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

[Nick Desaulniers via libc-commits]

================
@@ -0,0 +1,71 @@
+//===-- Unittests for VDSO ------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "hdr/time_macros.h"
+#include "hdr/types/clockid_t.h"
+#include "hdr/types/struct_timespec.h"
+#include "hdr/types/struct_timeval.h"
+#include "include/llvm-libc-macros/linux/time-macros.h"
+#include "src/__support/OSUtil/linux/vdso.h"
+#include "test/UnitTest/LibcTest.h"
+#include "test/UnitTest/Test.h"
+
+namespace LIBC_NAMESPACE {
+TEST(LlvmLibcOSUtilVDSOTest, SymbolsDefined) {
+  for (size_t i = 0; i < static_cast<size_t>(vdso::VDSOSym::VDSOSymCount);
+       ++i) {
+    // riscv_hwprobe is provided only on >=6.4 kernels. Skip it for now.
+#ifdef LIBC_VDSO_HAS_RISCV_HWPROBE
+    if (static_cast<vdso::VDSOSym>(i) == vdso::VDSOSym::RiscvHwProbe)
+      continue;
+#endif
+    EXPECT_NE(vdso::get_symbol(static_cast<vdso::VDSOSym>(i)),
+              static_cast<void *>(nullptr));
+  }
+}
+
+#ifdef LIBC_VDSO_HAS_GETTIMEOFDAY
+TEST(LlvmLibcOSUtilVDSOTest, GetTimeOfDay) {
+  using FuncTy = int (*)(timeval *, struct timezone *);
+  auto func =
+      reinterpret_cast<FuncTy>(vdso::get_symbol(vdso::VDSOSym::GetTimeOfDay));
+  timeval tv;
+  EXPECT_EQ(func(&tv, nullptr), 0);
+  // hopefully people are not building time machines using our libc.
+  EXPECT_GT(tv.tv_sec, static_cast<decltype(tv.tv_sec)>(0));
+}
+#endif
+
+#ifdef LIBC_VDSO_HAS_CLOCK_GETTIME
+TEST(LlvmLibcOSUtilVDSOTest, ClockGetTime) {
+  using FuncTy = int (*)(clockid_t, timespec *);
+  auto func =
+      reinterpret_cast<FuncTy>(vdso::get_symbol(vdso::VDSOSym::ClockGetTime));
+  timespec a, b;
+  EXPECT_EQ(func(CLOCK_MONOTONIC, &a), 0);
+  EXPECT_EQ(func(CLOCK_MONOTONIC, &b), 0);
+  if (a.tv_sec == b.tv_sec) {
+    EXPECT_LT(a.tv_nsec, b.tv_nsec);
+  } else {
+    EXPECT_LT(a.tv_sec, b.tv_sec);
+  }
+}
+#endif
+
+#ifdef LIBC_VDSO_HAS_CLOCK_GETRES
+TEST(LlvmLibcOSUtilVDSOTest, ClockGetRes) {
+  using FuncTy = int (*)(clockid_t, timespec *);
+  auto func =
+      reinterpret_cast<FuncTy>(vdso::get_symbol(vdso::VDSOSym::ClockGetRes));
+  timespec res{};
+  EXPECT_EQ(func(CLOCK_MONOTONIC, &res), 0);
+  EXPECT_TRUE(res.tv_sec > 0 || res.tv_nsec > 0);
+}
+#endif
----------------
nickdesaulniers wrote:

missing tests for:
- LIBC_VDSO_HAS_RT_SIGRETURN
- LIBC_VDSO_HAS_CLOCK_GETTIME64
- LIBC_VDSO_HAS_GETCPU
- LIBC_VDSO_HAS_FLUSH_ICACHE
- LIBC_VDSO_HAS_RISCV_HWPROBE
- LIBC_VDSO_HAS_TIME

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