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* hook_hvsc.h.s -- PL3 - Hooks all hvsc instructions
* Copyright (C) Youness Alaoui (KaKaRoTo)
* This software is distributed under the terms of the GNU General Public
* License ("GPL") version 3, as published by the Free Software Foundation.
#ifndef __HOOK_HVSC_H_S__
#define __HOOK_HVSC_H_S__
mflr %r0
stdu %r1, -0x80(%r1)
std %r31, 0x70(%r1)
std %r0, 0x90(%r1)
mr %r3, %r31 // start of memory
lis %r4, 0x4400
ori %r4, %r4, 0x0022 // load 0x44000022 (hvsc instruction)
oris %r5, %r31, 0x30 // end of memory (0x300000)
LOAD_LABEL2 (%r7, %r31, hvsc_handler) // load our handler in %r7
lwz %r6, 0(%r3)
cmpw %r6, %r4
bne l_hook_hvsc_incr // Found an hvsc instruction
LOAD_LABEL2 (%r8, %r31, hvsc_call)
cmpw %r3, %r8 // Make sure it's not our handler's hvsc
beq l_hook_hvsc_incr
// Build a branch instruction
li %r8, 18 // bits 0-5='18' means 'b/bl/ba/bla'
rldicr %r8, %r8, 26, 37
subf %r9, %r3, %r7 // relative address = target - current
rldicl %r9, %r9, 0, 38 // Clear the sign extension of the 24bit
// address to avoid ORing the 0-5 bits
or %r8, %r8, %r9 // or the instruction with the address
ori %r8, %r8, 1 // or the link bit == 'bl' instruction
stw %r8, 0(%r3) // replace the hvsc instruction
addi %r3, %r3, 4
cmpw %r3, %r5 // loop until the end of the memory
bne l_hook_hvsc_loop
ld %r31, 0x70(%r1)
ld %r0, 0x90(%r1)
addi %r1, %r1, 0x80
mtlr %r0
#endif /* __HOOK_HVSC_H_S__ */