glibc/sysdeps/unix/sysv/linux/nios2/clone.S

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/* clone() implementation for Nios II.
Copyright (C) 2008-2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
Contributed by Andrew Jenner <andrew@codesourcery.com>, 2008.
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/>. */
/* 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>
#define _ERRNO_H 1
#include <bits/errno.h>
#include <tcb-offsets.h>
/* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg,
void *parent_tidptr, void *tls, void *child_tidptr) */
.text
ENTRY(__clone)
/* Sanity check arguments. */
movi r2, EINVAL
/* No NULL function pointers. */
beq r4, zero, SYSCALL_ERROR_LABEL
/* No NULL stack pointers. */
beq r5, zero, SYSCALL_ERROR_LABEL
subi r5, r5, 8 /* Reserve argument save space. */
stw r4, 4(r5) /* Save function pointer. */
stw r7, 0(r5) /* Save argument pointer. */
/* Load arguments. */
mov r4, r6
ldw r6, 0(sp)
ldw r7, 8(sp)
ldw r8, 4(sp)
/* Do the system call. */
movi r2, SYS_ify (clone)
/* End FDE now, because in the child the unwind info will be
wrong. */
cfi_endproc
trap
/* Check for errors. */
bne r7, zero, SYSCALL_ERROR_LABEL
/* See if we're on the newly created thread. */
beq r2, zero, thread_start
/* Successful return from the parent */
ret
thread_start:
cfi_startproc
cfi_undefined (ra)
ldw r5, 4(sp) /* Function pointer. */
ldw r4, 0(sp) /* Argument pointer. */
addi sp, sp, 8
/* Call the user's function. */
callr r5
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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/* exit with the result. */
movi r2, SYS_ify (exit)
trap
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cfi_endproc
cfi_startproc
PSEUDO_END (__clone)
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)