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 <richard.henderson@linaro.org>

Reviewed-by: Warner Losh <imp@bsdimp.com>

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

---

gdbstub/user.c | 10 ++++++++++

1 file changed, 10 insertions(+)

diff --git a/gdbstub/user.c b/gdbstub/user.c

index XXXXXXX..XXXXXXX 100644

--- a/gdbstub/user.c

+++ b/gdbstub/user.c

@@ -XXX,XX +XXX,XX @@ 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");

--

2.47.0

In case an emulated process execve()s another emulated process, bind()

will fail, because the socket already exists. So try deleting it.

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 <iii@linux.ibm.com>

---

gdbstub/user.c | 1 +

1 file changed, 1 insertion(+)

diff --git a/gdbstub/user.c b/gdbstub/user.c

index XXXXXXX..XXXXXXX 100644

--- a/gdbstub/user.c

+++ b/gdbstub/user.c

@@ -XXX,XX +XXX,XX @@ static int gdbserver_open_socket(const char *path)

sockaddr.sun_family = AF_UNIX;

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

+ unlink(sockaddr.sun_path);

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

if (ret < 0) {

perror("bind socket");

--

2.47.0

gdbstub needs target_to_host_signal(), so move its declaration to a

public header.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Warner Losh <imp@bsdimp.com>

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

---

bsd-user/signal-common.h | 1 -

bsd-user/signal.c | 1 +

include/user/signal.h | 23 +++++++++++++++++++++++

linux-user/signal-common.h | 1 -

linux-user/signal.c | 1 +

linux-user/syscall.c | 1 +

6 files changed, 26 insertions(+), 2 deletions(-)

create mode 100644 include/user/signal.h

diff --git a/bsd-user/signal-common.h b/bsd-user/signal-common.h

index XXXXXXX..XXXXXXX 100644

--- a/bsd-user/signal-common.h

+++ b/bsd-user/signal-common.h

@@ -XXX,XX +XXX,XX @@ void process_pending_signals(CPUArchState *env);

void queue_signal(CPUArchState *env, int sig, int si_type,

target_siginfo_t *info);

void signal_init(void);

-int target_to_host_signal(int sig);

void target_to_host_sigset(sigset_t *d, const target_sigset_t *s);

/*

diff --git a/bsd-user/signal.c b/bsd-user/signal.c

index XXXXXXX..XXXXXXX 100644

--- a/bsd-user/signal.c

+++ b/bsd-user/signal.c

@@ -XXX,XX +XXX,XX @@

#include "qemu/log.h"

#include "qemu.h"

#include "exec/page-protection.h"

+#include "user/signal.h"

#include "user/tswap-target.h"

#include "gdbstub/user.h"

#include "signal-common.h"

diff --git a/include/user/signal.h b/include/user/signal.h

new file mode 100644

index XXXXXXX..XXXXXXX

--- /dev/null

+++ b/include/user/signal.h

@@ -XXX,XX +XXX,XX @@

+/*

+ * Signal-related declarations.

+ *

+ * SPDX-License-Identifier: GPL-2.0-or-later

+ */

+#ifndef USER_SIGNAL_H

+#define USER_SIGNAL_H

+

+#ifndef CONFIG_USER_ONLY

+#error Cannot include this header from system emulation

+#endif

+

+/**

+ * target_to_host_signal:

+ * @sig: target signal.

+ *

+ * On success, return the host signal between 0 (inclusive) and NSIG

+ * (exclusive) corresponding to the target signal @sig. Return any other value

+ * on failure.

+ */

+int target_to_host_signal(int sig);

+

+#endif

diff --git a/linux-user/signal-common.h b/linux-user/signal-common.h

index XXXXXXX..XXXXXXX 100644

--- a/linux-user/signal-common.h

+++ b/linux-user/signal-common.h

@@ -XXX,XX +XXX,XX @@ void queue_signal(CPUArchState *env, int sig, int si_type,

target_siginfo_t *info);

void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info);

void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo);

-int target_to_host_signal(int sig);

int host_to_target_signal(int sig);

long do_sigreturn(CPUArchState *env);

long do_rt_sigreturn(CPUArchState *env);

diff --git a/linux-user/signal.c b/linux-user/signal.c

index XXXXXXX..XXXXXXX 100644

--- a/linux-user/signal.c

+++ b/linux-user/signal.c

@@ -XXX,XX +XXX,XX @@

#include "signal-common.h"

