[libc] update clock_gettime implementation with vDSO

libc/src/__support/OSUtil/CMakeLists.txt

@@ -15,3 +15,11 @@ add_object_library(
   DEPENDS
     ${target_os_util}
 )
+
+add_header_library(
+  vdso
+  HDRS
+    vdso.h
+  DEPENDS
+    .${LIBC_TARGET_OS}.vdso
+)

libc/src/__support/OSUtil/fuchsia/vdso.h

@@ -0,0 +1,12 @@
+//===------------- Fuchsia VDSO Header --------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_FUCHSIA_VDSO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_FUCHSIA_VDSO_H
+/// TODO: implement fuchsia VDSO
+/// https://fuchsia.dev/fuchsia-src/concepts/kernel/vdso
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_FUCHSIA_VDSO_H

libc/src/__support/OSUtil/linux/CMakeLists.txt

@@ -16,3 +16,19 @@ add_object_library(
     libc.src.__support.common
     libc.src.__support.CPP.string_view
 )
+
+add_object_library(
+  vdso
+  HDRS
+    vdso.h
+  SRCS
+    vdso.cpp
+  DEPENDS
+    .${LIBC_TARGET_ARCHITECTURE}.vdso
+    libc.src.__support.CPP.array
+    libc.src.__support.CPP.string_view
+    libc.src.__support.threads.callonce
+    libc.src.__support.threads.linux.futex_word_type
+    libc.src.errno.errno
+    libc.src.sys.auxv.getauxval
+)

libc/src/__support/OSUtil/linux/aarch64/CMakeLists.txt

@@ -5,3 +5,12 @@ add_header_library(
   DEPENDS
     libc.src.__support.common
 )
+
+add_header_library(
+  vdso
+  HDRS
+    vdso.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.CPP.string_view
+)

libc/src/__support/OSUtil/linux/aarch64/vdso.h

@@ -0,0 +1,50 @@
+//===---------- aarch64 vdso configuration ------------------------* 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
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_AARCH64_VDSO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_AARCH64_VDSO_H
+#include "src/__support/CPP/string_view.h"
+namespace LIBC_NAMESPACE {
+namespace vdso {
+// macro definitions
+#define LIBC_VDSO_HAS_RT_SIGRETURN
+#define LIBC_VDSO_HAS_GETTIMEOFDAY
+#define LIBC_VDSO_HAS_CLOCK_GETTIME
+#define LIBC_VDSO_HAS_CLOCK_GETRES
+
+// list of VDSO symbols
+enum class VDSOSym {
+  RTSigReturn,
+  GetTimeOfDay,
+  ClockGetTime,
+  ClockGetRes,
+  VDSOSymCount
+};
+
+// translate VDSOSym to symbol names
+LIBC_INLINE constexpr cpp::string_view symbol_name(VDSOSym sym) {
+  switch (sym) {
+  case VDSOSym::RTSigReturn:
+    return "__kernel_rt_sigreturn";
+  case VDSOSym::GetTimeOfDay:
+    return "__kernel_gettimeofday";
+  case VDSOSym::ClockGetTime:
+    return "__kernel_clock_gettime";
+  case VDSOSym::ClockGetRes:
+    return "__kernel_clock_getres";
+  default:
+    return "";
+  }
+}
+
+// symbol versions
+LIBC_INLINE constexpr cpp::string_view symbol_version(VDSOSym) {
+  return "LINUX_2.6.39";
+}
+} // namespace vdso
+} // namespace LIBC_NAMESPACE
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_AARCH64_VDSO_H

libc/src/__support/OSUtil/linux/arm/CMakeLists.txt

@@ -5,3 +5,12 @@ add_header_library(
   DEPENDS
     libc.src.__support.common
 )
+
+add_header_library(
+  vdso
+  HDRS
+    vdso.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.CPP.string_view
+)

libc/src/__support/OSUtil/linux/arm/vdso.h

@@ -0,0 +1,39 @@
+//===---------- arm vdso configuration ----------------------------* 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
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_ARM_VDSO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_ARM_VDSO_H
+#include "src/__support/CPP/string_view.h"
+namespace LIBC_NAMESPACE {
+namespace vdso {
+// macro definitions
+#define LIBC_VDSO_HAS_GETTIMEOFDAY
+#define LIBC_VDSO_HAS_CLOCK_GETTIME
+
+// list of VDSO symbols
+enum class VDSOSym {
+  GetTimeOfDay,
+  ClockGetTime,
+};
+
+// translate VDSOSym to symbol names
+LIBC_INLINE constexpr cpp::string_view symbol_name(VDSOSym sym) {
+  switch (sym) {
+  case VDSOSym::GetTimeOfDay:
+    return "__vdso_gettimeofday";
+  case VDSOSym::ClockGetTime:
+    return "__vdso_clock_gettime";
+  }
+}
+
+// symbol versions
+LIBC_INLINE constexpr cpp::string_view symbol_version(VDSOSym) {
+  return "LINUX_2.6";
+}
+} // namespace vdso
+} // namespace LIBC_NAMESPACE
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_ARM_VDSO_H

libc/src/__support/OSUtil/linux/riscv/CMakeLists.txt

@@ -5,3 +5,12 @@ add_header_library(
   DEPENDS
     libc.src.__support.common
 )
+
+add_header_library(
+  vdso
+  HDRS
+    vdso.h
+  DEPENDS
+    libc.src.__support.common
+    libc.src.__support.CPP.string_view
+)

libc/src/__support/OSUtil/linux/riscv/vdso.h

@@ -0,0 +1,58 @@
+//===---------- RISC-V vdso configuration -------------------------* 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
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_RISCV_VDSO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_RISCV_VDSO_H
+#include "src/__support/CPP/string_view.h"
+namespace LIBC_NAMESPACE {
+namespace vdso {
+// macro definitions
+#define LIBC_VDSO_HAS_RT_SIGRETURN
+#define LIBC_VDSO_HAS_GETTIMEOFDAY
+#define LIBC_VDSO_HAS_CLOCK_GETTIME
+#define LIBC_VDSO_HAS_CLOCK_GETRES
+#define LIBC_VDSO_HAS_GETCPU
+#define LIBC_VDSO_HAS_FLUSH_ICACHE
+
+// list of VDSO symbols
+enum class VDSOSym {
+  RTSigReturn,
+  GetTimeOfDay,
+  ClockGetTime,
+  ClockGetRes,
+  GetCpu,
+  FlushICache,
+  VDSOSymCount
+};
+
+// translate VDSOSym to symbol names
+LIBC_INLINE constexpr cpp::string_view symbol_name(VDSOSym sym) {
+  switch (sym) {
+  case VDSOSym::RTSigReturn:
+    return "__vdso_rt_sigreturn";
+  case VDSOSym::GetTimeOfDay:
+    return "__vdso_gettimeofday";
+  case VDSOSym::ClockGetTime:
+    return "__vdso_clock_gettime";
+  case VDSOSym::ClockGetRes:
+    return "__vdso_clock_getres";
+  case VDSOSym::GetCpu:
+    return "__vdso_getcpu";
+  case VDSOSym::FlushICache:
+    return "__vdso_flush_icache";
+  default:
+    return "";
+  }
+}
+
+// symbol versions
+LIBC_INLINE constexpr cpp::string_view symbol_version(VDSOSym) {
+  return "LINUX_4.15";
+}
+} // namespace vdso
+} // namespace LIBC_NAMESPACE
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_LINUX_RISCV_VDSO_H