Skip to content

Commit

Permalink
AK: Generalize ByteReader
Browse files Browse the repository at this point in the history 
Also use it instead of CPU.h's possibly_unaligned_data interface
  • Loading branch information
@Hendiadyoin1 @alimpfard
Hendiadyoin1 authored and alimpfard committed Jul 14, 2021
1 parent b98e741 commit d761c50
Show file tree
Hide file tree
Showing 4 changed files with 20 additions and 113 deletions.
59 changes: 10 additions & 49 deletions AK/ByteReader.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6,68 +6,29 @@

#pragma once

#include <AK/StdLibExtraDetails.h>
#include <AK/Types.h>

namespace AK {

struct ByteReader {
static void store(u8* address, u16 value)
{
union {
u16 _16;
u8 _8[2];
} const v { ._16 = value };
__builtin_memcpy(address, v._8, 2);
}

static void store(u8* address, u32 value)
{
union {
u32 _32;
u8 _8[4];
} const v { ._32 = value };
__builtin_memcpy(address, v._8, 4);
}

static void load(const u8* address, u16& value)
{
union {
u16 _16;
u8 _8[2];
} v { ._16 = 0 };
__builtin_memcpy(&v._8, address, 2);
value = v._16;
}

static void load(const u8* address, u32& value)
template<typename T>
requires(IsTriviallyCopyable<T>) static void store(u8* addr, T value)
{
union {
u32 _32;
u8 _8[4];
} v { ._32 = 0 };
__builtin_memcpy(&v._8, address, 4);
value = v._32;
__builtin_memcpy(addr, &value, sizeof(T));
}

static void load(const u8* address, u64& value)
template<typename T>
requires(IsTriviallyConstructible<T>) static void load(const u8* addr, T& value)
{
union {
u64 _64;
u8 _8[8];
} v { ._64 = 0 };
__builtin_memcpy(&v._8, address, 8);
value = v._64;
__builtin_memcpy(&value, addr, sizeof(T));
}

template<typename T>
static T* load_pointer(const u8* address)
{
if constexpr (sizeof(T*) == 4) {
return reinterpret_cast<T*>(load32(address));
} else {
static_assert(sizeof(T*) == 8, "sizeof(T*) must be either 4 or 8");
return reinterpret_cast<T*>(load64(address));
}
FlatPtr value;
load<FlatPtr>(address, value);
return reinterpret_cast<T*>(value);
}

static u16 load16(const u8* address)
Expand Down
56 changes: 0 additions & 56 deletions Kernel/Arch/x86/CPU.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -30,62 +30,6 @@ inline u32 get_iopl_from_eflags(u32 eflags)
return (eflags & iopl_mask) >> 12;
}

template<Integral T>
void read_possibly_unaligned_data(u8* where, T& data) requires(sizeof(T) == 8 || sizeof(T) == 4 || sizeof(T) == 2)
{
if (((FlatPtr)where % alignof(T)) == 0) {
data = *(T*)where;
return;
}
if constexpr (sizeof(T) == 2) {
data = *where | ((u16)(*(where + 1)) << 8);
return;
}
if constexpr (sizeof(T) == 4) {
data = *where | (((u32) * (where + 1)) << 8) | (((u32) * (where + 2)) << 16) | (((u32) * (where + 3)) << 24);
return;
}
if constexpr (sizeof(T) == 8) {
data = *where | (((u32) * (where + 1)) << 8) | (((u64) * (where + 2)) << 16) | (((u64) * (where + 3)) << 24)
| (((u64) * (where + 4)) << 32) | (((u64) * (where + 5)) << 40) | (((u64) * (where + 6)) << 48) | (((u64) * (where + 7)) << 56);
return;
}
VERIFY_NOT_REACHED();
}

template<Integral T>
void write_possibly_unaligned_data(u8* where, T data) requires(sizeof(T) == 8 || sizeof(T) == 4 || sizeof(T) == 2)
{
if (((FlatPtr)where % alignof(T)) == 0) {
*(T*)where = data;
return;
}
if constexpr (sizeof(T) == 2) {
where[0] = (u8)(data & 0xFF);
where[1] = (u8)((data >> 8) & 0xFF);
return;
}
if constexpr (sizeof(T) == 4) {
where[0] = (u8)(data & 0xFF);
where[1] = (u8)((data >> 8) & 0xFF);
where[2] = (u8)((data >> 16) & 0xFF);
where[3] = (u8)((data >> 24) & 0xFF);
return;
}
if constexpr (sizeof(T) == 8) {
where[0] = (u8)(data & 0xFF);
where[1] = (u8)((data >> 8) & 0xFF);
where[2] = (u8)((data >> 16) & 0xFF);
where[3] = (u8)((data >> 24) & 0xFF);
where[5] = (u8)(data >> 32 & 0xFF);
where[5] = (u8)((data >> 40) & 0xFF);
where[6] = (u8)((data >> 48) & 0xFF);
where[7] = (u8)((data >> 52) & 0xFF);
return;
}
VERIFY_NOT_REACHED();
}

const DescriptorTablePointer& get_gdtr();
const DescriptorTablePointer& get_idtr();

