src/ld/passes/dtrace_dof.cpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
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   9  * Version 2.0 (the 'License'). You may not use this file except in
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  11  * http://www.opensource.apple.com/apsl/ and read it before using this
  12  * file.
  13  *
  14  * The Original Code and all software distributed under the License are
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  24
  25
  26 #include <stdint.h>
  27 #include <math.h>
  28 #include <unistd.h>
  29 #include <dlfcn.h>
  30
  31 #include <vector>
  32 #include <map>
  33 #include <ext/hash_map>
  34
  35 #include "ld.hpp"
  36 #include "dtrace_dof.h"
  37
  38 // prototype for entry point in libdtrace.dylib
  39 typedef uint8_t* (*createdof_func_t)(cpu_type_t, unsigned int, const char*[], unsigned int, const char*[], const char*[], uint64_t offsetsInDOF[], size_t* size);
  40
  41
  42 namespace ld {
  43 namespace passes {
  44 namespace dtrace {
  45
  46 class File; // forward reference
  47
  48 class Atom : public ld::Atom {
  49 public:
  50                                                                                         Atom(class File& f, const char* n,  const uint8_t* content, uint64_t sz);
  51
  52         virtual ld::File*                                               file() const                                    { return (ld::File*)&_file; }
  53         virtual bool                                                    translationUnitSource(const char** dir, const char** ) const
  54                                                                                                                                                         { return false; }
  55         virtual const char*                                             name() const                                    { return _name; }
  56         virtual uint64_t                                                size() const                                    { return _size; }
  57         virtual uint64_t                                                objectAddress() const                   { return 0; }
  58         virtual void                                                    copyRawContent(uint8_t buffer[]) const
  59                                                                                                                                                         { memcpy(buffer, _content, _size); }
  60         virtual void                                                    setScope(Scope)                                 { }
  61         virtual ld::Fixup::iterator                             fixupsBegin() const                             { return &_fixups[0]; }
  62         virtual ld::Fixup::iterator                             fixupsEnd() const                               { return &_fixups[_fixups.size()]; }
  63
  64 protected:
  65         friend class File;
  66         virtual                                                                 ~Atom() {}
  67
  68         class File&                                                             _file;
  69         const char*                                                             _name;
  70         const uint8_t*                                                  _content;
  71         uint64_t                                                                _size;
  72         mutable std::vector<ld::Fixup>                  _fixups;
  73 };
  74
  75
  76 class File : public ld::File
  77 {
  78 public:
  79                                                                 File(const char* segmentName, const char* sectionName, const char* pth,
  80                                                                         const uint8_t fileContent[], uint64_t fileLength, uint32_t ord,
  81                                                                         const char* symbolName="dof")
  82                                                                         : ld::File(pth, 0, ord),
  83                                                                           _atom(*this, symbolName, fileContent, fileLength),
  84                                                                           _section(segmentName, sectionName, ld::Section::typeDtraceDOF) { }
  85         virtual                                         ~File() {}
  86
  87         virtual bool                            forEachAtom(AtomHandler& h) const { h.doAtom(_atom); return true; }
  88         virtual bool                            justInTimeforEachAtom(const char* name, AtomHandler&) const { return false; }
  89
  90         void                                            reserveFixups(unsigned int count) { _atom._fixups.reserve(count); }
  91         void                                            addSectionFixup(const ld::Fixup& f) { _atom._fixups.push_back(f); }
