1/* 2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2016 SAP SE. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26#ifndef CPU_S390_VM_RELOCINFO_S390_HPP 27#define CPU_S390_VM_RELOCINFO_S390_HPP 28 29//---------------------------- 30// relocInfo layout 31//---------------------------- 32 33// This description should be contained in code/relocInfo.hpp 34// but was put here to minimize shared code diffs. 35 36// Relocation information for a nmethod is stored in compressed 37// form in an array of element type short int (16 bits). 38// Each array element constitutes one relocInfo record. 39// The layout of one such record is described here. 40 41// +------------+---+---+------------------------------+ 42// | type | fmt | offset/offset_unit | 43// +------------+---+---+------------------------------+ 44// 45// |<-- value_width (16) ----------------------------->| 46// |<type_width>|<-- nontype_width (12) -------------->| 47// (4) 48// | |<--+-->|<-- offset_width (10) ------->| 49// / \ 50// / (2) \ 51// /<--format->\ 52// | width | 53 54 55// only for type == data_prefix_tag: 56// +------------+---+---+------------------------------+ 57// | type | | data | 58// +------------+---+---+------------------------------+ 59// | 15 |<->|<-- datalen_width (11) ---------->| 60// | 61// +--datalen_tag (1) 62 63// relocType 64// The type field holds a value of relocType (which is 65// an enum of all possible relocation types). Currently, 66// there are 16 distinct relocation types, requiring 67// type_width to be (at least) 4. 68// relocFormat 69// The format field holds a value of relocFormat (which is 70// an enum of all possible relocation formats). Currently, 71// there are 4 distinct relocation formats, requiring 72// format_width to be (at least) 2. 73// offset 74// Each relocInfo is related to one specific address in the CodeBlob. 75// The address always points to the first byte of the target instruction. 76// It does NOT refer directly to the relocation subfield or embedded constant. 77// offset contains the distance of this relocInfo from the previous one. 78// offset is scaled by offset_unit (the platform-specific instruction 79// alignment requirement) to maximize the encodable distance. 80// To obtain the absolute address in the CodeBlob the relocInfo is 81// related to, you have to iterate over all relocInfos from the 82// beginning, and then use RelocIterator::addr() to get the address. 83 84// relocType == data_prefix_tag 85// These are relocInfo records containing inline data that belongs to 86// the next non-data relocInfo record. Usage of that inline data is 87// specific and private to that relocInfo record. 88// For details refer to code/relocInfo.hpp 89 90 91 // machine-dependent parts of class relocInfo 92 private: 93 enum { 94 // Instructions are HW (2-byte) aligned on z/Architecture. 95 offset_unit = 2, 96 97 // Encodes Assembler::disp32_operand vs. Assembler::imm64_operand. 98 // (Assembler::call32_operand is used on call instructions only.) 99 format_width = 2 100 }; 101 102 public: 103 104 enum relocFormat { 105 no_format = 0, 106 uncompressed_format = 0, // Relocation is for a regular oop. 107 compressed_format = 1, // Relocation is for a narrow (compressed) oop or klass. 108 // Similar to relocInfo::narrow_oop_in_const. 109 pcrel_addr_format = 2, // Relocation is for the target LOCATION of a pc-relative instruction. 110 pcrel_data_format = 3 // Relocation is for the target data of a pc-relative instruction. 111 }; 112 113 // Store the new target address into an oop_Relocation cell, if any. 114 // Return indication if update happened. 115 static bool update_oop_pool(address begin, address end, address newTarget, CodeBlob* cb); 116 117#endif // CPU_S390_VM_RELOCINFO_S390_HPP 118