TermiNexus
3583f78efc
- 去掉不再需要的 import t, c - class → struct（纯数据聚合） - t.CArray[T, N] → [N]T - static 修饰符移到类型前 - @__attribute(packed) → @__attribute__(packed) - UHCI 中断回调参数改用 callable[[], int] - 同步 CPUID 注释中的旧类型名
153 lines
5.4 KiB
Plaintext
153 lines
5.4 KiB
Plaintext
@__attribute__(packed)
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struct gdt_entry:
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limit_low: uint16
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base_low: uint16
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base_middle: uint8
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access: uint8
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granularity: uint8
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base_high: uint8
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@__attribute__(packed)
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struct gdt_entry64:
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limit_low: uint16
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base_low: uint16
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base_middle: uint8
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access: uint8
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granularity: uint8
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base_high: uint8
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base_upper: uint32
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reserved: uint32
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@__attribute__(packed)
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struct gdt_ptr:
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limit: uint16
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base: uint64
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export gdt: [8]gdt_entry = []
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export gp: [10]uint8 = []
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# TSS buffer: 104 bytes, raw byte array to avoid packed struct issues
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# x86_64 TSS layout: reserved0(4) rsp0(8) rsp1(8) rsp2(8) reserved1(8) ist1-ist7(56) reserved2(8) reserved3(2) iomap_base(2)
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export tss_buf: [104]uint8
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# 选择子布局（**必须与 SYSRET 的硬性要求一致**：SYSRET 加载 CS = STAR[63:48]+16、SS = +8，
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# 且 cs_sel 必须正好是 ss_sel 上面 8 字节；STAR[63:48] 在 syscall.vp 里是 0x1B）：
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# 0x08 内核代码 0x10 内核数据
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# 0x20 用户数据(USER_DATA_SEG) 0x28 用户代码(USER_CODE_SEG) ← 0x28 = 0x1B+16 ✓ / 0x20 = 0x1B+8 ✓
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# 0x30 TSS(16 字节描述符，占 GDT 第 6/7 项)
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# 注：gdt[3]（0x18）保留一份同样的用户代码描述符作兼容镜像 —— 早期路径曾用 0x1B iretq 进用户态。
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define CODE_SEG: uint16 = 0x08
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define DATA_SEG: uint16 = 0x10
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define USER_CODE_SEG: uint16 = 0x28
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define USER_DATA_SEG: uint16 = 0x20
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define TSS_SEG: uint16 = 0x30
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def init():
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global gp, gdt, tss_buf
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gdt[0].limit_low = 0
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gdt[0].base_low = 0
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gdt[0].base_middle = 0
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gdt[0].access = 0
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gdt[0].granularity = 0
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gdt[0].base_high = 0
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gdt[1].limit_low = 0
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gdt[1].base_low = 0
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gdt[1].base_middle = 0
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gdt[1].access = 0x9A
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gdt[1].granularity = 0x20
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gdt[1].base_high = 0
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gdt[2].limit_low = 0
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gdt[2].base_low = 0
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gdt[2].base_middle = 0
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gdt[2].access = 0x92
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gdt[2].granularity = 0xCF
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gdt[2].base_high = 0
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gdt[3].limit_low = 0
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gdt[3].base_low = 0
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gdt[3].base_middle = 0
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gdt[3].access = 0xFA
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gdt[3].granularity = 0x20
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gdt[3].base_high = 0
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gdt[4].limit_low = 0
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gdt[4].base_low = 0
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gdt[4].base_middle = 0
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gdt[4].access = 0xF2
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gdt[4].granularity = 0xCF
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gdt[4].base_high = 0
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# 用户代码段必须落在第 5 项（选择子 0x28）：sysretq 返回用户态时硬件按 STAR[63:48]+16 算 CS=0x2B，
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# SS=0x23（第 4 项用户数据）—— 若第 5 项不是代码段，严格实现会在 SYSRET 处 #GP（QEMU 不校验才长期没暴露）。
