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Commit d356630

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author
George Rimar
committedJun 20, 2016
[ELF] - Recommit r273143("[ELF] - Basic versioned symbols support implemented.")
With fix: -soname flag was not set in testcase. Hash calculated for base def was different on local and bot machines because filename fos used for calculating. Initial commit message: Patch implements basic support of versioned symbols. There is no wildcards patterns matching except local: *; There is no support for hierarchies. There is no support for symbols overrides (@ vs @@ not handled). This patch allows programs that using simple scripts to link and run. Differential revision: http://reviews.llvm.org/D21018 llvm-svn: 273152
1 parent 7b8481b commit d356630

13 files changed

+409
-42
lines changed
 

‎lld/ELF/Config.h

Lines changed: 10 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -32,6 +32,15 @@ enum ELFKind {
3232

3333
enum class BuildIdKind { None, Fnv1, Md5, Sha1, Hexstring };
3434

35+
// This struct contains symbols version definition that
36+
// can be found in version script if it is used for link.
37+
struct Version {
38+
Version(llvm::StringRef Name) : Name(Name) {}
39+
llvm::StringRef Name;
40+
std::vector<llvm::StringRef> Globals;
41+
size_t NameOff; // Offset in string table.
42+
};
43+
3544
// This struct contains the global configuration for the linker.
3645
// Most fields are direct mapping from the command line options
3746
// and such fields have the same name as the corresponding options.
@@ -50,6 +59,7 @@ struct Configuration {
5059
llvm::StringRef SoName;
5160
llvm::StringRef Sysroot;
5261
std::string RPath;
62+
std::vector<Version> SymbolVersions;
5363
std::vector<llvm::StringRef> DynamicList;
5464
std::vector<llvm::StringRef> SearchPaths;
5565
std::vector<llvm::StringRef> Undefined;

‎lld/ELF/OutputSections.cpp

Lines changed: 88 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -591,6 +591,11 @@ void GnuHashTableSection<ELFT>::addSymbols(
591591
V.push_back({Sym.Body, Sym.STName});
592592
}
593593

594+
// Returns the number of version definition entries. Because the first entry
595+
// is for the version definition itself, it is the number of versioned symbols
596+
// plus one. Note that we don't support multiple versions yet.
597+
static unsigned getVerDefNum() { return Config->SymbolVersions.size() + 1; }
598+
594599
template <class ELFT>
595600
DynamicSection<ELFT>::DynamicSection()
596601
: OutputSectionBase<ELFT>(".dynamic", SHT_DYNAMIC, SHF_ALLOC | SHF_WRITE) {
@@ -693,10 +698,16 @@ template <class ELFT> void DynamicSection<ELFT>::finalize() {
693698
if (!Config->Entry.empty())
694699
Add({DT_DEBUG, (uint64_t)0});
695700

696-
if (size_t NeedNum = Out<ELFT>::VerNeed->getNeedNum()) {
701+
bool HasVerNeed = Out<ELFT>::VerNeed->getNeedNum() != 0;
702+
if (HasVerNeed || Out<ELFT>::VerDef)
697703
Add({DT_VERSYM, Out<ELFT>::VerSym});
704+
if (Out<ELFT>::VerDef) {
705+
Add({DT_VERDEF, Out<ELFT>::VerDef});
706+
Add({DT_VERDEFNUM, getVerDefNum()});
707+
}
708+
if (HasVerNeed) {
698709
Add({DT_VERNEED, Out<ELFT>::VerNeed});
699-
Add({DT_VERNEEDNUM, NeedNum});
710+
Add({DT_VERNEEDNUM, Out<ELFT>::VerNeed->getNeedNum()});
700711
}
701712

702713
if (Config->EMachine == EM_MIPS) {
@@ -1434,6 +1445,68 @@ SymbolTableSection<ELFT>::getOutputSection(SymbolBody *Sym) {
14341445
return nullptr;
14351446
}
14361447

