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-rw-r--r--lib/scudo/standalone/linux.cpp171
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+//===-- 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