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Luma3DS-3GX/patches/k11modules.s

100 lines
3.4 KiB
ArmAsm

;
; This file is part of Luma3DS
; Copyright (C) 2016 Aurora Wright, TuxSH
;
; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
;
; Additional Terms 7.b of GPLv3 applies to this file: Requiring preservation of specified
; reasonable legal notices or author attributions in that material or in the Appropriate Legal
; Notices displayed by works containing it.
;
; This is mainly Subv's code, big thanks to him.
.arm.little
.create "build/k11modules.bin", 0
.arm
; This code searches the sm module for a specific byte pattern and patches some of the instructions
; in the code to disable service access checks when calling srv:GetServiceHandle
; It also searches the fs module for archive access check code
; Save the registers we'll be using
; Register contents:
; r4: Pointer to a pointer to the exheader of the current NCCH
; r6: Constant 0
; SP + 0x80 - 0x7C: Pointer to the memory location where the NCCH text was loaded
; Save the value of the register we use
push {r1-r4}
ldr r0, [sp, #20] ; Load the .text address
ldr r1, [r4]
ldr r2, [r1, #0x200] ; Load the low title id of the current NCCH
ldr r1, [r1, #0x18] ; Load the size of the .text
add r1, r0, r1 ; Max bounds of the memory region
ldr r3, =0x1002 ; Low title id of the sm module
cmp r2, r3 ; Compare the low title id to the id of the sm module
bne fs_patch ; Skip if they're not the same
ldr r2, =0xE1A01006 ; mov r1, r6
loop:
cmp r1, r0
blo out ; Check if we didn't go past the bounds of the memory region
ldr r3, [r0]
cmp r3, r2
ldreqh r3, [r0, #4]
cmpeq r3, #5
addne r0, #4
bne loop
; r0 now contains the start address of the pattern we found
ldr r1, =0xE3A00001 ; mov r0, #1
str r1, [r0, #8] ; Patch the bl
b out
fs_patch: ; patch adapted from BootNTR
ldr r3, =0x1102 ; Low title id of the fs module
cmp r2, r3 ; Compare the low title id to the id of the sm module
bne out ; Skip if they're not the same
ldr r2, =0x4618 ; mov r0, r3
ldr r3, =0x3481 ; add r4, #0x81
loop_fs:
cmp r1, r0
blo out
ldrh r4, [r0]
cmp r4, r2
ldreqh r4, [r0, #2]
cmpeq r4, r3
subeq r0, #8
addne r0, #2
bne loop_fs
; r0 now contains the start address of the pattern we found
ldr r1, =0x2001 ; mov r0, #1
ldr r2, =0x4770 ; bx lr
strh r1, [r0]
strh r2, [r0, #2]
out:
pop {r1-r4} ; Restore the registers we used
ldr r0, [r4] ; Execute the instruction we overwrote in our detour
bx lr ; Jump back to whoever called us
.pool
.close