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| 1 | +// Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved. |
| 2 | +// SPDX-License-Identifier: Apache-2.0 |
| 3 | + |
| 4 | +use std::os::fd::RawFd; |
| 5 | +use std::os::unix::net::UnixStream; |
| 6 | +use std::sync::mpsc::Receiver; |
| 7 | +use std::sync::mpsc::TryRecvError::Empty; |
| 8 | +use std::sync::{Arc, Mutex}; |
| 9 | + |
| 10 | +use gdbstub::common::{Signal, Tid}; |
| 11 | +use gdbstub::conn::{Connection, ConnectionExt}; |
| 12 | +use gdbstub::stub::run_blocking::{self, WaitForStopReasonError}; |
| 13 | +use gdbstub::stub::{DisconnectReason, GdbStub, MultiThreadStopReason}; |
| 14 | +use gdbstub::target::Target; |
| 15 | +use vm_memory::GuestAddress; |
| 16 | + |
| 17 | +use super::target::{vcpuid_to_tid, Error, FirecrackerTarget}; |
| 18 | +use crate::logger::trace; |
| 19 | +use crate::Vmm; |
| 20 | + |
| 21 | +/// Starts the GDB event loop which acts as a proxy between the Vcpus and GDB |
| 22 | +pub fn event_loop( |
| 23 | + connection: UnixStream, |
| 24 | + vmm: Arc<Mutex<Vmm>>, |
| 25 | + vcpu_fds: Vec<RawFd>, |
| 26 | + gdb_event_receiver: Receiver<usize>, |
| 27 | + entry_addr: GuestAddress, |
| 28 | +) { |
| 29 | + let target = FirecrackerTarget::new(vmm, vcpu_fds, gdb_event_receiver, entry_addr); |
| 30 | + let connection: Box<dyn ConnectionExt<Error = std::io::Error>> = { Box::new(connection) }; |
| 31 | + let debugger = GdbStub::new(connection); |
| 32 | + |
| 33 | + gdb_event_loop_thread(debugger, target); |
| 34 | +} |
| 35 | + |
| 36 | +struct GdbBlockingEventLoop {} |
| 37 | + |
| 38 | +impl run_blocking::BlockingEventLoop for GdbBlockingEventLoop { |
| 39 | + type Target = FirecrackerTarget; |
| 40 | + type Connection = Box<dyn ConnectionExt<Error = std::io::Error>>; |
| 41 | + |
| 42 | + type StopReason = MultiThreadStopReason<u64>; |
| 43 | + |
| 44 | + /// Poll for events from either Vcpu's or packets from the GDB connection |
| 45 | + fn wait_for_stop_reason( |
| 46 | + target: &mut FirecrackerTarget, |
| 47 | + conn: &mut Self::Connection, |
| 48 | + ) -> Result< |
| 49 | + run_blocking::Event<MultiThreadStopReason<u64>>, |
| 50 | + run_blocking::WaitForStopReasonError< |
| 51 | + <Self::Target as Target>::Error, |
| 52 | + <Self::Connection as Connection>::Error, |
| 53 | + >, |
| 54 | + > { |
| 55 | + loop { |
| 56 | + match target.gdb_event.try_recv() { |
| 57 | + Ok(cpu_id) => { |
| 58 | + // The Vcpu reports it's id from raw_id so we straight convert here |
| 59 | + let tid = Tid::new(cpu_id).expect("Error converting cpu id to Tid"); |
| 60 | + // If notify paused returns false this means we were already debugging a single |
| 61 | + // core, the target will track this for us to pick up later |
| 62 | + target.update_paused_vcpu(tid); |
| 63 | + trace!("Vcpu: {tid:?} paused from debug exit"); |
| 64 | + |
| 65 | + let stop_reason = target |
| 66 | + .get_stop_reason(tid) |
| 67 | + .map_err(WaitForStopReasonError::Target)?; |
| 68 | + |
| 69 | + let Some(stop_response) = stop_reason else { |
| 70 | + // If we returned None this is a break which should be handled by |