#include "host-signal.h"

#include "user/safe-syscall.h"

+#include "user/signal.h"

#include "tcg/tcg.h"

/* target_siginfo_t must fit in gdbstub's siginfo save area. */

diff --git a/linux-user/syscall.c b/linux-user/syscall.c

index XXXXXXX..XXXXXXX 100644

--- a/linux-user/syscall.c

+++ b/linux-user/syscall.c

@@ -XXX,XX +XXX,XX @@

#include "loader.h"

#include "user-mmap.h"

#include "user/safe-syscall.h"

+#include "user/signal.h"

#include "qemu/guest-random.h"

#include "qemu/selfmap.h"

#include "user/syscall-trace.h"

--

2.47.0

Attaching to the gdbstub of a running process requires stopping its

threads. For threads that run on a CPU, cpu_exit() is enough, but the

only way to grab attention of a thread that is stuck in a long-running

syscall is to interrupt it with a signal.

Reserve a host realtime signal for this, just like it's already done

for TARGET_SIGABRT on Linux. This may reduce the number of available

guest realtime signals by one, but this is acceptable, since there are

quite a lot of them, and it's unlikely that there are apps that need

them all.

Set signal_pending for the safe_sycall machinery to prevent invoking

the syscall. This is a lie, since we don't queue a guest signal, but

process_pending_signals() can handle the absence of pending signals.

The syscall returns with QEMU_ERESTARTSYS errno, which arranges for

the automatic restart. This is important, because it helps avoiding

disturbing poorly written guests.

Reviewed-by: Warner Losh <imp@bsdimp.com>

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

---

bsd-user/signal.c | 12 ++++++++++++

include/user/signal.h | 2 ++

linux-user/signal.c | 25 ++++++++++++++++++++-----

3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/bsd-user/signal.c b/bsd-user/signal.c

index XXXXXXX..XXXXXXX 100644

--- a/bsd-user/signal.c

+++ b/bsd-user/signal.c

@@ -XXX,XX +XXX,XX @@ static inline int sas_ss_flags(TaskState *ts, unsigned long sp)

on_sig_stack(ts, sp) ? SS_ONSTACK : 0;

}

+int host_interrupt_signal = SIGRTMAX;

+

/*

* The BSD ABIs use the same signal numbers across all the CPU architectures, so

* (unlike Linux) these functions are just the identity mapping. This might not

@@ -XXX,XX +XXX,XX @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)

uintptr_t pc = 0;

bool sync_sig = false;

+ if (host_sig == host_interrupt_signal) {

+ ts->signal_pending = 1;

+ cpu_exit(thread_cpu);

+ return;

+ }

+

/*

* Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special

* handling wrt signal blocking and unwinding.

@@ -XXX,XX +XXX,XX @@ void signal_init(void)

for (i = 1; i <= TARGET_NSIG; i++) {

host_sig = target_to_host_signal(i);

+ if (host_sig == host_interrupt_signal) {

+ continue;

+ }

sigaction(host_sig, NULL, &oact);

if (oact.sa_sigaction == (void *)SIG_IGN) {

sigact_table[i - 1]._sa_handler = TARGET_SIG_IGN;

@@ -XXX,XX +XXX,XX @@ void signal_init(void)

sigaction(host_sig, &act, NULL);

}

}

+ sigaction(host_interrupt_signal, &act, NULL);

}

static void handle_pending_signal(CPUArchState *env, int sig,

diff --git a/include/user/signal.h b/include/user/signal.h

index XXXXXXX..XXXXXXX 100644

--- a/include/user/signal.h

+++ b/include/user/signal.h

@@ -XXX,XX +XXX,XX @@

*/

int target_to_host_signal(int sig);

+extern int host_interrupt_signal;

+

#endif

diff --git a/linux-user/signal.c b/linux-user/signal.c

index XXXXXXX..XXXXXXX 100644

--- a/linux-user/signal.c

+++ b/linux-user/signal.c

@@ -XXX,XX +XXX,XX @@ static int core_dump_signal(int sig)

}

}

+int host_interrupt_signal;

+

static void signal_table_init(const char *rtsig_map)

{

int hsig, tsig, count;

@@ -XXX,XX +XXX,XX @@ static void signal_table_init(const char *rtsig_map)

* Attempts for configure "missing" signals via sigaction will be

* silently ignored.

*

- * Reserve one signal for internal usage (see below).

+ * Reserve two signals for internal usage (see below).

