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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/Memory/Region.h>
#include <Kernel/PerformanceManager.h>
#include <Kernel/Process.h>
namespace Kernel {
ErrorOr<FlatPtr> Process::sys$fork(RegisterState& regs)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
TRY(require_promise(Pledge::proc));
RefPtr<Thread> child_first_thread;
auto child_name = TRY(m_name->try_clone());
auto child = TRY(Process::try_create(child_first_thread, move(child_name), uid(), gid(), pid(), m_is_kernel_process, m_cwd, m_executable, m_tty, this));
child->m_veil_state = m_veil_state;
child->m_unveiled_paths = m_unveiled_paths.deep_copy();
TRY(child->m_fds.with([&](auto& child_fds) {
return m_fds.with([&](auto& parent_fds) {
return child_fds.try_clone(parent_fds);
});
}));
child->m_pg = m_pg;
{
ProtectedDataMutationScope scope { *child };
child->m_protected_values.promises = m_protected_values.promises.load();
child->m_protected_values.execpromises = m_protected_values.execpromises.load();
child->m_protected_values.has_promises = m_protected_values.has_promises.load();
child->m_protected_values.has_execpromises = m_protected_values.has_execpromises.load();
child->m_protected_values.sid = m_protected_values.sid;
child->m_protected_values.extra_gids = m_protected_values.extra_gids;
child->m_protected_values.umask = m_protected_values.umask;
child->m_protected_values.signal_trampoline = m_protected_values.signal_trampoline;
child->m_protected_values.dumpable = m_protected_values.dumpable;
}
dbgln_if(FORK_DEBUG, "fork: child={}", child);
child->address_space().set_enforces_syscall_regions(address_space().enforces_syscall_regions());
// A child created via fork(2) inherits a copy of its parent's signal mask
child_first_thread->update_signal_mask(Thread::current()->signal_mask());
// A child process created via fork(2) inherits a copy of its parent's alternate signal stack settings.
child_first_thread->m_alternative_signal_stack = Thread::current()->m_alternative_signal_stack;
child_first_thread->m_alternative_signal_stack_size = Thread::current()->m_alternative_signal_stack_size;
#if ARCH(I386)
auto& child_regs = child_first_thread->m_regs;
child_regs.eax = 0; // fork() returns 0 in the child :^)
child_regs.ebx = regs.ebx;
child_regs.ecx = regs.ecx;
child_regs.edx = regs.edx;
child_regs.ebp = regs.ebp;
child_regs.esp = regs.userspace_esp;
child_regs.esi = regs.esi;
child_regs.edi = regs.edi;
child_regs.eflags = regs.eflags;
child_regs.eip = regs.eip;
child_regs.cs = regs.cs;
child_regs.ds = regs.ds;
child_regs.es = regs.es;
child_regs.fs = regs.fs;
child_regs.gs = regs.gs;
child_regs.ss = regs.userspace_ss;
dbgln_if(FORK_DEBUG, "fork: child will begin executing at {:#04x}:{:p} with stack {:#04x}:{:p}, kstack {:#04x}:{:p}",
child_regs.cs, child_regs.eip, child_regs.ss, child_regs.esp, child_regs.ss0, child_regs.esp0);
#else
auto& child_regs = child_first_thread->m_regs;
child_regs.rax = 0; // fork() returns 0 in the child :^)
child_regs.rbx = regs.rbx;
child_regs.rcx = regs.rcx;
child_regs.rdx = regs.rdx;
child_regs.rbp = regs.rbp;
child_regs.rsp = regs.userspace_rsp;
child_regs.rsi = regs.rsi;
child_regs.rdi = regs.rdi;
child_regs.r8 = regs.r8;
child_regs.r9 = regs.r9;
child_regs.r10 = regs.r10;
child_regs.r11 = regs.r11;
child_regs.r12 = regs.r12;
child_regs.r13 = regs.r13;
child_regs.r14 = regs.r14;
child_regs.r15 = regs.r15;
child_regs.rflags = regs.rflags;
child_regs.rip = regs.rip;
child_regs.cs = regs.cs;
dbgln_if(FORK_DEBUG, "fork: child will begin executing at {:#04x}:{:p} with stack {:p}, kstack {:p}",
child_regs.cs, child_regs.rip, child_regs.rsp, child_regs.rsp0);
#endif
{
SpinlockLocker lock(address_space().get_lock());
for (auto& region : address_space().regions()) {
dbgln_if(FORK_DEBUG, "fork: cloning Region({}) '{}' @ {}", region, region->name(), region->vaddr());
auto region_clone = TRY(region->try_clone());
auto* child_region = TRY(child->address_space().add_region(move(region_clone)));
TRY(child_region->map(child->address_space().page_directory(), Memory::ShouldFlushTLB::No));
if (region == m_master_tls_region.unsafe_ptr())
child->m_master_tls_region = child_region;
}
}
Process::register_new(*child);
PerformanceManager::add_process_created_event(*child);
SpinlockLocker lock(g_scheduler_lock);
child_first_thread->set_affinity(Thread::current()->affinity());
child_first_thread->set_state(Thread::State::Runnable);
auto child_pid = child->pid().value();
// NOTE: All user processes have a leaked ref on them. It's balanced by Thread::WaitBlockerSet::finalize().
(void)child.leak_ref();
return child_pid;
}
}
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