From 9853485dd420a567500019752d011cc8d38f7199 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Fri, 7 Feb 2025 15:31:05 +0000 Subject: gdbstub: Allow the %d placeholder in the socket path MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Just like for QEMU_LOG_FILENAME, replace %d with PID in the GDB socket path. This allows running multi-process applications with, e.g., export QEMU_GDB=/tmp/qemu-%d.sock. Currently this is not possible, since the first process will cause the subsequent ones to fail due to not being able to bind() the GDB socket. Reviewed-by: Richard Henderson Reviewed-by: Warner Losh Signed-off-by: Ilya Leoshkevich Message-Id: <20250117001542.8290-2-iii@linux.ibm.com> Signed-off-by: Alex Bennée Message-Id: <20250207153112.3939799-11-alex.bennee@linaro.org> --- gdbstub/user.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'gdbstub/user.c') diff --git a/gdbstub/user.c b/gdbstub/user.c index c2bdfc3d49..fd29d595f4 100644 --- a/gdbstub/user.c +++ b/gdbstub/user.c @@ -317,9 +317,19 @@ static bool gdb_accept_socket(int gdb_fd) static int gdbserver_open_socket(const char *path) { + g_autoptr(GString) buf = g_string_new(""); struct sockaddr_un sockaddr = {}; + char *pid_placeholder; int fd, ret; + pid_placeholder = strstr(path, "%d"); + if (pid_placeholder != NULL) { + g_string_append_len(buf, path, pid_placeholder - path); + g_string_append_printf(buf, "%d", qemu_get_thread_id()); + g_string_append(buf, pid_placeholder + 2); + path = buf->str; + } + fd = socket(AF_UNIX, SOCK_STREAM, 0); if (fd < 0) { perror("create socket"); -- cgit 1.4.1 From fccb744f41c69fec6fd92225fe907c6e69de5d44 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Fri, 7 Feb 2025 15:31:06 +0000 Subject: gdbstub: Try unlinking the unix socket before binding MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In case an emulated process execve()s another emulated process, bind() will fail, because the socket already exists. So try deleting it. Use the existing unix_listen() function which does this. Link qemu-user with qemu-sockets.c and add the monitor_get_fd() stub. Note that it is not possible to handle this in do_execv(): deleting gdbserver_user_state.socket_path before safe_execve() is not correct, because the latter may fail, and afterwards we may lose control. Signed-off-by: Ilya Leoshkevich Reviewed-by: Alex Bennée Message-Id: <20250117001542.8290-3-iii@linux.ibm.com> Signed-off-by: Alex Bennée Message-Id: <20250207153112.3939799-12-alex.bennee@linaro.org> --- gdbstub/user.c | 29 +++-------------------------- stubs/meson.build | 2 ++ stubs/monitor-fd.c | 9 +++++++++ util/meson.build | 2 ++ 4 files changed, 16 insertions(+), 26 deletions(-) create mode 100644 stubs/monitor-fd.c (limited to 'gdbstub/user.c') diff --git a/gdbstub/user.c b/gdbstub/user.c index fd29d595f4..8225b70280 100644 --- a/gdbstub/user.c +++ b/gdbstub/user.c @@ -315,12 +315,10 @@ static bool gdb_accept_socket(int gdb_fd) return true; } -static int gdbserver_open_socket(const char *path) +static int gdbserver_open_socket(const char *path, Error **errp) { g_autoptr(GString) buf = g_string_new(""); - struct sockaddr_un sockaddr = {}; char *pid_placeholder; - int fd, ret; pid_placeholder = strstr(path, "%d"); if (pid_placeholder != NULL) { @@ -330,28 +328,7 @@ static int gdbserver_open_socket(const char *path) path = buf->str; } - 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; + return