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Thu, 24 Oct 2024 20:00:36 +0000 (GMT) From: Ilya Leoshkevich To: Warner Losh , Riku Voipio , Laurent Vivier , Paolo Bonzini , Richard Henderson Cc: Kyle Evans , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, Ilya Leoshkevich Subject: [PATCH 6/8] gdbstub: Allow late attachment Date: Thu, 24 Oct 2024 21:59:13 +0200 Message-ID: <20241024200031.80327-7-iii@linux.ibm.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241024200031.80327-1-iii@linux.ibm.com> References: <20241024200031.80327-1-iii@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: wcx3YXcHizn-R8c8cfACB8Ba3G1cNo4- X-Proofpoint-GUID: wcx3YXcHizn-R8c8cfACB8Ba3G1cNo4- X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1051,Hydra:6.0.680,FMLib:17.12.62.30 definitions=2024-10-15_01,2024-10-11_01,2024-09-30_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 bulkscore=0 mlxlogscore=798 spamscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 phishscore=0 impostorscore=0 adultscore=0 suspectscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2409260000 definitions=main-2410240159 Received-SPF: pass client-ip=148.163.156.1; envelope-from=iii@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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 --- bsd-user/main.c | 1 - gdbstub/user.c | 120 ++++++++++++++++++++++++++++++++++++++++++---- linux-user/main.c | 1 - 3 files changed, 110 insertions(+), 12 deletions(-) diff --git a/bsd-user/main.c b/bsd-user/main.c index cc980e6f401..7c2f8e4e96e 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -618,7 +618,6 @@ int main(int argc, char **argv) if (gdbstub) { gdbserver_start(gdbstub); - gdb_handlesig(cpu, 0, NULL, NULL, 0); } cpu_loop(env); /* never exits */ diff --git a/gdbstub/user.c b/gdbstub/user.c index 26b25b1b7e9..455ecd6f831 100644 --- a/gdbstub/user.c +++ b/gdbstub/user.c @@ -10,6 +10,7 @@ */ #include "qemu/osdep.h" +#include #include "qemu/bitops.h" #include "qemu/cutils.h" #include "qemu/sockets.h" @@ -21,6 +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" @@ -416,11 +418,101 @@ static int gdbserver_open_port(int port) return fd; } -int gdbserver_start(const char *port_or_path) +static bool gdbserver_accept(int port, int gdb_fd, const char *port_or_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(port_or_path); + } + } + + if (!ret) { + close(gdb_fd); + } + + return ret; +} + +struct { + int port; int gdb_fd; + char *port_or_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.port_or_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.port_or_path); + + return NULL; +} + +__attribute__((__format__(__printf__, 1, 2))) +static void print_usage(const char *format, ...) +{ + va_list ap; + + va_start(ap, format); + vfprintf(stderr, format, ap); + va_end(ap); + fprintf(stderr, "Usage: -g {port|path}[,suspend={y|n}]\n"); +} + +#define SUSPEND "suspend=" + +int gdbserver_start(const char *args) +{ + 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++) { + if (g_str_has_prefix(*arg, SUSPEND)) { + const char *val = *arg + strlen(SUSPEND); + + suspend = (strcmp(val, "y") == 0); + if (!suspend && (strcmp(val, "n") != 0)) { + print_usage("Bad option value: %s", *arg); + return -1; + } + } else { + if (port_or_path) { + print_usage("Unknown option: %s", *arg); + return -1; + } + port_or_path = *arg; + } + } + if (!port_or_path) { + print_usage("Port or path not specified"); + return -1; + } + + port = g_ascii_strtoull(port_or_path, NULL, 10); if (port > 0) { gdb_fd = gdbserver_open_port(port); } else { @@ -431,16 +523,24 @@ int gdbserver_start(const char *port_or_path) return -1; } - if (port > 0 && gdb_accept_tcp(gdb_fd)) { - return 0; - } 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 0; + } else { + return -1; + } + } else { + QemuThread thread; + + gdbserver_args.port = port; + gdbserver_args.gdb_fd = gdb_fd; + gdbserver_args.port_or_path = g_strdup(port_or_path); + qemu_thread_create(&thread, "gdb-accept", + &gdbserver_accept_thread, NULL, + QEMU_THREAD_DETACHED); return 0; } - - /* gone wrong */ - close(gdb_fd); - return -1; } void gdbserver_fork_start(void) diff --git a/linux-user/main.c b/linux-user/main.c index 8143a0d4b02..db54925a6c9 100644 --- a/linux-user/main.c +++ b/linux-user/main.c @@ -1017,7 +1017,6 @@ int main(int argc, char **argv, char **envp) gdbstub); exit(EXIT_FAILURE); } - gdb_handlesig(cpu, 0, NULL, NULL, 0); } #ifdef CONFIG_SEMIHOSTING