- 537e863510a423968c2d319263dd1c100695a2e9 Add internal-only functionality to examine the stack, to ... by Derek Mauro <dmauro@google.com> - 1ded12406d8b8fd7be910c8dfe8c2a8edf66136e Explicitly suppress the default move constructor and assi... by Derek Mauro <dmauro@google.com> - 347d38447ebc38e5d33fec6b67988880eb3cd249 Move implementation detail do_mmap64 to a new file. by Greg Falcon <gfalcon@google.com> GitOrigin-RevId: a0673e81da7ee7e322283e518331a4cdaeca837b Change-Id: I5a347d34d5173082b3a78eb53432481b32c94b69pull/101/head
Abseil Team
7 years ago
committed by
Matt Calabrese
parent
475d64f2de
commit
a7e522daf1
5 changed files with 186 additions and 88 deletions
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Functions for directly invoking mmap() via syscall, avoiding the case where
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// mmap() has been locally overridden.
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#ifndef ABSL_BASE_INTERNAL_DIRECT_MMAP_H_ |
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#define ABSL_BASE_INTERNAL_DIRECT_MMAP_H_ |
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#include "absl/base/config.h" |
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#if ABSL_HAVE_MMAP |
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#include <sys/mman.h> |
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#ifdef __linux__ |
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#include <sys/types.h> |
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#ifdef __BIONIC__ |
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#include <sys/syscall.h> |
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#else |
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#include <syscall.h> |
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#endif |
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#include <linux/unistd.h> |
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#include <unistd.h> |
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#include <cerrno> |
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#include <cstdarg> |
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#include <cstdint> |
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#ifdef __mips__ |
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// Include definitions of the ABI currently in use.
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#ifdef __BIONIC__ |
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// Android doesn't have sgidefs.h, but does have asm/sgidefs.h, which has the
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// definitions we need.
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#include <asm/sgidefs.h> |
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#else |
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#include <sgidefs.h> |
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#endif // __BIONIC__
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#endif // __mips__
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// SYS_mmap and SYS_munmap are not defined in Android.
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#ifdef __BIONIC__ |
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extern "C" void* __mmap2(void*, size_t, int, int, int, long); |
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#if defined(__NR_mmap) && !defined(SYS_mmap) |
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#define SYS_mmap __NR_mmap |
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#endif |
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#ifndef SYS_munmap |
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#define SYS_munmap __NR_munmap |
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#endif |
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#endif // __BIONIC__
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namespace absl { |
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namespace base_internal { |
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// Platform specific logic extracted from
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// https://chromium.googlesource.com/linux-syscall-support/+/master/linux_syscall_support.h
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inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd, |
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off64_t offset) __THROW { |
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#if defined(__i386__) || defined(__ARM_ARCH_3__) || defined(__ARM_EABI__) || \ |
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(defined(__mips__) && _MIPS_SIM == _MIPS_SIM_ABI32) || \
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(defined(__PPC__) && !defined(__PPC64__)) || \
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(defined(__s390__) && !defined(__s390x__)) |
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// On these architectures, implement mmap with mmap2.
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static int pagesize = 0; |
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if (pagesize == 0) { |
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pagesize = getpagesize(); |
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} |
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if (offset < 0 || offset % pagesize != 0) { |
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errno = EINVAL; |
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return MAP_FAILED; |
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} |
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#ifdef __BIONIC__ |
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// SYS_mmap2 has problems on Android API level <= 16.
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// Workaround by invoking __mmap2() instead.
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return __mmap2(start, length, prot, flags, fd, offset / pagesize); |
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#else |
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return reinterpret_cast<void*>( |
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syscall(SYS_mmap2, start, length, prot, flags, fd, |
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static_cast<off_t>(offset / pagesize))); |
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#endif |
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#elif defined(__s390x__) |
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// On s390x, mmap() arguments are passed in memory.
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uint32_t buf[6] = { |
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reinterpret_cast<uint32_t>(start), static_cast<uint32_t>(length), |
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static_cast<uint32_t>(prot), static_cast<uint32_t>(flags), |
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static_cast<uint32_t>(fd), static_cast<uint32_t>(offset)}; |
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return reintrepret_cast<void*>(syscall(SYS_mmap, buf)); |
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#elif defined(__x86_64__) |
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// The x32 ABI has 32 bit longs, but the syscall interface is 64 bit.
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// We need to explicitly cast to an unsigned 64 bit type to avoid implicit
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// sign extension. We can't cast pointers directly because those are
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// 32 bits, and gcc will dump ugly warnings about casting from a pointer
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// to an integer of a different size. We also need to make sure __off64_t
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// isn't truncated to 32-bits under x32.
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#define MMAP_SYSCALL_ARG(x) ((uint64_t)(uintptr_t)(x)) |
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return reinterpret_cast<void*>( |
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syscall(SYS_mmap, MMAP_SYSCALL_ARG(start), MMAP_SYSCALL_ARG(length), |
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MMAP_SYSCALL_ARG(prot), MMAP_SYSCALL_ARG(flags), |
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MMAP_SYSCALL_ARG(fd), static_cast<uint64_t>(offset))); |
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#undef MMAP_SYSCALL_ARG |
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#else // Remaining 64-bit aritectures.
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static_assert(sizeof(unsigned long) == 8, "Platform is not 64-bit"); |
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return reinterpret_cast<void*>( |
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syscall(SYS_mmap, start, length, prot, flags, fd, offset)); |
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#endif |
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} |
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inline int DirectMunmap(void* start, size_t length) { |
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return static_cast<int>(syscall(SYS_munmap, start, length)); |
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} |
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} // namespace base_internal
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} // namespace absl
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#else // !__linux__
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// For non-linux platforms where we have mmap, just dispatch directly to the
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// actual mmap()/munmap() methods.
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inline void* DirectMmap(void* start, size_t length, int prot, int flags, int fd, |
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off_t offset) { |
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return mmap(start, length, prot, flags, fd, offset); |
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} |
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inline int DirectMunmap(void* start, size_t length) { |
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return munmap(start, length); |
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} |
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#endif // __linux__
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#endif // ABSL_HAVE_MMAP
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#endif // ABSL_BASE_INTERNAL_DIRECT_MMAP_H_
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