*/

- hsig = SIGRTMIN + 1;

+ hsig = SIGRTMIN + 2;

for (tsig = TARGET_SIGRTMIN;

hsig <= SIGRTMAX && tsig <= TARGET_NSIG;

hsig++, tsig++) {

@@ -XXX,XX +XXX,XX @@ static void signal_table_init(const char *rtsig_map)

host_to_target_signal_table[SIGABRT] = 0;

for (hsig = SIGRTMIN; hsig <= SIGRTMAX; hsig++) {

if (!host_to_target_signal_table[hsig]) {

- host_to_target_signal_table[hsig] = TARGET_SIGABRT;

- break;

+ if (host_interrupt_signal) {

+ host_to_target_signal_table[hsig] = TARGET_SIGABRT;

+ break;

+ } else {

+ host_interrupt_signal = hsig;

+ }

}

}

if (hsig > SIGRTMAX) {

- fprintf(stderr, "No rt signals left for SIGABRT mapping\n");

+ fprintf(stderr,

+ "No rt signals left for interrupt and SIGABRT mapping\n");

exit(EXIT_FAILURE);

}

@@ -XXX,XX +XXX,XX @@ void signal_init(const char *rtsig_map)

}

sigact_table[tsig - 1]._sa_handler = thand;

}

+

+ sigaction(host_interrupt_signal, &act, NULL);

}

/* Force a synchronously taken signal. The kernel force_sig() function

@@ -XXX,XX +XXX,XX @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc)

bool sync_sig = false;

void *sigmask;

+ if (host_sig == host_interrupt_signal) {

+ ts->signal_pending = 1;

+ cpu_exit(thread_cpu);

+ return;

+ }

+

/*

* Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special

* handling wrt signal blocking and unwinding. Non-spoofed SIGILL,

--

2.47.0

Add a function for sending signals to individual threads. It does not make

sense on Windows, so do not provide an implementation, so that if someone

uses it by accident, they will get a linker error.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

Reviewed-by: Warner Losh <imp@bsidmp.com>

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

---

include/qemu/osdep.h | 9 +++++++++

util/oslib-posix.c | 15 +++++++++++++++

2 files changed, 24 insertions(+)

diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h

index XXXXXXX..XXXXXXX 100644

--- a/include/qemu/osdep.h

+++ b/include/qemu/osdep.h

@@ -XXX,XX +XXX,XX @@ bool qemu_write_pidfile(const char *pidfile, Error **errp);

int qemu_get_thread_id(void);

+/**

+ * qemu_kill_thread:

+ * @tid: thread id.

+ * @sig: host signal.

+ *

+ * Send @sig to one of QEMU's own threads with identifier @tid.

+ */

+int qemu_kill_thread(int tid, int sig);

+

#ifndef CONFIG_IOVEC

struct iovec {

void *iov_base;

diff --git a/util/oslib-posix.c b/util/oslib-posix.c

index XXXXXXX..XXXXXXX 100644

--- a/util/oslib-posix.c

+++ b/util/oslib-posix.c

@@ -XXX,XX +XXX,XX @@ int qemu_get_thread_id(void)

#endif

}

+int qemu_kill_thread(int tid, int sig)

+{

+#if defined(__linux__)

+ return syscall(__NR_tgkill, getpid(), tid, sig);

+#elif defined(__FreeBSD__)

+ return thr_kill2(getpid(), tid, sig);

+#elif defined(__NetBSD__)

+ return _lwp_kill(tid, sig);

+#elif defined(__OpenBSD__)

+ return thrkill(tid, sig, NULL);

+#else

+ return kill(tid, sig);

+#endif

+}

+

int qemu_daemon(int nochdir, int noclose)

{

return daemon(nochdir, noclose);

--

2.47.0

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 <iii@linux.ibm.com>

---

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 XXXXXXX..XXXXXXX 100644

--- a/bsd-user/main.c

+++ b/bsd-user/main.c

@@ -XXX,XX +XXX,XX @@ 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 XXXXXXX..XXXXXXX 100644

--- a/gdbstub/user.c

+++ b/gdbstub/user.c

@@ -XXX,XX +XXX,XX @@

*/

#include "qemu/osdep.h"

+#include <sys/syscall.h>

#include "qemu/bitops.h"

#include "qemu/cutils.h"

#include "qemu/sockets.h"

@@ -XXX,XX +XXX,XX @@

#include "gdbstub/user.h"

#include "gdbstub/enums.h"

