From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Szabolcs Nagy <szabolcs.nagy@arm.com>,
"H . J . Lu" <hjl.tools@gmail.com>
Cc: Christian Brauner <brauner@kernel.org>
Subject: [PATCH v2 04/11] linux: Add clone3 CLONE_CLEAR_SIGHAND optimization to posix_spawn
Date: Fri, 4 Nov 2022 16:01:05 -0300 [thread overview]
Message-ID: <20221104190112.2566409-5-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20221104190112.2566409-1-adhemerval.zanella@linaro.org>
The clone3 flag resets all signal handlers of the child not set to
SIG_IGN to SIG_DFL. It allows to skip most of the sigaction calls
to setup child signal handling, where previously a posix_spawn
has to issue 2 times NSIG sigaction calls (one to obtain the current
disposition and another to set either SIG_DFL or SIG_IGN).
The expection is POSIX_SPAWN_SETSIGDEF the child still setup the
signal for the case the disposition is SIG_IGN.
It also need to handle the fallback where clone3 is not available,
to set the fallback in child. This is done by splitting of
__clone_internal_fallback from __clone_internal.
Checked on x86_64-linux-gnu.
---
include/clone_internal.h | 5 +
posix/Makefile | 3 +-
posix/tst-spawn7.c | 179 +++++++++++++++++++++++
sysdeps/unix/sysv/linux/Makefile | 3 +-
sysdeps/unix/sysv/linux/clone-internal.c | 37 +++--
sysdeps/unix/sysv/linux/clone3.h | 7 +
sysdeps/unix/sysv/linux/spawni.c | 31 ++--
7 files changed, 238 insertions(+), 27 deletions(-)
create mode 100644 posix/tst-spawn7.c
diff --git a/include/clone_internal.h b/include/clone_internal.h
index 5a48c7caa5..81292b3eb1 100644
--- a/include/clone_internal.h
+++ b/include/clone_internal.h
@@ -26,6 +26,11 @@ extern int __clone3 (struct clone_args *__cl_args, size_t __size,
fall back to clone or clone2. */
extern int __clone_internal (struct clone_args *__cl_args,
int (*__func) (void *__arg), void *__arg);
+/* The fallback code which calls clone/clone2 based on clone3 arguments. */
+extern int __clone_internal_fallback (struct clone_args *__cl_args,
+ int (*__func) (void *__arg),
+ void *__arg)
+ attribute_hidden;
#ifndef _ISOMAC
libc_hidden_proto (__clone3)
diff --git a/posix/Makefile b/posix/Makefile
index 4d60449426..6e61ce50f2 100644
--- a/posix/Makefile
+++ b/posix/Makefile
@@ -109,7 +109,7 @@ tests := test-errno tstgetopt testfnm runtests runptests \
tst-glob-tilde test-ssize-max tst-spawn4 bug-regex37 \
bug-regex38 tst-regcomp-truncated tst-spawn-chdir \
tst-wordexp-nocmd tst-execveat tst-spawn5 \
- tst-sched_getaffinity tst-spawn6
+ tst-sched_getaffinity tst-spawn6 tst-spawn7
# Test for the glob symbol version that was replaced in glibc 2.27.
ifeq ($(have-GLIBC_2.26)$(build-shared),yesyes)
@@ -291,6 +291,7 @@ tst-spawn-ARGS = -- $(host-test-program-cmd)
tst-spawn-static-ARGS = $(tst-spawn-ARGS)
tst-spawn5-ARGS = -- $(host-test-program-cmd)
tst-spawn6-ARGS = -- $(host-test-program-cmd)
+tst-spawn7-ARGS = -- $(host-test-program-cmd)
tst-dir-ARGS = `pwd` `cd $(common-objdir)/$(subdir); pwd` `cd $(common-objdir); pwd` $(objpfx)tst-dir
tst-chmod-ARGS = $(objdir)
tst-vfork3-ARGS = --test-dir=$(objpfx)
diff --git a/posix/tst-spawn7.c b/posix/tst-spawn7.c
new file mode 100644
index 0000000000..7cb7347c58
--- /dev/null
+++ b/posix/tst-spawn7.c
@@ -0,0 +1,179 @@
+/* Tests for posix_spawn signal handling.
