[libc-commits] [libc] [libc] implement vdso (PR #91572)

[Nick Desaulniers via libc-commits]

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@@ -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";
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nickdesaulniers wrote:

How did you verify these kernel version numbers per arch?

https://github.com/llvm/llvm-project/pull/91572