i686/DynamicLinker.cc

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
 
#include "DynamicLinker.h"
#include "pedigree/kernel/Log.h"
#include "pedigree/kernel/panic.h"
#include "pedigree/kernel/process/Scheduler.h"
#include "pedigree/kernel/processor/KernelCoreSyscallManager.h"
#include "pedigree/kernel/processor/PhysicalMemoryManager.h"
#include "pedigree/kernel/processor/Processor.h"
#include "pedigree/kernel/processor/VirtualAddressSpace.h"
#include "pedigree/kernel/utilities/StaticString.h"
 
#include "modules/Module.h"
#include "modules/system/vfs/VFS.h"
 
extern "C" void resolveSymbol(void);
 
void DynamicLinker::initPlt(Elf* pElf, uintptr_t value) {
  // Value == loadBase. If this changes, add an extra parameter to get
  // loadBase here!
  uint32_t* got = reinterpret_cast<uint32_t*>(pElf->getGlobalOffsetTable() + value);
  if (reinterpret_cast<uintptr_t>(got) == value) {
    WARNING("DynamicLinker: Global offset table not found [" << pElf->getGlobalOffsetTable()
                                                             << "]!");
    return;
  }
 
  got++;                      // Go to GOT+4
  *got = value & 0xFFFFFFFF;  // Library ID
  got++;                      // Got to GOT+8
 
  // Check if the resolve function has been set already...
  if (*got == 0) {
    uintptr_t resolveLocation = 0;
 
    // Grab a page to copy the PLT resolve function to.
    // Start at 0x20000000, looking for the next free page.
    const size_t pageSize = PhysicalMemoryManager::getPageSize();
    for (uintptr_t i = 0x40000000; i < 0x50000000; i += pageSize) {
      bool failed = false;
      if (Processor::information().getVirtualAddressSpace().isMapped(reinterpret_cast<void*>(i))) {
        failed = true;
        continue;
      }
 
      resolveLocation = i;
      break;
    }
 
    if (resolveLocation == 0) {
      ERROR("DynamicLinker: nowhere to put resolve function.");
      return;
    }
 
    physical_uintptr_t physPage = PhysicalMemoryManager::instance().allocatePage();
    bool b = Processor::information().getVirtualAddressSpace().map(
        physPage, reinterpret_cast<void*>(resolveLocation), VirtualAddressSpace::Write);
 
    if (!b) {
      ERROR("DynamicLinker: Could not map resolve function.");
    }
 
    // Memcpy over the resolve function into the user address space.
    // resolveSymbol is an ASM function, defined in ./asm-i686.s
    MemoryCopy(reinterpret_cast<uint8_t*>(resolveLocation),
               reinterpret_cast<uint8_t*>(&::resolveSymbol), pageSize);
 
    *got = resolveLocation;
  }
}
 
uintptr_t DynamicLinker::resolvePltSymbol(uintptr_t libraryId, uintptr_t symIdx) {
  // Find the correct ELF to patch.
  Elf* pElf = 0;
  uintptr_t loadBase = libraryId;
 
  if (libraryId == 0)
    pElf = m_pProgramElf;
  else {
    SharedObject* pSo = m_Objects.lookup(libraryId);
    if (pSo)
      pElf = pSo->elf;
  }
 
  if (!pElf) {
    ERROR("DynamicLinker::resolvePltSymbol: No library found for id `" << Hex << libraryId << "'");
    return 0;
  }
 
  uintptr_t result =
      pElf->applySpecificRelocation(symIdx, m_pProgramElf->getSymbolTable(), loadBase);
  if (result == 0)
    result = pElf->applySpecificRelocation(symIdx, m_pProgramElf->getSymbolTable(), loadBase,
                                           SymbolTable::NotOriginatingElf);
 
  return result;
}