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gdt[5].limit_low = 0
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gdt[5].base_low = 0
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gdt[5].base_middle = 0
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gdt[5].access = 0xFA
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gdt[5].granularity = 0x20
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gdt[5].base_high = 0
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# Set up TSS descriptor in GDT entries 6-7 (selector 0x30)
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setTSS64(6, uint64(&tss_buf), 103)
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__asm__("""lea rax, [rip + gdt]
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lea rcx, [rip + gp]
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mov word ptr [rcx], 0x3F
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mov qword ptr [rcx+2], rax""",
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op=[ASM_DESCR.CLOBBER_MEMORY, ASM_DESCR.CLOBBER_RAX, ASM_DESCR.CLOBBER_RCX])
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__asm__("sfence; mfence", op=[ASM_DESCR.CLOBBER_MEMORY])
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flush()
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# Initialize TSS: set iomap_base = 104 (0x68) at offset 102
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tss_buf[102] = 0x68
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tss_buf[103] = 0x00
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# Load Task Register with TSS selector 0x30 (GDT entries 6-7)
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__asm__("""mov ax, 0x30
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ltr ax""",
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op=[ASM_DESCR.CLOBBER_RAX])
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@__attribute__(naked)
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def flush():
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__asm__("""lea rax, [rip + gp]
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lgdt [rax]
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push 0x08
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lea rax, [rip+2f]
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push rax
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.byte 0x48, 0xcb
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2:
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mov eax, 0x10
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mov ds, eax
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mov es, eax
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mov fs, eax
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mov gs, eax
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mov ss, eax
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ret""", op=[ASM_DESCR.CLOBBER_MEMORY, ASM_DESCR.CLOBBER_RAX])
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def set_tss_rsp0(rsp0: uint64):
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global tss_buf
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# TSS RSP0 is at offset 4 (8 bytes) in x86_64 TSS layout
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tss_buf[4] = uint8(rsp0 & 0xFF)
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tss_buf[5] = uint8((rsp0 >> 8) & 0xFF)
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tss_buf[6] = uint8((rsp0 >> 16) & 0xFF)
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tss_buf[7] = uint8((rsp0 >> 24) & 0xFF)
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tss_buf[8] = uint8((rsp0 >> 32) & 0xFF)
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tss_buf[9] = uint8((rsp0 >> 40) & 0xFF)
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tss_buf[10] = uint8((rsp0 >> 48) & 0xFF)
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tss_buf[11] = uint8((rsp0 >> 56) & 0xFF)
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def setGate(num: int, base: uint64, limit: uint32, access: uint8, gran: uint8):
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global gdt
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gdt[num].limit_low = uint16(limit & 0xFFFF)
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gdt[num].base_low = uint16(base & 0xFFFF)
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gdt[num].base_middle = uint8((base >> 16) & 0xFF)
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gdt[num].base_high = uint8((base >> 24) & 0xFF)
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gdt[num].granularity = uint8((limit >> 16) & 0x0F) | (gran & 0xF0)
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gdt[num].access = uint8(access)
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def setTSS64(num: int, base: uint64, limit: uint32):
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global gdt
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# 64 位 TSS 描述符占 16 字节（GDT 两项），复用同一地址按 gdt_entry64 整体写入：
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# 前 8 字节为常规描述符字段，后 8 字节为 base[63:32] + 保留 0
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e: gdt_entry64* = gdt_entry64*(&gdt[num])
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e.limit_low = uint16(limit & 0xFFFF)
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e.base_low = uint16(base & 0xFFFF)
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e.base_middle = uint8((base >> 16) & 0xFF)
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e.access = 0x89
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e.granularity = uint8((limit >> 16) & 0x0F)
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e.base_high = uint8((base >> 24) & 0xFF)
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e.base_upper = uint32(base >> 32)
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e.reserved = 0
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