1448+
template <class ELFT>
1449+
VersionDefinitionSection<ELFT>::VersionDefinitionSection()
1450+
: OutputSectionBase<ELFT>(".gnu.version_d", SHT_GNU_verdef, SHF_ALLOC) {}
1451+
1452+
static StringRef getFileDefName() {
1453+
if (!Config->SoName.empty())
1454+
return Config->SoName;
1455+
return Config->OutputFile;
1456+
}
1457+
1458+
template <class ELFT> void VersionDefinitionSection<ELFT>::finalize() {
1459+
FileDefNameOff = Out<ELFT>::DynStrTab->addString(getFileDefName());
1460+
for (Version &V : Config->SymbolVersions)
1461+
V.NameOff = Out<ELFT>::DynStrTab->addString(V.Name);
1462+
1463+
this->Header.sh_size =
1464+
(sizeof(Elf_Verdef) + sizeof(Elf_Verdaux)) * getVerDefNum();
1465+
this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
1466+
this->Header.sh_addralign = sizeof(uint32_t);
1467+
1468+
// sh_info should be set to the number of definitions. This fact is missed in
1469+
// documentation, but confirmed by binutils community:
1470+
// https://sourceware.org/ml/binutils/2014-11/msg00355.html
1471+
this->Header.sh_info = getVerDefNum();
1472+
}
1473+
1474+
template <class Elf_Verdef, class Elf_Verdaux>
1475+
static void writeDefinition(Elf_Verdef *&Verdef, Elf_Verdaux *&Verdaux,
1476+
uint32_t Flags, uint32_t Index, StringRef Name,
1477+
size_t StrTabOffset) {
1478+
Verdef->vd_version = 1;
1479+
Verdef->vd_cnt = 1;
1480+
Verdef->vd_aux =
1481+
reinterpret_cast<char *>(Verdaux) - reinterpret_cast<char *>(Verdef);
1482+
Verdef->vd_next = sizeof(Elf_Verdef);
1483+
1484+
Verdef->vd_flags = Flags;
1485+
Verdef->vd_ndx = Index;
1486+
Verdef->vd_hash = hashSysv(Name);
1487+
++Verdef;
1488+
1489+
Verdaux->vda_name = StrTabOffset;
1490+
Verdaux->vda_next = 0;
1491+
++Verdaux;
1492+
}
1493+
1494+
template <class ELFT>
1495+
void VersionDefinitionSection<ELFT>::writeTo(uint8_t *Buf) {
1496+
Elf_Verdef *Verdef = reinterpret_cast<Elf_Verdef *>(Buf);
1497+
Elf_Verdaux *Verdaux =
1498+
reinterpret_cast<Elf_Verdaux *>(Verdef + getVerDefNum());
1499+
1500+
writeDefinition(Verdef, Verdaux, VER_FLG_BASE, 1, getFileDefName(),
1501+
FileDefNameOff);
1502+
1503+
uint32_t I = 2;
1504+
for (Version &V : Config->SymbolVersions)
1505+
writeDefinition(Verdef, Verdaux, 0 /* Flags */, I++, V.Name, V.NameOff);
1506+
1507+
Verdef[-1].vd_next = 0;
1508+
}
1509+
14371510
template <class ELFT>
14381511
VersionTableSection<ELFT>::VersionTableSection()
14391512
: OutputSectionBase<ELFT>(".gnu.version", SHT_GNU_versym, SHF_ALLOC) {
@@ -1453,10 +1526,7 @@ template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
14531526
auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
14541527
for (const std::pair<SymbolBody *, size_t> &P :
14551528
Out<ELFT>::DynSymTab->getSymbols()) {
1456-
if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(P.first))
1457-
OutVersym->vs_index = SS->VersionId;
1458-
else
1459-
OutVersym->vs_index = VER_NDX_GLOBAL;
1529+
OutVersym->vs_index = P.first->symbol()->VersionId;
14601530
++OutVersym;
14611531
}
14621532
}
@@ -1465,12 +1535,17 @@ template <class ELFT>
14651535
VersionNeedSection<ELFT>::VersionNeedSection()
14661536
: OutputSectionBase<ELFT>(".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC) {
14671537
this->Header.sh_addralign = sizeof(uint32_t);
1538+
1539+
// Identifiers in verneed section start at 2 because 0 and 1 are reserved
1540+
// for VER_NDX_LOCAL and VER_NDX_GLOBAL.
1541+
// First identifiers are reserved by verdef section if it exist.
1542+
NextIndex = getVerDefNum() + 1;
14681543
}
14691544

