diff options
Diffstat (limited to 'arch/i386/boot/gdt.c')
| -rw-r--r-- | arch/i386/boot/gdt.c | 141 |
1 files changed, 78 insertions, 63 deletions
diff --git a/arch/i386/boot/gdt.c b/arch/i386/boot/gdt.c index 6552721..3972e53 100644 --- a/arch/i386/boot/gdt.c +++ b/arch/i386/boot/gdt.c @@ -1,80 +1,95 @@ +#include <kernel/string.h> #include <stdint.h> -#define SEG_DESCTYPE(x) ((x) << 0x04) // Descriptor type (0 for system, 1 for code/data) -#define SEG_PRES(x) ((x) << 0x07) // Present -#define SEG_SAVL(x) ((x) << 0x0C) // Available for system use -#define SEG_LONG(x) ((x) << 0x0D) // Long mode -#define SEG_SIZE(x) ((x) << 0x0E) // Size (0 for 16-bit, 1 for 32) -#define SEG_GRAN(x) ((x) << 0x0F) // Granularity (0 for 1B - 1MB, 1 for 4KB - 4GB) -#define SEG_PRIV(x) (((x) & 0x03) << 0x05) // Set privilege level (0 - 3) - -#define SEG_DATA_RD 0x00 // Read-Only -#define SEG_DATA_RDA 0x01 // Read-Only, accessed -#define SEG_DATA_RDWR 0x02 // Read/Write -#define SEG_DATA_RDWRA 0x03 // Read/Write, accessed -#define SEG_DATA_RDEXPD 0x04 // Read-Only, expand-down -#define SEG_DATA_RDEXPDA 0x05 // Read-Only, expand-down, accessed -#define SEG_DATA_RDWREXPD 0x06 // Read/Write, expand-down -#define SEG_DATA_RDWREXPDA 0x07 // Read/Write, expand-down, accessed -#define SEG_CODE_EX 0x08 // Execute-Only -#define SEG_CODE_EXA 0x09 // Execute-Only, accessed -#define SEG_CODE_EXRD 0x0A // Execute/Read -#define SEG_CODE_EXRDA 0x0B // Execute/Read, accessed -#define SEG_CODE_EXC 0x0C // Execute-Only, conforming -#define SEG_CODE_EXCA 0x0D // Execute-Only, conforming, accessed -#define SEG_CODE_EXRDC 0x0E // Execute/Read, conforming -#define SEG_CODE_EXRDCA 0x0F // Execute/Read, conforming, accessed - -#define GDT_CODE_PL0 (SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \ - SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \ - SEG_PRIV(0) | SEG_CODE_EXRD) - -#define GDT_DATA_PL0 (SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \ - SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \ - SEG_PRIV(0) | SEG_DATA_RDWR) - -#define GDT_CODE_PL3 (SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \ - SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \ - SEG_PRIV(3) | SEG_CODE_EXRD) - -#define GDT_DATA_PL3 (SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \ - SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \ - SEG_PRIV(3) | SEG_DATA_RDWR) +struct gdt_entry { + uint16_t limit_low; + uint16_t base_low; + uint8_t base_middle; + uint8_t access; + uint8_t gran; + uint8_t base_high; +} __attribute__((packed)); -struct gpt_ptr { +struct gdt_ptr { uint16_t limit; uint32_t base; -}__attribute__((packed)); +} __attribute__((packed)); -uint64_t gdt_desc[5]; -struct gpt_ptr gp; +struct tss_entry { + uint32_t link; + uint32_t esp0; + uint32_t ss0; + uint32_t esp1; + uint32_t ss2; + uint32_t cr3; + uint32_t eip; + uint32_t eflags; + uint32_t eax; + uint32_t ecx; + uint32_t edx; + uint32_t ebx; + uint32_t esp; + uint32_t ebp; + uint32_t esi; + uint32_t edi; + uint32_t es; + uint32_t cs; + uint32_t ss; + uint32_t ds; + uint32_t fs; + uint32_t gs; + uint32_t ldtr; + uint16_t trap; + uint16_t iomap_base; +} __attribute__((packed)); -extern void flush_gdt(struct gpt_ptr *ptr); +struct gdt_entry desc[6]; +struct gdt_ptr gp; +struct tss_entry tss_entry; -uint64_t create_gdt_entry(uint32_t base, uint32_t limit, uint16_t flag) { - uint64_t ret; +extern void flush_gdt(void); +extern void flush_tss(void); - ret = limit & 0x000F0000; - ret |= (flag << 8) & 0x00F0FF00; - ret |= (base >> 16) & 0x000000FF; - ret |= base & 0xFF000000; +void gdt_set_gate(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran) { + desc[num].base_low = (base & 0xFFFF); + desc[num].base_middle = (base >> 16) & 0xFF; + desc[num].base_high = (base >> 24) & 0xFF; - ret <<= 32; + desc[num].limit_low = (limit & 0xFFFF); + desc[num].gran = (limit >> 16) & 0x0F; + desc[num].gran |= (gran & 0xF0); + desc[num].access = access; +} - ret |= base << 16; - ret |= limit & 0x0000FFFF; +void write_tss(int num, uint16_t ss0, uint16_t esp0) { + uint32_t base = (uint32_t)&tss_entry; + uint32_t limit = base + sizeof(tss_entry); - return ret; + gdt_set_gate(num, base, limit, 0xE9, 0x00); + memset(&tss_entry, 0x0, sizeof(tss_entry)); + + tss_entry.ss0 = ss0; + tss_entry.esp0 = esp0; + tss_entry.cs = 0x0B; + tss_entry.ss = 0x13; + tss_entry.ds = 0x13; + tss_entry.es = 0x13; + tss_entry.fs = 0x13; + tss_entry.gs = 0x13; + tss_entry.iomap_base = sizeof(tss_entry); } void gdt_install(void) { - gp.limit = 64 * 5 - 1; - gp.base = (uint32_t)&gdt_desc; + gp.limit = (sizeof(struct gdt_entry) * 6) - 1; + gp.base = (uint32_t)&desc; + + gdt_set_gate(0, 0, 0, 0, 0); + gdt_set_gate(1, 0, 0xFFFFFFFF, 0x9A, 0xCF); + gdt_set_gate(2, 0, 0xFFFFFFFF, 0x92, 0xCF); + gdt_set_gate(3, 0, 0xFFFFFFFF, 0xFA, 0xCF); + gdt_set_gate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF); + write_tss(5, 0x10, 0x0); - gdt_desc[0] = create_gdt_entry(0, 0, 0); - gdt_desc[1] = create_gdt_entry(0, 0x000FFFFF, GDT_CODE_PL0); - gdt_desc[2] = create_gdt_entry(0, 0x000FFFFF, GDT_DATA_PL0); - gdt_desc[3] = create_gdt_entry(0, 0x000FFFFF, GDT_DATA_PL3); - gdt_desc[4] = create_gdt_entry(0, 0x000FFFFF, GDT_DATA_PL3); - flush_gdt(&gp); + flush_gdt(); + flush_tss(); } |