Expand Down
9 changes: 5 additions & 4 deletions Kernel/Bus/PCI/MMIOAccess.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/

#include <AK/ByteReader.h>
#include <AK/Optional.h>
#include <Kernel/Arch/x86/InterruptDisabler.h>
#include <Kernel/Bus/PCI/MMIOAccess.h>
Expand Down Expand Up @@ -128,7 +129,7 @@ u16 MMIOAccess::read16_field(Address address, u32 field)
VERIFY(field < 0xfff);
dbgln_if(PCI_DEBUG, "PCI: MMIO Reading 16-bit field {:#08x} for {}", field, address);
u16 data = 0;
read_possibly_unaligned_data<u16>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), data);
ByteReader::load<u16>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), data);
return data;
}

Expand All @@ -138,7 +139,7 @@ u32 MMIOAccess::read32_field(Address address, u32 field)
VERIFY(field <= 0xffc);
dbgln_if(PCI_DEBUG, "PCI: MMIO Reading 32-bit field {:#08x} for {}", field, address);
u32 data = 0;
read_possibly_unaligned_data<u32>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), data);
ByteReader::load<u32>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), data);
return data;
}

Expand All @@ -154,14 +155,14 @@ void MMIOAccess::write16_field(Address address, u32 field, u16 value)
ScopedSpinLock lock(m_access_lock);
VERIFY(field < 0xfff);
dbgln_if(PCI_DEBUG, "PCI: MMIO Writing 16-bit field {:#08x}, value={:#02x} for {}", field, value, address);
write_possibly_unaligned_data<u16>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), value);
ByteReader::store<u16>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), value);
}
void MMIOAccess::write32_field(Address address, u32 field, u32 value)
{
ScopedSpinLock lock(m_access_lock);
VERIFY(field <= 0xffc);
dbgln_if(PCI_DEBUG, "PCI: MMIO Writing 32-bit field {:#08x}, value={:#02x} for {}", field, value, address);
write_possibly_unaligned_data<u32>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), value);
ByteReader::store<u32>(get_device_configuration_space(address).offset(field & 0xfff).as_ptr(), value);
}

void MMIOAccess::enumerate_hardware(Function<void(Address, ID)> callback)
Expand Down
9 changes: 5 additions & 4 deletions Kernel/Bus/PCI/WindowedMMIOAccess.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
* SPDX-License-Identifier: BSD-2-Clause
*/

#include <AK/ByteReader.h>
#include <AK/Optional.h>
#include <AK/StringView.h>
#include <Kernel/Arch/x86/InterruptDisabler.h>
Expand Down Expand Up @@ -79,7 +80,7 @@ u16 WindowedMMIOAccess::read16_field(Address address, u32 field)
VERIFY(field < 0xfff);
dbgln_if(PCI_DEBUG, "PCI: MMIO Reading 16-bit field {:#08x} for {}", field, address);
u16 data = 0;
read_possibly_unaligned_data<u16>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), data);
ByteReader::load<u16>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), data);
return data;
}

Expand All @@ -89,7 +90,7 @@ u32 WindowedMMIOAccess::read32_field(Address address, u32 field)
VERIFY(field <= 0xffc);
dbgln_if(PCI_DEBUG, "PCI: MMIO Reading 32-bit field {:#08x} for {}", field, address);
u32 data = 0;
read_possibly_unaligned_data<u32>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), data);
ByteReader::load<u32>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), data);
return data;
}

Expand All @@ -105,14 +106,14 @@ void WindowedMMIOAccess::write16_field(Address address, u32 field, u16 value)
InterruptDisabler disabler;
VERIFY(field < 0xfff);
dbgln_if(PCI_DEBUG, "PCI: MMIO Writing 16-bit field {:#08x}, value={:#02x} for {}", field, value, address);
write_possibly_unaligned_data<u16>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), value);
ByteReader::store<u16>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), value);
}
void WindowedMMIOAccess::write32_field(Address address, u32 field, u32 value)
{
InterruptDisabler disabler;
VERIFY(field <= 0xffc);
dbgln_if(PCI_DEBUG, "PCI: MMIO Writing 32-bit field {:#08x}, value={:#02x} for {}", field, value, address);
write_possibly_unaligned_data<u32>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), value);
ByteReader::store<u32>(get_device_configuration_space(address).value().offset(field & 0xfff).as_ptr(), value);
}

}
Expand Down

0 comments on commit d761c50

Please sign in to comment.