Commit fcedd920 authored by Alex Bennée's avatar Alex Bennée
Browse files

gdbstub/linux-user: support debugging over a unix socket 



While debugging over TCP is fairly straightforward now we have test
cases that want to orchestrate via make and currently a parallel build
fails as two processes can't use the same listening port. While system
emulation offers a wide cornucopia of connection methods thanks to the
chardev abstraction we are a little more limited for linux user.
Thankfully the programming API for a TCP socket and a local UNIX
socket is pretty much the same once it's set up.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Message-Id: <20200430190122.4592-7-alex.bennee@linaro.org>
parent e0a1e208

bsd-user/main.c

+4 −4
Original line number Diff line number Diff line
@@ -738,7 +738,7 @@ int main(int argc, char **argv) 
    CPUState *cpu;

    int optind;

    const char *r;

    int gdbstub_port = 0;

    const char *gdbstub = NULL;

    char **target_environ, **wrk;

    envlist_t *envlist = NULL;

    char *trace_file = NULL;
@@ -814,7 +814,7 @@ int main(int argc, char **argv) 
                exit(1);

            }

        } else if (!strcmp(r, "g")) {

            gdbstub_port = atoi(argv[optind++]);

            gdbstub = g_strdup(argv[optind++]);

        } else if (!strcmp(r, "r")) {

            qemu_uname_release = argv[optind++];

        } else if (!strcmp(r, "cpu")) {
@@ -1124,8 +1124,8 @@ int main(int argc, char **argv) 
#error unsupported target CPU

#endif



    if (gdbstub_port) {

        gdbserver_start (gdbstub_port);

    if (gdbstub) {

        gdbserver_start(gdbstub);

        gdb_handlesig(cpu, 0);

    }

    cpu_loop(env);

gdbstub.c

+87 −16
Original line number Diff line number Diff line
@@ -355,6 +355,7 @@ typedef struct GDBState { 
    int signal;

#ifdef CONFIG_USER_ONLY

    int fd;

    char *socket_path;

    int running_state;

#else

    CharBackend chr;
@@ -2962,6 +2963,9 @@ void gdb_exit(CPUArchState *env, int code) 
      return;

  }

#ifdef CONFIG_USER_ONLY

  if (gdbserver_state.socket_path) {

      unlink(gdbserver_state.socket_path);

  }

  if (gdbserver_state.fd < 0) {

      return;

  }
@@ -3066,7 +3070,66 @@ void gdb_signalled(CPUArchState *env, int sig) 
    put_packet(buf);

}



static bool gdb_accept(int gdb_fd)

static void gdb_accept_init(int fd)

{

    init_gdbserver_state();

    create_default_process(&gdbserver_state);

    gdbserver_state.processes[0].attached = true;

    gdbserver_state.c_cpu = gdb_first_attached_cpu();

    gdbserver_state.g_cpu = gdbserver_state.c_cpu;

    gdbserver_state.fd = fd;

    gdb_has_xml = false;

}



static bool gdb_accept_socket(int gdb_fd)

{

    int fd;



    for(;;) {

        fd = accept(gdb_fd, NULL, NULL);

        if (fd < 0 && errno != EINTR) {

            perror("accept socket");

            return false;

        } else if (fd >= 0) {

            qemu_set_cloexec(fd);

            break;

        }

    }



    gdb_accept_init(fd);

    return true;

}



static int gdbserver_open_socket(const char *path)

{

    struct sockaddr_un sockaddr;

    int fd, ret;



    fd = socket(AF_UNIX, SOCK_STREAM, 0);

    if (fd < 0) {

        perror("create socket");

        return -1;

    }



    sockaddr.sun_family = AF_UNIX;

    pstrcpy(sockaddr.sun_path, sizeof(sockaddr.sun_path) - 1, path);

    ret = bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr));

    if (ret < 0) {

        perror("bind socket");

        close(fd);

        return -1;

