From 1af72b898cc2f2b3f22ff7bbaf55dd8757d318e5 Mon Sep 17 00:00:00 2001
From: Simon Atanasyan <simon@atanasyan.com>
Date: Mon, 22 Jun 2015 09:26:33 +0000
Subject: [PATCH] [Mips] Reject R_MIPS_GPREL32 against external symbols

llvm-svn: 240264
---
 .../ReaderWriter/ELF/Mips/MipsRelocationPass.cpp   | 18 ++++++++--
 lld/test/elf/Mips/validate-rel-02.test             | 41 ++++++++++++++++++++++
 2 files changed, 57 insertions(+), 2 deletions(-)
 create mode 100644 lld/test/elf/Mips/validate-rel-02.test

diff --git a/lld/lib/ReaderWriter/ELF/Mips/MipsRelocationPass.cpp b/lld/lib/ReaderWriter/ELF/Mips/MipsRelocationPass.cpp
index b1eb218..3729908 100644
--- a/lld/lib/ReaderWriter/ELF/Mips/MipsRelocationPass.cpp
+++ b/lld/lib/ReaderWriter/ELF/Mips/MipsRelocationPass.cpp
@@ -680,15 +680,29 @@ make_reject_for_shared_lib_reloc_error(const ELFLinkingContext &ctx,
                                  atom.file().path() + " with -fPIC");
 }
 
+static std::error_code
+make_external_gprel32_reloc_error(const ELFLinkingContext &ctx,
+                                  const DefinedAtom &atom,
+                                  const Reference &ref) {
+  return make_dynamic_error_code(
+      "R_MIPS_GPREL32 (12) relocation cannot be used "
+      "against external symbol " +
+      ref.target()->name() + " in file " + atom.file().path());
+}
+
 template <typename ELFT>
 std::error_code
 RelocationPass<ELFT>::validateRelocation(const DefinedAtom &atom,
                                          const Reference &ref) const {
-  if (this->_ctx.getOutputELFType() != ET_DYN)
-    return std::error_code();
   if (!ref.target())
     return std::error_code();
 
+  if (ref.kindValue() == R_MIPS_GPREL32 && !isLocal(ref.target()))
+    return make_external_gprel32_reloc_error(this->_ctx, atom, ref);
+
+  if (this->_ctx.getOutputELFType() != ET_DYN)
+    return std::error_code();
+
   switch (ref.kindValue()) {
   case R_MIPS16_HI16:
   case R_MIPS_HI16:
diff --git a/lld/test/elf/Mips/validate-rel-02.test b/lld/test/elf/Mips/validate-rel-02.test
new file mode 100644
index 0000000..01160ee
--- /dev/null
+++ b/lld/test/elf/Mips/validate-rel-02.test
@@ -0,0 +1,41 @@
+# Check that the linker does not accept R_MIPS_GPREL32 relocation
+# against external symbol.
+
+# RUN: yaml2obj -format=elf -docnum 1 %s > %t.o
+# RUN: not lld -flavor gnu -target mipsel -e T0 -o %t.exe %t.o 2>&1 \
+# RUN:       | FileCheck %s
+
+# CHECK: R_MIPS_GPREL32 (12) relocation cannot be used against external symbol T0 in file {{.*}}validate-rel-02.test.tmp.o
+
+---
+FileHeader:      
+  Class:    ELFCLASS32
+  Data:     ELFDATA2LSB
+  Type:     ET_REL
+  Machine:  EM_MIPS
+  Flags:    [EF_MIPS_CPIC, EF_MIPS_ABI_O32, EF_MIPS_ARCH_32]
+
+Sections:        
+  - Name:          .text
+    Type:          SHT_PROGBITS
+    Flags:         [ SHF_ALLOC, SHF_EXECINSTR ]
+    AddressAlign:  16
+    Size:          4
+
+  - Name:          .rel.text
+    Type:          SHT_REL
+    Link:          .symtab
+    AddressAlign:  4
+    Info:          .text
+    Relocations:   
+      - Offset:  0
+        Symbol:  T0
+        Type:    R_MIPS_GPREL32
+
+Symbols:         
+  Global:          
+    - Name:     T0
+      Type:     STT_FUNC
+      Section:  .text
+      Size:     4
+...
-- 
2.7.4