glibc/sysdeps/unix/sysv/linux/alpha/clone.S

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/* Copyright (C) 1996-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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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.
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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
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
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<https://www.gnu.org/licenses/>. */
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/* clone() is even more special than fork() as it mucks with stacks
and invokes a function in the right context after its all over. */
#include <sysdep.h>
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#define _ERRNO_H 1
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#include <bits/errno.h>
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/* int clone(int (*fn)(void *arg), void *child_stack, int flags,
void *arg, pid_t *ptid, void *tls, pid_t *ctid);
Note that everything past ARG is technically optional, based
on FLAGS, and that CTID is arg 7, and thus is on the stack.
However, since a load from top-of-stack better be legal always,
we don't bother checking FLAGS. */
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.text
.align 4
.globl __clone
.ent __clone
.usepv __clone, USEPV_PROF
cfi_startproc
__clone:
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#ifdef PROF
.set noat
ldgp gp,0(pv)
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lda AT, _mcount
jsr AT, (AT), _mcount
.set at
#endif
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/* Sanity check arguments. */
ldiq v0, EINVAL
beq a0, SYSCALL_ERROR_LABEL /* no NULL function pointers */
beq a1, SYSCALL_ERROR_LABEL /* no NULL stack pointers */
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/* Save the fn ptr and arg on the new stack. */
subq a1, 32, a1
stq a0, 0(a1)
stq a3, 8(a1)
stq a2, 16(a1)
/* The syscall is of the form clone(flags, usp, ptid, ctid, tls).
Shift the flags, ptid, ctid, tls arguments into place; the
child_stack argument is already correct. */
mov a2, a0
mov a4, a2
ldq a3, 0(sp)
mov a5, a4
/* Do the system call. */
ldiq v0, __NR_clone
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call_pal PAL_callsys
bne a3, SYSCALL_ERROR_LABEL
beq v0, thread_start
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/* Successful return from the parent. */
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ret
PSEUDO_END(__clone)
cfi_endproc
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/* Load up the arguments to the function. Put this block of code in
its own function so that we can terminate the stack trace with our
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debug info. */
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.align 4
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.ent thread_start
cfi_startproc
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thread_start:
mov 0, fp
cfi_def_cfa_register(fp)
cfi_undefined(ra)
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/* Load up the arguments. */
ldq pv, 0(sp)
ldq a0, 8(sp)
addq sp, 32, sp
/* Call the user's function. */
jsr ra, (pv)
ldgp gp, 0(ra)
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mov v0, a0
Call exit directly in clone (BZ #21512) On aarch64, alpha, arm, hppa, mips, nios2, powerpc, sh, sparc, tile, and x86_64 the clone syscall jumps to _exit after the child execution and the function ends the process execution by calling exit_group. This behavior have a small issue where threads created with CLONE_THREAD using clone syscall directly will eventually exit the whole group altogether instead of just the thread created. Also, s390, microblaze, ia64, i386, and m68k differs by calling exit syscall directly. This patch changes all architectures to call the exit syscall directly, as for s390, microblaze, ia64, i386, and m68k. This do not have change glibc internal behavior in any sort, since the only usage of clone implementation in posix_spawn calls _exit directly in the created child (fork uses a direct call to clone). Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, powerpc-linux-gnu, powerpc64le-linux-gnu, sparc64-linux-gnu, and sparcv9-linux-gnu. [BZ #21512] * sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Call exit syscall instead of jump to _exit. (CLONE_VM_BIT): Remove unused define. (CLONE_VM): Likewise. (CLONE_THREAD_BIT): Likewise. (CLONE_THREAD): Likewise. * sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. * sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. (CLONE_THREAD): Likewise. * sysdeps/unix/sysv/linux/i386/clone.S (CLONE_VM): Likewise. * sysdeps/unix/sysv/linux/ia64/clone2.S (__clone2): Call exit syscall instead of jump to _exit. * sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. (CLONE_THREAD): Likewise. * sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. * sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. (CLONE_THREAD): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. (CLONE_THREAD): Likewise. * sysdeps/unix/sysv/linux/sh/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/sparc/sparc32/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. * sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. * sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise. (CLONE_VM): Remove unused define. * sysdeps/unix/sysv/linux/Makefile (tests): Add tst-clone3. * sysdeps/unix/sysv/linux/tst-clone3.c: New file. Fix
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ldiq v0, __NR_exit
call_pal PAL_callsys
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/* Die horribly. */
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.align 4
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halt
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.align 4
cfi_endproc
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.end thread_start
posix: New Linux posix_spawn{p} implementation This patch implements a new posix_spawn{p} implementation for Linux. The main difference is it uses the clone syscall directly with CLONE_VM and CLONE_VFORK flags and a direct allocated stack. The new stack and start function solves most the vfork limitation (possible parent clobber due stack spilling). The remaning issue are related to signal handling: 1. That no signal handlers must run in child context, to avoid corrupt parent's state. 2. Child must synchronize with parent to enforce stack deallocation and to possible return execv issues. The first one is solved by blocking all signals in child, even NPTL-internal ones (SIGCANCEL and SIGSETXID). The second issue is done by a stack allocation in parent and a synchronization with using a pipe or waitpid (in case or error). The pipe has the advantage of allowing the child signal an exec error (checked with new tst-spawn2 test). There is an inherent race condition in pipe2 usage for architectures that do not support the syscall directly. In such cases the a pipe plus fctnl is used instead and it may lead to file descriptor leak in parent (as decribed by fcntl documentation). The child process stack is allocate with a mmap with MAP_STACK flag using default architecture stack size. Although it is slower than use a stack buffer from parent, it allows some slack for the compatibility code to run scripts with no shebang (which may use a buffer with size depending of argument list count). Performance should be similar to the vfork default posix implementation and way faster than fork path (vfork on mostly linux ports are basically clone with CLONE_VM plus CLONE_VFORK). The only difference is the syscalls required for the stack allocation/deallocation. It fixes BZ#10354, BZ#14750, and BZ#18433. Tested on i386, x86_64, powerpc64le, and aarch64. [BZ #14750] [BZ #10354] [BZ #18433] * include/sched.h (__clone): Add hidden prototype. (__clone2): Likewise. * include/unistd.h (__dup): Likewise. * posix/Makefile (tests): Add tst-spawn2. * posix/tst-spawn2.c: New file. * sysdeps/posix/dup.c (__dup): Add hidden definition. * sysdeps/unix/sysv/linux/aarch64/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/alpha/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/arm/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/hppa/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/i386/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/ia64/clone2.S (__clone): Likewise. * sysdeps/unix/sysv/linux/m68k/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/microblaze/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/mips/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/nios2/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/s390/s390-32/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/s390/s390-64/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/sh/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/sparc/sparc32/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/tile/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/x86_64/clone.S (__clone): Likewise. * sysdeps/unix/sysv/linux/nptl-signals.h (____nptl_is_internal_signal): New function. * sysdeps/unix/sysv/linux/spawni.c: New file.
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libc_hidden_def (__clone)
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weak_alias (__clone, clone)