    }

    ret = listen(fd, 1);

    if (ret < 0) {

        perror("listen socket");

        close(fd);

        return -1;

    }



    return fd;

}



static bool gdb_accept_tcp(int gdb_fd)

{

    struct sockaddr_in sockaddr;

    socklen_t len;
@@ -3091,17 +3154,11 @@ static bool gdb_accept(int gdb_fd) 
        return false;

    }



    init_gdbserver_state();

    create_default_process(&gdbserver_state);

    gdbserver_state.processes[0].attached = true;

    gdbserver_state.c_cpu = gdb_first_attached_cpu();

    gdbserver_state.g_cpu = gdbserver_state.c_cpu;

    gdbserver_state.fd = fd;

    gdb_has_xml = false;

    gdb_accept_init(fd);

    return true;

}



static int gdbserver_open(int port)

static int gdbserver_open_port(int port)

{

    struct sockaddr_in sockaddr;

    int fd, ret;
@@ -3130,22 +3187,36 @@ static int gdbserver_open(int port) 
        close(fd);

        return -1;

    }



    return fd;

}



int gdbserver_start(int port)

int gdbserver_start(const char *port_or_path)

{

    int gdb_fd = gdbserver_open(port);

    int port = g_ascii_strtoull(port_or_path, NULL, 10);

    int gdb_fd;



    if (port > 0) {

        gdb_fd = gdbserver_open_port(port);

    } else {

        gdb_fd = gdbserver_open_socket(port_or_path);

    }



    if (gdb_fd < 0) {

        return -1;

    }

    /* accept connections */

    if (!gdb_accept(gdb_fd)) {



    if (port > 0 && gdb_accept_tcp(gdb_fd)) {

        return 0;

    } else if (gdb_accept_socket(gdb_fd)) {

        gdbserver_state.socket_path = g_strdup(port_or_path);

        return 0;

    }



    /* gone wrong */

    close(gdb_fd);

    return -1;

}

    return 0;

}



/* Disable gdb stub for child processes.  */

void gdbserver_fork(CPUState *cpu)

include/exec/gdbstub.h

+9 −5
Original line number Diff line number Diff line
@@ -177,11 +177,15 @@ static inline uint8_t * gdb_get_reg_ptr(GByteArray *buf, int len) 


#endif



#ifdef CONFIG_USER_ONLY

int gdbserver_start(int);

#else

int gdbserver_start(const char *port);

#endif

/**

 * gdbserver_start: start the gdb server

 * @port_or_device: connection spec for gdb

 *

 * For CONFIG_USER this is either a tcp port or a path to a fifo. For

 * system emulation you can use a full chardev spec for your gdbserver

 * port.

 */

int gdbserver_start(const char *port_or_device);



void gdbserver_cleanup(void);

linux-user/main.c

+6 −6
Original line number Diff line number Diff line
@@ -51,7 +51,7 @@ char *exec_path; 


int singlestep;

static const char *argv0;

static int gdbstub_port;

static const char *gdbstub;

static envlist_t *envlist;

static const char *cpu_model;

static const char *cpu_type;
@@ -310,7 +310,7 @@ static void handle_arg_seed(const char *arg) 


static void handle_arg_gdb(const char *arg)

{

    gdbstub_port = atoi(arg);

    gdbstub = g_strdup(arg);

}



static void handle_arg_uname(const char *arg)
@@ -861,10 +861,10 @@ int main(int argc, char **argv, char **envp) 


    target_cpu_copy_regs(env, regs);



    if (gdbstub_port) {

        if (gdbserver_start(gdbstub_port) < 0) {

            fprintf(stderr, "qemu: could not open gdbserver on port %d\n",

                    gdbstub_port);

    if (gdbstub) {

        if (gdbserver_start(gdbstub) < 0) {

            fprintf(stderr, "qemu: could not open gdbserver on %s\n",

                    gdbstub);

            exit(EXIT_FAILURE);

        }

        gdb_handlesig(cpu, 0);