14701545
template <class ELFT>
14711546
void VersionNeedSection<ELFT>::addSymbol(SharedSymbol<ELFT> *SS) {
14721547
if (!SS->Verdef) {
1473-
SS->VersionId = VER_NDX_GLOBAL;
1548+
SS->symbol()->VersionId = VER_NDX_GLOBAL;
14741549
return;
14751550
}
14761551
SharedFile<ELFT> *F = SS->File;
@@ -1488,7 +1563,7 @@ void VersionNeedSection<ELFT>::addSymbol(SharedSymbol<ELFT> *SS) {
14881563
SS->File->getStringTable().data() + SS->Verdef->getAux()->vda_name);
14891564
NV.Index = NextIndex++;
14901565
}
1491-
SS->VersionId = NV.Index;
1566+
SS->symbol()->VersionId = NV.Index;
14921567
}
14931568

14941569
template <class ELFT> void VersionNeedSection<ELFT>::writeTo(uint8_t *Buf) {
@@ -1744,6 +1819,11 @@ template class VersionNeedSection<ELF32BE>;
17441819
template class VersionNeedSection<ELF64LE>;
17451820
template class VersionNeedSection<ELF64BE>;
17461821

1822+
template class VersionDefinitionSection<ELF32LE>;
1823+
template class VersionDefinitionSection<ELF32BE>;
1824+
template class VersionDefinitionSection<ELF64LE>;
1825+
template class VersionDefinitionSection<ELF64BE>;
1826+
17471827
template class BuildIdSection<ELF32LE>;
17481828
template class BuildIdSection<ELF32BE>;
17491829
template class BuildIdSection<ELF64LE>;

‎lld/ELF/OutputSections.h

Lines changed: 26 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -25,6 +25,7 @@ namespace elf {
2525

2626
class SymbolBody;
2727
struct SectionPiece;
28+
struct Version;
2829
template <class ELFT> class SymbolTable;
2930
template <class ELFT> class SymbolTableSection;
3031
template <class ELFT> class StringTableSection;
@@ -248,10 +249,30 @@ class SymbolTableSection final : public OutputSectionBase<ELFT> {
248249
// For more information about .gnu.version and .gnu.version_r see:
249250
// https://www.akkadia.org/drepper/symbol-versioning
250251

252+
// The .gnu.version_d section which has a section type of SHT_GNU_verdef shall
253+
// contain symbol version definitions. The number of entries in this section
254+
// shall be contained in the DT_VERDEFNUM entry of the .dynamic section.
255+
// The section shall contain an array of Elf_Verdef structures, optionally
256+
// followed by an array of Elf_Verdaux structures.
257+
template <class ELFT>
258+
class VersionDefinitionSection final : public OutputSectionBase<ELFT> {
259+
typedef typename ELFT::Verdef Elf_Verdef;
260+
typedef typename ELFT::Verdaux Elf_Verdaux;
261+
262+
unsigned FileDefNameOff;
263+
264+
public:
265+
VersionDefinitionSection();
266+
void finalize() override;
267+
void writeTo(uint8_t *Buf) override;
268+
};
269+
251270
// The .gnu.version section specifies the required version of each symbol in the
252271
// dynamic symbol table. It contains one Elf_Versym for each dynamic symbol
253272
// table entry. An Elf_Versym is just a 16-bit integer that refers to a version
254-
// identifier defined in the .gnu.version_r section.
273+
// identifier defined in the either .gnu.version_r or .gnu.version_d section.
274+
// The values 0 and 1 are reserved. All other values are used for versions in
275+
// the own object or in any of the dependencies.
255276
template <class ELFT>
256277
class VersionTableSection final : public OutputSectionBase<ELFT> {
257278
typedef typename ELFT::Versym Elf_Versym;
@@ -276,9 +297,8 @@ class VersionNeedSection final : public OutputSectionBase<ELFT> {
276297
// string table offsets of their sonames.
277298
std::vector<std::pair<SharedFile<ELFT> *, size_t>> Needed;
278299

