- 6194c9b0d6dbdbeeb27b19d5c61562f985b25ff2 Removing support for NaCL in dynamic_annotations.h. by Abseil Team <absl-team@google.com>

  - 6f89386971a21422c4cd9653e965c96d9f7a3573 Fix handling of VDSOs that are loaded lower then their li... by Abseil Team <absl-team@google.com>
  - f27a7269ab714c9c75fe4e15fa1bce8b12531a92 Check that __GLIBC__ is defined before checking for __GLI... by Derek Mauro <dmauro@google.com>

GitOrigin-RevId: 6194c9b0d6dbdbeeb27b19d5c61562f985b25ff2
Change-Id: I3eceb6f76bf2b25d55d1f5f77fba57af947da0cf

3 files changed, 3 insertions, 42 deletions

diff --git a/absl/base/dynamic_annotations.h b/absl/base/dynamic_annotations.h
index 3b6d6ef43137..7e328d9622c5 100644
--- a/absl/base/dynamic_annotations.h
+++ b/absl/base/dynamic_annotations.h
@@ -50,25 +50,6 @@
 # define DYNAMIC_ANNOTATIONS_ENABLED 0
 #endif
 
-#if defined(__native_client__)
-  #include "nacl/dynamic_annotations.h"
-
-  // Stub out the macros missing from the NaCl version.
-  #ifndef ANNOTATE_CONTIGUOUS_CONTAINER
-    #define ANNOTATE_CONTIGUOUS_CONTAINER(beg, end, old_mid, new_mid)
-  #endif
-  #ifndef ANNOTATE_RWLOCK_CREATE_STATIC
-    #define ANNOTATE_RWLOCK_CREATE_STATIC(lock)
-  #endif
-  #ifndef ADDRESS_SANITIZER_REDZONE
-    #define ADDRESS_SANITIZER_REDZONE(name)
-  #endif
-  #ifndef ANNOTATE_MEMORY_IS_UNINITIALIZED
-    #define ANNOTATE_MEMORY_IS_UNINITIALIZED(address, size)
-  #endif
-
-#else /* !__native_client__ */
-
 #if DYNAMIC_ANNOTATIONS_ENABLED != 0
 
   /* -------------------------------------------------------------
@@ -404,6 +385,4 @@ inline T ANNOTATE_UNPROTECTED_READ(const volatile T &x) { /* NOLINT */
 #undef ATTRIBUTE_IGNORE_READS_BEGIN
 #undef ATTRIBUTE_IGNORE_READS_END
 
-#endif /* !__native_client__ */
-
 #endif  /* ABSL_BASE_DYNAMIC_ANNOTATIONS_H_ */
diff --git a/absl/base/policy_checks.h b/absl/base/policy_checks.h
index d634dac68dcf..0a07fc035e15 100644
--- a/absl/base/policy_checks.h
+++ b/absl/base/policy_checks.h
@@ -86,7 +86,7 @@
 // in May, 2010 and includes some functionality used in Google software
 // (for instance pthread_setname_np):
 // https://sourceware.org/ml/libc-alpha/2010-05/msg00000.html
-#ifdef __GLIBC_PREREQ
+#if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
 #if !__GLIBC_PREREQ(2, 12)
 #error "Minimum required version of glibc is 2.12."
 #endif
diff --git a/absl/debugging/internal/elf_mem_image.cc b/absl/debugging/internal/elf_mem_image.cc
index d6d519246036..3f747e7f958e 100644
--- a/absl/debugging/internal/elf_mem_image.cc
+++ b/absl/debugging/internal/elf_mem_image.cc
@@ -121,7 +121,7 @@ const void *ElfMemImage::GetSymAddr(const ElfW(Sym) *sym) const {
     return reinterpret_cast<const void *>(sym->st_value);
   }
   ABSL_RAW_CHECK(link_base_ < sym->st_value, "symbol out of range");
-  return GetTableElement<char>(ehdr_, 0, 1, sym->st_value) - link_base_;
+  return GetTableElement<char>(ehdr_, 0, 1, sym->st_value - link_base_);
 }
 
 const ElfW(Verdef) *ElfMemImage::GetVerdef(int index) const {
@@ -161,10 +161,6 @@ void ElfMemImage::Init(const void *base) {
   if (!base) {
     return;
   }
-  const intptr_t base_as_uintptr_t = reinterpret_cast<uintptr_t>(base);
-  // Fake VDSO has low bit set.
-  const bool fake_vdso = ((base_as_uintptr_t & 1) != 0);
-  base = reinterpret_cast<const void *>(base_as_uintptr_t & ~1);
   const char *const base_as_char = reinterpret_cast<const char *>(base);
   if (base_as_char[EI_MAG0] != ELFMAG0 || base_as_char[EI_MAG1] != ELFMAG1 ||
       base_as_char[EI_MAG2] != ELFMAG2 || base_as_char[EI_MAG3] != ELFMAG3) {
@@ -224,21 +220,7 @@ void ElfMemImage::Init(const void *base) {
       reinterpret_cast<ElfW(Dyn) *>(dynamic_program_header->p_vaddr +
                                     relocation);
   for (; dynamic_entry->d_tag != DT_NULL; ++dynamic_entry) {
-    ElfW(Xword) value = dynamic_entry->d_un.d_val;
-    if (fake_vdso) {
-      // A complication: in the real VDSO, dynamic entries are not relocated
-      // (it wasn't loaded by a dynamic loader). But when testing with a
-      // "fake" dlopen()ed vdso library, the loader relocates some (but
-      // not all!) of them before we get here.
-      if (dynamic_entry->d_tag == DT_VERDEF) {
-        // The only dynamic entry (of the ones we care about) libc-2.3.6
-        // loader doesn't relocate.
-        value += relocation;
-      }
-    } else {
-      // Real VDSO. Everything needs to be relocated.
-      value += relocation;
-    }
+    const ElfW(Xword) value = dynamic_entry->d_un.d_val + relocation;
     switch (dynamic_entry->d_tag) {
       case DT_HASH:
         hash_ = reinterpret_cast<ElfW(Word) *>(value);