1 //===-- common.h ------------------------------------------------*- 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 #ifndef SCUDO_COMMON_H_
10 #define SCUDO_COMMON_H_
11 
12 #include "internal_defs.h"
13 
14 #include "fuchsia.h"
15 #include "linux.h"
16 #include "trusty.h"
17 
18 #include <stddef.h>
19 #include <string.h>
20 
21 namespace scudo {
22 
23 template <class Dest, class Source> inline Dest bit_cast(const Source &S) {
24   static_assert(sizeof(Dest) == sizeof(Source), "");
25   Dest D;
26   memcpy(&D, &S, sizeof(D));
27   return D;
28 }
29 
30 inline constexpr bool isPowerOfTwo(uptr X) { return (X & (X - 1)) == 0; }
31 
32 inline constexpr uptr roundUp(uptr X, uptr Boundary) {
33   DCHECK(isPowerOfTwo(Boundary));
34   return (X + Boundary - 1) & ~(Boundary - 1);
35 }
36 inline constexpr uptr roundUpSlow(uptr X, uptr Boundary) {
37   return ((X + Boundary - 1) / Boundary) * Boundary;
38 }
39 
40 inline constexpr uptr roundDown(uptr X, uptr Boundary) {
41   DCHECK(isPowerOfTwo(Boundary));
42   return X & ~(Boundary - 1);
43 }
44 inline constexpr uptr roundDownSlow(uptr X, uptr Boundary) {
45   return (X / Boundary) * Boundary;
46 }
47 
48 inline constexpr bool isAligned(uptr X, uptr Alignment) {
49   DCHECK(isPowerOfTwo(Alignment));
50   return (X & (Alignment - 1)) == 0;
51 }
52 inline constexpr bool isAlignedSlow(uptr X, uptr Alignment) {
53   return X % Alignment == 0;
54 }
55 
56 template <class T> constexpr T Min(T A, T B) { return A < B ? A : B; }
57 
58 template <class T> constexpr T Max(T A, T B) { return A > B ? A : B; }
59 
60 template <class T> void Swap(T &A, T &B) {
61   T Tmp = A;
62   A = B;
63   B = Tmp;
64 }
65 
66 inline uptr getMostSignificantSetBitIndex(uptr X) {
67   DCHECK_NE(X, 0U);
68   return SCUDO_WORDSIZE - 1U - static_cast<uptr>(__builtin_clzl(X));
69 }
70 
71 inline uptr roundUpPowerOfTwo(uptr Size) {
72   DCHECK(Size);
73   if (isPowerOfTwo(Size))
74     return Size;
75   const uptr Up = getMostSignificantSetBitIndex(Size);
76   DCHECK_LT(Size, (1UL << (Up + 1)));
77   DCHECK_GT(Size, (1UL << Up));
78   return 1UL << (Up + 1);
79 }
80 
81 inline uptr getLeastSignificantSetBitIndex(uptr X) {
82   DCHECK_NE(X, 0U);
83   return static_cast<uptr>(__builtin_ctzl(X));
84 }
85 
86 inline uptr getLog2(uptr X) {
87   DCHECK(isPowerOfTwo(X));
88   return getLeastSignificantSetBitIndex(X);
89 }
90 
91 inline u32 getRandomU32(u32 *State) {
92   // ANSI C linear congruential PRNG (16-bit output).
93   // return (*State = *State * 1103515245 + 12345) >> 16;
94   // XorShift (32-bit output).
95   *State ^= *State << 13;
96   *State ^= *State >> 17;
97   *State ^= *State << 5;
98   return *State;
99 }
100 
101 inline u32 getRandomModN(u32 *State, u32 N) {
102   return getRandomU32(State) % N; // [0, N)
103 }
104 
105 template <typename T> inline void shuffle(T *A, u32 N, u32 *RandState) {
106   if (N <= 1)
107     return;
108   u32 State = *RandState;
109   for (u32 I = N - 1; I > 0; I--)
110     Swap(A[I], A[getRandomModN(&State, I + 1)]);
111   *RandState = State;
112 }
113 
114 // Hardware specific inlinable functions.
115 
116 inline void yieldProcessor(UNUSED u8 Count) {
117 #if defined(__i386__) || defined(__x86_64__)
118   __asm__ __volatile__("" ::: "memory");
119   for (u8 I = 0; I < Count; I++)
120     __asm__ __volatile__("pause");
121 #elif defined(__aarch64__) || defined(__arm__)
122   __asm__ __volatile__("" ::: "memory");
123   for (u8 I = 0; I < Count; I++)
124     __asm__ __volatile__("yield");
125 #endif
126   __asm__ __volatile__("" ::: "memory");
127 }
128 
129 // Platform specific functions.
