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
19namespace __memprof {
20
21static 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
41void 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
63