| 71 | + // the guest kernel (e.g. kernel int3 self testing) so we won't notify |
| 72 | + // GDB and instead inject this back into the guest |
| 73 | + target |
| 74 | + .inject_bp_to_guest(tid) |
| 75 | + .map_err(WaitForStopReasonError::Target)?; |
| 76 | + target |
| 77 | + .request_resume(tid) |
| 78 | + .map_err(WaitForStopReasonError::Target)?; |
| 79 | + |
| 80 | + trace!("Injected BP into guest early exit"); |
| 81 | + continue; |
| 82 | + }; |
| 83 | + |
| 84 | + trace!("Returned stop reason to gdb: {stop_response:?}"); |
| 85 | + return Ok(run_blocking::Event::TargetStopped(stop_response)); |
| 86 | + } |
| 87 | + Err(Empty) => (), |
| 88 | + Err(_) => { |
| 89 | + return Err(WaitForStopReasonError::Target(Error::GdbQueueError)); |
| 90 | + } |
| 91 | + } |
| 92 | + |
| 93 | + if conn.peek().map(|b| b.is_some()).unwrap_or(false) { |
| 94 | + let byte = conn |
| 95 | + .read() |
| 96 | + .map_err(run_blocking::WaitForStopReasonError::Connection)?; |
| 97 | + return Ok(run_blocking::Event::IncomingData(byte)); |
| 98 | + } |
| 99 | + } |
| 100 | + } |
| 101 | + |
| 102 | + /// Invoked when the GDB client sends a Ctrl-C interrupt. |
| 103 | + fn on_interrupt( |
| 104 | + target: &mut FirecrackerTarget, |
| 105 | + ) -> Result<Option<MultiThreadStopReason<u64>>, <FirecrackerTarget as Target>::Error> { |
| 106 | + // notify the target that a ctrl-c interrupt has occurred. |
| 107 | + let main_core = vcpuid_to_tid(0)?; |
| 108 | + |
| 109 | + target.request_pause(main_core)?; |
| 110 | + target.update_paused_vcpu(main_core); |
| 111 | + |
| 112 | + let exit_reason = MultiThreadStopReason::SignalWithThread { |
| 113 | + tid: main_core, |
| 114 | + signal: Signal::SIGINT, |
| 115 | + }; |
| 116 | + Ok(Some(exit_reason)) |
| 117 | + } |
| 118 | +} |
| 119 | + |
| 120 | +/// Runs while communication with GDB is in progress, after GDB disconnects we |
| 121 | +/// shutdown firecracker |
| 122 | +fn gdb_event_loop_thread( |
| 123 | + debugger: GdbStub<FirecrackerTarget, Box<dyn ConnectionExt<Error = std::io::Error>>>, |
| 124 | + mut target: FirecrackerTarget, |
| 125 | +) { |
| 126 | + match debugger.run_blocking::<GdbBlockingEventLoop>(&mut target) { |
| 127 | + Ok(disconnect_reason) => match disconnect_reason { |
| 128 | + DisconnectReason::Disconnect => { |
| 129 | + trace!("Client disconnected") |
| 130 | + } |
| 131 | + DisconnectReason::TargetExited(code) => { |
| 132 | + trace!("Target exited with code {}", code) |
| 133 | + } |
| 134 | + DisconnectReason::TargetTerminated(sig) => { |
| 135 | + trace!("Target terminated with signal {}", sig) |
| 136 | + } |
| 137 | + DisconnectReason::Kill => trace!("GDB sent a kill command"), |
| 138 | + }, |
| 139 | + Err(e) => { |
| 140 | + if e.is_target_error() { |
| 141 | + trace!("target encountered a fatal error: {e:?}") |
| 142 | + } else if e.is_connection_error() { |
| 143 | + trace!("connection error: {e:?}") |
| 144 | + } else { |
| 145 | + trace!("gdbstub encountered a fatal error {e:?}") |
| 146 | + } |
| 147 | + } |
| 148 | + } |
| 149 | + |
| 150 | + target.shutdown(); |
| 151 | +} |
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