mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
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582 lines
21 KiB
NASM
582 lines
21 KiB
NASM
;/** @file
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; Low level x64 routines used by the debug support driver.
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;
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; Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
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; SPDX-License-Identifier: BSD-2-Clause-Patent
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;
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;**/
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%define EXCPT64_DIVIDE_ERROR 0
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%define EXCPT64_DEBUG 1
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%define EXCPT64_NMI 2
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%define EXCPT64_BREAKPOINT 3
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%define EXCPT64_OVERFLOW 4
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%define EXCPT64_BOUND 5
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%define EXCPT64_INVALID_OPCODE 6
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%define EXCPT64_DOUBLE_FAULT 8
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%define EXCPT64_INVALID_TSS 10
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%define EXCPT64_SEG_NOT_PRESENT 11
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%define EXCPT64_STACK_FAULT 12
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%define EXCPT64_GP_FAULT 13
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%define EXCPT64_PAGE_FAULT 14
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%define EXCPT64_FP_ERROR 16
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%define EXCPT64_ALIGNMENT_CHECK 17
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%define EXCPT64_MACHINE_CHECK 18
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%define EXCPT64_SIMD 19
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%define FXSTOR_FLAG 0x1000000 ; bit cpuid 24 of feature flags
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;; The FXSTOR and FXRSTOR commands are used for saving and restoring the x87,
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;; MMX, SSE, SSE2, etc registers. The initialization of the debugsupport driver
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;; MUST check the CPUID feature flags to see that these instructions are available
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;; and fail to init if they are not.
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;; fxstor [rdi]
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%macro FXSTOR_RDI 0
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db 0xf, 0xae, 00000111y ; mod = 00, reg/op = 000, r/m = 111 = [rdi]
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%endmacro
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;; fxrstor [rsi]
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%macro FXRSTOR_RSI 0
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db 0xf, 0xae, 00001110y ; mod = 00, reg/op = 001, r/m = 110 = [rsi]
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%endmacro
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SECTION .data
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global ASM_PFX(OrigVector)
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global ASM_PFX(InterruptEntryStub)
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global ASM_PFX(StubSize)
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global ASM_PFX(CommonIdtEntry)
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global ASM_PFX(FxStorSupport)
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extern ASM_PFX(InterruptDistrubutionHub)
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ASM_PFX(StubSize): dd InterruptEntryStubEnd - ASM_PFX(InterruptEntryStub)
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AppRsp: dq 0x1111111111111111 ; ?
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DebugRsp: dq 0x2222222222222222 ; ?
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ExtraPush: dq 0x3333333333333333 ; ?
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ExceptData: dq 0x4444444444444444 ; ?
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Rflags: dq 0x5555555555555555 ; ?
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ASM_PFX(OrigVector): dq 0x6666666666666666 ; ?
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;; The declarations below define the memory region that will be used for the debug stack.
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;; The context record will be built by pushing register values onto this stack.
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;; It is imparitive that alignment be carefully managed, since the FXSTOR and
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;; FXRSTOR instructions will GP fault if their memory operand is not 16 byte aligned.
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;;
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;; The stub will switch stacks from the application stack to the debuger stack
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;; and pushes the exception number.
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;;
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;; Then we building the context record on the stack. Since the stack grows down,
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;; we push the fields of the context record from the back to the front. There
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;; are 336 bytes of stack used prior allocating the 512 bytes of stack to be
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;; used as the memory buffer for the fxstor instruction. Therefore address of
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;; the buffer used for the FXSTOR instruction is &Eax - 336 - 512, which
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;; must be 16 byte aligned.
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;;
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;; We carefully locate the stack to make this happen.