#include "hw/core/cpu.h"

+#include "user/signal.h"

#include "trace.h"

#include "internals.h"

@@ -XXX,XX +XXX,XX @@ 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 {

@@ -XXX,XX +XXX,XX @@ 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 XXXXXXX..XXXXXXX 100644

--- a/linux-user/main.c

+++ b/linux-user/main.c

@@ -XXX,XX +XXX,XX @@ int main(int argc, char **argv, char **envp)

gdbstub);

exit(EXIT_FAILURE);

}

- gdb_handlesig(cpu, 0, NULL, NULL, 0);

}

#ifdef CONFIG_SEMIHOSTING

--

2.47.0

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

---

docs/user/main.rst | 16 +++++++++++++---

1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/docs/user/main.rst b/docs/user/main.rst

index XXXXXXX..XXXXXXX 100644

--- a/docs/user/main.rst

+++ b/docs/user/main.rst

@@ -XXX,XX +XXX,XX @@ Command line options

::

- qemu-i386 [-h] [-d] [-L path] [-s size] [-cpu model] [-g port] [-B offset] [-R size] program [arguments...]

+ qemu-i386 [-h] [-d] [-L path] [-s size] [-cpu model] [-g endpoint] [-B offset] [-R size] program [arguments...]

``-h``

Print the help

@@ -XXX,XX +XXX,XX @@ Debug options:

Activate logging of the specified items (use '-d help' for a list of

log items)

-``-g port``

- Wait gdb connection to port

+``-g endpoint``

+ Wait gdb connection to a port (e.g., ``1234``) or a unix socket (e.g.,

+ ``/tmp/qemu.sock``).

+

+ If a unix socket path contains single ``%d`` placeholder (e.g.,

+ ``/tmp/qemu-%d.sock``), it is replaced by the emulator PID, which is useful

+ when passing this option via the ``QEMU_GDB`` environment variable to a

+ multi-process application.

+

+ If the endpoint address is followed by ``,suspend=n`` (e.g.,

+ ``1234,suspend=n``), then the emulated program starts without waiting for a

+ connection, which can be established at any later point in time.

``-one-insn-per-tb``

Run the emulation with one guest instruction per translation block.

--

2.47.0

Add a small test to prevent regressions.

Make sure that host_interrupt_signal is not visible to the guest.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>

---

tests/guest-debug/run-test.py | 15 ++++++--

tests/tcg/multiarch/Makefile.target | 9 ++++-

tests/tcg/multiarch/gdbstub/late-attach.py | 28 +++++++++++++++

tests/tcg/multiarch/late-attach.c | 41 ++++++++++++++++++++++

4 files changed, 90 insertions(+), 3 deletions(-)

create mode 100644 tests/tcg/multiarch/gdbstub/late-attach.py

create mode 100644 tests/tcg/multiarch/late-attach.c

diff --git a/tests/guest-debug/run-test.py b/tests/guest-debug/run-test.py

index XXXXXXX..XXXXXXX 100755

--- a/tests/guest-debug/run-test.py

+++ b/tests/guest-debug/run-test.py

@@ -XXX,XX +XXX,XX @@ def get_args():

parser.add_argument("--gdb-args", help="Additional gdb arguments")

parser.add_argument("--output", help="A file to redirect output to")

parser.add_argument("--stderr", help="A file to redirect stderr to")

+ parser.add_argument("--no-suspend", action="store_true",

+ help="Ask the binary to not wait for GDB connection")

return parser.parse_args()

@@ -XXX,XX +XXX,XX @@ def log(output, msg):

# Launch QEMU with binary

if "system" in args.qemu:

+ if args.no_suspend:

+ suspend = ''

+ else:

+ suspend = ' -S'

cmd = f'{args.qemu} {args.qargs} {args.binary}' \

- f' -S -gdb unix:path={socket_name},server=on'

+ f'{suspend} -gdb unix:path={socket_name},server=on'

else:

- cmd = f'{args.qemu} {args.qargs} -g {socket_name} {args.binary}'

+ if args.no_suspend:

+ suspend = ',suspend=n'

+ else:

+ suspend = ''

