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Kernel+Userland: Remove shared buffers (shbufs)

Browse source 
All users of this mechanism have been switched to anonymous files and
passing file descriptors with sendfd()/recvfd().

Shbufs got us where we are today, but it's time we say good-bye to them
and welcome a much more idiomatic replacement. :^)
This commit is contained in:
Andreas Kling 2021-01-17 08:51:41 +01:00
parent 2cd16778b5
commit bf0719092f
28 changed files with 2 additions and 1022 deletions
Download patch file Download diff file Expand all files Collapse all files

4
Kernel/API/Syscall.h
View file

@ -121,10 +121,6 @@ namespace Kernel {
S(accept) \
S(listen) \
S(connect) \
S(shbuf_create) \
S(shbuf_allow_pid) \
S(shbuf_get) \
S(shbuf_release) \
S(link) \
S(chown) \
S(fchmod) \

2
Kernel/CMakeLists.txt
View file

@ -101,7 +101,6 @@ set(KERNEL_SOURCES
RTC.cpp
Random.cpp
Scheduler.cpp
SharedBuffer.cpp
StdLib.cpp
Syscall.cpp
Syscalls/anon_create.cpp
@ -157,7 +156,6 @@ set(KERNEL_SOURCES
Syscalls/setkeymap.cpp
Syscalls/setpgid.cpp
Syscalls/setuid.cpp
Syscalls/shbuf.cpp
Syscalls/shutdown.cpp
Syscalls/sigaction.cpp
Syscalls/socket.cpp

1
Kernel/Forward.h
View file

@ -60,7 +60,6 @@ class RangeAllocator;
class Region;
class Scheduler;
class SchedulerPerProcessorData;
class SharedBuffer;
class Socket;
template<typename BaseType>
class SpinLock;

3
Kernel/Process.cpp
View file

@ -45,10 +45,10 @@
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
#include <Kernel/RTC.h>
#include <Kernel/SharedBuffer.h>
#include <Kernel/StdLib.h>
#include <Kernel/TTY/TTY.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/AnonymousVMObject.h>
#include <Kernel/VM/PageDirectory.h>
#include <Kernel/VM/PrivateInodeVMObject.h>
#include <Kernel/VM/ProcessPagingScope.h>
@ -644,7 +644,6 @@ void Process::finalize()
m_dead = true;
disown_all_shared_buffers();
{
// FIXME: PID/TID BUG
if (auto parent_thread = Thread::from_tid(m_ppid.value())) {

8
Kernel/Process.h
View file

@ -80,8 +80,7 @@ extern VirtualAddress g_return_to_ring3_from_signal_trampoline;
__ENUMERATE_PLEDGE_PROMISE(accept) \
__ENUMERATE_PLEDGE_PROMISE(settime) \
__ENUMERATE_PLEDGE_PROMISE(sigaction) \
__ENUMERATE_PLEDGE_PROMISE(setkeymap) \
__ENUMERATE_PLEDGE_PROMISE(shared_buffer)
__ENUMERATE_PLEDGE_PROMISE(setkeymap)
enum class Pledge : u32 {
#define __ENUMERATE_PLEDGE_PROMISE(x) x,
@ -334,10 +333,6 @@ public:
int sys$get_thread_name(pid_t tid, Userspace<char*> buffer, size_t buffer_size);
int sys$rename(Userspace<const Syscall::SC_rename_params*>);
int sys$mknod(Userspace<const Syscall::SC_mknod_params*>);
int sys$shbuf_create(int, void** buffer);
int sys$shbuf_allow_pid(int, pid_t peer_pid);
void* sys$shbuf_get(int shbuf_id, Userspace<size_t*> size);
int sys$shbuf_release(int shbuf_id);
int sys$halt();
int sys$reboot();
int sys$realpath(Userspace<const Syscall::SC_realpath_params*>);
@ -530,7 +525,6 @@ private:
KResultOr<RefPtr<FileDescription>> find_elf_interpreter_for_executable(const String& path, const Elf32_Ehdr& elf_header, int nread, size_t file_size);
int alloc_fd(int first_candidate_fd = 0);
void disown_all_shared_buffers();
KResult do_kill(Process&, int signal);
KResult do_killpg(ProcessGroupID pgrp, int signal);

