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Diffstat (limited to 'third_party/abseil_cpp/absl/debugging/internal/vdso_support.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/debugging/internal/vdso_support.h | 158 |
1 files changed, 0 insertions, 158 deletions
diff --git a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.h b/third_party/abseil_cpp/absl/debugging/internal/vdso_support.h deleted file mode 100644 index 6562c6c235..0000000000 --- a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.h +++ /dev/null @@ -1,158 +0,0 @@ -// -// 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 -// -// https://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. -// - -// Allow dynamic symbol lookup in the kernel VDSO page. -// -// VDSO stands for "Virtual Dynamic Shared Object" -- a page of -// executable code, which looks like a shared library, but doesn't -// necessarily exist anywhere on disk, and which gets mmap()ed into -// every process by kernels which support VDSO, such as 2.6.x for 32-bit -// executables, and 2.6.24 and above for 64-bit executables. -// -// More details could be found here: -// http://www.trilithium.com/johan/2005/08/linux-gate/ -// -// VDSOSupport -- a class representing kernel VDSO (if present). -// -// Example usage: -// VDSOSupport vdso; -// VDSOSupport::SymbolInfo info; -// typedef (*FN)(unsigned *, void *, void *); -// FN fn = nullptr; -// if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) { -// fn = reinterpret_cast<FN>(info.address); -// } - -#ifndef ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_ -#define ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_ - -#include <atomic> - -#include "absl/base/attributes.h" -#include "absl/debugging/internal/elf_mem_image.h" - -#ifdef ABSL_HAVE_ELF_MEM_IMAGE - -#ifdef ABSL_HAVE_VDSO_SUPPORT -#error ABSL_HAVE_VDSO_SUPPORT cannot be directly set -#else -#define ABSL_HAVE_VDSO_SUPPORT 1 -#endif - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace debugging_internal { - -// NOTE: this class may be used from within tcmalloc, and can not -// use any memory allocation routines. -class VDSOSupport { - public: - VDSOSupport(); - - typedef ElfMemImage::SymbolInfo SymbolInfo; - typedef ElfMemImage::SymbolIterator SymbolIterator; - - // On PowerPC64 VDSO symbols can either be of type STT_FUNC or STT_NOTYPE - // depending on how the kernel is built. The kernel is normally built with - // STT_NOTYPE type VDSO symbols. Let's make things simpler first by using a - // compile-time constant. -#ifdef __powerpc64__ - enum { kVDSOSymbolType = STT_NOTYPE }; -#else - enum { kVDSOSymbolType = STT_FUNC }; -#endif - - // Answers whether we have a vdso at all. - bool IsPresent() const { return image_.IsPresent(); } - - // Allow to iterate over all VDSO symbols. - SymbolIterator begin() const { return image_.begin(); } - SymbolIterator end() const { return image_.end(); } - - // Look up versioned dynamic symbol in the kernel VDSO. - // Returns false if VDSO is not present, or doesn't contain given - // symbol/version/type combination. - // If info_out != nullptr, additional details are filled in. - bool LookupSymbol(const char *name, const char *version, - int symbol_type, SymbolInfo *info_out) const; - - // Find info about symbol (if any) which overlaps given address. - // Returns true if symbol was found; false if VDSO isn't present - // or doesn't have a symbol overlapping given address. - // If info_out != nullptr, additional details are filled in. - bool LookupSymbolByAddress(const void *address, SymbolInfo *info_out) const; - - // Used only for testing. Replace real VDSO base with a mock. - // Returns previous value of vdso_base_. After you are done testing, - // you are expected to call SetBase() with previous value, in order to - // reset state to the way it was. - const void *SetBase(const void *s); - - // Computes vdso_base_ and returns it. Should be called as early as - // possible; before any thread creation, chroot or setuid. - static const void *Init(); - - private: - // image_ represents VDSO ELF image in memory. - // image_.ehdr_ == nullptr implies there is no VDSO. - ElfMemImage image_; - - // Cached value of auxv AT_SYSINFO_EHDR, computed once. - // This is a tri-state: - // kInvalidBase => value hasn't been determined yet. - // 0 => there is no VDSO. - // else => vma of VDSO Elf{32,64}_Ehdr. - // - // When testing with mock VDSO, low bit is set. - // The low bit is always available because vdso_base_ is - // page-aligned. - static std::atomic<const void *> vdso_base_; - - // NOLINT on 'long' because these routines mimic kernel api. - // The 'cache' parameter may be used by some versions of the kernel, - // and should be nullptr or point to a static buffer containing at - // least two 'long's. - static long InitAndGetCPU(unsigned *cpu, void *cache, // NOLINT 'long'. - void *unused); - static long GetCPUViaSyscall(unsigned *cpu, void *cache, // NOLINT 'long'. - void *unused); - typedef long (*GetCpuFn)(unsigned *cpu, void *cache, // NOLINT 'long'. - void *unused); - - // This function pointer may point to InitAndGetCPU, - // GetCPUViaSyscall, or __vdso_getcpu at different stages of initialization. - ABSL_CONST_INIT static std::atomic<GetCpuFn> getcpu_fn_; - - friend int GetCPU(void); // Needs access to getcpu_fn_. - - VDSOSupport(const VDSOSupport&) = delete; - VDSOSupport& operator=(const VDSOSupport&) = delete; -}; - -// Same as sched_getcpu() on later glibc versions. -// Return current CPU, using (fast) __vdso_getcpu@LINUX_2.6 if present, -// otherwise use syscall(SYS_getcpu,...). -// May return -1 with errno == ENOSYS if the kernel doesn't -// support SYS_getcpu. -int GetCPU(); - -} // namespace debugging_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_HAVE_ELF_MEM_IMAGE - -#endif // ABSL_DEBUGGING_INTERNAL_VDSO_SUPPORT_H_ |