From 98ccb3a2d41015b42d46d8b382decc755a003c3f Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Tue, 4 Jun 2024 13:41:11 -0400 Subject: project: Initial commit Signed-off-by: Ian Moffett --- sys/include/arch/amd64/gdt.h | 47 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 sys/include/arch/amd64/gdt.h (limited to 'sys/include/arch/amd64/gdt.h') diff --git a/sys/include/arch/amd64/gdt.h b/sys/include/arch/amd64/gdt.h new file mode 100644 index 0000000..6f8a914 --- /dev/null +++ b/sys/include/arch/amd64/gdt.h @@ -0,0 +1,47 @@ +#ifndef _AMD64_GDT_H_ +#define _AMD64_GDT_H_ + +#include +#include + +#define KERNEL_CS 0x08 +#define KERNEL_DS 0x10 + +struct __packed gdt_entry { + uint16_t limit; + uint16_t base_low; + uint8_t base_mid; + uint8_t access; + uint8_t granularity; + uint8_t base_hi; +}; + +struct __packed gdtr { + uint16_t limit; + uintptr_t offset; +}; + +__always_inline static inline void +gdt_load(struct gdtr *gdtr) +{ + __ASMV("lgdt %0\n" + "push $8\n" /* Push CS */ + "lea 1f(%%rip), %%rax\n" /* Load 1 label address into RAX */ + "push %%rax\n" /* Push the return address (label 1) */ + "lretq\n" /* Far return to update CS */ + "1:\n" + " mov $0x10, %%eax\n" + " mov %%eax, %%ds\n" + " mov %%eax, %%es\n" + " mov %%eax, %%fs\n" + " mov %%eax, %%gs\n" + " mov %%eax, %%ss\n" + : + : "m" (*gdtr) + : "rax", "memory" + ); +} + +extern struct gdt_entry g_gdt_data[256]; + +#endif /* !AMD64_GDT_H_ */ -- cgit v1.2.3