188
Kernel/SharedBuffer.cpp
View file

@ -1,188 +0,0 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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 HOLDER 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.
*/
#include <AK/Debug.h>
#include <AK/Singleton.h>
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
//#define SHARED_BUFFER_DEBUG
namespace Kernel {
static AK::Singleton<Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>> s_map;
Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>& shared_buffers()
{
return *s_map;
}
void SharedBuffer::sanity_check(const char* what)
{
LOCKER(shared_buffers().lock(), Lock::Mode::Shared);
unsigned found_refs = 0;
for (const auto& ref : m_refs)
found_refs += ref.count;
if (found_refs != m_total_refs) {
dbgln("{} sanity -- SharedBuffer({}) id: {} has total refs {} but we found {}",
what,
this,
m_shbuf_id,
m_total_refs,
found_refs);
for (const auto& ref : m_refs)
dbgln(" ref from pid {}: reference count {}", ref.pid.value(), ref.count);
ASSERT_NOT_REACHED();
}
}
bool SharedBuffer::is_shared_with(ProcessID peer_pid) const
{
LOCKER(shared_buffers().lock(), Lock::Mode::Shared);
for (auto& ref : m_refs) {
if (ref.pid == peer_pid) {
return true;
}
}
return false;
}
void* SharedBuffer::ref_for_process_and_get_address(Process& process)
{
LOCKER(shared_buffers().lock());
ASSERT(is_shared_with(process.pid()));
for (auto& ref : m_refs) {
if (ref.pid == process.pid()) {
if (!ref.region) {
auto region_or_error = process.allocate_region_with_vmobject(VirtualAddress(), size(), m_vmobject, 0, "SharedBuffer", PROT_READ | (m_writable ? PROT_WRITE : 0), true);
if (region_or_error.is_error())
return (void*)region_or_error.error().error();
ref.region = region_or_error.value();
}
ref.count++;
m_total_refs++;
sanity_check("ref_for_process_and_get_address");
return ref.region.unsafe_ptr()->vaddr().as_ptr(); // TODO: Region needs to be RefCounted!
}
}
ASSERT_NOT_REACHED();
}
void SharedBuffer::share_with(ProcessID peer_pid)
{
LOCKER(shared_buffers().lock());
for (auto& ref : m_refs) {
if (ref.pid == peer_pid) {
// don't increment the reference count yet; let them shbuf_get it first.
sanity_check("share_with (old ref)");
return;
}
}
m_refs.append(Reference(peer_pid));
sanity_check("share_with (new ref)");
}
void SharedBuffer::share_all_shared_buffers(Process& from_process, Process& with_process)
{
LOCKER(shared_buffers().lock());
for (auto& shbuf : shared_buffers().resource()) {
auto& shared_buffer = *shbuf.value;
// We need to clone all references (including for global shared buffers),
// and the reference counts as well.
for (auto& ref : shared_buffer.m_refs) {
if (ref.pid == from_process.pid()) {
auto ref_count = ref.count;
shared_buffer.m_refs.append(Reference(with_process.pid(), ref_count));
// NOTE: ref may become invalid after we appended!
shared_buffer.m_total_refs += ref_count;
break;
}
}
}
}
void SharedBuffer::deref_for_process(Process& process)
{
LOCKER(shared_buffers().lock());
for (size_t i = 0; i < m_refs.size(); ++i) {
auto& ref = m_refs[i];
if (ref.pid == process.pid()) {
ASSERT(ref.count > 0);
ref.count--;
ASSERT(m_total_refs > 0);
m_total_refs--;
if (ref.count == 0) {
dbgln<debug_shared_buffer>("Releasing shared buffer reference on {} of size {} by PID {}", m_shbuf_id, size(), process.pid().value());
process.deallocate_region(*ref.region.unsafe_ptr()); // TODO: Region needs to be RefCounted!
dbgln<debug_shared_buffer>("Released shared buffer reference on {} of size {} by PID {}", m_shbuf_id, size(), process.pid().value());
sanity_check("deref_for_process");
destroy_if_unused();
return;
}
return;
}
}
ASSERT_NOT_REACHED();
}
bool SharedBuffer::disown(ProcessID pid)
{
LOCKER(shared_buffers().lock());
for (size_t i = 0; i < m_refs.size(); ++i) {
auto& ref = m_refs[i];
if (ref.pid == pid) {
dbgln<debug_shared_buffer>("Disowning shared buffer {} of size {} by PID {}", m_shbuf_id, size(), pid.value());
ASSERT(m_total_refs >= ref.count);
m_total_refs -= ref.count;
m_refs.unstable_take(i);
dbgln<debug_shared_buffer>("Disowned shared buffer {} of size {} by PID {}", m_shbuf_id, size(), pid.value());
destroy_if_unused();
break;
}
}
return m_total_refs == 0;
}
void SharedBuffer::destroy_if_unused()
{
LOCKER(shared_buffers().lock());
sanity_check("destroy_if_unused");
if (m_total_refs == 0) {
dbgln<debug_shared_buffer>("Destroying unused SharedBuffer({}) id={}", this, m_shbuf_id);
auto count_before = shared_buffers().resource().size();
shared_buffers().resource().remove(m_shbuf_id);
ASSERT(count_before != shared_buffers().resource().size());
}
}
}