  92         ld::Atom&                                       atom() { return _atom; }
  93 private:
  94         friend class Atom;
  95
  96         Atom                                            _atom;
  97         ld::Section                                     _section;
  98 };
  99
 100 Atom::Atom(File& f, const char* n,  const uint8_t* content, uint64_t sz)
 101         : ld::Atom(f._section, ld::Atom::definitionRegular, ld::Atom::combineNever,
 102                 ld::Atom::scopeTranslationUnit, ld::Atom::typeUnclassified,
 103                 symbolTableNotIn, false, false, false, ld::Atom::Alignment(0)),
 104                 _file(f), _name(strdup(n)), _content(content), _size(sz) {}
 105
 106
 107
 108 class CStringEquals
 109 {
 110 public:
 111         bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
 112 };
 113
 114 struct DTraceProbeInfo {
 115         DTraceProbeInfo(const ld::Atom* a, uint32_t o, const char* n) : atom(a), offset(o), probeName(n) {}
 116         const ld::Atom*                                 atom;
 117         uint32_t                                                offset;
 118         const char*                                             probeName;
 119 };
 120 typedef __gnu_cxx::hash_map<const char*, std::vector<DTraceProbeInfo>, __gnu_cxx::hash<const char*>, CStringEquals>     ProviderToProbes;
 121 typedef __gnu_cxx::hash_set<const char*, __gnu_cxx::hash<const char*>, CStringEquals>  CStringSet;
 122
 123
 124
 125 void doPass(const Options& opts, ld::Internal& internal)
 126 {
 127         static bool log = false;
 128
 129         // only make __dof section in final linked images
 130         if ( opts.outputKind() == Options::kObjectFile )
 131                 return;
 132
 133         // scan all atoms looking for dtrace probes
 134         std::vector<DTraceProbeInfo>                                    probeSites;
 135         std::vector<DTraceProbeInfo>                                    isEnabledSites;
 136         std::map<const ld::Atom*,CStringSet>                    atomToDtraceTypes;
 137         for (std::vector<ld::Internal::FinalSection*>::iterator sit=internal.sections.begin(); sit != internal.sections.end(); ++sit) {
 138                 ld::Internal::FinalSection* sect = *sit;
 139                 if ( sect->type() != ld::Section::typeCode )
 140                         continue;
 141                 for (std::vector<const ld::Atom*>::iterator ait=sect->atoms.begin();  ait != sect->atoms.end(); ++ait) {
 142                         const ld::Atom* atom = *ait;
 143                         for (ld::Fixup::iterator fit = atom->fixupsBegin(), end=atom->fixupsEnd(); fit != end; ++fit) {
 144                                 switch ( fit->kind ) {
 145                                         case ld::Fixup::kindStoreX86DtraceCallSiteNop:
 146                                         case ld::Fixup::kindStoreARMDtraceCallSiteNop:
 147                                         case ld::Fixup::kindStoreThumbDtraceCallSiteNop:
 148                                                 probeSites.push_back(DTraceProbeInfo(atom, fit->offsetInAtom, fit->u.name));
 149                                                 break;
 150                                         case ld::Fixup::kindStoreX86DtraceIsEnableSiteClear:
 151                                         case ld::Fixup::kindStoreARMDtraceIsEnableSiteClear:
 152                                         case ld::Fixup::kindStoreThumbDtraceIsEnableSiteClear:
 153                                                 isEnabledSites.push_back(DTraceProbeInfo(atom, fit->offsetInAtom, fit->u.name));
 154                                                 break;
 155                                         case ld::Fixup::kindDtraceExtra:
 156                                                 atomToDtraceTypes[atom].insert(fit->u.name);
 157                                                 break;
 158                                         default:
 159                                                 break;
 160                                 }
 161                         }
 162                 }
 163         }
 164
 165         // if no probes, we're done
 166         if ( (probeSites.size() == 0) && (isEnabledSites.size() == 0) )
 167                 return;
 168
 169         ld::Fixup::Kind storeKind = ld::Fixup::kindNone;
 170         switch ( opts.architecture() ) {
 171                 case CPU_TYPE_I386:
 172                 case CPU_TYPE_X86_64:
 173                 case CPU_TYPE_ARM:
 174                         storeKind = ld::Fixup::kindStoreLittleEndian32;
 175                         break;
 176                 default:
 177                         throw "unsupported arch for DOF";
 178         }
 179
 180         // partition probes by provider name
