- 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

1 files changed, 2 insertions, 20 deletions

diff --git a/absl/debugging/internal/elf_mem_image.cc b/absl/debugging/internal/elf_mem_image.cc
index d6d51924..3f747e7f 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);