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Set TSS and load it

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This commit is contained in:
Justin C. Miller
2018-05-17 01:39:47 -07:00
parent 87d80f84c2
commit abaa007c54
2 changed files with 55 additions and 2 deletions
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56
src/kernel/interrupts.cpp
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@@ -44,6 +44,30 @@ struct idt_descriptor
uint32_t reserved; // must be zero
} __attribute__ ((packed));
struct tss_descriptor
{
uint16_t limit_low;
uint16_t base_00;
uint8_t base_16;
gdt_type type;
uint8_t size;
uint8_t base_24;
uint32_t base_32;
uint32_t reserved;
} __attribute__ ((packed));
struct tss_entry
{
uint32_t reserved0;
uint64_t rsp[3]; // stack pointers for CPL 0-2
uint64_t ist[8]; // ist[0] is reserved
uint64_t reserved1;
uint16_t reserved2;
uint16_t iomap_offset;
};
struct table_ptr
{
uint16_t limit;
@@ -54,6 +78,7 @@ gdt_descriptor g_gdt_table[10];
idt_descriptor g_idt_table[256];
table_ptr g_gdtr;
table_ptr g_idtr;
tss_entry g_tss;
struct registers;
@@ -61,7 +86,7 @@ extern "C" {
void idt_write();
void idt_load();
void gdt_write(uint16_t cs, uint16_t ds);
void gdt_write(uint16_t cs, uint16_t ds, uint16_t tr);
void gdt_load();
void isr_handler(registers);
@@ -116,6 +141,26 @@ set_gdt_entry(uint8_t i, uint32_t base, uint64_t limit, bool is64, gdt_type type
g_gdt_table[i].type = type | gdt_type::system | gdt_type::present;
}
void
set_tss_entry(uint8_t i, uint64_t base, uint64_t limit)
{
tss_descriptor tssd;
tssd.limit_low = limit & 0xffff;
tssd.size = (limit >> 16) & 0xf;
tssd.base_00 = base & 0xffff;
tssd.base_16 = (base >> 16) & 0xff;
tssd.base_24 = (base >> 24) & 0xff;
tssd.base_32 = (base >> 32) & 0xffffffff;
tssd.type =
gdt_type::accessed |
gdt_type::execute |
gdt_type::ring3 |
gdt_type::present;
kutil::memcpy(&g_gdt_table[i], &tssd, sizeof(tss_descriptor));
}
void
set_idt_entry(uint8_t i, uint64_t addr, uint16_t selector, uint8_t flags)
{
@@ -173,7 +218,14 @@ interrupts_init()
set_gdt_entry(3, 0, 0xfffff, true, gdt_type::ring3 | gdt_type::read_write | gdt_type::execute);
set_gdt_entry(4, 0, 0xfffff, true, gdt_type::ring3 | gdt_type::read_write);
gdt_write(1 << 3, 2 << 3);
kutil::memset(&g_tss, 0, sizeof(tss_entry));
addr_t tss_base = reinterpret_cast<addr_t>(&g_tss);
// Note that this takes TWO GDT entries
set_tss_entry(6, tss_base, sizeof(tss_entry));
// TODO: Set up TSS stack pointers!
gdt_write(1 << 3, 2 << 3, 6 << 3);
g_idtr.limit = sizeof(g_idt_table) - 1;
g_idtr.base = reinterpret_cast<uint64_t>(&g_idt_table);

1
src/kernel/interrupts.s
View File

@@ -25,6 +25,7 @@ gdt_write:
push rax
o64 retf
.next:
ltr dx
ret
global gdt_load