ladybird/Kernel/Devices/KCOVDevice.cpp
Andreas Kling 30861daa93 Kernel: Simplify the File memory-mapping API
Before this change, we had File::mmap() which did all the work of
setting up a VMObject, and then creating a Region in the current
process's address space.

This patch simplifies the interface by removing the region part.
Files now only have to return a suitable VMObject from
vmobject_for_mmap(), and then sys$mmap() itself will take care of
actually mapping it into the address space.

This fixes an issue where we'd try to block on I/O (for inode metadata
lookup) while holding the address space spinlock. It also reduces time
spent holding the address space lock.
2022-08-24 14:57:51 +02:00

132 lines
4.2 KiB
C++

/*
* Copyright (c) 2021, Patrick Meyer <git@the-space.agency>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/NonnullOwnPtr.h>
#include <Kernel/Devices/DeviceManagement.h>
#include <Kernel/Devices/KCOVDevice.h>
#include <Kernel/Devices/KCOVInstance.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <LibC/sys/ioctl_numbers.h>
#include <Kernel/Panic.h>
namespace Kernel {
HashMap<ProcessID, KCOVInstance*>* KCOVDevice::proc_instance;
HashMap<ThreadID, KCOVInstance*>* KCOVDevice::thread_instance;
UNMAP_AFTER_INIT NonnullLockRefPtr<KCOVDevice> KCOVDevice::must_create()
{
auto kcov_device_or_error = DeviceManagement::try_create_device<KCOVDevice>();
// FIXME: Find a way to propagate errors
VERIFY(!kcov_device_or_error.is_error());
return kcov_device_or_error.release_value();
}
UNMAP_AFTER_INIT KCOVDevice::KCOVDevice()
: CharacterDevice(30, 0)
{
proc_instance = new HashMap<ProcessID, KCOVInstance*>();
thread_instance = new HashMap<ThreadID, KCOVInstance*>();
dbgln("KCOVDevice created");
}
void KCOVDevice::free_thread()
{
auto thread = Thread::current();
auto tid = thread->tid();
auto maybe_kcov_instance = thread_instance->get(tid);
if (!maybe_kcov_instance.has_value())
return;
auto kcov_instance = maybe_kcov_instance.value();
VERIFY(kcov_instance->state() == KCOVInstance::TRACING);
kcov_instance->set_state(KCOVInstance::OPENED);
thread_instance->remove(tid);
}
void KCOVDevice::free_process()
{
auto pid = Process::current().pid();
auto maybe_kcov_instance = proc_instance->get(pid);
if (!maybe_kcov_instance.has_value())
return;
auto kcov_instance = maybe_kcov_instance.value();
VERIFY(kcov_instance->state() == KCOVInstance::OPENED);
kcov_instance->set_state(KCOVInstance::UNUSED);
proc_instance->remove(pid);
delete kcov_instance;
}
ErrorOr<NonnullLockRefPtr<OpenFileDescription>> KCOVDevice::open(int options)
{
auto pid = Process::current().pid();
if (proc_instance->get(pid).has_value())
return EBUSY; // This process already open()ed the kcov device
auto kcov_instance = new KCOVInstance(pid);
kcov_instance->set_state(KCOVInstance::OPENED);
proc_instance->set(pid, kcov_instance);
return File::open(options);
}
ErrorOr<void> KCOVDevice::ioctl(OpenFileDescription&, unsigned request, Userspace<void*> arg)
{
auto thread = Thread::current();
auto tid = thread->tid();
auto pid = thread->pid();
auto maybe_kcov_instance = proc_instance->get(pid);
if (!maybe_kcov_instance.has_value())
return ENXIO; // This proc hasn't opened the kcov dev yet
auto kcov_instance = maybe_kcov_instance.value();
SpinlockLocker locker(kcov_instance->spinlock());
switch (request) {
case KCOV_SETBUFSIZE:
if (kcov_instance->state() >= KCOVInstance::TRACING)
return EBUSY;
return kcov_instance->buffer_allocate((FlatPtr)arg.unsafe_userspace_ptr());
case KCOV_ENABLE:
if (kcov_instance->state() >= KCOVInstance::TRACING)
return EBUSY;
if (!kcov_instance->has_buffer())
return ENOBUFS;
VERIFY(kcov_instance->state() == KCOVInstance::OPENED);
kcov_instance->set_state(KCOVInstance::TRACING);
thread_instance->set(tid, kcov_instance);
return {};
case KCOV_DISABLE: {
auto maybe_kcov_instance = thread_instance->get(tid);
if (!maybe_kcov_instance.has_value())
return ENOENT;
VERIFY(kcov_instance->state() == KCOVInstance::TRACING);
kcov_instance->set_state(KCOVInstance::OPENED);
thread_instance->remove(tid);
return {};
}
default:
return EINVAL;
}
}
ErrorOr<NonnullLockRefPtr<Memory::VMObject>> KCOVDevice::vmobject_for_mmap(Process& process, Memory::VirtualRange const&, u64&, bool)
{
auto pid = process.pid();
auto maybe_kcov_instance = proc_instance->get(pid);
VERIFY(maybe_kcov_instance.has_value()); // Should happen on fd open()
auto kcov_instance = maybe_kcov_instance.value();
if (!kcov_instance->vmobject())
return ENOBUFS; // mmaped, before KCOV_SETBUFSIZE
return *kcov_instance->vmobject();
}
}