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Serial: add input path overriding stdin for --serial

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Allowing the input to be specified for file-based serial ports allows
the user of pipes as input/output. That enables kgdb over serial.

TEST=
Build a kernel with support for gdb

```
make x86_64_defconfig
make kvmconfig
./scripts/config --enable GDB_SCRIPTS
./scripts/config --enable KGDB
./scripts/config --enable KGDB_SERIAL_CONSOLE
./scripts/config --enable KGDB_LOW_LEVEL_TRAP
./scripts/config --enable KGDB_KDB
./scripts/config --enable KDB_KEYBOARD
./scripts/config --enable GDB_SCRIPTS
./scripts/config --set-val KDB_CONTINUE_CATASTROPHIC 0
make -j33
```

Setup devices for PTYs

To make sure crosvm doesn't create an ordinary file if socat is started
after it, create these named pipes first:

```
mkfifo ~/console_{in,out} ~/kgdb_{in,out}
```

Set up two PTYs: ~/kgdb for the debugger, and ~/serial for the console.
PTY ~/kgdb connects to ~/kgdb{in,out}, and ~/serial connects to
~/console{in,out}

```
socat -d -d -d \
    'PIPE:$HOME/console_out,rdonly=1,nonblock=1,ignoreeof=1!!PIPE:$HOME/console_in,wronly=1' \
    PTY,link=$HOME/serial,ctty,raw,echo=0

socat -d -d -d \
    'PIPE:$HOME/kgdb_out,rdonly=1,nonblock=1,ignoreeof=1!!PIPE:$HOME/kgdb_in,wronly=1' \
    PTY,link=$HOME/kgdb,ctty,raw,echo=0
```

Start crosvm with serial ports pointed at ~/console{in,out} and ~/kgdb{in,out}.

```
cargo run run -p 'init=/bin/sh panic=0 kgdboc=ttyS1,115200 kgdbwait kgdbcon' \
    --serial type=file,path=$HOME/console_out,num=1,console=true,stdin=false,input=$HOME/console_in \
    --serial type=file,path=$HOME/kgdb_out,input=$HOME/kgdb_in,num=2,console=false,stdin=false \
    -r ~/rootfs.img \
    ~/src/linux/arch/x86/boot/bzImage
```

Start GDB

```
gdb vmlinux -ex "target remote /home/dgreid/kgdb"
```

To break into gdb, open up the serial console, mount /proc and send a SysRq

```
minicom -D ~/serial
mount -t proc none /proc
echo g > /proc/sysrq-trigger
```

Change-Id: I18a9c1087d38301df49de08eeae2f8559b03463a
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2151856
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: Dylan Reid <dgreid@chromium.org>
Commit-Queue: Dylan Reid <dgreid@chromium.org>
This commit is contained in:
Iliyan Malchev 2020-04-14 09:40:41 -07:00 committed by Commit Bot
parent 043aaea79b
commit 2c1417b43a
3 changed files with 29 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
devices/src/serial.rs
View file

