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;------------------------------------------------------------------------------
;*
;* Copyright (c) 2020 - 2021, Intel Corporation. All rights reserved.<BR>
;* SPDX-License-Identifier: BSD-2-Clause-Patent
;*
;*
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
%define TDVMCALL_EXPOSE_REGS_MASK 0xffec
%define TDVMCALL 0x0
%macro tdcall 0
db 0x66,0x0f,0x01,0xcc
%endmacro
%macro tdcall_push_regs 0
push rbp
mov rbp, rsp
push r15
push r14
push r13
push r12
push rbx
push rsi
push rdi
%endmacro
%macro tdcall_pop_regs 0
pop rdi
pop rsi
pop rbx
pop r12
pop r13
pop r14
pop r15
pop rbp
%endmacro
%define number_of_regs_pushed 8
%define number_of_parameters 4
;
; Keep these in sync for push_regs/pop_regs, code below
; uses them to find 5th or greater parameters
;
%define first_variable_on_stack_offset \
((number_of_regs_pushed * 8) + (number_of_parameters * 8) + 8)
%define second_variable_on_stack_offset \
((first_variable_on_stack_offset) + 8)
%macro tdcall_regs_preamble 2
mov rax, %1
xor rcx, rcx
mov ecx, %2
; R10 = 0 (standard TDVMCALL)
xor r10d, r10d
; Zero out unused (for standard TDVMCALL) registers to avoid leaking
; secrets to the VMM.
xor ebx, ebx
xor esi, esi
xor edi, edi
xor edx, edx
xor ebp, ebp
xor r8d, r8d
xor r9d, r9d
%endmacro
%macro tdcall_regs_postamble 0
xor ebx, ebx
xor esi, esi
xor edi, edi
xor ecx, ecx
xor edx, edx
xor r8d, r8d
xor r9d, r9d
xor r10d, r10d
xor r11d, r11d
%endmacro
;------------------------------------------------------------------------------
; 0 => RAX = TDCALL leaf
; M => RCX = TDVMCALL register behavior
; 1 => R10 = standard vs. vendor
; RDI => R11 = TDVMCALL function / nr
; RSI = R12 = p1
; RDX => R13 = p2
; RCX => R14 = p3
; R8 => R15 = p4
; UINT64
; EFIAPI
; TdVmCall (
; UINT64 Leaf, // Rcx
; UINT64 P1, // Rdx
; UINT64 P2, // R8
; UINT64 P3, // R9
; UINT64 P4, // rsp + 0x28
; UINT64 *Val // rsp + 0x30
; )
global ASM_PFX(TdVmCall)
ASM_PFX(TdVmCall):
tdcall_push_regs
mov r11, rcx
mov r12, rdx
mov r13, r8
mov r14, r9
mov r15, [rsp + first_variable_on_stack_offset ]
tdcall_regs_preamble TDVMCALL, TDVMCALL_EXPOSE_REGS_MASK
tdcall
; ignore return dataif TDCALL reports failure.
test rax, rax
jnz .no_return_data
; Propagate TDVMCALL success/failure to return value.
mov rax, r10
; Retrieve the Val pointer.
mov r9, [rsp + second_variable_on_stack_offset ]
test r9, r9
jz .no_return_data
; Propagate TDVMCALL output value to output param
mov [r9], r11
.no_return_data:
tdcall_regs_postamble
tdcall_pop_regs
ret
|
