1// Bionic-specific support for sections.
2// Copyright (C) 2019-2020 Free Software Foundation, Inc.
3
4// GCC is free software; you can redistribute it and/or modify it under
5// the terms of the GNU General Public License as published by the Free
6// Software Foundation; either version 3, or (at your option) any later
7// version.
8
9// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
10// WARRANTY; without even the implied warranty of MERCHANTABILITY or
11// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12// for more details.
13
14// Under Section 7 of GPL version 3, you are granted additional
15// permissions described in the GCC Runtime Library Exception, version
16// 3.1, as published by the Free Software Foundation.
17
18// You should have received a copy of the GNU General Public License and
19// a copy of the GCC Runtime Library Exception along with this program;
20// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
21// <http://www.gnu.org/licenses/>.
22
23module gcc.sections.android;
24
25version (CRuntime_Bionic):
26
27// debug = PRINTF;
28debug(PRINTF) import core.stdc.stdio;
29import core.stdc.stdlib : malloc, free;
30import rt.deh, rt.minfo;
31import core.sys.posix.pthread;
32import core.stdc.stdlib : calloc;
33import core.stdc.string : memcpy;
34
35struct SectionGroup
36{
37    static int opApply(scope int delegate(ref SectionGroup) dg)
38    {
39        return dg(_sections);
40    }
41
42    static int opApplyReverse(scope int delegate(ref SectionGroup) dg)
43    {
44        return dg(_sections);
45    }
46
47    @property immutable(ModuleInfo*)[] modules() const nothrow @nogc
48    {
49        return _moduleGroup.modules;
50    }
51
52    @property ref inout(ModuleGroup) moduleGroup() inout nothrow @nogc
53    {
54        return _moduleGroup;
55    }
56
57    @property immutable(FuncTable)[] ehTables() const nothrow @nogc
58    {
59        auto pbeg = cast(immutable(FuncTable)*)&__start_deh;
60        auto pend = cast(immutable(FuncTable)*)&__stop_deh;
61        return pbeg[0 .. pend - pbeg];
62    }
63
64    @property inout(void[])[] gcRanges() inout nothrow @nogc
65    {
66        return _gcRanges[];
67    }
68
69private:
70    ModuleGroup _moduleGroup;
71    void[][1] _gcRanges;
72}
73
74void initSections() nothrow @nogc
75{
76    pthread_key_create(&_tlsKey, null);
77
78    auto mbeg = cast(immutable ModuleInfo**)&__start_minfo;
79    auto mend = cast(immutable ModuleInfo**)&__stop_minfo;
80    _sections.moduleGroup = ModuleGroup(mbeg[0 .. mend - mbeg]);
81
82    auto pbeg = cast(void*)&_tlsend;
83    auto pend = cast(void*)&__bss_end__;
84    // _tlsend is a 32-bit int and may not be 64-bit void*-aligned, so align pbeg.
85    version (D_LP64) pbeg = cast(void*)(cast(size_t)(pbeg + 7) & ~cast(size_t)7);
86    _sections._gcRanges[0] = pbeg[0 .. pend - pbeg];
87}
88
89void finiSections() nothrow @nogc
90{
91    pthread_key_delete(_tlsKey);
92}
93
94void[]* initTLSRanges() nothrow @nogc
95{
96    return &getTLSBlock();
97}
98
99void finiTLSRanges(void[]* rng) nothrow @nogc
100{
101    .free(rng.ptr);
102    .free(rng);
103}
104
105void scanTLSRanges(void[]* rng, scope void delegate(void* pbeg, void* pend) nothrow dg) nothrow
106{
107    dg(rng.ptr, rng.ptr + rng.length);
108}
109
110/* NOTE: The Bionic C library ignores thread-local data stored in the normal
111 *       .tbss/.tdata ELF sections, which are marked with the SHF_TLS/STT_TLS
112 *       flags.  So instead we roll our own by keeping TLS data in the
113 *       .tdata/.tbss sections but removing the SHF_TLS/STT_TLS flags, and
114 *       access the TLS data using this function and the _tlsstart/_tlsend
115 *       symbols as delimiters.
116 *
117 *       This function is called by the code emitted by the compiler.  It
118 *       is expected to translate an address in the TLS static data to
119 *       the corresponding address in the TLS dynamic per-thread data.
120 */
121
122extern(C) void* __tls_get_addr( void* p ) nothrow @nogc
123{
124    debug(PRINTF) printf("  __tls_get_addr input - %p\n", p);
125    immutable offset = cast(size_t)(p - cast(void*)&_tlsstart);
126    auto tls = getTLSBlockAlloc();
127    assert(offset < tls.length);
128    return tls.ptr + offset;
129}
130
131private:
132
133__gshared pthread_key_t _tlsKey;
134
135ref void[] getTLSBlock() nothrow @nogc
136{
137    auto pary = cast(void[]*)pthread_getspecific(_tlsKey);
138    if (pary is null)
139    {
140        pary = cast(void[]*).calloc(1, (void[]).sizeof);
141        if (pthread_setspecific(_tlsKey, pary) != 0)
142        {
143            import core.stdc.stdio;
144            perror("pthread_setspecific failed with");
145            assert(0);
146        }
147    }
148    return *pary;
149}
150
151ref void[] getTLSBlockAlloc() nothrow @nogc
152{
153    auto pary = &getTLSBlock();
154    if (!pary.length)
155    {
156        auto pbeg = cast(void*)&_tlsstart;
157        auto pend = cast(void*)&_tlsend;
158        auto p = .malloc(pend - pbeg);
159        memcpy(p, pbeg, pend - pbeg);
160        *pary = p[0 .. pend - pbeg];
161    }
162    return *pary;
163}
164
165__gshared SectionGroup _sections;
166
167extern(C)
168{
169    /* Symbols created by the compiler/linker and inserted into the
170     * object file that 'bracket' sections.
171     */
172    extern __gshared
173    {
174        void* __start_deh;
175        void* __stop_deh;
176        void* __start_minfo;
177        void* __stop_minfo;
178
179        size_t __bss_end__;
180
181        int _tlsstart;
182        int _tlsend;
183    }
184}
185