@ -130,6 +130,7 @@ impl FromStr for SerialType {
pub struct SerialParameters {
pub type_: SerialType,
pub path: Option<PathBuf>,
pub input: Option<PathBuf>,
pub num: u8,
pub console: bool,
pub stdin: bool,
@ -149,7 +150,11 @@ impl SerialParameters {
) -> std::result::Result<Serial, Error> {
let evt_fd = evt_fd.try_clone().map_err(Error::CloneEventFd)?;
keep_fds.push(evt_fd.as_raw_fd());
let input: Option<Box<dyn io::Read + Send>> = if self.stdin {
let input: Option<Box<dyn io::Read + Send>> = if let Some(input_path) = &self.input {
let input_file = File::open(input_path.as_path()).map_err(Error::FileError)?;
keep_fds.push(input_file.as_raw_fd());
Some(Box::new(input_file))
} else if self.stdin {
keep_fds.push(stdin().as_raw_fd());
// This wrapper is used in place of the libstd native version because we don't want
// buffering for stdin.
@ -181,12 +186,12 @@ impl SerialParameters {
))
}
SerialType::File => match &self.path {
None => Err(Error::PathRequired),
Some(path) => {
let file = File::create(path.as_path()).map_err(Error::FileError)?;
keep_fds.push(file.as_raw_fd());
Ok(Serial::new(evt_fd, input, Some(Box::new(file))))
}
_ => Err(Error::PathRequired),
},
SerialType::UnixSocket => Err(Error::Unimplemented(SerialType::UnixSocket)),
}
@ -198,6 +203,7 @@ pub const DEFAULT_SERIAL_PARAMS: [SerialParameters; 4] = [
SerialParameters {
type_: SerialType::Stdout,
path: None,
input: None,
num: 1,
console: true,
stdin: true,
@ -205,6 +211,7 @@ pub const DEFAULT_SERIAL_PARAMS: [SerialParameters; 4] = [
SerialParameters {
type_: SerialType::Sink,
path: None,
input: None,
num: 2,
console: false,
stdin: false,
@ -212,6 +219,7 @@ pub const DEFAULT_SERIAL_PARAMS: [SerialParameters; 4] = [
SerialParameters {
type_: SerialType::Sink,
path: None,
input: None,
num: 3,
console: false,
stdin: false,
@ -219,6 +227,7 @@ pub const DEFAULT_SERIAL_PARAMS: [SerialParameters; 4] = [
SerialParameters {
type_: SerialType::Sink,
path: None,
input: None,
num: 4,
console: false,
stdin: false,

19
src/main.rs
View file

@ -302,6 +302,7 @@ fn parse_serial_options(s: &str) -> argument::Result<SerialParameters> {
let mut serial_setting = SerialParameters {
type_: SerialType::Sink,
path: None,
input: None,
num: 1,
console: false,
stdin: false,
@ -342,9 +343,22 @@ fn parse_serial_options(s: &str) -> argument::Result<SerialParameters> {
"stdin" => {
serial_setting.stdin = v.parse::<bool>().map_err(|e| {
argument::Error::Syntax(format!("serial device stdin is not parseable: {}", e))
})?
})?;
if serial_setting.stdin && serial_setting.input.is_some() {
return Err(argument::Error::TooManyArguments(
"Cannot specify both stdin and input options".to_string(),
));
}
}
"path" => serial_setting.path = Some(PathBuf::from(v)),
"input" => {
if serial_setting.stdin {
return Err(argument::Error::TooManyArguments(
"Cannot specify both stdin and input options".to_string(),
));
}
serial_setting.input = Some(PathBuf::from(v));
}
_ => {
return Err(argument::Error::UnknownArgument(format!(
"serial parameter {}",
@ -1267,12 +1281,13 @@ fn run_vm(args: std::env::Args) -> std::result::Result<(), ()> {
capture - Enable audio capture
capture_effects - | separated effects to be enabled for recording. The only supported effect value now is EchoCancellation or aec."),
Argument::value("serial",
"type=TYPE,[num=NUM,path=PATH,console,stdin]",
"type=TYPE,[num=NUM,path=PATH,input=PATH,console,stdin]",
"Comma separated key=value pairs for setting up serial devices. Can be given more than once.
Possible key values:
type=(stdout,syslog,sink,file) - Where to route the serial device
num=(1,2,3,4) - Serial Device Number. If not provided, num will default to 1.
path=PATH - The path to the file to write to when type=file
input=PATH - The path to the file to read from when not stdin
console - Use this serial device as the guest console. Can only be given once. Will default to first serial port if not provided.
stdin - Direct standard input to this serial device. Can only be given once. Will default to first serial port if not provided.
"),

1
tests/boot.rs
View file

@ -232,6 +232,7 @@ fn boot() {
SerialParameters {
type_: SerialType::Sink,
path: None,
input: None,
num: 1,
console: false,
stdin: false,