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Diffstat (limited to 'lib/scudo/standalone/linux.cpp')
-rw-r--r-- | lib/scudo/standalone/linux.cpp | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/lib/scudo/standalone/linux.cpp b/lib/scudo/standalone/linux.cpp new file mode 100644 index 000000000000..8266a528f42c --- /dev/null +++ b/lib/scudo/standalone/linux.cpp @@ -0,0 +1,171 @@ +//===-- linux.cpp -----------------------------------------------*- 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 +// +//===----------------------------------------------------------------------===// + +#include "platform.h" + +#if SCUDO_LINUX + +#include "common.h" +#include "linux.h" +#include "mutex.h" +#include "string_utils.h" + +#include <errno.h> +#include <fcntl.h> +#include <linux/futex.h> +#include <sched.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/syscall.h> +#include <sys/time.h> +#include <time.h> +#include <unistd.h> + +#if SCUDO_ANDROID +#include <sys/prctl.h> +// Definitions of prctl arguments to set a vma name in Android kernels. +#define ANDROID_PR_SET_VMA 0x53564d41 +#define ANDROID_PR_SET_VMA_ANON_NAME 0 +#endif + +namespace scudo { + +uptr getPageSize() { return static_cast<uptr>(sysconf(_SC_PAGESIZE)); } + +void NORETURN die() { abort(); } + +void *map(void *Addr, uptr Size, UNUSED const char *Name, uptr Flags, + UNUSED MapPlatformData *Data) { + int MmapFlags = MAP_PRIVATE | MAP_ANONYMOUS; + int MmapProt; + if (Flags & MAP_NOACCESS) { + MmapFlags |= MAP_NORESERVE; + MmapProt = PROT_NONE; + } else { + MmapProt = PROT_READ | PROT_WRITE; + } + if (Addr) { + // Currently no scenario for a noaccess mapping with a fixed address. + DCHECK_EQ(Flags & MAP_NOACCESS, 0); + MmapFlags |= MAP_FIXED; + } + void *P = mmap(Addr, Size, MmapProt, MmapFlags, -1, 0); + if (P == MAP_FAILED) { + if (!(Flags & MAP_ALLOWNOMEM) || errno != ENOMEM) + dieOnMapUnmapError(errno == ENOMEM); + return nullptr; + } +#if SCUDO_ANDROID + if (!(Flags & MAP_NOACCESS)) + prctl(ANDROID_PR_SET_VMA, ANDROID_PR_SET_VMA_ANON_NAME, P, Size, Name); +#endif + return P; +} + +void unmap(void *Addr, uptr Size, UNUSED uptr Flags, + UNUSED MapPlatformData *Data) { + if (munmap(Addr, Size) != 0) + dieOnMapUnmapError(); +} + +void releasePagesToOS(uptr BaseAddress, uptr Offset, uptr Size, + UNUSED MapPlatformData *Data) { + void *Addr = reinterpret_cast<void *>(BaseAddress + Offset); + while (madvise(Addr, Size, MADV_DONTNEED) == -1 && errno == EAGAIN) { + } +} + +// Calling getenv should be fine (c)(tm) at any time. +const char *getEnv(const char *Name) { return getenv(Name); } + +namespace { +enum State : u32 { Unlocked = 0, Locked = 1, Sleeping = 2 }; +} + +bool HybridMutex::tryLock() { + return atomic_compare_exchange(&M, Unlocked, Locked) == Unlocked; +} + +// The following is based on https://akkadia.org/drepper/futex.pdf. +void HybridMutex::lockSlow() { + u32 V = atomic_compare_exchange(&M, Unlocked, Locked); + if (V == Unlocked) + return; + if (V != Sleeping) + V = atomic_exchange(&M, Sleeping, memory_order_acquire); + while (V != Unlocked) { + syscall(SYS_futex, reinterpret_cast<uptr>(&M), FUTEX_WAIT_PRIVATE, Sleeping, + nullptr, nullptr, 0); + V = atomic_exchange(&M, Sleeping, memory_order_acquire); + } +} + +void HybridMutex::unlock() { + if (atomic_fetch_sub(&M, 1U, memory_order_release) != Locked) { + atomic_store(&M, Unlocked, memory_order_release); + syscall(SYS_futex, reinterpret_cast<uptr>(&M), FUTEX_WAKE_PRIVATE, 1, + nullptr, nullptr, 0); + } +} + +u64 getMonotonicTime() { + timespec TS; + clock_gettime(CLOCK_MONOTONIC, &TS); + return static_cast<u64>(TS.tv_sec) * (1000ULL * 1000 * 1000) + + static_cast<u64>(TS.tv_nsec); +} + +u32 getNumberOfCPUs() { + cpu_set_t CPUs; + CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0); + return static_cast<u32>(CPU_COUNT(&CPUs)); +} + +// Blocking is possibly unused if the getrandom block is not compiled in. +bool getRandom(void *Buffer, uptr Length, UNUSED bool Blocking) { + if (!Buffer || !Length || Length > MaxRandomLength) + return false; + ssize_t ReadBytes; +#if defined(SYS_getrandom) +#if !defined(GRND_NONBLOCK) +#define GRND_NONBLOCK 1 +#endif + // Up to 256 bytes, getrandom will not be interrupted. + ReadBytes = + syscall(SYS_getrandom, Buffer, Length, Blocking ? 0 : GRND_NONBLOCK); + if (ReadBytes == static_cast<ssize_t>(Length)) + return true; +#endif // defined(SYS_getrandom) + // Up to 256 bytes, a read off /dev/urandom will not be interrupted. + // Blocking is moot here, O_NONBLOCK has no effect when opening /dev/urandom. + const int FileDesc = open("/dev/urandom", O_RDONLY); + if (FileDesc == -1) + return false; + ReadBytes = read(FileDesc, Buffer, Length); + close(FileDesc); + return (ReadBytes == static_cast<ssize_t>(Length)); +} + +void outputRaw(const char *Buffer) { + static HybridMutex Mutex; + ScopedLock L(Mutex); + write(2, Buffer, strlen(Buffer)); +} + +extern "C" WEAK void android_set_abort_message(const char *); + +void setAbortMessage(const char *Message) { + if (&android_set_abort_message) + android_set_abort_message(Message); +} + +} // namespace scudo + +#endif // SCUDO_LINUX |