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;;
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;; For reference, the context structure looks like this:
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;; struct {
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;; UINT64 ExceptionData;
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;; FX_SAVE_STATE_X64 FxSaveState; // 512 bytes, must be 16 byte aligned
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;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
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;; UINT64 Cr0, Cr1, Cr2, Cr3, Cr4, Cr8;
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;; UINT64 RFlags;
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;; UINT64 Ldtr, Tr;
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;; UINT64 Gdtr[2], Idtr[2];
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;; UINT64 Rip;
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;; UINT64 Gs, Fs, Es, Ds, Cs, Ss;
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;; UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
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;; UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
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;; } SYSTEM_CONTEXT_X64; // 64 bit system context record
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align 16
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DebugStackEnd: db "DbgStkEnd >>>>>>" ;; 16 byte long string - must be 16 bytes to preserve alignment
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times 0x1ffc dd 0x0 ;; 32K should be enough stack
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;; This allocation is coocked to insure
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;; that the the buffer for the FXSTORE instruction
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;; will be 16 byte aligned also.
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;;
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ExceptionNumber: dq 0 ;; first entry will be the vector number pushed by the stub
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DebugStackBegin: db "<<<< DbgStkBegin" ;; initial debug ESP == DebugStackBegin, set in stub
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DEFAULT REL
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SECTION .text
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;------------------------------------------------------------------------------
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; BOOLEAN
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; FxStorSupport (
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; void
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; )
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;
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; Abstract: Returns TRUE if FxStor instructions are supported
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;
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global ASM_PFX(FxStorSupport)
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ASM_PFX(FxStorSupport):
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;
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; cpuid corrupts rbx which must be preserved per the C calling convention
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;
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push rbx
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mov rax, dword 1
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cpuid
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mov eax, edx
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and rax, FXSTOR_FLAG
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shr rax, 24
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pop rbx
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ret
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;------------------------------------------------------------------------------
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; void
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; Vect2Desc (
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; IA32_IDT_GATE_DESCRIPTOR * DestDesc, // rcx
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; void (*Vector) (void) // rdx
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; )
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;
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; Abstract: Encodes an IDT descriptor with the given physical address
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;
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global ASM_PFX(Vect2Desc)
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ASM_PFX(Vect2Desc):
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mov rax, rdx
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mov word [rcx], ax ; write bits 15..0 of offset
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mov dx, cs
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mov word [rcx+2], dx ; SYS_CODE_SEL from GDT
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mov word [rcx+4], 0xe00 | 0x8000 ; type = 386 interrupt gate, present
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shr rax, 16
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mov word [rcx+6], ax ; write bits 31..16 of offset
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shr rax, 16
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mov dword [rcx+8], eax ; write bits 63..32 of offset
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ret
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;------------------------------------------------------------------------------
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; InterruptEntryStub
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;
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; Abstract: This code is not a function, but is a small piece of code that is
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; copied and fixed up once for each IDT entry that is hooked.
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;
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ASM_PFX(InterruptEntryStub):
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push 0 ; push vector number - will be modified before installed
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db 0xe9 ; jump rel32
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dd 0 ; fixed up to relative address of CommonIdtEntry
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InterruptEntryStubEnd:
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;------------------------------------------------------------------------------
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; CommonIdtEntry
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;
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; Abstract: This code is not a function, but is the common part for all IDT
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; vectors.
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;
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ASM_PFX(CommonIdtEntry):
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;;
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;; At this point, the stub has saved the current application stack esp into AppRsp
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;; and switched stacks to the debug stack, where it pushed the vector number
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;;
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;; The application stack looks like this:
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;;
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;; ...
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;; (last application stack entry)
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;; [16 bytes alignment, do not care it]
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;; SS from interrupted task
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;; RSP from interrupted task
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;; rflags from interrupted task
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;; CS from interrupted task
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;; RIP from interrupted task
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;; Error code <-------------------- Only present for some exeption types
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;;
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;; Vector Number <----------------- pushed in our IDT Entry
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;;
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;; The stub switched us to the debug stack and pushed the interrupt number.
