lldb/source/Target/CoreFileMemoryRanges.cpp

   1 //===-- CoreFileMemoryRanges.cpp --------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "lldb/Target/CoreFileMemoryRanges.h"
  10
  11 using namespace lldb;
  12 using namespace lldb_private;
  13
  14 using Entry = CoreFileMemoryRanges::Entry;
  15
  16 static bool Overlaps(const Entry *region_one, const Entry *region_two) {
  17   return !(region_one->GetRangeEnd() < region_two->GetRangeBase() ||
  18            region_two->GetRangeEnd() < region_one->GetRangeBase());
  19 }
  20
  21 static bool IntersectHelper(const Entry *region_one, const Entry *region_two) {
  22   return region_one->GetRangeBase() == region_two->GetRangeEnd() ||
  23          region_one->GetRangeEnd() == region_two->GetRangeBase();
  24 }
  25
  26 static bool OnlyIntersects(const Entry *region_one, const Entry *region_two) {
  27   return IntersectHelper(region_one, region_two) ||
  28          IntersectHelper(region_two, region_one);
  29 }
  30
  31 static bool PermissionsMatch(const Entry *region_one, const Entry *region_two) {
  32   return region_one->data.lldb_permissions == region_two->data.lldb_permissions;
  33 }
  34
  35 // This assumes any overlapping ranges will share the same permissions
  36 // and that adjacent ranges could have different permissions.
  37 Status CoreFileMemoryRanges::FinalizeCoreFileSaveRanges() {
  38   Status error;
  39   this->Sort();
  40   for (size_t i = this->GetSize() - 1; i > 0; i--) {
  41     auto region_one = this->GetMutableEntryAtIndex(i);
  42     auto region_two = this->GetMutableEntryAtIndex(i - 1);
  43     if (Overlaps(region_one, region_two)) {
  44       // It's okay for interesecting regions to have different permissions but
  45       // if they overlap we fail because we don't know what to do with them.
  46       if (!PermissionsMatch(region_one, region_two)) {
  47         // Permissions mismatch and it's not a simple intersection.
  48         if (!OnlyIntersects(region_one, region_two)) {
  49           error = Status::FromErrorStringWithFormatv(
  50               "Memory region at {0}::{1} has different permssions than "
  51               "overlapping region at {2}::{3}",
  52               region_one->GetRangeBase(), region_one->GetRangeEnd(),
  53               region_two->GetRangeBase(), region_two->GetRangeEnd());
  54           return error;
  55         }
  56         // Simple intersection, we can just not merge these.
  57         else
  58           continue;
  59       }
  60       const addr_t base =
  61           std::min(region_one->GetRangeBase(), region_two->GetRangeBase());
  62       const addr_t byte_size =
  63           std::max(region_one->GetRangeEnd(), region_two->GetRangeEnd()) - base;
  64
  65       region_two->SetRangeBase(base);
  66       region_two->SetByteSize(byte_size);
  67
  68       // Because this is a range data vector, the entry has a base as well
  69       // as the data contained in the entry. So we have to update both.
  70       // And llvm::AddressRange isn't mutable so we have to create a new one.
  71       llvm::AddressRange range(base, base + byte_size);
  72       const CoreFileMemoryRange core_range = {
  73           range, region_two->data.lldb_permissions};
  74       region_two->data = core_range;
  75       // Erase is delete from [Inclusive, exclusive index).
  76       if (!this->Erase(i, i + 1)) {
  77         error = Status::FromErrorStringWithFormat(
  78             "Core file memory ranges mutated outside of "
  79             "CalculateCoreFileSaveRanges");
  80         return error;
  81       }
  82     }
  83   }
  84
  85   return error;
  86 }