87
Kernel/SharedBuffer.h
View file

@ -1,87 +0,0 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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 HOLDER 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.
*/
#pragma once
#include <AK/Debug.h>
#include <AK/OwnPtr.h>
#include <AK/WeakPtr.h>
#include <Kernel/VM/AnonymousVMObject.h>
#include <Kernel/VM/MemoryManager.h>
namespace Kernel {
class SharedBuffer {
private:
struct Reference {
Reference(ProcessID pid, unsigned count = 0)
: pid(pid)
, count(count)
{
}
ProcessID pid;
unsigned count { 0 };
WeakPtr<Region> region;
};
public:
SharedBuffer(int id, NonnullRefPtr<AnonymousVMObject>&& vmobject)
: m_shbuf_id(id)
, m_vmobject(move(vmobject))
{
dbgln<debug_shared_buffer>("Created shared buffer {} of size {}", m_shbuf_id, size());
}
~SharedBuffer()
{
dbgln<debug_shared_buffer>("Destroyed shared buffer {} of size {}", m_shbuf_id, size());
}
void sanity_check(const char* what);
bool is_shared_with(ProcessID peer_pid) const;
void* ref_for_process_and_get_address(Process& process);
void share_with(ProcessID peer_pid);
void deref_for_process(Process& process);
bool disown(ProcessID pid);
static void share_all_shared_buffers(Process& from_process, Process& with_process);
size_t size() const { return m_vmobject->size(); }
void destroy_if_unused();
AnonymousVMObject& vmobject() { return m_vmobject; }
const AnonymousVMObject& vmobject() const { return m_vmobject; }
int id() const { return m_shbuf_id; }
private:
int m_shbuf_id { -1 };
bool m_writable { true };
NonnullRefPtr<AnonymousVMObject> m_vmobject;
Vector<Reference, 2> m_refs;
unsigned m_total_refs { 0 };
};
Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>& shared_buffers();
}

2
Kernel/Syscalls/execve.cpp
View file

@ -522,8 +522,6 @@ int Process::do_exec(NonnullRefPtr<FileDescription> main_program_description, Ve
m_region_lookup_cache = {};
disown_all_shared_buffers();
set_dumpable(!executable_is_setid);
for (size_t i = 0; i < m_fds.size(); ++i) {

3
Kernel/Syscalls/fork.cpp
View file

@ -27,7 +27,6 @@
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
#include <Kernel/VM/Region.h>
//#define FORK_DEBUG
@ -80,8 +79,6 @@ pid_t Process::sys$fork(RegisterState& regs)
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);
#endif
SharedBuffer::share_all_shared_buffers(*this, *child);
{
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {

1
Kernel/Syscalls/process.cpp
View file

@ -26,7 +26,6 @@
#include <AK/Types.h>
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
namespace Kernel {

