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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2022, kleines Filmröllchen <filmroellchen@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/API/Syscall.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
namespace Kernel {
ErrorOr<FlatPtr> Process::sys$yield()
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_promise(Pledge::stdio));
Thread::current()->yield_without_releasing_big_lock();
return 0;
}
ErrorOr<NonnullRefPtr<Thread>> Process::get_thread_from_pid_or_tid(pid_t pid_or_tid, Syscall::SchedulerParametersMode mode)
{
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
Thread* peer;
switch (mode) {
case Syscall::SchedulerParametersMode::Thread: {
peer = Thread::current();
if (pid_or_tid != 0)
peer = Thread::from_tid(pid_or_tid);
// Only superuser can access other processes' threads.
if (!credentials()->is_superuser() && peer && &peer->process() != this)
return EPERM;
break;
}
case Syscall::SchedulerParametersMode::Process: {
auto* searched_process = this;
if (pid_or_tid != 0)
searched_process = Process::from_pid_in_same_jail(pid_or_tid);
if (searched_process == nullptr)
return ESRCH;
auto pid = searched_process->pid().value();
// Main thread has tid == pid
this->thread_list().for_each([&](auto& thread) {
if (thread.tid().value() == pid)
peer = &thread;
});
break;
}
default:
VERIFY_NOT_REACHED();
}
if (!peer)
return ESRCH;
return NonnullRefPtr<Thread> { *peer };
}
ErrorOr<FlatPtr> Process::sys$scheduler_set_parameters(Userspace<Syscall::SC_scheduler_parameters_params const*> user_param)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_promise(Pledge::proc));
auto parameters = TRY(copy_typed_from_user(user_param));
if (parameters.parameters.sched_priority < THREAD_PRIORITY_MIN || parameters.parameters.sched_priority > THREAD_PRIORITY_MAX)
return EINVAL;
SpinlockLocker lock(g_scheduler_lock);
auto peer = TRY(get_thread_from_pid_or_tid(parameters.pid_or_tid, parameters.mode));
auto credentials = this->credentials();
auto peer_credentials = peer->process().credentials();
if (!credentials->is_superuser() && credentials->euid() != peer_credentials->uid() && credentials->uid() != peer_credentials->uid())
return EPERM;
peer->set_priority((u32)parameters.parameters.sched_priority);
// POSIX says that process scheduling parameters have precedence over thread scheduling parameters.
// We don't track them separately, so overwrite the thread scheduling settings manually for now.
if (parameters.mode == Syscall::SchedulerParametersMode::Process) {
peer->process().for_each_thread([&](auto& thread) {
thread.set_priority((u32)parameters.parameters.sched_priority);
});
}
return 0;
}
ErrorOr<FlatPtr> Process::sys$scheduler_get_parameters(Userspace<Syscall::SC_scheduler_parameters_params*> user_param)
{
VERIFY_NO_PROCESS_BIG_LOCK(this);
TRY(require_promise(Pledge::proc));
Syscall::SC_scheduler_parameters_params parameters;
TRY(copy_from_user(¶meters, user_param));
int priority;
{
SpinlockLocker lock(g_scheduler_lock);
auto peer = TRY(get_thread_from_pid_or_tid(parameters.pid_or_tid, parameters.mode));
auto credentials = this->credentials();
auto peer_credentials = peer->process().credentials();
if (!credentials->is_superuser() && credentials->euid() != peer_credentials->uid() && credentials->uid() != peer_credentials->uid())
return EPERM;
priority = (int)peer->priority();
}
parameters.parameters.sched_priority = priority;
TRY(copy_to_user(user_param, ¶meters));
return 0;
}
}
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