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Kernel: Make IDT Entries their one struct

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This is to make them a bit more transparent, and with a bit of Compiler
magic we get the 64-bit implementation in the same package
This commit is contained in:
Hendiadyoin1 2021-03-07 22:11:30 +01:00 committed by Andreas Kling
parent 0d934fc991
commit 61240aaad3
Notes: sideshowbarker 2024-07-18 21:12:55 +09:00 
Author: https://github.com/Hendiadyoin1
Commit: https://github.com/SerenityOS/serenity/commit/61240aaad37
Pull-request: https://github.com/SerenityOS/serenity/pull/5679
Reviewed-by: https://github.com/ADKaster
Reviewed-by: https://github.com/linusg
2 changed files with 74 additions and 5 deletions
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14
Kernel/Arch/i386/CPU.cpp
View File

@ -58,7 +58,7 @@ extern FlatPtr end_of_ro_after_init;
namespace Kernel {
READONLY_AFTER_INIT static DescriptorTablePointer s_idtr;
READONLY_AFTER_INIT static Descriptor s_idt[256];
READONLY_AFTER_INIT static IDTEntry s_idt[256];
static GenericInterruptHandler* s_interrupt_handler[GENERIC_INTERRUPT_HANDLERS_COUNT];
@ -484,14 +484,18 @@ void unregister_generic_interrupt_handler(u8 interrupt_number, GenericInterruptH
UNMAP_AFTER_INIT void register_interrupt_handler(u8 index, void (*handler)())
{
s_idt[index].low = 0x00080000 | LSW((FlatPtr)(handler));
s_idt[index].high = ((FlatPtr)(handler)&0xffff0000) | 0x8e00;
// FIXME: Why is that with selector 8?
// FIXME: Is the Gate Type really required to be an Interupt
// FIXME: Whats up with that storage segment 0?
s_idt[index] = IDTEntry((FlatPtr)handler, 8, IDTEntryType::InterruptGate32, 0, 0);
}
UNMAP_AFTER_INIT void register_user_callable_interrupt_handler(u8 index, void (*handler)())
{
s_idt[index].low = 0x00080000 | LSW(((FlatPtr)handler));
s_idt[index].high = ((FlatPtr)(handler)&0xffff0000) | 0xef00;
// FIXME: Why is that with selector 8?
// FIXME: Is the Gate Type really required to be a Trap
// FIXME: Whats up with that storage segment 0?
s_idt[index] = IDTEntry((FlatPtr)handler, 8, IDTEntryType::TrapGate32, 0, 3);
}
UNMAP_AFTER_INIT void flush_idt()

65
Kernel/Arch/x86/DescriptorTable.h
View File

@ -111,4 +111,69 @@ union [[gnu::packed]] Descriptor {
}
};
enum class IDTEntryType {
TaskGate32 = 0b0101,
InterruptGate16 = 0b110,
TrapGate16 = 0b111,
InterruptGate32 = 0b1110,
TrapGate32 = 0b1111,
};
// Clang doesn't format this right due to the compiler magic
// clang-format off
struct [[gnu::packed]] IDTEntry
{
u16 offset_1; // offset bits 0..15
u16 selector; // a code segment selector in GDT or LDT
u8 zero; // unused, set to 0 (maybe used on amd64)
struct {
// FIXME: Is the order correct?
u8 gate_type : 4;
u8 storage_segment : 1;
u8 descriptor_privilege_level : 2;
u8 present : 1;
} type_attr; // type and attributes
u16 offset_2; // offset bits 16..31
#if !ARCH(I386)
// we may need to switch those around?
u32 offset_3;
u32 zeros;
#endif
IDTEntry() = default;
IDTEntry(FlatPtr callback, u16 selector_, IDTEntryType type, u8 storage_segment, u8 privilige_level)
: offset_1 { (u16)((FlatPtr)callback & 0xFFFF) }
, selector { selector_ }
, zero { 0 }
, type_attr {
.gate_type = (u8)type,
.storage_segment = storage_segment,
.descriptor_privilege_level = (u8)(privilige_level & 0b11),
.present = 1,
}
, offset_2 { (u16)((FlatPtr)callback >> 16) }
#if !ARCH(I386)
, offset_3 { (u32)(((FlatPtr)callback) >> 32) }
, zeros { 0 }
#endif
{
}
u32 off()
{
#if ARCH(I386)
return (u32)offset_2 << 16 & (u32)offset_1;
#else
return (u64)offset_3 << 32 & (u64)offset_2 << 16 & (u64)offset_1;
#endif
}
IDTEntryType type()
{
return IDTEntryType(type_attr.gate_type);
}
};
// clang-format on
}