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https://github.com/LadybirdBrowser/ladybird.git
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f1b5def8fd
This patch adds Space, a class representing a process's address space. - Each Process has a Space. - The Space owns the PageDirectory and all Regions in the Process. This allows us to reorganize sys$execve() so that it constructs and populates a new Space fully before committing to it. Previously, we would construct the new address space while still running in the old one, and encountering an error meant we had to do tedious and error-prone rollback. Those problems are now gone, replaced by what's hopefully a set of much smaller problems and missing cleanups. :^)
115 lines
4.5 KiB
C++
115 lines
4.5 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <Kernel/Debug.h>
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#include <Kernel/FileSystem/Custody.h>
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#include <Kernel/FileSystem/FileDescription.h>
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#include <Kernel/Process.h>
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#include <Kernel/VM/Region.h>
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namespace Kernel {
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pid_t Process::sys$fork(RegisterState& regs)
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{
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REQUIRE_PROMISE(proc);
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RefPtr<Thread> child_first_thread;
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auto child = adopt(*new Process(child_first_thread, m_name, m_uid, m_gid, m_pid, m_is_kernel_process, m_cwd, m_executable, m_tty, this));
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if (!child_first_thread)
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return -ENOMEM;
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child->m_root_directory = m_root_directory;
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child->m_root_directory_relative_to_global_root = m_root_directory_relative_to_global_root;
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child->m_promises = m_promises;
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child->m_execpromises = m_execpromises;
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child->m_has_promises = m_has_promises;
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child->m_has_execpromises = m_has_execpromises;
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child->m_veil_state = m_veil_state;
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child->m_unveiled_paths = m_unveiled_paths.deep_copy();
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child->m_fds = m_fds;
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child->m_sid = m_sid;
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child->m_pg = m_pg;
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child->m_umask = m_umask;
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child->m_extra_gids = m_extra_gids;
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dbgln_if(FORK_DEBUG, "fork: child={}", child);
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child->space().set_enforces_syscall_regions(space().enforces_syscall_regions());
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auto& child_tss = child_first_thread->m_tss;
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child_tss.eax = 0; // fork() returns 0 in the child :^)
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child_tss.ebx = regs.ebx;
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child_tss.ecx = regs.ecx;
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child_tss.edx = regs.edx;
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child_tss.ebp = regs.ebp;
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child_tss.esp = regs.userspace_esp;
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child_tss.esi = regs.esi;
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child_tss.edi = regs.edi;
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child_tss.eflags = regs.eflags;
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child_tss.eip = regs.eip;
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child_tss.cs = regs.cs;
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child_tss.ds = regs.ds;
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child_tss.es = regs.es;
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child_tss.fs = regs.fs;
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child_tss.gs = regs.gs;
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child_tss.ss = regs.userspace_ss;
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#if FORK_DEBUG
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dbgln("fork: child will begin executing at {:04x}:{:08x} with stack {:04x}:{:08x}, kstack {:04x}:{:08x}", child_tss.cs, child_tss.eip, child_tss.ss, child_tss.esp, child_tss.ss0, child_tss.esp0);
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#endif
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{
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ScopedSpinLock lock(space().get_lock());
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for (auto& region : space().regions()) {
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dbgln_if(FORK_DEBUG, "fork: cloning Region({}) '{}' @ {}", ®ion, region.name(), region.vaddr());
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auto region_clone = region.clone(*child);
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if (!region_clone) {
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dbgln("fork: Cannot clone region, insufficient memory");
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// TODO: tear down new process?
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return -ENOMEM;
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}
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auto& child_region = child->space().add_region(region_clone.release_nonnull());
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child_region.map(child->space().page_directory());
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if (®ion == m_master_tls_region.unsafe_ptr())
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child->m_master_tls_region = child_region;
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}
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ScopedSpinLock processes_lock(g_processes_lock);
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g_processes->prepend(child);
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}
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ScopedSpinLock lock(g_scheduler_lock);
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child_first_thread->set_affinity(Thread::current()->affinity());
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child_first_thread->set_state(Thread::State::Runnable);
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auto child_pid = child->pid().value();
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// We need to leak one reference so we don't destroy the Process,
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// which will be dropped by Process::reap
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(void)child.leak_ref();
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return child_pid;
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}
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}
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