From a7e522daf1ec9cda69b356472f662142dd0c1215 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Wed, 11 Apr 2018 09:52:42 -0700 Subject: - a0673e81da7ee7e322283e518331a4cdaeca837b Internal change by Abseil Team - 537e863510a423968c2d319263dd1c100695a2e9 Add internal-only functionality to examine the stack, to ... by Derek Mauro - 1ded12406d8b8fd7be910c8dfe8c2a8edf66136e Explicitly suppress the default move constructor and assi... by Derek Mauro - 347d38447ebc38e5d33fec6b67988880eb3cd249 Move implementation detail do_mmap64 to a new file. by Greg Falcon GitOrigin-RevId: a0673e81da7ee7e322283e518331a4cdaeca837b Change-Id: I5a347d34d5173082b3a78eb53432481b32c94b69 --- absl/base/internal/direct_mmap.h | 145 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 145 insertions(+) create mode 100644 absl/base/internal/direct_mmap.h (limited to 'absl/base/internal/direct_mmap.h') diff --git a/absl/base/internal/direct_mmap.h b/absl/base/internal/direct_mmap.h new file mode 100644 index 00000000..87576df6 --- /dev/null +++ b/absl/base/internal/direct_mmap.h @@ -0,0 +1,145 @@ +// Copyright 2017 The Abseil Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +// Functions for directly invoking mmap() via syscall, avoiding the case where +// mmap() has been locally overridden. + +#ifndef ABSL_BASE_INTERNAL_DIRECT_MMAP_H_ +#define ABSL_BASE_INTERNAL_DIRECT_MMAP_H_ + +#include "absl/base/config.h" + +#if ABSL_HAVE_MMAP + +#include + +#ifdef __linux__ + +#include +#ifdef __BIONIC__ +#include +#else +#include +#endif + +#include +#include +#include +#include +#include + +#ifdef __mips__ +// Include definitions of the ABI currently in use. +#ifdef __BIONIC__ +// Android doesn't have sgidefs.h, but does have asm/sgidefs.h, which has the +// definitions we need. +#include +#else +#include +#endif // __BIONIC__ +#endif // __mips__ + +// SYS_mmap and SYS_munmap are not defined in Android. +#ifdef __BIONIC__ +extern "C" void* __mmap2(void*, size_t, int, int, int, long); +#if defined(__NR_mmap) && !defined(SYS_mmap) +#define SYS_mmap __NR_mmap +#endif +#ifndef SYS_munmap +#define SYS_munmap __NR_munmap +#endif +#endif // __BIONIC__ + +namespace absl { +namespace base_internal { + +// Platform specific logic extracted from +// https://chromium.googlesource.com/linux-syscall-support/+/master/linux_syscall_support.h +inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd, + off64_t offset) __THROW { +#if defined(__i386__) || defined(__ARM_ARCH_3__) || defined(__ARM_EABI__) || \ + (defined(__mips__) && _MIPS_SIM == _MIPS_SIM_ABI32) || \ + (defined(__PPC__) && !defined(__PPC64__)) || \ + (defined(__s390__) && !defined(__s390x__)) + // On these architectures, implement mmap with mmap2. + static int pagesize = 0; + if (pagesize == 0) { + pagesize = getpagesize(); + } + if (offset < 0 || offset % pagesize != 0) { + errno = EINVAL; + return MAP_FAILED; + } +#ifdef __BIONIC__ + // SYS_mmap2 has problems on Android API level <= 16. + // Workaround by invoking __mmap2() instead. + return __mmap2(start, length, prot, flags, fd, offset / pagesize); +#else + return reinterpret_cast( + syscall(SYS_mmap2, start, length, prot, flags, fd, + static_cast(offset / pagesize))); +#endif +#elif defined(__s390x__) + // On s390x, mmap() arguments are passed in memory. + uint32_t buf[6] = { + reinterpret_cast(start), static_cast(length), + static_cast(prot), static_cast(flags), + static_cast(fd), static_cast(offset)}; + return reintrepret_cast(syscall(SYS_mmap, buf)); +#elif defined(__x86_64__) +// The x32 ABI has 32 bit longs, but the syscall interface is 64 bit. +// We need to explicitly cast to an unsigned 64 bit type to avoid implicit +// sign extension. We can't cast pointers directly because those are +// 32 bits, and gcc will dump ugly warnings about casting from a pointer +// to an integer of a different size. We also need to make sure __off64_t +// isn't truncated to 32-bits under x32. +#define MMAP_SYSCALL_ARG(x) ((uint64_t)(uintptr_t)(x)) + return reinterpret_cast( + syscall(SYS_mmap, MMAP_SYSCALL_ARG(start), MMAP_SYSCALL_ARG(length), + MMAP_SYSCALL_ARG(prot), MMAP_SYSCALL_ARG(flags), + MMAP_SYSCALL_ARG(fd), static_cast(offset))); +#undef MMAP_SYSCALL_ARG +#else // Remaining 64-bit aritectures. + static_assert(sizeof(unsigned long) == 8, "Platform is not 64-bit"); + return reinterpret_cast( + syscall(SYS_mmap, start, length, prot, flags, fd, offset)); +#endif +} + +inline int DirectMunmap(void* start, size_t length) { + return static_cast(syscall(SYS_munmap, start, length)); +} + +} // namespace base_internal +} // namespace absl + +#else // !__linux__ + +// For non-linux platforms where we have mmap, just dispatch directly to the +// actual mmap()/munmap() methods. + +inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd, + off_t offset) { + return mmap(start, length, prot, flags, fd, offset); +} + +inline int DirectMunmap(void* start, size_t length) { + return munmap(start, length); +} + +#endif // __linux__ + +#endif // ABSL_HAVE_MMAP + +#endif // ABSL_BASE_INTERNAL_DIRECT_MMAP_H_ -- cgit v1.2.3