diff options
author | Vincent Ambo <mail@tazj.in> | 2022-02-07T23·05+0300 |
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committer | clbot <clbot@tvl.fyi> | 2022-02-07T23·09+0000 |
commit | 5aa5d282eac56a21e74611c1cdbaa97bb5db2dca (patch) | |
tree | 8cc5dce8157a1470ff76719dd15d65f648a05522 /third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc | |
parent | a25675804c4f429fab5ee5201fe25e89865dfd13 (diff) |
chore(3p/abseil_cpp): unvendor abseil_cpp r/3786
we weren't actually using these sources anymore, okay? Change-Id: If701571d9716de308d3512e1eb22c35db0877a66 Reviewed-on: https://cl.tvl.fyi/c/depot/+/5248 Tested-by: BuildkiteCI Reviewed-by: grfn <grfn@gws.fyi> Autosubmit: tazjin <tazjin@tvl.su>
Diffstat (limited to 'third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc')
-rw-r--r-- | third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc | 173 |
1 files changed, 0 insertions, 173 deletions
diff --git a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc b/third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc deleted file mode 100644 index 6be16d907275..000000000000 --- a/third_party/abseil_cpp/absl/debugging/internal/vdso_support.cc +++ /dev/null @@ -1,173 +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. -// -// VDSOSupport -- a class representing kernel VDSO (if present). - -#include "absl/debugging/internal/vdso_support.h" - -#ifdef ABSL_HAVE_VDSO_SUPPORT // defined in vdso_support.h - -#include <errno.h> -#include <fcntl.h> -#include <sys/syscall.h> -#include <unistd.h> - -#if __GLIBC_PREREQ(2, 16) // GLIBC-2.16 implements getauxval. -#include <sys/auxv.h> -#endif - -#include "absl/base/dynamic_annotations.h" -#include "absl/base/internal/raw_logging.h" -#include "absl/base/port.h" - -#ifndef AT_SYSINFO_EHDR -#define AT_SYSINFO_EHDR 33 // for crosstoolv10 -#endif - -namespace absl { -ABSL_NAMESPACE_BEGIN -namespace debugging_internal { - -ABSL_CONST_INIT -std::atomic<const void *> VDSOSupport::vdso_base_( - debugging_internal::ElfMemImage::kInvalidBase); - -std::atomic<VDSOSupport::GetCpuFn> VDSOSupport::getcpu_fn_(&InitAndGetCPU); -VDSOSupport::VDSOSupport() - // If vdso_base_ is still set to kInvalidBase, we got here - // before VDSOSupport::Init has been called. Call it now. - : image_(vdso_base_.load(std::memory_order_relaxed) == - debugging_internal::ElfMemImage::kInvalidBase - ? Init() - : vdso_base_.load(std::memory_order_relaxed)) {} - -// NOTE: we can't use GoogleOnceInit() below, because we can be -// called by tcmalloc, and none of the *once* stuff may be functional yet. -// -// In addition, we hope that the VDSOSupportHelper constructor -// causes this code to run before there are any threads, and before -// InitGoogle() has executed any chroot or setuid calls. -// -// Finally, even if there is a race here, it is harmless, because -// the operation should be idempotent. -const void *VDSOSupport::Init() { - const auto kInvalidBase = debugging_internal::ElfMemImage::kInvalidBase; -#if __GLIBC_PREREQ(2, 16) - if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) { - errno = 0; - const void *const sysinfo_ehdr = - reinterpret_cast<const void *>(getauxval(AT_SYSINFO_EHDR)); - if (errno == 0) { - vdso_base_.store(sysinfo_ehdr, std::memory_order_relaxed); - } - } -#endif // __GLIBC_PREREQ(2, 16) - if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) { - int fd = open("/proc/self/auxv", O_RDONLY); - if (fd == -1) { - // Kernel too old to have a VDSO. - vdso_base_.store(nullptr, std::memory_order_relaxed); - getcpu_fn_.store(&GetCPUViaSyscall, std::memory_order_relaxed); - return nullptr; - } - ElfW(auxv_t) aux; - while (read(fd, &aux, sizeof(aux)) == sizeof(aux)) { - if (aux.a_type == AT_SYSINFO_EHDR) { - vdso_base_.store(reinterpret_cast<void *>(aux.a_un.a_val), - std::memory_order_relaxed); - break; - } - } - close(fd); - if (vdso_base_.load(std::memory_order_relaxed) == kInvalidBase) { - // Didn't find AT_SYSINFO_EHDR in auxv[]. - vdso_base_.store(nullptr, std::memory_order_relaxed); - } - } - GetCpuFn fn = &GetCPUViaSyscall; // default if VDSO not present. - if (vdso_base_.load(std::memory_order_relaxed)) { - VDSOSupport vdso; - SymbolInfo info; - if (vdso.LookupSymbol("__vdso_getcpu", "LINUX_2.6", STT_FUNC, &info)) { - fn = reinterpret_cast<GetCpuFn>(const_cast<void *>(info.address)); - } - } - // Subtle: this code runs outside of any locks; prevent compiler - // from assigning to getcpu_fn_ more than once. - getcpu_fn_.store(fn, std::memory_order_relaxed); - return vdso_base_.load(std::memory_order_relaxed); -} - -const void *VDSOSupport::SetBase(const void *base) { - ABSL_RAW_CHECK(base != debugging_internal::ElfMemImage::kInvalidBase, - "internal error"); - const void *old_base = vdso_base_.load(std::memory_order_relaxed); - vdso_base_.store(base, std::memory_order_relaxed); - image_.Init(base); - // Also reset getcpu_fn_, so GetCPU could be tested with simulated VDSO. - getcpu_fn_.store(&InitAndGetCPU, std::memory_order_relaxed); - return old_base; -} - -bool VDSOSupport::LookupSymbol(const char *name, - const char *version, - int type, - SymbolInfo *info) const { - return image_.LookupSymbol(name, version, type, info); -} - -bool VDSOSupport::LookupSymbolByAddress(const void *address, - SymbolInfo *info_out) const { - return image_.LookupSymbolByAddress(address, info_out); -} - -// NOLINT on 'long' because this routine mimics kernel api. -long VDSOSupport::GetCPUViaSyscall(unsigned *cpu, // NOLINT(runtime/int) - void *, void *) { -#ifdef SYS_getcpu - return syscall(SYS_getcpu, cpu, nullptr, nullptr); -#else - // x86_64 never implemented sys_getcpu(), except as a VDSO call. - static_cast<void>(cpu); // Avoid an unused argument compiler warning. - errno = ENOSYS; - return -1; -#endif -} - -// Use fast __vdso_getcpu if available. -long VDSOSupport::InitAndGetCPU(unsigned *cpu, // NOLINT(runtime/int) - void *x, void *y) { - Init(); - GetCpuFn fn = getcpu_fn_.load(std::memory_order_relaxed); - ABSL_RAW_CHECK(fn != &InitAndGetCPU, "Init() did not set getcpu_fn_"); - return (*fn)(cpu, x, y); -} - -// This function must be very fast, and may be called from very -// low level (e.g. tcmalloc). Hence I avoid things like -// GoogleOnceInit() and ::operator new. -ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY -int GetCPU() { - unsigned cpu; - int ret_code = (*VDSOSupport::getcpu_fn_)(&cpu, nullptr, nullptr); - return ret_code == 0 ? cpu : ret_code; -} - -} // namespace debugging_internal -ABSL_NAMESPACE_END -} // namespace absl - -#endif // ABSL_HAVE_VDSO_SUPPORT |