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Kernel: Reorder the 64-bit GDT a bit

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Add a kernel data segment and make the user code segment come after
the data segment. We need the GDT to be in a certain order to support
the syscall and sysret instruction pair.
This commit is contained in:
Owen Smith 2021-07-23 21:41:57 +01:00 • committed by Andreas Kling
parent 33b78915d3
commit d36c84c331
2 changed files with 6 additions and 4 deletions
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7
Kernel/Arch/x86/DescriptorTable.h
View file

@ -31,10 +31,11 @@ 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_DATA0 0x10
# define GDT_SELECTOR_DATA3 0x18
# define GDT_SELECTOR_TSS 0x20
# define GDT_SELECTOR_TSS_PART2 0x28
# define GDT_SELECTOR_CODE3 0x20
# define GDT_SELECTOR_TSS 0x28
# define GDT_SELECTOR_TSS_PART2 0x30
#endif
namespace Kernel {

3
Kernel/Arch/x86/common/Processor.cpp
View file

@ -1156,8 +1156,9 @@ UNMAP_AFTER_INIT void Processor::gdt_init()
write_raw_gdt_entry(GDT_SELECTOR_DATA3, 0x0000ffff, 0x00cff200); // data3
#else
write_raw_gdt_entry(GDT_SELECTOR_CODE0, 0x0000ffff, 0x00af9a00); // code0
write_raw_gdt_entry(GDT_SELECTOR_CODE3, 0x0000ffff, 0x00affa00); // code3
write_raw_gdt_entry(GDT_SELECTOR_DATA0, 0x0000ffff, 0x00af9200); // data0
write_raw_gdt_entry(GDT_SELECTOR_DATA3, 0x0000ffff, 0x008ff200); // data3
write_raw_gdt_entry(GDT_SELECTOR_CODE3, 0x0000ffff, 0x00affa00); // code3
#endif
#if ARCH(I386)