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Kernel: TSS stack can be set after initialization

This commit is contained in:
Bananymous 2023-04-25 14:48:12 +03:00
parent bd95f17426
commit 6ecc8cac0e
2 changed files with 16 additions and 8 deletions
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23
kernel/arch/x86_64/GDT.cpp
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@ -54,6 +54,8 @@ namespace Kernel::GDT
uint64_t address; uint64_t address;
} __attribute__((packed)); } __attribute__((packed));
static constexpr uint8_t s_tss_offset = 0x28;
static TaskStateSegment* s_tss = nullptr; static TaskStateSegment* s_tss = nullptr;
static SegmentDescriptor* s_gdt = nullptr; static SegmentDescriptor* s_gdt = nullptr;
static GDTR s_gdtr; static GDTR s_gdtr;
@ -73,30 +75,35 @@ namespace Kernel::GDT
desc.flags = flags; desc.flags = flags;
} }
static void write_tss(uint8_t offset) static void write_tss()
{ {
s_tss = new TaskStateSegment(); s_tss = new TaskStateSegment();
ASSERT(s_tss); ASSERT(s_tss);
memset(s_tss, 0x00, sizeof(TaskStateSegment)); memset(s_tss, 0x00, sizeof(TaskStateSegment));
s_tss->rsp0 = (uintptr_t)g_boot_stack_top; s_tss->rsp0 = 0;
uintptr_t base = (uintptr_t)s_tss; uintptr_t base = (uintptr_t)s_tss;
write_entry(offset, (uint32_t)base, sizeof(TaskStateSegment), 0x89, 0x0); write_entry(s_tss_offset, (uint32_t)base, sizeof(TaskStateSegment), 0x89, 0x0);
SegmentDescriptor& desc = *(SegmentDescriptor*)((uintptr_t)s_gdt + offset + 0x08); SegmentDescriptor& desc = *(SegmentDescriptor*)((uintptr_t)s_gdt + s_tss_offset + 0x08);
desc.low = base >> 32; desc.low = base >> 32;
desc.high = 0; desc.high = 0;
} }
void set_tss_stack(uintptr_t rsp)
{
s_tss->rsp0 = rsp;
}
static void flush_gdt() static void flush_gdt()
{ {
asm volatile("lgdt %0" :: "m"(s_gdtr)); asm volatile("lgdt %0" :: "m"(s_gdtr));
} }
extern "C" void flush_tss(uint16_t offset) static void flush_tss()
{ {
asm volatile("ltr %0" :: "m"(offset)); asm volatile("ltr %0" :: "m"(s_tss_offset));
} }
void initialize() void initialize()
@ -113,10 +120,10 @@ namespace Kernel::GDT
write_entry(0x10, 0x00000000, 0xFFFFF, 0x92, 0xC); // kernel data write_entry(0x10, 0x00000000, 0xFFFFF, 0x92, 0xC); // kernel data
write_entry(0x18, 0x00000000, 0xFFFFF, 0xFA, 0xA); // user code write_entry(0x18, 0x00000000, 0xFFFFF, 0xFA, 0xA); // user code
write_entry(0x20, 0x00000000, 0xFFFFF, 0xF2, 0xC); // user data write_entry(0x20, 0x00000000, 0xFFFFF, 0xF2, 0xC); // user data
write_tss(0x28); write_tss();
flush_gdt(); flush_gdt();
flush_tss(0x28); flush_tss();
} }
} }

1
kernel/include/kernel/GDT.h
View File

@ -6,5 +6,6 @@ namespace Kernel::GDT
{ {
void initialize(); void initialize();
void set_tss_stack(uintptr_t);
} }