 181         // The symbol names looks like:
 182         //      "___dtrace_probe$" provider-name "$" probe-name [ "$"... ]
 183         //      "___dtrace_isenabled$" provider-name "$" probe-name [ "$"... ]
 184         ProviderToProbes providerToProbes;
 185         std::vector<DTraceProbeInfo> emptyList;
 186         for(std::vector<DTraceProbeInfo>::iterator it = probeSites.begin(); it != probeSites.end(); ++it) {
 187                 // ignore probes in functions that were coalesed away rdar://problem/5628149
 188                 if ( it->atom->coalescedAway() )
 189                         continue;
 190                 const char* providerStart = &it->probeName[16];
 191                 const char* providerEnd = strchr(providerStart, '$');
 192                 if ( providerEnd != NULL ) {
 193                         char providerName[providerEnd-providerStart+1];
 194                         strlcpy(providerName, providerStart, providerEnd-providerStart+1);
 195                         ProviderToProbes::iterator pos = providerToProbes.find(providerName);
 196                         if ( pos == providerToProbes.end() ) {
 197                                 const char* dup = strdup(providerName);
 198                                 providerToProbes[dup] = emptyList;
 199                         }
 200                         providerToProbes[providerName].push_back(*it);
 201                 }
 202         }
 203         for(std::vector<DTraceProbeInfo>::iterator it = isEnabledSites.begin(); it != isEnabledSites.end(); ++it) {
 204                 // ignore probes in functions that were coalesed away rdar://problem/5628149
 205                 if ( it->atom->coalescedAway() )
 206                         continue;
 207                 const char* providerStart = &it->probeName[20];
 208                 const char* providerEnd = strchr(providerStart, '$');
 209                 if ( providerEnd != NULL ) {
 210                         char providerName[providerEnd-providerStart+1];
 211                         strlcpy(providerName, providerStart, providerEnd-providerStart+1);
 212                         ProviderToProbes::iterator pos = providerToProbes.find(providerName);
 213                         if ( pos == providerToProbes.end() ) {
 214                                 const char* dup = strdup(providerName);
 215                                 providerToProbes[dup] = emptyList;
 216                         }
 217                         providerToProbes[providerName].push_back(*it);
 218                 }
 219         }
 220
 221         // create a DOF section for each provider
 222         int dofIndex=1;
 223         CStringSet sectionNamesUsed;
 224         for(ProviderToProbes::iterator pit = providerToProbes.begin(); pit != providerToProbes.end(); ++pit, ++dofIndex) {
 225                 const char* providerName = pit->first;
 226                 const std::vector<DTraceProbeInfo>& probes = pit->second;
 227
 228                 // open library and find dtrace_create_dof()
 229                 void* handle = dlopen("/usr/lib/libdtrace.dylib", RTLD_LAZY);
 230                 if ( handle == NULL )
 231                         throwf("couldn't dlopen() /usr/lib/libdtrace.dylib: %s", dlerror());
 232                 createdof_func_t pCreateDOF = (createdof_func_t)dlsym(handle, "dtrace_ld_create_dof");
 233                 if ( pCreateDOF == NULL )
 234                         throwf("couldn't find \"dtrace_ld_create_dof\" in /usr/lib/libdtrace.dylib: %s", dlerror());
 235                 // build list of typedefs/stability infos for this provider
 236                 CStringSet types;
 237                 for(std::vector<DTraceProbeInfo>::const_iterator it = probes.begin(); it != probes.end(); ++it) {
 238                         std::map<const ld::Atom*,CStringSet>::iterator pos = atomToDtraceTypes.find(it->atom);
 239                         if ( pos != atomToDtraceTypes.end() ) {
 240                                 for(CStringSet::iterator sit = pos->second.begin(); sit != pos->second.end(); ++sit) {
 241                                         const char* providerStart = strchr(*sit, '$')+1;
 242                                         const char* providerEnd = strchr(providerStart, '$');
 243                                         if ( providerEnd != NULL ) {
 244                                                 char aProviderName[providerEnd-providerStart+1];
 245                                                 strlcpy(aProviderName, providerStart, providerEnd-providerStart+1);
 246                                                 if ( strcmp(aProviderName, providerName) == 0 )
 247                                                         types.insert(*sit);
 248                                         }
 249                                 }
 250                         }
 251                 }
