink generic based messages, used by kernel to
notify about various ACPI related events (in fact, the "acpi_event" is
one of registered by the kernel generic netlink family). This commit
adds support for de-capsulating and parsing acpi events from the netlink
generic message.

BUG=b:197247746
TEST=Build crosvm-direct and listen on acpi events, parse and use them
[above done with additional WIP patches but without acpi_event.rs modification]

Change-Id: I1671d95b1bca1fbd31ba042eac49f5d2d99cb92a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3407320
Reviewed-by: Dmitry Torokhov <dtor@chromium.org>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Grzegorz Jaszczyk <jaszczyk@google.com>
This commit is contained in:
Grzegorz Jaszczyk 2022-01-20 22:12:01 +00:00 committed by Commit Bot
parent 7d7fb7c567
commit 1f4e67e324
3 changed files with 130 additions and 0 deletions

View file

@ -0,0 +1,109 @@
// Copyright 2022 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use std::str;
use crate::netlink::*;
use thiserror::Error;
use data_model::DataInit;
const ACPI_EVENT_SIZE: usize = std::mem::size_of::<AcpiGenlEvent>();
const GENL_HDRLEN: usize = std::mem::size_of::<GenlMsgHdr>();
const NLA_HDRLEN: usize = std::mem::size_of::<NlAttr>();
#[derive(Error, Debug)]
pub enum AcpiEventError {
#[error("GenmsghdrCmd or NlAttrType inappropriate for acpi event")]
TypeAttrMissmatch,
#[error("Something goes wrong: msg_len {0} is not correct")]
InvalidMsgLen(usize),
}
type Result<T> = std::result::Result<T, AcpiEventError>;
/// attributes of AcpiGenlFamily
#[allow(dead_code)]
enum NlAttrType {
AcpiGenlAttrUnspec,
AcpiGenlAttrEvent, // acpi_event (needed by user space)
AcpiGenlAttrMax,
}
/// commands supported by the AcpiGenlFamily
#[allow(dead_code)]
enum GenmsghdrCmd {
AcpiGenlCmdUnspec,
AcpiGenlCmdEvent, // kernel->user notifications for acpi_events
AcpiGenlCmdMax,
}
#[repr(C)]
#[derive(Copy, Clone)]
struct AcpiGenlEvent {
device_class: [::std::os::raw::c_char; 20usize],
bus_id: [::std::os::raw::c_char; 15usize],
_type: u32,
data: u32,
}
unsafe impl DataInit for AcpiGenlEvent {}
pub struct AcpiNotifyEvent {
pub device_class: String,
pub bus_id: String,
pub _type: u32,
pub data: u32,
}
impl AcpiNotifyEvent {
/// Create acpi event by decapsulating it from NetlinkMessage.
pub fn new(netlink_message: NetlinkMessage) -> Result<Self> {
let msg_len = netlink_message.data.len();
if msg_len != GENL_HDRLEN + NLA_HDRLEN + ACPI_EVENT_SIZE {
return Err(AcpiEventError::InvalidMsgLen(msg_len));
}
let genl_hdr = GenlMsgHdr::from_slice(&netlink_message.data[..GENL_HDRLEN])
.expect("unable to get GenlMsgHdr from slice");
let nlattr_end = GENL_HDRLEN + NLA_HDRLEN;
let nl_attr = NlAttr::from_slice(&netlink_message.data[GENL_HDRLEN..nlattr_end])
.expect("unable to get NlAttr from slice");
// Sanity check that the headers have correct for acpi event `cmd` and `_type`
if genl_hdr.cmd != GenmsghdrCmd::AcpiGenlCmdEvent as u8
|| nl_attr._type != NlAttrType::AcpiGenlAttrEvent as u16
{
return Err(AcpiEventError::TypeAttrMissmatch);
}
let acpi_event = AcpiGenlEvent::from_slice(&netlink_message.data[nlattr_end..msg_len])
.expect("unable to get AcpiGenlEvent from slice");
// The raw::c_char is either i8 or u8 which is known portability issue:
// https://github.com/rust-lang/rust/issues/79089,
// before using device_class further cast it to u8.
let device_class: &[u8; 20usize] =
unsafe { ::std::mem::transmute(&acpi_event.device_class) };
let bus_id: &[u8; 15usize] = unsafe { ::std::mem::transmute(&acpi_event.bus_id) };
Ok(AcpiNotifyEvent {
device_class: strip_padding(device_class).to_owned(),
bus_id: strip_padding(bus_id).to_owned(),
_type: acpi_event._type,
data: acpi_event.data,
})
}
}
// Like `CStr::from_bytes_with_nul` but strips any bytes starting from first '\0'-byte and
// returns &str. Panics if `b` doesn't contain any '\0' bytes.
fn strip_padding(b: &[u8]) -> &str {
// It would be nice if we could use memchr here but that's locked behind an unstable gate.
let pos = b
.iter()
.position(|&c| c == 0)
.expect("`b` doesn't contain any nul bytes");
str::from_utf8(&b[..pos]).unwrap()
}

View file

@ -19,6 +19,7 @@ pub mod handle_eintr;
pub mod ioctl;
#[macro_use]
pub mod syslog;
mod acpi_event;
mod capabilities;
mod clock;
mod descriptor;
@ -51,6 +52,7 @@ mod timerfd;
pub mod vsock;
mod write_zeroes;
pub use crate::acpi_event::*;
pub use crate::alloc::LayoutAllocation;
pub use crate::capabilities::drop_capabilities;
pub use crate::clock::{Clock, FakeClock};

View file

@ -23,6 +23,25 @@ struct NlMsgHdr {
}
unsafe impl DataInit for NlMsgHdr {}
/// Netlink attribute struct, can be used by netlink consumer
#[repr(C)]
#[derive(Copy, Clone)]
pub struct NlAttr {
pub len: u16,
pub _type: u16,
}
unsafe impl DataInit for NlAttr {}
/// Generic netlink header struct, can be used by netlink consumer
#[repr(C)]
#[derive(Copy, Clone)]
pub struct GenlMsgHdr {
pub cmd: u8,
pub version: u8,
pub reserved: u16,
}
unsafe impl DataInit for GenlMsgHdr {}
/// A single netlink message, including its header and data.
pub struct NetlinkMessage<'a> {
pub _type: u16,