+ Copyright (C) 2022 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <assert.h>
+#include <getopt.h>
+#include <spawn.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/xsignal.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+/* Nonzero if the program gets called via `exec'. */
+#define CMDLINE_OPTIONS \
+ { "restart", no_argument, &restart, 1 },
+static int restart;
+
+/* Hold the four initial argument used to respawn the process, plus the extra
+ '--direct', '--restart', the check type ('SIG_IGN' or 'SIG_DFL'), and a
+ final NULL. */
+static char *spargs[8];
+static int check_type_argc;
+
+/* Called on process re-execution. */
+_Noreturn static void
+handle_restart (int argc, char *argv[])
+{
+ assert (argc == 1);
+
+ if (strcmp (argv[0], "SIG_DFL") == 0)
+ {
+ for (int i = 1; i < NSIG; i++)
+ {
+ struct sigaction sa;
+ int r = sigaction (i, NULL, &sa);
+ /* Skip internal signals (such as SIGCANCEL). */
+ if (r == -1)
+ continue;
+ TEST_VERIFY_EXIT (sa.sa_handler == SIG_DFL);
+ }
+ exit (EXIT_SUCCESS);
+ }
+ else if (strcmp (argv[0], "SIG_IGN") == 0)
+ {
+ for (int i = 1; i < NSIG; i++)
+ {
+ struct sigaction sa;
+ int r = sigaction (i, NULL, &sa);
+ /* Skip internal signals (such as SIGCANCEL). */
+ if (r == -1)
+ continue;
+ if (i == SIGUSR1 || i == SIGUSR2)
+ TEST_VERIFY_EXIT (sa.sa_handler == SIG_IGN);
+ else
+ TEST_VERIFY_EXIT (sa.sa_handler == SIG_DFL);
+ }
+ exit (EXIT_SUCCESS);
+ }
+
+ exit (EXIT_FAILURE);
+}
+
+static void
+spawn_signal_test (const char *type, const posix_spawnattr_t *attr)
+{
+ spargs[check_type_argc] = (char*) type;
+
+ pid_t pid;
+ int status;
+
+ TEST_COMPARE (posix_spawn (&pid, spargs[0], NULL, attr, spargs, environ), 0);
+ TEST_COMPARE (xwaitpid (pid, &status, 0), pid);
+ TEST_VERIFY (WIFEXITED (status));
+ TEST_VERIFY (!WIFSIGNALED (status));
+ TEST_COMPARE (WEXITSTATUS (status), 0);
+}
+
+static void
+dummy_sa_handler (int)
+{
+}
+
+static void
+do_test_signals (void)
+{
+ {
+ /* Check if all signals handler are set to SIG_DFL on spawned process. */
+ spawn_signal_test ("SIG_DFL", NULL);
+ }
+
+ {
+ /* Same as before, but set SIGUSR1 and SIGUSR2 to a handler different than
+ SIG_IGN or SIG_DFL. */
+ struct sigaction sa = { 0 };
+ sa.sa_handler = dummy_sa_handler;
+ xsigaction (SIGUSR1, &sa, NULL);
+ xsigaction (SIGUSR2, &sa, NULL);
+ spawn_signal_test ("SIG_DFL", NULL);
+ }
+
+ {
+ /* Check if SIG_IGN is keep as is. */
+ struct sigaction sa = { 0 };
+ sa.sa_handler = SIG_IGN;
+ xsigaction (SIGUSR1, &sa, NULL);
+ xsigaction (SIGUSR2, &sa, NULL);
+ spawn_signal_test ("SIG_IGN", NULL);
+ }
+
+ {
+ /* Check if SIG_IGN handlers are set to SIG_DFL. */
+ posix_spawnattr_t attr;
+ posix_spawnattr_init (&attr);
+ sigset_t mask;
+ sigemptyset (&mask);
+ sigaddset (&mask, SIGUSR1);
+ sigaddset (&mask, SIGUSR2);
+ posix_spawnattr_setsigdefault (&attr, &mask);
+ posix_spawnattr_setflags (&attr, POSIX_SPAWN_SETSIGDEF);
+ spawn_signal_test ("SIG_DFL", &attr);
+ posix_spawnattr_destroy (&attr);
+ }
+}
+
+static int
+do_test (int argc, char *argv[])
+{
+ /* We must have either:
+
+ - one or four parameters if called initially:
+ + argv[1]: path for ld.so optional
+ + argv[2]: "--library-path" optional
+ + argv[3]: the library path optional
+ + argv[4]: the application name
+
+ - six parameters left if called through re-execution:
+ + argv[1]: the application name
+ + argv[2]: check SIG_IGN/SIG_DFL.
