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
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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