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([2804:1b3:a7c2:3736:cce5:8b83:d63b:2954]) by smtp.gmail.com with ESMTPSA id h197-20020a1f21ce000000b0039ecbaa55d8sm2381545vkh.44.2022.09.30.12.26.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Sep 2022 12:26:20 -0700 (PDT) From: Adhemerval Zanella To: libc-alpha@sourceware.org, Christian Brauner Subject: [PATCH v2 2/9] linux: Add clone3 CLONE_CLEAR_SIGHAND optimization to posix_spawn Date: Fri, 30 Sep 2022 16:26:06 -0300 Message-Id: <20220930192613.3491147-3-adhemerval.zanella@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220930192613.3491147-1-adhemerval.zanella@linaro.org> References: <20220930192613.3491147-1-adhemerval.zanella@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: 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/clone-internal.c | 37 +++-- sysdeps/unix/sysv/linux/clone3.h | 6 + sysdeps/unix/sysv/linux/spawni.c | 31 ++-- 6 files changed, 236 insertions(+), 25 deletions(-) create mode 100644 posix/tst-spawn7.c diff --git a/include/clone_internal.h b/include/clone_internal.h index 4b23ef33ce..320640e64b 100644 --- a/include/clone_internal.h +++ b/include/clone_internal.h @@ -7,6 +7,11 @@ extern __typeof (clone3) __clone3; -1 with ENOSYS, 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 d1df7c27cb..7887eb1c8b 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 + . */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* 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 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 889014a6a9..a150363f89 100644 --- a/sysdeps/unix/sysv/linux/clone3.h +++ b/sysdeps/unix/sysv/linux/clone3.h @@ -25,6 +25,12 @@ __BEGIN_DECLS +/* 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