157 lines
3.5 KiB
C++
157 lines
3.5 KiB
C++
/******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along
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with Sortix. If not, see <http://www.gnu.org/licenses/>.
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syscall.h
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Handles system calls from userspace safely.
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******************************************************************************/
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#include <sortix/kernel/platform.h>
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#include <libmaxsi/error.h>
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#include "syscall.h"
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#include <sortix/syscallnum.h>
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#include <sortix/kernel/panic.h>
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#include "process.h"
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#include "thread.h"
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#include "scheduler.h"
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using namespace Maxsi;
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namespace Sortix
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{
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namespace Syscall
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{
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extern "C"
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{
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CPU::SyscallRegisters* syscall_state_ptr;
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unsigned system_was_incomplete;
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size_t SYSCALL_MAX;
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volatile void* syscall_list[SYSCALL_MAX_NUM];
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}
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int BadSyscall()
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{
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// TODO: Send signal, set errno, or crash/abort process?
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return -1;
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}
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void Init()
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{
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SYSCALL_MAX = SYSCALL_MAX_NUM;
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for ( size_t i = 0; i < SYSCALL_MAX_NUM; i++ )
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{
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syscall_list[i] = (void*) BadSyscall;
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}
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}
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void Register(size_t index, void* funcptr)
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{
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if ( SYSCALL_MAX_NUM <= index )
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{
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PanicF("attempted to register syscall 0x%p to index %zu, but "
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"SYSCALL_MAX_NYN = %zu", funcptr, index, SYSCALL_MAX_NUM);
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}
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syscall_list[index] = funcptr;
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}
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void Incomplete()
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{
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Thread* thread = CurrentThread();
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system_was_incomplete = 1;
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CPU::InterruptRegisters* regs = InterruptRegs();
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thread->SaveRegisters(regs);
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Scheduler::SetThreadState(thread, Thread::State::BLOCKING);
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Scheduler::Switch(regs);
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}
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void Yield()
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{
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Panic("Syscall::Yield() is not implemented because it caused "
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"instability and other issues.");
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}
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void AsIs()
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{
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system_was_incomplete = 1;
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}
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void ScheduleResumption(Thread* thread)
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{
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Scheduler::SetThreadState(thread, Thread::State::RUNNABLE);
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}
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extern "C" void update_userspace_errno()
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{
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int error = Error::Last();
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if ( !error ) { return; }
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Process* process = CurrentProcess();
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if ( !process->errno ) { return; }
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// TODO: Validate that process->errno is in userspace memory!
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*process->errno = error;
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}
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extern "C" size_t resume_syscall(void* scfunc, size_t scsize, size_t* scstate);
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void Resume(CPU::InterruptRegisters* regs)
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{
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Thread* thread = CurrentThread();
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syscall_state_ptr = (CPU::SyscallRegisters*) regs;
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ASSERT(thread->scfunc);
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size_t* scstate = thread->scstate;
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size_t scsize = thread->scsize;
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void* scfunc = thread->scfunc;
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system_was_incomplete = 0;
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Error::Set(0);
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size_t result = resume_syscall(scfunc, scsize, scstate);
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bool incomplete = (system_was_incomplete);
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system_was_incomplete = 1;
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if ( !incomplete )
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{
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syscall_state_ptr->result = result;
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update_userspace_errno();
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return;
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}
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Incomplete();
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}
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CPU::InterruptRegisters* InterruptRegs()
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{
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return (CPU::InterruptRegisters*) syscall_state_ptr;
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}
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CPU::SyscallRegisters* SyscallRegs()
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{
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return syscall_state_ptr;
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}
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}
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}
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