[solved] Xor qword

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AE

Joined: 07 Apr 2022
Posts: 72

AE 11 Apr 2022, 17:37

What would be the shortest way to implement such a pseudocode

Code:

xor rax, 7E7E7E7E7E7E7E7Eh

11 Apr 2022, 17:37

ProMiNick

Joined: 24 Mar 2012
Posts: 821
Location: Russian Federation, Sochi

ProMiNick 11 Apr 2022, 17:48

if operand cannot be encoded as imm part of instruction fastest way to place it in initialized data:

Code:

format PE64 GUI
entry start

section '.text' code readable executable

  start:
        xor     rax,qword[xorpattern]

section '.data' data readable writeable

  xorpattern db 8 dup ($7E)

11 Apr 2022, 17:48

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20759
Location: In your JS exploiting you and your system

revolution 11 Apr 2022, 20:05

You can do 64-bit loads into an unused register.

Code:

mov r8, 0x7E7E7E7E7E7E7E7E
xor rax, r8

11 Apr 2022, 20:05

AE

Joined: 07 Apr 2022
Posts: 72

AE 11 Apr 2022, 20:27

Thanks! That's it.

11 Apr 2022, 20:27

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