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;;
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;; Next, construct the context record. It will be build on the debug stack by
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;; pushing the registers in the correct order so as to create the context structure
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;; on the debug stack. The context record must be built from the end back to the
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;; beginning because the stack grows down...
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;
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;; For reference, the context record looks like this:
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;;
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;; typedef
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;; struct {
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;; UINT64 ExceptionData;
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;; FX_SAVE_STATE_X64 FxSaveState;
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;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
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;; UINT64 Cr0, Cr2, Cr3, Cr4, Cr8;
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;; UINT64 RFlags;
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;; UINT64 Ldtr, Tr;
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;; UINT64 Gdtr[2], Idtr[2];
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;; UINT64 Rip;
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;; UINT64 Gs, Fs, Es, Ds, Cs, Ss;
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;; UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
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;; UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
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;; } SYSTEM_CONTEXT_X64; // 64 bit system context record
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;; NOTE: we save rsp here to prevent compiler put rip reference cause error AppRsp
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push rax
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mov rax, qword [rsp+8] ; save vector number
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mov [ExceptionNumber], rax ; save vector number
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pop rax
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add rsp, 8 ; pop vector number
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mov [AppRsp], rsp ; save stack top
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lea rsp, [DebugStackBegin] ; switch to debugger stack
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sub rsp, 8 ; leave space for vector number
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;; UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
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;; UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
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push r15
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push r14
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push r13
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push r12
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push r11
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push r10
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push r9
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push r8
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push rax
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push rcx
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push rdx
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push rbx
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push rsp
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push rbp
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push rsi
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push rdi
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;; Save interrupt state rflags register...
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pushfq
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pop rax
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mov [Rflags], rax
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;; We need to determine if any extra data was pushed by the exception, and if so, save it
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;; To do this, we check the exception number pushed by the stub, and cache the
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;; result in a variable since we'll need this again.
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cmp qword [ExceptionNumber], EXCPT64_DOUBLE_FAULT
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jz ExtraPushOne
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cmp qword [ExceptionNumber], EXCPT64_INVALID_TSS
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jz ExtraPushOne
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cmp qword [ExceptionNumber], EXCPT64_SEG_NOT_PRESENT
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jz ExtraPushOne
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cmp qword [ExceptionNumber], EXCPT64_STACK_FAULT
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jz ExtraPushOne
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cmp qword [ExceptionNumber], EXCPT64_GP_FAULT
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jz ExtraPushOne
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cmp qword [ExceptionNumber], EXCPT64_PAGE_FAULT
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jz ExtraPushOne
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cmp qword [ExceptionNumber], EXCPT64_ALIGNMENT_CHECK
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jz ExtraPushOne
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mov qword [ExtraPush], 0
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mov qword [ExceptData], 0
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jmp ExtraPushDone
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ExtraPushOne:
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mov qword [ExtraPush], 1
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;; If there's some extra data, save it also, and modify the saved AppRsp to effectively
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;; pop this value off the application's stack.
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mov rax, [AppRsp]
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mov rbx, [rax]
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mov qword [ExceptData], rbx
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add rax, 8
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mov [AppRsp], rax
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ExtraPushDone:
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;; The "push" above pushed the debug stack rsp. Since what we're actually doing
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;; is building the context record on the debug stack, we need to save the pushed
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;; debug RSP, and replace it with the application's last stack entry...
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mov rax, [rsp + 24]
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mov [DebugRsp], rax
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mov rax, [AppRsp]
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mov rax, QWORD [rax + 24]
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; application stack has ss, rsp, rflags, cs, & rip, so
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; last actual application stack entry is saved at offset
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; 24 bytes from stack top.
