compiler-rt/lib/memprof/memprof_shadow_setup.cpp

   1 //===-- memprof_shadow_setup.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 // This file is a part of MemProfiler, a memory profiler.
  10 //
  11 // Set up the shadow memory.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "sanitizer_common/sanitizer_platform.h"
  15
  16 #include "memprof_internal.h"
  17 #include "memprof_mapping.h"
  18
  19 namespace __memprof {
  20
  21 static void ProtectGap(uptr addr, uptr size) {
  22   if (!flags()->protect_shadow_gap) {
  23     // The shadow gap is unprotected, so there is a chance that someone
  24     // is actually using this memory. Which means it needs a shadow...
  25     uptr GapShadowBeg = RoundDownTo(MEM_TO_SHADOW(addr), GetPageSizeCached());
  26     uptr GapShadowEnd =
  27         RoundUpTo(MEM_TO_SHADOW(addr + size), GetPageSizeCached()) - 1;
  28     if (Verbosity())
  29       Printf("protect_shadow_gap=0:"
  30              " not protecting shadow gap, allocating gap's shadow\n"
  31              "|| `[%p, %p]` || ShadowGap's shadow ||\n",
  32              GapShadowBeg, GapShadowEnd);
  33     ReserveShadowMemoryRange(GapShadowBeg, GapShadowEnd,
  34                              "unprotected gap shadow");
  35     return;
  36   }
  37   __sanitizer::ProtectGap(addr, size, kZeroBaseShadowStart,
  38                           kZeroBaseMaxShadowStart);
  39 }
  40
  41 void InitializeShadowMemory() {
  42   uptr shadow_start = FindDynamicShadowStart();
  43   // Update the shadow memory address (potentially) used by instrumentation.
  44   __memprof_shadow_memory_dynamic_address = shadow_start;
  45
  46   if (kLowShadowBeg)
  47     shadow_start -= GetMmapGranularity();
  48
  49   if (Verbosity())
  50     PrintAddressSpaceLayout();
  51
  52   // mmap the low shadow plus at least one page at the left.
  53   if (kLowShadowBeg)
  54     ReserveShadowMemoryRange(shadow_start, kLowShadowEnd, "low shadow");
  55   // mmap the high shadow.
  56   ReserveShadowMemoryRange(kHighShadowBeg, kHighShadowEnd, "high shadow");
  57   // protect the gap.
  58   ProtectGap(kShadowGapBeg, kShadowGapEnd - kShadowGapBeg + 1);
  59   CHECK_EQ(kShadowGapEnd, kHighShadowBeg - 1);
  60 }
  61
  62 } // namespace __memprof