279-
// The next available version identifier. Identifiers start at 2 because 0 and
280-
// 1 are reserved.
281-
unsigned NextIndex = 2;
300+
// The next available version identifier.
301+
unsigned NextIndex;
282302

283303
public:
284304
VersionNeedSection();
@@ -630,6 +650,7 @@ template <class ELFT> struct Out {
630650
static StringTableSection<ELFT> *StrTab;
631651
static SymbolTableSection<ELFT> *DynSymTab;
632652
static SymbolTableSection<ELFT> *SymTab;
653+
static VersionDefinitionSection<ELFT> *VerDef;
633654
static VersionTableSection<ELFT> *VerSym;
634655
static VersionNeedSection<ELFT> *VerNeed;
635656
static Elf_Phdr *TlsPhdr;
@@ -658,6 +679,7 @@ template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::ShStrTab;
658679
template <class ELFT> StringTableSection<ELFT> *Out<ELFT>::StrTab;
659680
template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::DynSymTab;
660681
template <class ELFT> SymbolTableSection<ELFT> *Out<ELFT>::SymTab;
682+
template <class ELFT> VersionDefinitionSection<ELFT> *Out<ELFT>::VerDef;
661683
template <class ELFT> VersionTableSection<ELFT> *Out<ELFT>::VerSym;
662684
template <class ELFT> VersionNeedSection<ELFT> *Out<ELFT>::VerNeed;
663685
template <class ELFT> typename ELFT::Phdr *Out<ELFT>::TlsPhdr;

‎lld/ELF/SymbolListFile.cpp

Lines changed: 18 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -77,21 +77,21 @@ class VersionScriptParser final : public ScriptParserBase {
7777
void run();
7878

7979
private:
80-
void parseVersion();
80+
void parseVersion(StringRef Version);
8181
void parseLocal();
82-
void parseVersionSymbols();
82+
void parseVersionSymbols(StringRef Version);
8383
};
8484

85-
void VersionScriptParser::parseVersion() {
85+
void VersionScriptParser::parseVersion(StringRef Version) {
8686
expect("{");
8787
if (peek() == "global:") {
8888
next();
89-
parseVersionSymbols();
89+
parseVersionSymbols(Version);
9090
}
9191
if (peek() == "local:")
9292
parseLocal();
9393
else
94-
parseVersionSymbols();
94+
parseVersionSymbols(Version);
9595

9696
expect("}");
9797
expect(";");
@@ -104,13 +104,21 @@ void VersionScriptParser::parseLocal() {
104104
Config->VersionScriptGlobalByDefault = false;
105105
}
106106