+
+ * When built with --enable-hardcoded-path-in-tests or issued without
+ using the loader directly. */
+
+ if (restart)
+ handle_restart (argc - 1, &argv[1]);
+
+ TEST_VERIFY_EXIT (argc == 2 || argc == 5);
+
+ int i;
+ for (i = 0; i < argc - 1; i++)
+ spargs[i] = argv[i + 1];
+ spargs[i++] = (char *) "--direct";
+ spargs[i++] = (char *) "--restart";
+ check_type_argc = i++;
+ spargs[i] = NULL;
+
+
+ do_test_signals ();
+
+ return 0;
+}
+
+#define TEST_FUNCTION_ARGV do_test
+#include <support/test-driver.c>
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 60e4cb1521..c183ccd4ab 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -175,8 +175,7 @@ tests-clone-internal = \
tst-align-clone-internal \
tst-clone2-internal \
tst-clone3-internal \
- tst-getpid1-internal \
- tst-misalign-clone-internal
+ tst-getpid1-internal
tests-internal += $(tests-clone-internal)
tests-static += $(tests-clone-internal)
diff --git a/sysdeps/unix/sysv/linux/clone-internal.c b/sysdeps/unix/sysv/linux/clone-internal.c
index a71effcbd3..7bc991e033 100644
--- a/sysdeps/unix/sysv/linux/clone-internal.c
+++ b/sysdeps/unix/sysv/linux/clone-internal.c
@@ -44,27 +44,15 @@ _Static_assert (sizeof (struct clone_args) == CLONE_ARGS_SIZE_VER2,
"sizeof (struct clone_args) != CLONE_ARGS_SIZE_VER2");
int
-__clone_internal (struct clone_args *cl_args,
- int (*func) (void *arg), void *arg)
+__clone_internal_fallback (struct clone_args *cl_args,
+ int (*func) (void *arg), void *arg)
{
- int ret;
-#ifdef HAVE_CLONE3_WRAPPER
- /* Try clone3 first. */
- int saved_errno = errno;
- ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
- if (ret != -1 || errno != ENOSYS)
- return ret;
-
- /* NB: Restore errno since errno may be checked against non-zero
- return value. */
- __set_errno (saved_errno);
-#endif
-
/* Map clone3 arguments to clone arguments. NB: No need to check
invalid clone3 specific bits in flags nor exit_signal since this
is an internal function. */
int flags = cl_args->flags | cl_args->exit_signal;
void *stack = cast_to_pointer (cl_args->stack);
+ int ret;
#ifdef __ia64__
ret = __clone2 (func, stack, cl_args->stack_size,
@@ -88,4 +76,23 @@ __clone_internal (struct clone_args *cl_args,
return ret;
}
+
+int
+__clone_internal (struct clone_args *cl_args,
+ int (*func) (void *arg), void *arg)
+{
+#ifdef HAVE_CLONE3_WRAPPER
+ int saved_errno = errno;
+ int ret = __clone3 (cl_args, sizeof (*cl_args), func, arg);
+ if (ret != -1 || errno != ENOSYS)
+ return ret;
+
+ /* NB: Restore errno since errno may be checked against non-zero
+ return value. */
+ __set_errno (saved_errno);
+#endif
+
+ return __clone_internal_fallback (cl_args, func, arg);
+}
+
libc_hidden_def (__clone_internal)
diff --git a/sysdeps/unix/sysv/linux/clone3.h b/sysdeps/unix/sysv/linux/clone3.h
index 7c7e2cdcb0..7dd42ec2d2 100644
--- a/sysdeps/unix/sysv/linux/clone3.h
+++ b/sysdeps/unix/sysv/linux/clone3.h
@@ -23,6 +23,13 @@
#include <stddef.h>
#include <bits/types.h>
+
+/* Flags for the clone3 syscall. */
+#define CLONE_CLEAR_SIGHAND 0x100000000ULL /* Clear any signal handler and
+ reset to SIG_DFL. */
+#define CLONE_INTO_CGROUP 0x200000000ULL /* Clone into a specific cgroup given
+ the right permissions. */
+
/* The unsigned 64-bit and 8-byte aligned integer type. */
typedef __U64_TYPE __aligned_uint64_t __attribute__ ((__aligned__ (8)));
diff --git a/sysdeps/unix/sysv/linux/spawni.c b/sysdeps/unix/sysv/linux/spawni.c
index 65ee03c804..ebc3c3e521 100644
--- a/sysdeps/unix/sysv/linux/spawni.c
+++ b/sysdeps/unix/sysv/linux/spawni.c
@@ -66,6 +66,7 @@ struct posix_spawn_args
ptrdiff_t argc;
char *const *envp;
int xflags;
+ bool use_clone3;
int err;
};
@@ -104,12 +105,11 @@ __spawni_child (void *arguments)
const posix_spawnattr_t *restrict attr = args->attr;
