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//===-- common.h ------------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef SCUDO_COMMON_H_
#define SCUDO_COMMON_H_
#include "internal_defs.h"
#include "fuchsia.h"
#include "linux.h"
#include "trusty.h"
#include <stddef.h>
#include <string.h>
#include <unistd.h>
namespace scudo {
template <class Dest, class Source> inline Dest bit_cast(const Source &S) {
static_assert(sizeof(Dest) == sizeof(Source), "");
Dest D;
memcpy(&D, &S, sizeof(D));
return D;
}
inline constexpr bool isPowerOfTwo(uptr X) { return (X & (X - 1)) == 0; }
inline constexpr uptr roundUp(uptr X, uptr Boundary) {
DCHECK(isPowerOfTwo(Boundary));
return (X + Boundary - 1) & ~(Boundary - 1);
}
inline constexpr uptr roundUpSlow(uptr X, uptr Boundary) {
return ((X + Boundary - 1) / Boundary) * Boundary;
}
inline constexpr uptr roundDown(uptr X, uptr Boundary) {
DCHECK(isPowerOfTwo(Boundary));
return X & ~(Boundary - 1);
}
inline constexpr uptr roundDownSlow(uptr X, uptr Boundary) {
return (X / Boundary) * Boundary;
}
inline constexpr bool isAligned(uptr X, uptr Alignment) {
DCHECK(isPowerOfTwo(Alignment));
return (X & (Alignment - 1)) == 0;
}
inline constexpr bool isAlignedSlow(uptr X, uptr Alignment) {
return X % Alignment == 0;
}
template <class T> constexpr T Min(T A, T B) { return A < B ? A : B; }
template <class T> constexpr T Max(T A, T B) { return A > B ? A : B; }
template <class T> void Swap(T &A, T &B) {
T Tmp = A;
A = B;
B = Tmp;
}
inline uptr getMostSignificantSetBitIndex(uptr X) {
DCHECK_NE(X, 0U);
return SCUDO_WORDSIZE - 1U - static_cast<uptr>(__builtin_clzl(X));
}
inline uptr roundUpPowerOfTwo(uptr Size) {
DCHECK(Size);
if (isPowerOfTwo(Size))
return Size;
const uptr Up = getMostSignificantSetBitIndex(Size);
DCHECK_LT(Size, (1UL << (Up + 1)));
DCHECK_GT(Size, (1UL << Up));
return 1UL << (Up + 1);
}
inline uptr getLeastSignificantSetBitIndex(uptr X) {
DCHECK_NE(X, 0U);
return static_cast<uptr>(__builtin_ctzl(X));
}
inline uptr getLog2(uptr X) {
DCHECK(isPowerOfTwo(X));
return getLeastSignificantSetBitIndex(X);
}
inline u32 getRandomU32(u32 *State) {
// ANSI C linear congruential PRNG (16-bit output).
// return (*State = *State * 1103515245 + 12345) >> 16;
// XorShift (32-bit output).
*State ^= *State << 13;
*State ^= *State >> 17;
*State ^= *State << 5;
return *State;
}
inline u32 getRandomModN(u32 *State, u32 N) {
return getRandomU32(State) % N; // [0, N)
}
template <typename T> inline void shuffle(T *A, u32 N, u32 *RandState) {
if (N <= 1)
return;
u32 State = *RandState;
for (u32 I = N - 1; I > 0; I--)
Swap(A[I], A[getRandomModN(&State, I + 1)]);
*RandState = State;
}
inline void computePercentage(uptr Numerator, uptr Denominator, uptr *Integral,
uptr *Fractional) {
constexpr uptr Digits = 100;
if (Denominator == 0) {
*Integral = 100;
*Fractional = 0;
return;
}
*Integral = Numerator * Digits / Denominator;
*Fractional =
(((Numerator * Digits) % Denominator) * Digits + Denominator / 2) /
Denominator;
}
// Platform specific functions.
extern uptr PageSizeCached;
uptr getPageSizeSlow();
inline uptr getPageSizeCached() {
#if SCUDO_ANDROID && defined(PAGE_SIZE)
// Most Android builds have a build-time constant page size.
return PAGE_SIZE;
#endif
if (LIKELY(PageSizeCached))
return PageSizeCached;
return getPageSizeSlow();
}
// Returns 0 if the number of CPUs could not be determined.
u32 getNumberOfCPUs();
const char *getEnv(const char *Name);
u64 getMonotonicTime();
// Gets the time faster but with less accuracy. Can call getMonotonicTime
// if no fast version is available.
u64 getMonotonicTimeFast();
u32 getThreadID();
// Our randomness gathering function is limited to 256 bytes to ensure we get
// as many bytes as requested, and avoid interruptions (on Linux).
constexpr uptr MaxRandomLength = 256U;
bool getRandom(void *Buffer, uptr Length, bool Blocking = false);
// Platform memory mapping functions.
#define MAP_ALLOWNOMEM (1U << 0)
#define MAP_NOACCESS (1U << 1)
#define MAP_RESIZABLE (1U << 2)
#define MAP_MEMTAG (1U << 3)
#define MAP_PRECOMMIT (1U << 4)
// Our platform memory mapping use is restricted to 3 scenarios:
// - reserve memory at a random address (MAP_NOACCESS);
// - commit memory in a previously reserved space;
// - commit memory at a random address.
// As such, only a subset of parameters combinations is valid, which is checked
// by the function implementation. The Data parameter allows to pass opaque
// platform specific data to the function.
// Returns nullptr on error or dies if MAP_ALLOWNOMEM is not specified.
void *map(void *Addr, uptr Size, const char *Name, uptr Flags = 0,
MapPlatformData *Data = nullptr);
// Indicates that we are getting rid of the whole mapping, which might have
// further consequences on Data, depending on the platform.
#define UNMAP_ALL (1U << 0)
void unmap(void *Addr, uptr Size, uptr Flags = 0,
MapPlatformData *Data = nullptr);
void setMemoryPermission(uptr Addr, uptr Size, uptr Flags,
MapPlatformData *Data = nullptr);
void releasePagesToOS(uptr BaseAddress, uptr Offset, uptr Size,
MapPlatformData *Data = nullptr);
// Logging related functions.
void setAbortMessage(const char *Message);
struct BlockInfo {
uptr BlockBegin;
uptr BlockSize;
uptr RegionBegin;
uptr RegionEnd;
};
enum class Option : u8 {
ReleaseInterval, // Release to OS interval in milliseconds.
MemtagTuning, // Whether to tune tagging for UAF or overflow.
ThreadDisableMemInit, // Whether to disable automatic heap initialization and,
// where possible, memory tagging, on this thread.
MaxCacheEntriesCount, // Maximum number of blocks that can be cached.
MaxCacheEntrySize, // Maximum size of a block that can be cached.
MaxTSDsCount, // Number of usable TSDs for the shared registry.
};
enum class ReleaseToOS : u8 {
Normal, // Follow the normal rules for releasing pages to the OS
Force, // Force release pages to the OS, but avoid cases that take too long.
ForceAll, // Force release every page possible regardless of how long it will
// take.
};
constexpr unsigned char PatternFillByte = 0xAB;
enum FillContentsMode {
NoFill = 0,
ZeroFill = 1,
PatternOrZeroFill = 2 // Pattern fill unless the memory is known to be
// zero-initialized already.
};
} // namespace scudo
#endif // SCUDO_COMMON_H_
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