137
Kernel/Syscalls/shbuf.cpp
View file

@ -1,137 +0,0 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. 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 HOLDER 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.
*/
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
//#define SHARED_BUFFER_DEBUG
namespace Kernel {
void Process::disown_all_shared_buffers()
{
LOCKER(shared_buffers().lock());
Vector<SharedBuffer*, 32> buffers_to_disown;
for (auto& it : shared_buffers().resource())
buffers_to_disown.append(it.value.ptr());
for (auto* shared_buffer : buffers_to_disown) {
if (shared_buffer->disown(m_pid)) {
shared_buffers().resource().remove(shared_buffer->id());
delete shared_buffer;
}
}
}
int Process::sys$shbuf_create(int size, void** buffer)
{
REQUIRE_PROMISE(shared_buffer);
if (!size || size < 0)
return -EINVAL;
size = PAGE_ROUND_UP(size);
auto vmobject = AnonymousVMObject::create_with_size(size, AllocationStrategy::Reserve);
if (!vmobject)
return -ENOMEM;
LOCKER(shared_buffers().lock());
static int s_next_shbuf_id;
int shbuf_id = ++s_next_shbuf_id;
auto shared_buffer = make<SharedBuffer>(shbuf_id, vmobject.release_nonnull());
shared_buffer->share_with(m_pid);
void* address = shared_buffer->ref_for_process_and_get_address(*this);
if (!copy_to_user(buffer, &address))
return -EFAULT;
ASSERT((int)shared_buffer->size() >= size);
#ifdef SHARED_BUFFER_DEBUG
klog() << "Created shared buffer " << shbuf_id << " @ " << buffer << " (" << size << " bytes, vmobject is " << shared_buffer->size() << ")";
#endif
shared_buffers().resource().set(shbuf_id, move(shared_buffer));
return shbuf_id;
}
int Process::sys$shbuf_allow_pid(int shbuf_id, pid_t peer_pid)
{
REQUIRE_PROMISE(shared_buffer);
if (!peer_pid || peer_pid < 0 || ProcessID(peer_pid) == m_pid)
return -EINVAL;
LOCKER(shared_buffers().lock());
auto it = shared_buffers().resource().find(shbuf_id);
if (it == shared_buffers().resource().end())
return -EINVAL;
auto& shared_buffer = *(*it).value;
if (!shared_buffer.is_shared_with(m_pid))
return -EPERM;
{
ScopedSpinLock lock(g_processes_lock);
auto peer = Process::from_pid(peer_pid);
if (!peer)
return -ESRCH;
}
shared_buffer.share_with(peer_pid);
return 0;
}
int Process::sys$shbuf_release(int shbuf_id)
{
REQUIRE_PROMISE(shared_buffer);
LOCKER(shared_buffers().lock());
auto it = shared_buffers().resource().find(shbuf_id);
if (it == shared_buffers().resource().end())
return -EINVAL;
auto& shared_buffer = *(*it).value;
if (!shared_buffer.is_shared_with(m_pid))
return -EPERM;
#ifdef SHARED_BUFFER_DEBUG
klog() << "Releasing shared buffer " << shbuf_id << ", buffer count: " << shared_buffers().resource().size();
#endif
shared_buffer.deref_for_process(*this);
return 0;
}
void* Process::sys$shbuf_get(int shbuf_id, Userspace<size_t*> user_size)
{
REQUIRE_PROMISE(shared_buffer);
LOCKER(shared_buffers().lock());
auto it = shared_buffers().resource().find(shbuf_id);
if (it == shared_buffers().resource().end())
return (void*)-EINVAL;
auto& shared_buffer = *(*it).value;
if (!shared_buffer.is_shared_with(m_pid))
return (void*)-EPERM;
#ifdef SHARED_BUFFER_DEBUG
klog() << "Retaining shared buffer " << shbuf_id << ", buffer count: " << shared_buffers().resource().size();
#endif
if (user_size) {
size_t size = shared_buffer.size();
if (!copy_to_user(user_size, &size))
return (void*)-EFAULT;
}
return shared_buffer.ref_for_process_and_get_address(*this);
}
}