# IBM_PROLOG_BEGIN_TAG
# This is an automatically generated prolog.
#
# $Source: src/securerom/secureromasm.S $
#
# OpenPOWER HostBoot Project
#
# Contributors Listed Below - COPYRIGHT 2017
# [+] Google Inc.
# [+] International Business Machines Corp.
#
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied. See the License for the specific language governing
# permissions and limitations under the License.
#
# IBM_PROLOG_END_TAG
.include "kernel/ppcconsts.S"

#****************************************************************************
#*  SecureROM info - useful info used by HBBL. Must match ROM.H
#****************************************************************************
.set SECROM_EYECATCHER, 0x23534543524F4D00   # uint64_t '#SECROM.'
.set SECROM_VERSION, 0x0000000900000001   # uint64_t

# Before the SecureRom code starts there is SecureRomInfo see ROM.H
# - [8 bytes] - eyeCatch
# - [8 bytes] - version
# - [8 bytes] - branchtable offset
# - [16 bytes] - reserved
.section .text.securerominfo

eyeCatch:
    .quad SECROM_EYECATCHER

version:
    .quad SECROM_VERSION

branchtableoffset:
    .quad .text.branchtable

reserved:
    .zero 16 # 'reserve 16 bytes'

#****************************************************************************
#*  branch table - a more stable location for software entering rom code
#****************************************************************************
.section .text.branchtable

    .globl _SHA512_Init
_SHA512_Init:
    li r0, .L.SHA512_Init@l
    b remove_sha512_init_offset

    .globl _SHA512_Update
_SHA512_Update:
    li r0, .L.SHA512_Update@l
    b remove_sha512_update_offset

    .globl _SHA512_Final
_SHA512_Final:
    li r0, .L.SHA512_Final@l
    b remove_sha512_final_offset

    .globl _SHA512_Hash
_SHA512_Hash:
    li r0, .L.SHA512_Hash@l
    b remove_sha512_hash_offset

    .globl _ec_verify
_ec_verify:
    li r0, .L.ec_verify@l
    b remove_ec_verify_offset

    .globl _ROM_verify
_ROM_verify:
    li r0, .L.ROM_verify@l
    b remove_rom_verify_offset

# Helper Functions to load the negative offset into r10.
#
# In an effort to not move anything around in the branchtable nor change any of
# the parameters in the Hostboot C code, we have these helper functions to
# provide springboard with the offest to subtract to find the base secureROM
# address.

# NOTE: Originally each of the following helper functions was formatted to
# subtract the starting offset of the calling assembly from r10 like the
# following example:
#     li r10, -_SHA512_Init
#     b springboard
# However, some tool chain versions do not correctly support this convention, so
# instead put the non-negative offset into r10 and then negate it

remove_sha512_init_offset:
    li r10, _SHA512_Init
    neg r10,r10
    b springboard

remove_sha512_update_offset:
    li r10, _SHA512_Update
    neg r10,r10
    b springboard

remove_sha512_final_offset:
    li r10, _SHA512_Final
    neg r10,r10
    b springboard

remove_sha512_hash_offset:
    li r10, _SHA512_Hash
    neg r10,r10
    b springboard

remove_ec_verify_offset:
    li r10, _ec_verify
    neg r10,r10
    b springboard

remove_rom_verify_offset:
    li r10, _ROM_verify
    neg r10,r10
    b springboard

springboard:
    b boingboing
boingboing:
    mfctr r2
    add r2, r2, r10 # get secureROM base address
    add r0, r0, r2 # calculate entry relative
    addi r2, r2, 0x4000 #TOC+0x8000  part 1
    addi r2, r2, (__toc_start+0x4000)@l #TOC+0x8000  part 2
    mtctr r0
    bctr # jump

# could put other assembly code routines here to conserve ROM space
# including the sreset routine

# need to align on branchtablebase+0x100 !!!
    .org .text.branchtable+0x100
    .globl _rom_sreset
_rom_sreset:
    li r0, rom_sreset@l
    b springboard
    nop

.section .data