From bb050128b3713a478caaf2e302dd1c115bac2009 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@cs.stanford.edu>
Date: Tue, 8 Jun 2021 19:39:22 +0900
Subject: [PATCH] Allow R_NONE in .rel.eh_frame

---
 arch_i386.cc   |  2 ++
 arch_x86_64.cc |  2 ++
 elf.h          |  2 ++
 object_file.cc | 17 ++---------------
 4 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/arch_i386.cc b/arch_i386.cc
index b3743681..93ecd609 100644
--- a/arch_i386.cc
+++ b/arch_i386.cc
@@ -99,6 +99,8 @@ void EhFrameSection<I386>::apply_reloc(Context<I386> &ctx,
   u8 *base = ctx.buf + this->shdr.sh_offset;
 
   switch (rel.r_type) {
+  case R_386_NONE:
+    return;
   case R_386_32:
     *(u32 *)(base + loc) = val;
     return;
diff --git a/arch_x86_64.cc b/arch_x86_64.cc
index ceaee52f..4ba21cec 100644
--- a/arch_x86_64.cc
+++ b/arch_x86_64.cc
@@ -73,6 +73,8 @@ void EhFrameSection<X86_64>::apply_reloc(Context<X86_64> &ctx,
   u8 *base = ctx.buf + this->shdr.sh_offset;
 
   switch (rel.r_type) {
+  case R_X86_64_NONE:
+    return;
   case R_X86_64_32:
     *(u32 *)(base + loc) = val;
     return;
diff --git a/elf.h b/elf.h
index 89455392..ef1c8f4a 100644
--- a/elf.h
+++ b/elf.h
@@ -609,6 +609,7 @@ template <typename E> struct ElfNhdr;
 struct X86_64 {
   typedef u64 WordTy;
 
+  static constexpr u32 R_NONE = R_X86_64_NONE;
   static constexpr u32 R_COPY = R_X86_64_COPY;
   static constexpr u32 R_GLOB_DAT = R_X86_64_GLOB_DAT;
   static constexpr u32 R_JUMP_SLOT = R_X86_64_JUMP_SLOT;
@@ -643,6 +644,7 @@ template <> struct ElfNhdr<X86_64> : public Elf64Nhdr {};
 struct I386 {
   typedef u32 WordTy;
 
+  static constexpr u32 R_NONE = R_386_NONE;
   static constexpr u32 R_COPY = R_386_COPY;
   static constexpr u32 R_GLOB_DAT = R_386_GLOB_DAT;
   static constexpr u32 R_JUMP_SLOT = R_386_JUMP_SLOT;
diff --git a/object_file.cc b/object_file.cc
index 63b2c7ed..45240353 100644
--- a/object_file.cc
+++ b/object_file.cc
@@ -330,20 +330,6 @@ void ObjectFile<E>::initialize_ehframe_sections(Context<E> &ctx) {
   }
 }
 
-template <typename E>
-static bool is_valid_ehframe_reloc(u32 type);
-
-template <>
-bool is_valid_ehframe_reloc<X86_64>(u32 type) {
-  return type == R_X86_64_32   || type == R_X86_64_64 ||
-         type == R_X86_64_PC32 || type == R_X86_64_PC64;
-}
-
-template <>
-bool is_valid_ehframe_reloc<I386>(u32 type) {
-  return type == R_386_32 || type == R_386_PC32;
-}
-
 // .eh_frame contains data records explaining how to handle exceptions.
 // When an exception is thrown, the runtime searches a record from
 // .eh_frame with the current program counter as a key. A record that
@@ -379,7 +365,8 @@ void ObjectFile<E>::read_ehframe(Context<E> &ctx, InputSection<E> &isec) {
 
   // Verify relocations.
   for (i64 i = 1; i < rels.size(); i++)
-    if (rels[i].r_offset <= rels[i - 1].r_offset)
+    if (rels[i].r_type != E::R_NONE &&
+        rels[i].r_offset <= rels[i - 1].r_offset)
       Fatal(ctx) << isec << ": relocation offsets must increase monotonically";
 
   // Read CIEs and FDEs until empty.