Revert "Use the dynamic table instead of __rela?_iplt_* to find the linker's IRELATIVE relocs."

This reverts commit 65bdf655c4afceb151f619e584f2097ae0ed3a84.

Reason for revert: checking the failure of avd/avd_boot_test
Bug: 197781964
Change-Id: I70eb03b45cdfbd87ef6edb03b74ad6d1970dc08c
diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 513a903..2a690e9 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -39,7 +39,6 @@
 #include "linker_globals.h"
 #include "linker_phdr.h"
 #include "linker_relocate.h"
-#include "linker_relocs.h"
 #include "linker_tls.h"
 #include "linker_utils.h"
 
@@ -597,66 +596,25 @@
   }
 }
 
+// TODO: There is a similar ifunc resolver calling loop in libc_init_static.cpp, but that version
+// uses weak symbols, which don't work in the linker prior to its relocation. This version also
+// supports a load bias. When we stop supporting the gold linker in the NDK, then maybe we can use
+// non-weak definitions and merge the two loops.
 #if defined(USE_RELA)
-using RelType = ElfW(Rela);
-#else
-using RelType = ElfW(Rel);
-#endif
+extern __LIBC_HIDDEN__ ElfW(Rela) __rela_iplt_start[], __rela_iplt_end[];
 
-extern __LIBC_HIDDEN__ ElfW(Ehdr) __ehdr_start;
-
-static void find_irelative_relocs(RelType **begin, RelType **end) {
-  // Find the IRELATIVE relocations using the DT_JMPREL and DT_PLTRELSZ dynamic
-  // tags. In theory this could include more than just IRELATIVE relocations,
-  // but in practice the linker doesn't dynamically link against any other
-  // binaries, so we shouldn't expect to see anything else.
-  auto* ehdr = reinterpret_cast<char*>(&__ehdr_start);
-  auto* phdr = reinterpret_cast<ElfW(Phdr)*>(ehdr + __ehdr_start.e_phoff);
-  for (size_t i = 0; i != __ehdr_start.e_phnum; ++i) {
-    if (phdr[i].p_type != PT_DYNAMIC) {
-      continue;
-    }
-    auto *dyn = reinterpret_cast<ElfW(Dyn)*>(ehdr + phdr[i].p_vaddr);
-    ElfW(Addr) jmprel = 0, pltrelsz = 0;
-    for (size_t j = 0, size = phdr[i].p_filesz / sizeof(ElfW(Dyn)); j != size; ++j) {
-      if (dyn[j].d_tag == DT_JMPREL) {
-        jmprel = dyn[j].d_un.d_ptr;
-      } else if (dyn[j].d_tag == DT_PLTRELSZ) {
-        pltrelsz = dyn[j].d_un.d_ptr;
-      }
-    }
-    if (jmprel && pltrelsz) {
-      *begin = reinterpret_cast<RelType*>(ehdr + jmprel);
-      *end = reinterpret_cast<RelType*>(ehdr + jmprel + pltrelsz);
-    } else {
-      *begin = *end = nullptr;
-    }
-  }
-}
-
-#if defined(USE_RELA)
 static void call_ifunc_resolvers(ElfW(Addr) load_bias) {
-  ElfW(Rela)* begin;
-  ElfW(Rela)* end;
-  find_irelative_relocs(&begin, &end);
-  for (ElfW(Rela) *r = begin; r != end; ++r) {
-    if (ELFW(R_TYPE)(r->r_info) != R_GENERIC_IRELATIVE) {
-      continue;
-    }
+  for (ElfW(Rela) *r = __rela_iplt_start; r != __rela_iplt_end; ++r) {
     ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset + load_bias);
     ElfW(Addr) resolver = r->r_addend + load_bias;
     *offset = __bionic_call_ifunc_resolver(resolver);
   }
 }
 #else
+extern __LIBC_HIDDEN__ ElfW(Rel) __rel_iplt_start[], __rel_iplt_end[];
+
 static void call_ifunc_resolvers(ElfW(Addr) load_bias) {
-  ElfW(Rel)* begin;
-  ElfW(Rel)* end;
-  find_irelative_relocs(&begin, &end);
-  for (ElfW(Rel) *r = begin; r != end; ++r) {
-    if (ELFW(R_TYPE)(r->r_info) != R_GENERIC_IRELATIVE) {
-      continue;
-    }
+  for (ElfW(Rel) *r = __rel_iplt_start; r != __rel_iplt_end; ++r) {
     ElfW(Addr)* offset = reinterpret_cast<ElfW(Addr)*>(r->r_offset + load_bias);
     ElfW(Addr) resolver = *offset + load_bias;
     *offset = __bionic_call_ifunc_resolver(resolver);