lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp

   1 //===-- LinuxProcMaps.cpp -------------------------------------------------===//
   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 "LinuxProcMaps.h"
  10 #include "lldb/Target/MemoryRegionInfo.h"
  11 #include "lldb/Utility/Status.h"
  12 #include "lldb/Utility/StringExtractor.h"
  13 #include "llvm/ADT/StringRef.h"
  14 #include <optional>
  15
  16 using namespace lldb_private;
  17
  18 enum class MapsKind { Maps, SMaps };
  19
  20 static llvm::Expected<MemoryRegionInfo> ProcMapError(const char *msg,
  21                                                      MapsKind kind) {
  22   return llvm::createStringError(llvm::inconvertibleErrorCode(), msg,
  23                                  kind == MapsKind::Maps ? "maps" : "smaps");
  24 }
  25
  26 static llvm::Expected<MemoryRegionInfo>
  27 ParseMemoryRegionInfoFromProcMapsLine(llvm::StringRef maps_line,
  28                                       MapsKind maps_kind) {
  29   MemoryRegionInfo region;
  30   StringExtractor line_extractor(maps_line);
  31
  32   // Format: {address_start_hex}-{address_end_hex} perms offset  dev   inode
  33   // pathname perms: rwxp   (letter is present if set, '-' if not, final
  34   // character is p=private, s=shared).
  35
  36   // Parse out the starting address
  37   lldb::addr_t start_address = line_extractor.GetHexMaxU64(false, 0);
  38
  39   // Parse out hyphen separating start and end address from range.
  40   if (!line_extractor.GetBytesLeft() || (line_extractor.GetChar() != '-'))
  41     return ProcMapError(
  42         "malformed /proc/{pid}/%s entry, missing dash between address range",
  43         maps_kind);
  44
  45   // Parse out the ending address
  46   lldb::addr_t end_address = line_extractor.GetHexMaxU64(false, start_address);
  47
  48   // Parse out the space after the address.
  49   if (!line_extractor.GetBytesLeft() || (line_extractor.GetChar() != ' '))
  50     return ProcMapError(
  51         "malformed /proc/{pid}/%s entry, missing space after range", maps_kind);
  52
  53   // Save the range.
  54   region.GetRange().SetRangeBase(start_address);
  55   region.GetRange().SetRangeEnd(end_address);
  56
  57   // Any memory region in /proc/{pid}/(maps|smaps) is by definition mapped
  58   // into the process.
  59   region.SetMapped(MemoryRegionInfo::OptionalBool::eYes);
  60
  61   // Parse out each permission entry.
  62   if (line_extractor.GetBytesLeft() < 4)
  63     return ProcMapError(
  64         "malformed /proc/{pid}/%s entry, missing some portion of "
  65         "permissions",
  66         maps_kind);
  67
  68   // Handle read permission.
  69   const char read_perm_char = line_extractor.GetChar();
  70   if (read_perm_char == 'r')
  71     region.SetReadable(MemoryRegionInfo::OptionalBool::eYes);
  72   else if (read_perm_char == '-')
  73     region.SetReadable(MemoryRegionInfo::OptionalBool::eNo);
  74   else
  75     return ProcMapError("unexpected /proc/{pid}/%s read permission char",
  76                         maps_kind);
  77
  78   // Handle write permission.
  79   const char write_perm_char = line_extractor.GetChar();
  80   if (write_perm_char == 'w')
  81     region.SetWritable(MemoryRegionInfo::OptionalBool::eYes);
  82   else if (write_perm_char == '-')
  83     region.SetWritable(MemoryRegionInfo::OptionalBool::eNo);
  84   else
  85     return ProcMapError("unexpected /proc/{pid}/%s write permission char",
  86                         maps_kind);
  87
  88   // Handle execute permission.
  89   const char exec_perm_char = line_extractor.GetChar();
  90   if (exec_perm_char == 'x')
  91     region.SetExecutable(MemoryRegionInfo::OptionalBool::eYes);
  92   else if (exec_perm_char == '-')
  93     region.SetExecutable(MemoryRegionInfo::OptionalBool::eNo);
  94   else
  95     return ProcMapError("unexpected /proc/{pid}/%s exec permission char",
  96                         maps_kind);
  97
  98   // Handle sharing status (private/shared).
