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Kernel: Add support for setting up a x86_64 GDT once in C++ land

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Gunnar Beutner 2021-06-25 14:34:04 +02:00 • committed by Andreas Kling
parent 29d9666e02
commit f630299d49
5 changed files with 55 additions and 11 deletions
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24
Kernel/Arch/x86/DescriptorTable.h
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@ -10,13 +10,14 @@
#include <AK/Types.h>
#include <Kernel/VirtualAddress.h>
#define GDT_SELECTOR_CODE0 0x08
#define GDT_SELECTOR_DATA0 0x10
#define GDT_SELECTOR_CODE3 0x18
#define GDT_SELECTOR_DATA3 0x20
#define GDT_SELECTOR_TLS 0x28
#define GDT_SELECTOR_PROC 0x30
#define GDT_SELECTOR_TSS 0x38
#if ARCH(I386)
# define GDT_SELECTOR_CODE0 0x08
# define GDT_SELECTOR_DATA0 0x10
# define GDT_SELECTOR_CODE3 0x18
# define GDT_SELECTOR_DATA3 0x20
# define GDT_SELECTOR_TLS 0x28
# define GDT_SELECTOR_PROC 0x30
# define GDT_SELECTOR_TSS 0x38
// SYSENTER makes certain assumptions on how the GDT is structured:
static_assert(GDT_SELECTOR_CODE0 + 8 == GDT_SELECTOR_DATA0); // SS0 = CS0 + 8
@ -24,6 +25,12 @@ static_assert(GDT_SELECTOR_CODE0 + 8 == GDT_SELECTOR_DATA0); // SS0 = CS0 + 8
// SYSEXIT makes certain assumptions on how the GDT is structured:
static_assert(GDT_SELECTOR_CODE0 + 16 == GDT_SELECTOR_CODE3); // CS3 = CS0 + 16
static_assert(GDT_SELECTOR_CODE0 + 24 == GDT_SELECTOR_DATA3); // SS3 = CS0 + 32
#else
# define GDT_SELECTOR_CODE0 0x08
# define GDT_SELECTOR_CODE3 0x10
# define GDT_SELECTOR_TSS 0x18
# define GDT_SELECTOR_TSS_PART2 0x20
#endif
namespace Kernel {
@ -82,6 +89,7 @@ union [[gnu::packed]] Descriptor {
base_lo = base.get() & 0xffffu;
base_hi = (base.get() >> 16u) & 0xffu;
base_hi2 = (base.get() >> 24u) & 0xffu;
VERIFY(base.get() <= 0xffffffff);
}
void set_limit(u32 length)
@ -91,6 +99,8 @@ union [[gnu::packed]] Descriptor {
}
};
static_assert(sizeof(Descriptor) == 8);
enum class IDTEntryType {
TaskGate32 = 0b0101,
InterruptGate16 = 0b110,