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mov [rsp + 24], rax
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;; continue building context record
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;; UINT64 Gs, Fs, Es, Ds, Cs, Ss; insure high 16 bits of each is zero
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mov rax, ss
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push rax
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; CS from application is one entry back in application stack
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mov rax, [AppRsp]
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movzx rax, word [rax + 8]
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push rax
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mov rax, ds
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push rax
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mov rax, es
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push rax
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mov rax, fs
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push rax
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mov rax, gs
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push rax
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;; UINT64 Rip;
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; Rip from application is on top of application stack
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mov rax, [AppRsp]
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push qword [rax]
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;; UINT64 Gdtr[2], Idtr[2];
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push 0
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push 0
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sidt [rsp]
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push 0
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push 0
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sgdt [rsp]
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;; UINT64 Ldtr, Tr;
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xor rax, rax
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str ax
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push rax
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sldt ax
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push rax
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;; UINT64 RFlags;
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;; Rflags from application is two entries back in application stack
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mov rax, [AppRsp]
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push qword [rax + 16]
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;; UINT64 Cr0, Cr1, Cr2, Cr3, Cr4, Cr8;
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;; insure FXSAVE/FXRSTOR is enabled in CR4...
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;; ... while we're at it, make sure DE is also enabled...
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mov rax, cr8
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push rax
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mov rax, cr4
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or rax, 0x208
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mov cr4, rax
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push rax
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mov rax, cr3
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push rax
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mov rax, cr2
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push rax
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push 0
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mov rax, cr0
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push rax
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;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
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mov rax, dr7
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push rax
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;; clear Dr7 while executing debugger itself
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xor rax, rax
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mov dr7, rax
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mov rax, dr6
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push rax
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;; insure all status bits in dr6 are clear...
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xor rax, rax
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mov dr6, rax
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mov rax, dr3
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push rax
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mov rax, dr2
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push rax
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mov rax, dr1
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push rax
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mov rax, dr0
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push rax
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;; FX_SAVE_STATE_X64 FxSaveState;
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sub rsp, 512
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mov rdi, rsp
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; IMPORTANT!! The debug stack has been carefully constructed to
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; insure that rsp and rdi are 16 byte aligned when we get here.
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; They MUST be. If they are not, a GP fault will occur.
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FXSTOR_RDI
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;; UEFI calling convention for x64 requires that Direction flag in EFLAGs is clear
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cld
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;; UINT64 ExceptionData;
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mov rax, [ExceptData]
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push rax
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; call to C code which will in turn call registered handler
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; pass in the vector number
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mov rdx, rsp
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mov rcx, [ExceptionNumber]
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sub rsp, 40
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call ASM_PFX(InterruptDistrubutionHub)
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add rsp, 40
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; restore context...
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;; UINT64 ExceptionData;
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add rsp, 8
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;; FX_SAVE_STATE_X64 FxSaveState;
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mov rsi, rsp
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FXRSTOR_RSI
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add rsp, 512
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;; UINT64 Dr0, Dr1, Dr2, Dr3, Dr6, Dr7;
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pop rax
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mov dr0, rax
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pop rax
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mov dr1, rax
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pop rax
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mov dr2, rax
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pop rax
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mov dr3, rax
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;; skip restore of dr6. We cleared dr6 during the context save.
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add rsp, 8
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pop rax
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mov dr7, rax
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;; UINT64 Cr0, Cr1, Cr2, Cr3, Cr4, Cr8;
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pop rax
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mov cr0, rax
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add rsp, 8
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pop rax
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mov cr2, rax
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pop rax
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mov cr3, rax
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pop rax
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mov cr4, rax
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pop rax
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mov cr8, rax
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;; UINT64 RFlags;
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mov rax, [AppRsp]
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pop qword [rax + 16]
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;; UINT64 Ldtr, Tr;
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;; UINT64 Gdtr[2], Idtr[2];
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;; Best not let anyone mess with these particular registers...
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add rsp, 48
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;; UINT64 Rip;
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pop qword [rax]
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;; UINT64 Gs, Fs, Es, Ds, Cs, Ss;
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;; NOTE - modified segment registers could hang the debugger... We
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;; could attempt to insulate ourselves against this possibility,
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;; but that poses risks as well.
