Aufgabe 4: Kontextwechsel
Remote stub for GNU Debugger (GDB) More...
#include <debug/gdb/stub.h>
Public Member Functions | |
GDB_Stub (bool wait=false, bool debug_output=false, ComPort port=COM1, BaudRate baud_rate=BAUD_9600) | |
constructor More... | |
Public Member Functions inherited from Serial | |
Serial (ComPort port=COM1, BaudRate baud_rate=BAUD_115200, DataBits data_bits=DATA_8BIT, StopBits stop_bits=STOP_1BIT, Parity parity=PARITY_NONE) | |
Constructor. More... | |
int | read (bool blocking=true) |
Read one byte from the serial interface. More... | |
int | write (char out, bool blocking=true) |
Write one byte to the serial interface. More... | |
bool | receiveInterrupt (bool enable) |
Activate or deactivate interrupts on data reception. More... | |
Static Public Attributes | |
static int | signal = 0 |
Last trap/interrupt vector handled in GDB. More... | |
Protected Member Functions | |
void | handle () |
Handling traps. More... | |
int | writeString (const char *buf, size_t len) |
Send a string via the serial connection. More... | |
int | readString (char *buf, size_t buf_len, size_t len) |
Receive a string via the serial connection. More... | |
int | sendPacket (const char *pkt_data, size_t pkt_len) |
Transmits a packet of data. More... | |
int | receivePacket (char *pkt_buf, size_t pkt_buf_len, size_t *pkt_len) |
Receives a packet of data assuming a 7-bit clean connection. More... | |
int | receiveAck (void) |
Receive acknowledgment for a packet. More... | |
int | sendOkPacket () |
Create and send an OK packet (OK ) More... | |
int | sendSignalPacket (char *buf, size_t buf_len, char signal) |
Create and send a signal packet (S [int] ) More... | |
int | sendErrorPacket (char *buf, size_t buf_len, char error) |
Create and send an error packet (E [code] ) More... | |
Static Protected Member Functions | |
static int | checksum (const char *buf, size_t len) |
Calculate 8-bit checksum of a buffer. More... | |
static int | memRead (char *buf, size_t buf_len, uintptr_t addr, size_t len, bool hex) |
Read contents of system memory area into the buffer. More... | |
static int | memWrite (const char *buf, size_t buf_len, uintptr_t addr, size_t len, bool hex) |
Write buffer contents to system memory area. More... | |
static void | sysContinue () |
Continue program execution (at current instruction pointer) | |
static void | sysStep () |
Single step the next instruction. | |
Friends | |
void | gdb_interrupt_handler (DebugContext *context) |
Allow the generic GDB interrupt handler to access the protected methods of this class. More... | |
Additional Inherited Members | |
Public Types inherited from Serial | |
enum | ComPort { COM1 = 0x3f8 , COM2 = 0x2f8 , COM3 = 0x3e8 , COM4 = 0x2e8 } |
COM-Port. More... | |
enum | BaudRate { BAUD_300 = 384 , BAUD_600 = 192 , BAUD_1200 = 96 , BAUD_2400 = 48 , BAUD_4800 = 24 , BAUD_9600 = 12 , BAUD_19200 = 6 , BAUD_38400 = 3 , BAUD_57600 = 2 , BAUD_115200 = 1 } |
Transmission speed. More... | |
enum | DataBits { DATA_5BIT = 0 , DATA_6BIT = 1 , DATA_7BIT = 2 , DATA_8BIT = 3 } |
Number of data bits per character. | |
enum | StopBits { STOP_1BIT = 0 , STOP_1_5BIT = 4 , STOP_2BIT = 4 } |
Number of stop bits per character. | |
enum | Parity { PARITY_NONE = 0 , PARITY_ODD = 8 , PARITY_EVEN = 24 , PARITY_MARK = 40 , PARITY_SPACE = 56 } |
parity bit | |
Protected Attributes inherited from Serial | |
const ComPort | port |
Selected COM port. | |
Detailed Description
Remote stub for GNU Debugger (GDB)
Allows remote debugging of the operating system with GDB on real (bare metal) hardware (but also in the emulator) by implementing the main part of the GDB Remote Serial Protocols (RSP), installing own interrupt handler routines for traps and communicating with the GDB host over the serial port.
To use this feature, GDB must be started on the host with the identical kernel binary file as the operating system on the target hardware runs with – ideally in the kernels source code directory, because then the source code can be embedded in the debug output of the GDB host.
In addition, the settings for serial transmission must be identical on both hardware and GDB.