const posix_spawn_file_actions_t *file_actions = args->fa;
- /* The child must ensure that no signal handler are enabled because it shared
- memory with parent, so the signal disposition must be either SIG_DFL or
- SIG_IGN. It does by iterating over all signals and although it could
- possibly be more optimized (by tracking which signal potentially have a
- signal handler), it might requires system specific solutions (since the
- sigset_t data type can be very different on different architectures). */
+ /* The child must ensure that no signal handler is enabled because it
+ shares memory with parent, so all signal dispositions must be either
+ SIG_DFL or SIG_IGN. If clone3/CLONE_CLEAR_SIGHAND is used, there is
+ only need to set the defined signals POSIX_SPAWN_SETSIGDEF to SIG_DFL;
+ otherwise, the code iterates over all signals. */
struct sigaction sa;
memset (&sa, '\0', sizeof (sa));
@@ -122,7 +122,7 @@ __spawni_child (void *arguments)
{
sa.sa_handler = SIG_DFL;
}
- else if (__sigismember (&hset, sig))
+ else if (!args->use_clone3 && __sigismember (&hset, sig))
{
if (is_internal_signal (sig))
sa.sa_handler = SIG_IGN;
@@ -382,12 +382,25 @@ __spawnix (pid_t * pid, const char *file,
for instance). */
struct clone_args clone_args =
{
- .flags = CLONE_VM | CLONE_VFORK,
+ /* Unsupported flags like CLONE_CLEAR_SIGHAND will be cleared up by
+ __clone_internal_fallback. */
+ .flags = CLONE_CLEAR_SIGHAND | CLONE_VM | CLONE_VFORK,
.exit_signal = SIGCHLD,
.stack = (uintptr_t) stack,
.stack_size = stack_size,
};
- new_pid = __clone_internal (&clone_args, __spawni_child, &args);
+#ifdef HAVE_CLONE3_WRAPPER
+ args.use_clone3 = true;
+ new_pid = __clone3 (&clone_args, sizeof (clone_args), __spawni_child,
+ &args);
+ /* clone3 was added on 5.3 and CLONE_CLEAR_SIGHAND on 5.5. */
+ if (new_pid == -1 && (errno == ENOSYS || errno == EINVAL))
+#endif
+ {
+ args.use_clone3 = false;
+ new_pid = __clone_internal_fallback (&clone_args, __spawni_child,
+ &args);
+ }
/* It needs to collect the case where the auxiliary process was created
but failed to execute the file (due either any preparation step or
--
2.34.1
next prev parent reply other threads:[~2022-11-04 19:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-04 19:01 [PATCH v2 00/11] Optimize posix_spawn signal setup with clone3 Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 01/11] linux: Do not reset signal handler in posix_spawn if it is already SIG_DFL Adhemerval Zanella
2023-01-11 21:27 ` Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 02/11] linux: Extend internal clone3 documentation Adhemerval Zanella
2022-11-07 16:40 ` Szabolcs Nagy
2023-01-11 21:35 ` Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 03/11] Linux: Do not align the stack for __clone3 Adhemerval Zanella
2023-01-11 21:43 ` Carlos O'Donell
2022-11-04 19:01 ` Adhemerval Zanella [this message]
2023-01-11 21:44 ` [PATCH v2 04/11] linux: Add clone3 CLONE_CLEAR_SIGHAND optimization to posix_spawn Carlos O'Donell
2022-11-04 19:01 ` [PATCH v2 05/11] powerpc64: Add the clone3 wrapper Adhemerval Zanella
2022-11-28 16:38 ` Paul E Murphy
2022-11-29 20:43 ` Adhemerval Zanella Netto
2022-11-04 19:01 ` [PATCH v2 06/11] aarch64: " Adhemerval Zanella
2022-11-07 16:14 ` Szabolcs Nagy
2022-11-04 19:01 ` [PATCH v2 07/11] s390x: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 08/11] riscv: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 09/11] arm: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 10/11] mips: " Adhemerval Zanella
2022-11-04 19:01 ` [PATCH v2 11/11] Linux: optimize clone3 internal usage Adhemerval Zanella
2023-01-11 21:45 ` Carlos O'Donell
2023-01-11 21:24 ` [PATCH v2 00/11] Optimize posix_spawn signal setup with clone3 Carlos O'Donell
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