 252                 int typeCount = types.size();
 253                 const char* typeNames[typeCount];
 254                 //fprintf(stderr, "types for %s:\n", providerName);
 255                 uint32_t index = 0;
 256                 for(CStringSet::iterator it = types.begin(); it != types.end(); ++it) {
 257                         typeNames[index] = *it;
 258                         //fprintf(stderr, "\t%s\n", *it);
 259                         ++index;
 260                 }
 261
 262                 // build list of probe/isenabled sites
 263                 const uint32_t probeCount = probes.size();
 264                 const char* probeNames[probeCount];
 265                 const char* funtionNames[probeCount];
 266                 uint64_t offsetsInDOF[probeCount];
 267                 index = 0;
 268                 for(std::vector<DTraceProbeInfo>::const_iterator it = probes.begin(); it != probes.end(); ++it) {
 269                         probeNames[index] = it->probeName;
 270                         funtionNames[index] = it->atom->name();
 271                         offsetsInDOF[index] = 0;
 272                         ++index;
 273                 }
 274                 if ( log ) {
 275                         fprintf(stderr, "calling libtrace to create DOF:\n");
 276                         fprintf(stderr, "   types::\n");
 277                         for(int i=0; i < typeCount; ++i)
 278                                 fprintf(stderr, "     [%u]\t %s\n", i, typeNames[i]);
 279                         fprintf(stderr, "   probes::\n");
 280                         for(uint32_t i=0; i < probeCount; ++i)
 281                                 fprintf(stderr, "     [%u]\t %s in %s\n", i, probeNames[i], funtionNames[i]);
 282                 }
 283
 284                 // call dtrace library to create DOF section
 285                 size_t dofSectionSize;
 286                 uint8_t* p = (*pCreateDOF)(opts.architecture(), typeCount, typeNames, probeCount, probeNames, funtionNames, offsetsInDOF, &dofSectionSize);
 287                 if ( p != NULL ) {
 288                         char* sectionName = new char[18]; // alloc new string, pass ownership to File()
 289                         strcpy(sectionName, "__dof_");
 290                         strlcpy(&sectionName[6], providerName, 10);
 291                         // create unique section name so each DOF is in its own section
 292                         if ( sectionNamesUsed.count(sectionName) != 0 ) {
 293                                 sectionName[15] = '0';
 294                                 sectionName[16] = '\0';
 295                                 while ( sectionNamesUsed.count(sectionName) != 0 ) {
 296                                         ++sectionName[15];
 297                                 }
 298                         }
 299                         sectionNamesUsed.insert(sectionName);
 300                         char symbolName[strlen(providerName)+64];
 301                         sprintf(symbolName, "__dtrace_dof_for_provider_%s", providerName);
 302                         File* f = new File("__TEXT", sectionName, "dtrace", p, dofSectionSize, 0, symbolName);
 303                         if ( log ) {
 304                                 fprintf(stderr, "libdtrace created DOF of size %ld\n", dofSectionSize);
 305                         }
 306                         // add references
 307                         f->reserveFixups(3*probeCount);
 308                         for (uint32_t i=0; i < probeCount; ++i) {
 309                                 uint64_t offset = offsetsInDOF[i];
 310                                 //fprintf(stderr, "%s offset[%d]=0x%08llX\n", providerName, i, offset);
 311                                 if ( offset > dofSectionSize )
 312                                         throwf("offsetsInDOF[%d]=%0llX > dofSectionSize=%0lX\n", i, offset, dofSectionSize);
 313                                 f->addSectionFixup(ld::Fixup(offset, ld::Fixup::k1of4, ld::Fixup::kindSetTargetAddress, probes[i].atom));
 314                                 f->addSectionFixup(ld::Fixup(offset, ld::Fixup::k2of4, ld::Fixup::kindAddAddend, probes[i].offset));
 315                                 f->addSectionFixup(ld::Fixup(offset, ld::Fixup::k3of4, ld::Fixup::kindSubtractTargetAddress, &f->atom()));
 316                                 f->addSectionFixup(ld::Fixup(offset, ld::Fixup::k4of4, storeKind));
 317                         }
 318                         // insert new section
 319                         internal.addAtom(f->atom());
 320                 }
 321                 else {
 322                         throw "error creating dtrace DOF section";
 323                 }
 324         }
 325
 326
 327
 328 }
 329
 330
 331 } // namespace dtrace
 332 } // namespace passes
 333 } // namespace ld