From fcedd920867b8eb26ec803901a24db53a38882c5 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Thu, 30 Apr 2020 20:01:19 +0100 Subject: [PATCH] gdbstub/linux-user: support debugging over a unix socket MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: Alex Bennée Reviewed-by: Richard Henderson Message-Id: <20200430190122.4592-7-alex.bennee@linaro.org> --- bsd-user/main.c | 8 ++-- gdbstub.c | 103 ++++++++++++++++++++++++++++++++++------- include/exec/gdbstub.h | 14 ++++-- linux-user/main.c | 12 ++--- 4 files changed, 106 insertions(+), 31 deletions(-) diff --git a/bsd-user/main.c b/bsd-user/main.c index 770c2b267a..28f122b80e 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -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); diff --git a/gdbstub.c b/gdbstub.c index b5381aa520..6950fd243f 100644 --- a/gdbstub.c +++ b/gdbstub.c @@ -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; @@ -3130,21 +3187,35 @@ 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)) { - close(gdb_fd); - return -1; + + 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; } - return 0; + + /* gone wrong */ + close(gdb_fd); + return -1; } /* Disable gdb stub for child processes. */ diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h index 4a2b8e3089..94d8f83e92 100644 --- a/include/exec/gdbstub.h +++ b/include/exec/gdbstub.h @@ -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); diff --git a/linux-user/main.c b/linux-user/main.c index 22578b1633..2cd443237d 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -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);