Example:
~> ssh i4stubs-serial cip6d0:~> cd mpstubs cip6d0:~/mpstubs> make netboot cip6d0:~/mpstubs> gdb .build/system64 GNU gdb (Debian 7.12-6) 7.12.0.20161007-git [...] Reading symbols from /proj/i4stubs/student/uj66ojab/kernel...done. (gdb) set arch i386:x86-64 (gdb) set serial baud 9600 (gdb) target remote /dev/ttyBS1 Remote debugging using /dev/ttyBS1 main () at main.cc:87
- Note
- The last (current) trap/interrupt vector handled by the GDB Stub can be queried inside the GDB shell using the command
print GDB_Stub::signal
. - GDB already comes with the i386-stub.c. However, it is ugly, poorly maintained and not very easy to integrate into this object-oriented operating system. Therefore we use a revised version of Matt Borgersons gdbstub (released 2016 under the GPL v2 license).
Constructor & Destructor Documentation
|
explicit |
constructor
configures interrupt handler and serial interface (as 8N1
)
- Parameters
-
wait Wait for a GDB connection after configuration debug_output Debug the stub by printing the communication on the DBG output (could be useful while extending the RSP) port COM port for the serial connection baud_rate Baud Rate, default for GDB is 9600
(can be a bottleneck)
Member Function Documentation
|
protected |
Handling traps.
Called by the generic debug interrupt handler after the current core state has been stored.
This contains the heart functionality of the GDB_Stub, including the communication with the GDB host.
|
protected |
Send a string via the serial connection.
- Parameters
-
buf Pointer to buffer len Size of buffer (or characters to transmit)
- Return values
-
0 on success -1 if no or not all bytes have been sent
|
protected |
Receive a string via the serial connection.
- Parameters
-
buf Pointer to buffer buf_len Size of buffer len Size of received characters
- Return values
-
0 on success -1 if no or not all bytes have been received
|
protected |
Transmits a packet of data.
Packets are of the form:
- Parameters
-
pkt_data Pointer to packet buffer pkt_len Size of packet buffer
- Return values
-
0 if the packet was transmitted and acknowledged 1 if the packet was transmitted but not acknowledged -1 otherwise
|
protected |
Receives a packet of data assuming a 7-bit clean connection.
- Parameters
-
pkt_buf Pointer to packet buffer pkt_buf_len Size of packet buffer pkt_len Size of packet to receive
- Return values
-
0 if the packet was received -1 otherwise
|
staticprotected |
Calculate 8-bit checksum of a buffer.
- Parameters
-
buf Pointer to buffer len Size of buffer
- Returns
- 8-bit checksum of buffer
|
protected |
Receive acknowledgment for a packet.
- Return values
-
0 received [positive] acknowledgment (ACK, +
)1 received negative acknowledgment (NACK, -
)-1 otherwise (invalid character)
|
protected |
Create and send an OK packet (OK
)
- Returns
- Status code returned from sendPacket
|
protected |
Create and send a signal packet (S [int]
)
- Parameters
-
buf Pointer to buffer buf_len Size of buffer signal Interrupt vector
- Returns
- Status code returned from sendPacket
|
protected |
Create and send an error packet (E [code]
)
- Parameters
-
buf Pointer to buffer buf_len Size of buffer error Error code
- Returns
- Status code returned from sendPacket
|
staticprotected |
Read contents of system memory area into the buffer.
- Parameters
-
buf Pointer to buffer buf_len Size of buffer addr Base address of system memory to read from len Size of memory area to read from hex Buffer content has hexadecimal ( true
) or binary (false
) encoding
- Returns
- Number of bytes read or
-1
on error (buffer to small)
|
staticprotected |
Write buffer contents to system memory area.
- Parameters
-
buf Pointer to buffer buf_len Size of buffer addr Base address of system memory to write at len Size of memory area to write at hex Buffer content has hexadecimal ( true
) or binary (false
) encoding
- Returns
- Number of written bytes or
-1
on error (buffer to big)
Friends And Related Function Documentation
|
friend |
Allow the generic GDB interrupt handler to access the protected methods of this class.
Similar to the default interrupt_handler. Called by the entry function written in assembly (see debug/gbd/handler.asm
) – these routines are installed in the constructor.
After preparing the data this function calls GDB_Stub::handle, which handles the communication with the host via the serial interface.
- Parameters
-
context contains a pointer to the stack, which can be used to access the debug interrupt context.
Member Data Documentation
|
static |
Last trap/interrupt vector handled in GDB.
store signal to simplify debugging
The documentation for this class was generated from the following files:
- debug/gdb/stub.h
- debug/gdb/handler.cc
- debug/gdb/protocol.cc