+ cmd = f'{args.qemu} {args.qargs} -g {socket_name}{suspend}' \

+ f' {args.binary}'

log(output, "QEMU CMD: %s" % (cmd))

inferior = subprocess.Popen(shlex.split(cmd))

diff --git a/tests/tcg/multiarch/Makefile.target b/tests/tcg/multiarch/Makefile.target

index XXXXXXX..XXXXXXX 100644

--- a/tests/tcg/multiarch/Makefile.target

+++ b/tests/tcg/multiarch/Makefile.target

@@ -XXX,XX +XXX,XX @@ run-gdbstub-follow-fork-mode-parent: follow-fork-mode

        --bin $< --test $(MULTIARCH_SRC)/gdbstub/follow-fork-mode-parent.py, \

    following parents on fork)

+run-gdbstub-late-attach: late-attach

+    $(call run-test, $@, env LATE_ATTACH_PY=1 $(GDB_SCRIPT) \

+        --gdb $(GDB) \

+        --qemu $(QEMU) --qargs "$(QEMU_OPTS)" --no-suspend \

+        --bin $< --test $(MULTIARCH_SRC)/gdbstub/late-attach.py, \

+    attaching to a running process)

+

else

run-gdbstub-%:

    $(call skip-test, "gdbstub test $*", "need working gdb with $(patsubst -%,,$(TARGET_NAME)) support")

@@ -XXX,XX +XXX,XX @@ EXTRA_RUNS += run-gdbstub-sha1 run-gdbstub-qxfer-auxv-read \

     run-gdbstub-registers run-gdbstub-prot-none \

     run-gdbstub-catch-syscalls run-gdbstub-follow-fork-mode-child \

     run-gdbstub-follow-fork-mode-parent \

-     run-gdbstub-qxfer-siginfo-read

+     run-gdbstub-qxfer-siginfo-read run-gdbstub-late-attach

# ARM Compatible Semi Hosting Tests

#

diff --git a/tests/tcg/multiarch/gdbstub/late-attach.py b/tests/tcg/multiarch/gdbstub/late-attach.py

new file mode 100644

index XXXXXXX..XXXXXXX

--- /dev/null

+++ b/tests/tcg/multiarch/gdbstub/late-attach.py

@@ -XXX,XX +XXX,XX @@

+"""Test attaching GDB to a running process.

+

+SPDX-License-Identifier: GPL-2.0-or-later

+"""

+from test_gdbstub import main, report

+

+

+def run_test():

+ """Run through the tests one by one"""

+ try:

+ phase = gdb.parse_and_eval("phase").string()

+ except gdb.error:

+ # Assume the guest did not reach main().

+ phase = "start"

+

+ if phase == "start":

+ gdb.execute("break sigwait")

+ gdb.execute("continue")

+ phase = gdb.parse_and_eval("phase").string()

+ report(phase == "sigwait", "{} == \"sigwait\"".format(phase))

+

+ gdb.execute("signal SIGUSR1")

+

+ exitcode = int(gdb.parse_and_eval("$_exitcode"))

+ report(exitcode == 0, "{} == 0".format(exitcode))

+

+

+main(run_test)

diff --git a/tests/tcg/multiarch/late-attach.c b/tests/tcg/multiarch/late-attach.c

new file mode 100644

index XXXXXXX..XXXXXXX

--- /dev/null

+++ b/tests/tcg/multiarch/late-attach.c

@@ -XXX,XX +XXX,XX @@

+/*

+ * Test attaching GDB to a running process.

+ *

+ * SPDX-License-Identifier: GPL-2.0-or-later

+ */

+#include <assert.h>

+#include <signal.h>

+#include <stdio.h>

+#include <stdlib.h>

+

+static const char *phase = "start";

+

+int main(void)

+{

+ sigset_t set;

+ int sig;

+

+ assert(sigfillset(&set) == 0);

+ assert(sigprocmask(SIG_BLOCK, &set, NULL) == 0);

+

+ /* Let GDB know it can send SIGUSR1. */

+ phase = "sigwait";

+ if (getenv("LATE_ATTACH_PY")) {

+ assert(sigwait(&set, &sig) == 0);

+ if (sig != SIGUSR1) {

+ fprintf(stderr, "Unexpected signal %d\n", sig);

+ return EXIT_FAILURE;

+ }

+ }

+

+ /* Check that the guest does not see host_interrupt_signal. */

+ assert(sigpending(&set) == 0);

+ for (sig = 1; sig < NSIG; sig++) {

+ if (sigismember(&set, sig)) {

+ fprintf(stderr, "Unexpected signal %d\n", sig);

+ return EXIT_FAILURE;

+ }

+ }

+

+ return EXIT_SUCCESS;

+}

--

2.47.0