  99   const char sharing_char = line_extractor.GetChar();
 100   if (sharing_char == 's')
 101     region.SetShared(MemoryRegionInfo::OptionalBool::eYes);
 102   else if (sharing_char == 'p')
 103     region.SetShared(MemoryRegionInfo::OptionalBool::eNo);
 104   else
 105     region.SetShared(MemoryRegionInfo::OptionalBool::eDontKnow);
 106
 107   line_extractor.SkipSpaces();           // Skip the separator
 108   line_extractor.GetHexMaxU64(false, 0); // Read the offset
 109   line_extractor.GetHexMaxU64(false, 0); // Read the major device number
 110   line_extractor.GetChar();              // Read the device id separator
 111   line_extractor.GetHexMaxU64(false, 0); // Read the major device number
 112   line_extractor.SkipSpaces();           // Skip the separator
 113   line_extractor.GetU64(0, 10);          // Read the inode number
 114
 115   line_extractor.SkipSpaces();
 116   const char *name = line_extractor.Peek();
 117   if (name)
 118     region.SetName(name);
 119
 120   return region;
 121 }
 122
 123 void lldb_private::ParseLinuxMapRegions(llvm::StringRef linux_map,
 124                                         LinuxMapCallback const &callback) {
 125   llvm::StringRef lines(linux_map);
 126   llvm::StringRef line;
 127   while (!lines.empty()) {
 128     std::tie(line, lines) = lines.split('\n');
 129     if (!callback(ParseMemoryRegionInfoFromProcMapsLine(line, MapsKind::Maps)))
 130       break;
 131   }
 132 }
 133
 134 void lldb_private::ParseLinuxSMapRegions(llvm::StringRef linux_smap,
 135                                          LinuxMapCallback const &callback) {
 136   // Entries in /smaps look like:
 137   // 00400000-0048a000 r-xp 00000000 fd:03 960637
 138   // Size:                552 kB
 139   // Rss:                 460 kB
 140   // <...>
 141   // VmFlags: rd ex mr mw me dw
 142   // 00500000-0058a000 rwxp 00000000 fd:03 960637
 143   // <...>
 144   //
 145   // Where the first line is identical to the /maps format
 146   // and VmFlags is only printed for kernels >= 3.8.
 147
 148   llvm::StringRef lines(linux_smap);
 149   llvm::StringRef line;
 150   std::optional<MemoryRegionInfo> region;
 151
 152   while (lines.size()) {
 153     std::tie(line, lines) = lines.split('\n');
 154
 155     // A property line looks like:
 156     // <word>: <value>
 157     // (no spaces on the left hand side)
 158     // A header will have a ':' but the LHS will contain spaces
 159     llvm::StringRef name;
 160     llvm::StringRef value;
 161     std::tie(name, value) = line.split(':');
 162
 163     // If this line is a property line
 164     if (!name.contains(' ')) {
 165       if (region) {
 166         if (name == "VmFlags") {
 167           if (value.contains("mt"))
 168             region->SetMemoryTagged(MemoryRegionInfo::eYes);
 169           else
 170             region->SetMemoryTagged(MemoryRegionInfo::eNo);
 171         }
 172         // Ignore anything else
 173       } else {
 174         // Orphaned settings line
 175         callback(ProcMapError(
 176             "Found a property line without a corresponding mapping "
 177             "in /proc/{pid}/%s",
 178             MapsKind::SMaps));
 179         return;
 180       }
 181     } else {
 182       // Must be a new region header
 183       if (region) {
 184         // Save current region
 185         callback(*region);
 186         region.reset();
 187       }
 188
 189       // Try to start a new region
 190       llvm::Expected<MemoryRegionInfo> new_region =
 191           ParseMemoryRegionInfoFromProcMapsLine(line, MapsKind::SMaps);
 192       if (new_region) {
 193         region = *new_region;
 194       } else {
 195         // Stop at first invalid region header
 196         callback(new_region.takeError());
 197         return;
 198       }
 199     }
 200   }
 201
 202   // Catch last region
 203   if (region)
 204     callback(*region);
 205 }