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

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This commit is contained in:
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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25
Kernel/Arch/x86/common/Processor.cpp
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@ -19,6 +19,7 @@
#include <Kernel/Arch/x86/CPUID.h>
#include <Kernel/Arch/x86/Interrupts.h>
#include <Kernel/Arch/x86/MSR.h>
#include <Kernel/Arch/x86/Processor.h>
#include <Kernel/Arch/x86/ProcessorInfo.h>
#include <Kernel/Arch/x86/SafeMem.h>
@ -1056,11 +1057,17 @@ UNMAP_AFTER_INIT void Processor::gdt_init()
m_gdtr.limit = 0;
write_raw_gdt_entry(0x0000, 0x00000000, 0x00000000);
#if ARCH(I386)
write_raw_gdt_entry(GDT_SELECTOR_CODE0, 0x0000ffff, 0x00cf9a00); // code0
write_raw_gdt_entry(GDT_SELECTOR_DATA0, 0x0000ffff, 0x00cf9200); // data0
write_raw_gdt_entry(GDT_SELECTOR_CODE3, 0x0000ffff, 0x00cffa00); // code3
write_raw_gdt_entry(GDT_SELECTOR_DATA3, 0x0000ffff, 0x00cff200); // data3
#else
write_raw_gdt_entry(GDT_SELECTOR_CODE0, 0x0000ffff, 0x00ef9a00); // code0
write_raw_gdt_entry(GDT_SELECTOR_CODE3, 0x0000ffff, 0x00effa00); // code3
#endif
#if ARCH(I386)
Descriptor tls_descriptor {};
tls_descriptor.low = tls_descriptor.high = 0;
tls_descriptor.dpl = 3;
@ -1083,10 +1090,11 @@ UNMAP_AFTER_INIT void Processor::gdt_init()
fs_descriptor.descriptor_type = 1;
fs_descriptor.type = 2;
write_gdt_entry(GDT_SELECTOR_PROC, fs_descriptor); // fs0
#endif
Descriptor tss_descriptor {};
tss_descriptor.set_base(VirtualAddress { &m_tss });
tss_descriptor.set_limit(sizeof(TSS32) - 1);
tss_descriptor.set_base(VirtualAddress { (size_t)&m_tss & 0xffffffff });
tss_descriptor.set_limit(sizeof(TSS) - 1);
tss_descriptor.dpl = 0;
tss_descriptor.segment_present = 1;
tss_descriptor.granularity = 0;
@ -1096,9 +1104,21 @@ UNMAP_AFTER_INIT void Processor::gdt_init()
tss_descriptor.type = 9;
write_gdt_entry(GDT_SELECTOR_TSS, tss_descriptor); // tss
#if ARCH(X86_64)
Descriptor tss_descriptor_part2 {};
tss_descriptor_part2.low = (size_t)&m_tss >> 32;
write_gdt_entry(GDT_SELECTOR_TSS_PART2, tss_descriptor_part2);
#endif
flush_gdt();
load_task_register(GDT_SELECTOR_TSS);
#if ARCH(X86_64)
MSR fs_base(MSR_FS_BASE);
fs_base.set((size_t)this & 0xffffffff, (size_t)this >> 32);
#endif
#if ARCH(I386)
asm volatile(
"mov %%ax, %%ds\n"
"mov %%ax, %%es\n"
@ -1107,7 +1127,6 @@ UNMAP_AFTER_INIT void Processor::gdt_init()
: "memory");
set_fs(GDT_SELECTOR_PROC);
#if ARCH(I386)
// Make sure CS points to the kernel code descriptor.
// clang-format off
asm volatile(