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;;
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pop rax
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; mov gs, rax
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pop rax
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; mov fs, rax
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pop rax
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mov es, rax
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pop rax
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mov ds, rax
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mov rax, [AppRsp]
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pop qword [rax + 8]
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pop rax
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mov ss, rax
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;; The next stuff to restore is the general purpose registers that were pushed
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;; using the "push" instruction.
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;;
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;; The value of RSP as stored in the context record is the application RSP
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;; including the 5 entries on the application stack caused by the exception
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;; itself. It may have been modified by the debug agent, so we need to
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;; determine if we need to relocate the application stack.
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mov rbx, [rsp + 24] ; move the potentially modified AppRsp into rbx
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mov rax, [AppRsp]
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mov rax, QWORD [rax + 24]
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cmp rbx, rax
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je NoAppStackMove
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mov rax, [AppRsp]
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mov rcx, [rax] ; RIP
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mov [rbx], rcx
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mov rcx, [rax + 8] ; CS
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mov [rbx + 8], rcx
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mov rcx, [rax + 16] ; RFLAGS
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mov [rbx + 16], rcx
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mov rcx, [rax + 24] ; RSP
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mov [rbx + 24], rcx
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mov rcx, [rax + 32] ; SS
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mov [rbx + 32], rcx
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mov rax, rbx ; modify the saved AppRsp to the new AppRsp
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mov [AppRsp], rax
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NoAppStackMove:
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mov rax, [DebugRsp] ; restore the DebugRsp on the debug stack
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; so our "pop" will not cause a stack switch
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mov [rsp + 24], rax
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cmp qword [ExceptionNumber], 0x68
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jne NoChain
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Chain:
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;; Restore rflags so when we chain, the flags will be exactly as if we were never here.
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;; We gin up the stack to do an iretq so we can get ALL the flags.
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mov rax, [AppRsp]
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mov rbx, [rax + 40]
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push rbx
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mov rax, ss
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push rax
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mov rax, rsp
|
|
add rax, 16
|
|
push rax
|
|
mov rax, [AppRsp]
|
|
mov rbx, [rax + 16]
|
|
and rbx, ~ 0x300 ; special handling for IF and TF
|
|
push rbx
|
|
mov rax, cs
|
|
push rax
|
|
lea rax, [PhonyIretq]
|
|
push rax
|
|
iretq
|
|
PhonyIretq:
|
|
|
|
;; UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
|
|
;; UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
|
|
pop rdi
|
|
pop rsi
|
|
pop rbp
|
|
pop rsp
|
|
pop rbx
|
|
pop rdx
|
|
pop rcx
|
|
pop rax
|
|
pop r8
|
|
pop r9
|
|
pop r10
|
|
pop r11
|
|
pop r12
|
|
pop r13
|
|
pop r14
|
|
pop r15
|
|
|
|
;; Switch back to application stack
|
|
mov rsp, [AppRsp]
|
|
|
|
;; Jump to original handler
|
|
jmp [ASM_PFX(OrigVector)]
|
|
|
|
NoChain:
|
|
;; UINT64 Rdi, Rsi, Rbp, Rsp, Rbx, Rdx, Rcx, Rax;
|
|
;; UINT64 R8, R9, R10, R11, R12, R13, R14, R15;
|
|
pop rdi
|
|
pop rsi
|
|
pop rbp
|
|
pop rsp
|
|
pop rbx
|
|
pop rdx
|
|
pop rcx
|
|
pop rax
|
|
pop r8
|
|
pop r9
|
|
pop r10
|
|
pop r11
|
|
pop r12
|
|
pop r13
|
|
pop r14
|
|
pop r15
|
|
|
|
;; Switch back to application stack
|
|
mov rsp, [AppRsp]
|
|
|
|
;; We're outa here...
|
|
iretq
|
|
|