130 
131 extern uptr PageSizeCached;
132 uptr getPageSizeSlow();
133 inline uptr getPageSizeCached() {
134   // Bionic uses a hardcoded value.
135   if (SCUDO_ANDROID)
136     return 4096U;
137   if (LIKELY(PageSizeCached))
138     return PageSizeCached;
139   return getPageSizeSlow();
140 }
141 
142 // Returns 0 if the number of CPUs could not be determined.
143 u32 getNumberOfCPUs();
144 
145 const char *getEnv(const char *Name);
146 
147 uptr GetRSS();
148 
149 u64 getMonotonicTime();
150 // Gets the time faster but with less accuracy. Can call getMonotonicTime
151 // if no fast version is available.
152 u64 getMonotonicTimeFast();
153 
154 u32 getThreadID();
155 
156 // Our randomness gathering function is limited to 256 bytes to ensure we get
157 // as many bytes as requested, and avoid interruptions (on Linux).
158 constexpr uptr MaxRandomLength = 256U;
159 bool getRandom(void *Buffer, uptr Length, bool Blocking = false);
160 
161 // Platform memory mapping functions.
162 
163 #define MAP_ALLOWNOMEM (1U << 0)
164 #define MAP_NOACCESS (1U << 1)
165 #define MAP_RESIZABLE (1U << 2)
166 #define MAP_MEMTAG (1U << 3)
167 #define MAP_PRECOMMIT (1U << 4)
168 
169 // Our platform memory mapping use is restricted to 3 scenarios:
170 // - reserve memory at a random address (MAP_NOACCESS);
171 // - commit memory in a previously reserved space;
172 // - commit memory at a random address.
173 // As such, only a subset of parameters combinations is valid, which is checked
174 // by the function implementation. The Data parameter allows to pass opaque
175 // platform specific data to the function.
176 // Returns nullptr on error or dies if MAP_ALLOWNOMEM is not specified.
177 void *map(void *Addr, uptr Size, const char *Name, uptr Flags = 0,
178           MapPlatformData *Data = nullptr);
179 
180 // Indicates that we are getting rid of the whole mapping, which might have
181 // further consequences on Data, depending on the platform.
182 #define UNMAP_ALL (1U << 0)
183 
184 void unmap(void *Addr, uptr Size, uptr Flags = 0,
185            MapPlatformData *Data = nullptr);
186 
187 void setMemoryPermission(uptr Addr, uptr Size, uptr Flags,
188                          MapPlatformData *Data = nullptr);
189 
190 void releasePagesToOS(uptr BaseAddress, uptr Offset, uptr Size,
191                       MapPlatformData *Data = nullptr);
192 
193 // Internal map & unmap fatal error. This must not call map(). SizeIfOOM shall
194 // hold the requested size on an out-of-memory error, 0 otherwise.
195 void NORETURN dieOnMapUnmapError(uptr SizeIfOOM = 0);
196 
197 // Logging related functions.
198 
199 void setAbortMessage(const char *Message);
200 
201 struct BlockInfo {
202   uptr BlockBegin;
203   uptr BlockSize;
204   uptr RegionBegin;
205   uptr RegionEnd;
206 };
207 
208 enum class Option : u8 {
209   ReleaseInterval,      // Release to OS interval in milliseconds.
210   MemtagTuning,         // Whether to tune tagging for UAF or overflow.
211   ThreadDisableMemInit, // Whether to disable automatic heap initialization and,
212                         // where possible, memory tagging, on this thread.
213   MaxCacheEntriesCount, // Maximum number of blocks that can be cached.
214   MaxCacheEntrySize,    // Maximum size of a block that can be cached.
215   MaxTSDsCount,         // Number of usable TSDs for the shared registry.
216 };
217 
218 enum class ReleaseToOS : u8 {
219   Normal, // Follow the normal rules for releasing pages to the OS
220   Force,  // Force release pages to the OS, but avoid cases that take too long.
221   ForceAll, // Force release every page possible regardless of how long it will
222             // take.
223 };
224 
225 constexpr unsigned char PatternFillByte = 0xAB;
226 
227 enum FillContentsMode {
228   NoFill = 0,
229   ZeroFill = 1,
230   PatternOrZeroFill = 2 // Pattern fill unless the memory is known to be
231                         // zero-initialized already.
232 };
233 
234 } // namespace scudo
235 
236 #endif // SCUDO_COMMON_H_
237