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Kernel: Pass current cpu index as a GDT limit

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I had no idea LSL was an instruction. This cleans up code to get the
current cpu by a lot and does not require extra segment usage :D
This commit is contained in:
Bananymous
2026-05-02 18:10:10 +03:00
parent 77ca525552
commit fde085e04b
9 changed files with 23 additions and 42 deletions
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16
kernel/include/kernel/GDT.h
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@@ -133,6 +133,12 @@ namespace Kernel
void set_gsbase(uintptr_t addr);
#endif
static uint16_t cpu_index_offset() { return m_cpu_index_offset; }
void set_cpu_index(uint8_t index)
{
write_entry(m_cpu_index_offset, 0, index, 0xF2, 0x4);
}
private:
GDT() = default;
@@ -151,11 +157,13 @@ namespace Kernel
private:
#if ARCH(x86_64)
BAN::Array<SegmentDescriptor, 8> m_gdt; // null, kernel code, kernel data, user code (32 bit), user data, user code (64 bit), tss low, tss high
static constexpr uint16_t m_tss_offset = 0x30;
BAN::Array<SegmentDescriptor, 9> m_gdt; // null, kernel code, kernel data, user code (32 bit), user data, user code (64 bit), cpu-index, tss low, tss high
static constexpr uint16_t m_cpu_index_offset = 0x30;
static constexpr uint16_t m_tss_offset = 0x38;
#elif ARCH(i686)
BAN::Array<SegmentDescriptor, 9> m_gdt; // null, kernel code, kernel data, user code, user data, processor data, fsbase, gsbase, tss
static constexpr uint16_t m_tss_offset = 0x40;
BAN::Array<SegmentDescriptor, 10> m_gdt; // null, kernel code, kernel data, user code, user data, processor data, fsbase, gsbase, cpu-index, tss
static constexpr uint16_t m_cpu_index_offset = 0x40;
static constexpr uint16_t m_tss_offset = 0x48;
#endif
TaskStateSegment m_tss;
const GDTR m_gdtr {