unix_listen(path, errp); } static bool gdb_accept_tcp(int gdb_fd) @@ -424,7 +401,7 @@ bool gdbserver_start(const char *port_or_path, Error **errp) if (port > 0) { gdb_fd = gdbserver_open_port(port, errp); } else { - gdb_fd = gdbserver_open_socket(port_or_path); + gdb_fd = gdbserver_open_socket(port_or_path, errp); } if (gdb_fd < 0) { diff --git a/stubs/meson.build b/stubs/meson.build index a8b3aeb564..b0fee37e05 100644 --- a/stubs/meson.build +++ b/stubs/meson.build @@ -61,6 +61,8 @@ if have_user if not have_system stub_ss.add(files('qdev.c')) endif + + stub_ss.add(files('monitor-fd.c')) endif if have_system diff --git a/stubs/monitor-fd.c b/stubs/monitor-fd.c new file mode 100644 index 0000000000..9bb6749885 --- /dev/null +++ b/stubs/monitor-fd.c @@ -0,0 +1,9 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include "qemu/osdep.h" +#include "monitor/monitor.h" + +int monitor_get_fd(Monitor *mon, const char *fdname, Error **errp) +{ + abort(); +} diff --git a/util/meson.build b/util/meson.build index 5d8bef9891..780b5977a8 100644 --- a/util/meson.build +++ b/util/meson.build @@ -84,6 +84,8 @@ if have_block or have_ga util_ss.add(files('qemu-coroutine.c', 'qemu-coroutine-lock.c', 'qemu-coroutine-io.c')) util_ss.add(files(f'coroutine-@coroutine_backend@.c')) util_ss.add(files('thread-pool.c', 'qemu-timer.c')) +endif +if have_block or have_ga or have_user util_ss.add(files('qemu-sockets.c')) endif if have_block -- cgit 1.4.1 From d156d5d1df12a73e06092dc5fa6595d6f16f8521 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Fri, 7 Feb 2025 15:31:10 +0000 Subject: gdbstub: Allow late attachment MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Allow debugging individual processes in multi-process applications by starting them with export QEMU_GDB=/tmp/qemu-%d.sock,suspend=n. Currently one would have to attach to every process to ensure the app makes progress. In case suspend=n is not specified, the flow remains unchanged. If it is specified, then accepting the client connection is delegated to a thread. In the future this machinery may be reused for handling reconnections and interruptions. On accepting a connection, the thread schedules gdb_handlesig() on the first CPU and wakes it up with host_interrupt_signal. Note that the result of this gdb_handlesig() invocation is handled, as opposed to many other existing call sites. These other call sites probably need to be fixed separately. Signed-off-by: Ilya Leoshkevich Message-Id: <20250117001542.8290-7-iii@linux.ibm.com> Signed-off-by: Alex Bennée Message-Id: <20250207153112.3939799-16-alex.bennee@linaro.org> --- bsd-user/main.c | 1 - gdbstub/user.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++------ linux-user/main.c | 1 - 3 files changed, 103 insertions(+), 14 deletions(-) (limited to 'gdbstub/user.c') diff --git a/bsd-user/main.c b/bsd-user/main.c index b2f6a9be2f..fdb160bed0 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -629,7 +629,6 @@ int main(int argc, char **argv) if (gdbstub) { gdbserver_start(gdbstub, &error_fatal); - gdb_handlesig(cpu, 0, NULL, NULL, 0); } cpu_loop(env); /* never exits */ diff --git a/gdbstub/user.c b/gdbstub/user.c index 8225b70280..3730f32c41 100644 --- a/gdbstub/user.c +++ b/gdbstub/user.c @@ -22,6 +22,7 @@ #include "gdbstub/user.h" #include "gdbstub/enums.h" #include "hw/core/cpu.h" +#include "user/signal.h" #include "trace.h" #include "internals.h" @@ -393,32 +394,122 @@ static int gdbserver_open_port(int port, Error **errp) return fd; } -bool gdbserver_start(const char *port_or_path, Error **errp) +static bool gdbserver_accept(int port, int gdb_fd, const char *path) { - int port = g_ascii_strtoull(port_or_path, NULL, 10); + bool ret; + + if (port > 0) { + ret = gdb_accept_tcp(gdb_fd); + } else { + ret = gdb_accept_socket(gdb_fd); + if (ret) { + gdbserver_user_state.socket_path = g_strdup(path); + } + } + + if (!ret) { + close(gdb_fd); + } + + return ret; +} + +struct { + int port; int gdb_fd; + char *path; +} gdbserver_args; + +static void do_gdb_handlesig(CPUState *cs, run_on_cpu_data arg) +{ + int sig; + + sig = target_to_host_signal(gdb_handlesig(cs, 0, NULL, NULL, 0)); + if (sig >= 1 && sig < NSIG) { + qemu_kill_thread(gdb_get_cpu_index(cs), sig); + } +} + +static void *gdbserver_accept_thread(void *arg) +{ + if (gdbserver_accept(gdbserver_args.port, gdbserver_args.gdb_fd, + gdbserver_args.path)) { + CPUState *cs = first_cpu; + + async_safe_run_on_cpu(cs, do_gdb_handlesig, RUN_ON_CPU_NULL); + qemu_kill_thread(gdb_get_cpu_index(cs), host_interrupt_signal); + } + + g_free(gdbserver_args.path); + gdbserver_args.path = NULL; + + return NULL; +} +#define USAGE "\nUsage: -g {port|path}[,suspend={y|n}]" + +bool gdbserver_start(const char *args, Error **errp) +{ + g_auto(GStrv) argv = g_strsplit(args, ",", 0); + const char *port_or_path = NULL; + bool suspend = true; + int gdb_fd, port; + GStrv arg; + + for (arg = argv; *arg; arg++) { + g_auto(GStrv) tokens = g_strsplit(*arg, "=", 2); + + if (g_strcmp0(tokens[0], "suspend") == 0) { + if (tokens[1] == NULL) { + error_setg(errp, + "gdbstub: missing \"suspend\" option value" USAGE); + return false; + } else if (!qapi_bool_parse(tokens[0], tokens[1], + &suspend, errp)) { + return false; + } + } else { + if (port_or_path) { + error_setg(errp, "gdbstub: unknown option \"%s\"" USAGE, *arg); + return false; + } + port_or_path = *arg; + } + } + if (!port_or_path) { + error_setg(errp, "gdbstub: port or path not specified" USAGE); + return false; + } + + port = g_ascii_strtoull(port_or_path, NULL, 10); if (port > 0) { gdb_fd = gdbserver_open_port(port, errp); } else { gdb_fd = gdbserver_open_socket(port_or_path, errp); } - if (gdb_fd < 0) { return false; } - if (port > 0 && gdb_accept_tcp(gdb_fd)) { - return true; - } else if (gdb_accept_socket(gdb_fd)) { - gdbserver_user_state.socket_path = g_strdup(port_or_path); + if (suspend) { + if (gdbserver_accept(port, gdb_fd, port_or_path)) { + gdb_handlesig(first_cpu, 0, NULL, NULL, 0); + return true; + } else { + error_setg(errp, "gdbstub: failed to accept connection"); + return false; + } + } else { + QemuThread thread; + + gdbserver_args.port = port; + gdbserver_args.gdb_fd = gdb_fd; + gdbserver_args.path = g_strdup(port_or_path); + qemu_thread_create(&thread, "gdb-accept", + &gdbserver_accept_thread, NULL, + QEMU_THREAD_DETACHED); return true; } - - /* gone wrong */ - close(gdb_fd); - error_setg(errp, "gdbstub: failed to accept connection"); - return false; } void gdbserver_fork_start(void) diff --git a/linux-user/main.c b/linux-user/main.c index 7198fa0986..5c74c52cc5 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -1024,7 +1024,6 @@ int main(int argc, char **argv, char **envp) if (gdbstub) { gdbserver_start(gdbstub, &error_fatal); - gdb_handlesig(cpu, 0, NULL, NULL, 0); } #ifdef CONFIG_SEMIHOSTING -- cgit 1.4.1