107-
void VersionScriptParser::parseVersionSymbols() {
107+
void VersionScriptParser::parseVersionSymbols(StringRef Version) {
108+
std::vector<StringRef> *Globals;
109+
if (Version.empty()) {
110+
Globals = &Config->VersionScriptGlobals;
111+
} else {
112+
Config->SymbolVersions.push_back(elf::Version(Version));
113+
Globals = &Config->SymbolVersions.back().Globals;
114+
}
115+
108116
for (;;) {
109117
StringRef Cur = peek();
110118
if (Cur == "}" || Cur == "local:")
111119
return;
112120
next();
113-
Config->VersionScriptGlobals.push_back(Cur);
121+
Globals->push_back(Cur);
114122
expect(";");
115123
}
116124
}
@@ -119,18 +127,18 @@ void VersionScriptParser::run() {
119127
StringRef Msg = "anonymous version definition is used in "
120128
"combination with other version definitions";
121129
if (peek() == "{") {
122-
parseVersion();
130+
parseVersion("");
123131
if (!atEOF())
124132
setError(Msg);
125133
return;
126134
}
127135

128136
while (!atEOF() && !Error) {
129-
if (next() == "{") {
137+
if (peek() == "{") {
130138
setError(Msg);
131139
return;
132140
}
133-
parseVersion();
141+
parseVersion(next());
134142
}
135143
}
136144

‎lld/ELF/SymbolListFile.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -11,6 +11,7 @@
1111
#define LLD_ELF_SYMBOL_LIST_FILE_H
1212

1313
#include "lld/Core/LLVM.h"
14+
#include "llvm/ADT/MapVector.h"
1415
#include "llvm/Support/MemoryBuffer.h"
1516

1617
namespace lld {

‎lld/ELF/SymbolTable.cpp

Lines changed: 22 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -175,7 +175,10 @@ std::pair<Symbol *, bool> SymbolTable<ELFT>::insert(StringRef Name) {
175175
Sym->Visibility = STV_DEFAULT;
176176
Sym->IsUsedInRegularObj = false;
177177
Sym->ExportDynamic = false;
178-
Sym->VersionScriptGlobal = Config->VersionScriptGlobalByDefault;
178+
if (Config->VersionScriptGlobalByDefault)
179+
Sym->VersionId = VER_NDX_GLOBAL;
180+
else
181+
Sym->VersionId = VER_NDX_LOCAL;
179182
SymVector.push_back(Sym);
180183
} else {
181184
Sym = SymVector[P.first->second];
@@ -514,9 +517,24 @@ template <class ELFT> void SymbolTable<ELFT>::scanDynamicList() {
514517
// symbols with the VersionScriptGlobal flag, which acts as a filter on the
515518
// dynamic symbol table.
516519
template <class ELFT> void SymbolTable<ELFT>::scanVersionScript() {
517-
for (StringRef S : Config->VersionScriptGlobals)
518-
if (SymbolBody *B = find(S))
519-
B->symbol()->VersionScriptGlobal = true;
520+
// If version script does not contain versions declarations,
521+
// we just should mark global symbols.
522+
if (!Config->VersionScriptGlobals.empty()) {
523+
for (StringRef S : Config->VersionScriptGlobals)
524+
if (SymbolBody *B = find(S))
525+
B->symbol()->VersionId = VER_NDX_GLOBAL;
526+
return;
527+
}
528+
529+
// If we have symbols version declarations, we should
530+
// assign version references for each symbol.
531+
size_t I = 2;
532+
for (Version &V : Config->SymbolVersions) {
533+
for (StringRef Name : V.Globals)
534+
if (SymbolBody *B = find(Name))
535+
B->symbol()->VersionId = I;
536+
++I;
537+
}
520538
}
521539

522540
template class elf::SymbolTable<ELF32LE>;

‎lld/ELF/Symbols.cpp

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -267,7 +267,7 @@ std::string elf::demangle(StringRef Name) {
267267
bool Symbol::includeInDynsym() const {
268268
if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
269269
return false;
270-
return (ExportDynamic && VersionScriptGlobal) || body()->isShared() ||
270+
return (ExportDynamic && VersionId != VER_NDX_LOCAL) || body()->isShared() ||
271271
(body()->isUndefined() && Config->Shared);
272272
}
273273

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