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/*
* Copyright (C) 2010 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#define _GNU_SOURCE 1
#include <sched.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/syscall.h>
#include "pthread_internal.h"
#include "private/bionic_defs.h"
#include "private/bionic_macros.h"
extern "C" pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg);
extern "C" __noreturn void __exit(int status);
// Called from the __bionic_clone assembler to call the thread function then exit.
__attribute__((no_sanitize("hwaddress")))
extern "C" __LIBC_HIDDEN__ void __start_thread(int (*fn)(void*), void* arg) {
BIONIC_STOP_UNWIND;
pthread_internal_t* self = __get_thread();
if (self && self->tid == -1) {
self->tid = syscall(__NR_gettid);
}
int status = (*fn)(arg);
__exit(status);
}
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) {
int* parent_tid = nullptr;
void* new_tls = nullptr;
int* child_tid = nullptr;
if (fn != nullptr && child_stack == nullptr) {
errno = EINVAL;
return -1;
}
// Extract any optional parameters required by the flags.
va_list args;
va_start(args, arg);
if ((flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
parent_tid = va_arg(args, int*);
}
if ((flags & (CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
new_tls = va_arg(args, void*);
}
if ((flags & (CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
child_tid = va_arg(args, int*);
}
va_end(args);
// Align 'child_stack' to 16 bytes.
uintptr_t child_stack_addr = reinterpret_cast<uintptr_t>(child_stack);
child_stack_addr &= ~0xf;
child_stack = reinterpret_cast<void*>(child_stack_addr);
// Remember the parent pid and invalidate the cached value while we clone.
pthread_internal_t* self = __get_thread();
pid_t parent_pid = self->invalidate_cached_pid();
// Remmber the caller's tid so that it can be restored in the parent after clone.
pid_t caller_tid = self->tid;
// Invalidate the tid before the syscall. The value is lazily cached in gettid(),
// and it will be updated by fork() and pthread_create(). We don't do this if
// we are sharing address space with the child.
if (!(flags & (CLONE_VM|CLONE_VFORK))) {
self->tid = -1;
}
// Actually do the clone.
int clone_result;
if (fn != nullptr) {
clone_result = __bionic_clone(flags, child_stack, parent_tid, new_tls, child_tid, fn, arg);
} else {
#if defined(__x86_64__) // sys_clone's last two arguments are flipped on x86-64.
clone_result = syscall(__NR_clone, flags, child_stack, parent_tid, child_tid, new_tls);
#else
clone_result = syscall(__NR_clone, flags, child_stack, parent_tid, new_tls, child_tid);
#endif
}
if (clone_result != 0) {
// We're the parent, so put our known pid and tid back in place.
// We leave the child without a cached pid and tid, but:
// 1. pthread_create gives its children their own pthread_internal_t with the correct pid and tid.
// 2. fork uses CLONE_CHILD_SETTID to get the new pid/tid.
// 3. The tid is lazily fetched in gettid().
// If any other cases become important, we could use a double trampoline like __pthread_start.
self->set_cached_pid(parent_pid);
self->tid = caller_tid;
} else if (self->tid == -1) {
self->tid = syscall(__NR_gettid);
self->set_cached_pid(self->tid);
}
return clone_result;
}
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