From 2cb7e0aaedad73b076ea18c6900b0e86c5760d79 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 15:00:47 +0200 Subject: Adding upstream version 247.3. Signed-off-by: Daniel Baumann --- src/basic/raw-clone.h | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 79 insertions(+) create mode 100644 src/basic/raw-clone.h (limited to 'src/basic/raw-clone.h') diff --git a/src/basic/raw-clone.h b/src/basic/raw-clone.h new file mode 100644 index 0000000..becf42e --- /dev/null +++ b/src/basic/raw-clone.h @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +#pragma once + +/*** + Copyright © 2016 Michael Karcher +***/ + +#include +#include +#include + +#include "log.h" +#include "macro.h" + +/** + * raw_clone() - uses clone to create a new process with clone flags + * @flags: Flags to pass to the clone system call + * + * Uses the clone system call to create a new process with the cloning flags and termination signal passed in the flags + * parameter. Opposed to glibc's clone function, using this function does not set up a separate stack for the child, but + * relies on copy-on-write semantics on the one stack at a common virtual address, just as fork does. + * + * To obtain copy-on-write semantics, flags must not contain CLONE_VM, and thus CLONE_THREAD and CLONE_SIGHAND (which + * require CLONE_VM) are not usable. + * + * Additionally, as this function does not pass the ptid, newtls and ctid parameters to the kernel, flags must not + * contain CLONE_PARENT_SETTID, CLONE_CHILD_SETTID, CLONE_CHILD_CLEARTID or CLONE_SETTLS. + * + * Returns: 0 in the child process and the child process id in the parent. + */ +static inline pid_t raw_clone(unsigned long flags) { + pid_t ret; + + assert((flags & (CLONE_VM|CLONE_PARENT_SETTID|CLONE_CHILD_SETTID| + CLONE_CHILD_CLEARTID|CLONE_SETTLS)) == 0); +#if defined(__s390x__) || defined(__s390__) || defined(__CRIS__) + /* On s390/s390x and cris the order of the first and second arguments + * of the raw clone() system call is reversed. */ + ret = (pid_t) syscall(__NR_clone, NULL, flags); +#elif defined(__sparc__) + { + /** + * sparc always returns the other process id in %o0, and + * a boolean flag whether this is the child or the parent in + * %o1. Inline assembly is needed to get the flag returned + * in %o1. + */ + int in_child, child_pid, error; + + asm volatile("mov %3, %%g1\n\t" + "mov %4, %%o0\n\t" + "mov 0 , %%o1\n\t" +#if defined(__arch64__) + "t 0x6d\n\t" +#else + "t 0x10\n\t" +#endif + "addx %%g0, 0, %2\n\t" + "mov %%o1, %0\n\t" + "mov %%o0, %1" : + "=r"(in_child), "=r"(child_pid), "=r"(error) : + "i"(__NR_clone), "r"(flags) : + "%o1", "%o0", "%g1", "cc" ); + + if (error) { + errno = child_pid; + ret = -1; + } else + ret = in_child ? 0 : child_pid; + } +#else + ret = (pid_t) syscall(__NR_clone, flags, NULL); +#endif + + if (ret == 0) + reset_cached_pid(); + + return ret; +} -- cgit v1.2.3