ladybird/Kernel/Devices/SerialDevice.h
Tom c8d9f1b9c9 Kernel: Make copy_to/from_user safe and remove unnecessary checks
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.

So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.

To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.

Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
2020-09-13 21:19:15 +02:00

152 lines
4.7 KiB
C++

/*
* 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 <Kernel/Devices/CharacterDevice.h>
namespace Kernel {
#define SERIAL_COM1_ADDR 0x3F8
#define SERIAL_COM2_ADDR 0x2F8
#define SERIAL_COM3_ADDR 0x3E8
#define SERIAL_COM4_ADDR 0x2E8
class SerialDevice final : public CharacterDevice {
AK_MAKE_ETERNAL
public:
SerialDevice(int base_addr, unsigned minor);
virtual ~SerialDevice() override;
// ^CharacterDevice
virtual bool can_read(const FileDescription&, size_t) const override;
virtual KResultOr<size_t> read(FileDescription&, size_t, UserOrKernelBuffer&, size_t) override;
virtual bool can_write(const FileDescription&, size_t) const override;
virtual KResultOr<size_t> write(FileDescription&, size_t, const UserOrKernelBuffer&, size_t) override;
enum InterruptEnable {
LowPowerMode = 0x01 << 5,
SleepMode = 0x01 << 4,
ModemStatusInterrupt = 0x01 << 3,
ReceiverLineStatusInterrupt = 0x01 << 2,
TransmitterHoldingRegisterEmptyInterrupt = 0x01 << 1,
ReceivedDataAvailableInterrupt = 0x01 << 0
};
enum Baud {
Baud50 = 2304,
Baud110 = 1047,
Baud220 = 524,
Baud300 = 384,
Baud600 = 192,
Baud1200 = 96,
Baud2400 = 48,
Baud4800 = 24,
Baud9600 = 12,
Baud19200 = 6,
Baud38400 = 3,
Baud57600 = 2,
Baud115200 = 1
};
enum ParitySelect {
None = 0x00 << 3,
Odd = 0x01 << 3,
Even = 0x03 << 3,
Mark = 0x05 << 3,
Space = 0x07 << 3
};
enum StopBits {
One = 0x00 << 2,
Two = 0x01 << 2
};
enum WordLength {
FiveBits = 0x00,
SixBits = 0x01,
SevenBits = 0x02,
EightBits = 0x03
};
enum FIFOControl {
EnableFIFO = 0x01 << 0,
ClearReceiveFIFO = 0x01 << 1,
ClearTransmitFIFO = 0x01 << 2,
Enable64ByteFIFO = 0x01 << 5,
TriggerLevel1 = 0x00 << 6,
TriggerLevel2 = 0x01 << 6,
TriggerLevel3 = 0x02 << 6,
TriggerLevel4 = 0x03 << 6
};
enum ModemControl {
AutoflowControlEnabled = 0x01 << 5,
LoopbackMode = 0x01 << 4,
AuxiliaryOutput2 = 0x01 << 3,
AuxiliaryOutput1 = 0x01 << 2,
RequestToSend = 0x01 << 1,
DataTerminalReady = 0x01 << 0
};
enum LineStatus {
ErrorInReceivedFIFO = 0x01 << 7,
EmptyDataHoldingRegisters = 0x01 << 6,
EmptyTransmitterHoldingRegister = 0x01 << 5,
BreakInterrupt = 0x01 << 4,
FramingError = 0x01 << 3,
ParityError = 0x01 << 2,
OverrunError = 0x01 << 1,
DataReady = 0x01 << 0
};
private:
// ^CharacterDevice
virtual const char* class_name() const override { return "SerialDevice"; }
void initialize();
void set_interrupts(char interrupt_enable);
void set_baud(Baud);
void set_fifo_control(char fifo_control);
void set_line_control(ParitySelect, StopBits, WordLength);
void set_break_enable(bool break_enable);
void set_modem_control(char modem_control);
char get_line_status() const;
bool rx_ready();
bool tx_ready();
int m_base_addr;
char m_interrupt_enable;
char m_fifo_control;
Baud m_baud;
ParitySelect m_parity_select;
StopBits m_stop_bits;
WordLength m_word_length;
bool m_break_enable;
char m_modem_control;
};
}