[PATCH] D61298: [LLD] Emit dynamic relocations for references to script symbols in -pie links

[ben via Phabricator via llvm-commits]

bd1976llvm created this revision.
bd1976llvm added reviewers: grimar, peter.smith, ruiu.
Herald added subscribers: llvm-commits, MaskRay, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

https://reviews.llvm.org/D55423 caused LLD to stop emitting dynamic relocations for references to script symbols in -pie links.

This patch fixes that regression.


https://reviews.llvm.org/D61298

Files:
  lld/ELF/Relocations.cpp
  lld/test/ELF/linkerscript/symbol-pie.s


Index: lld/test/ELF/linkerscript/symbol-pie.s
===================================================================
--- /dev/null
+++ lld/test/ELF/linkerscript/symbol-pie.s
@@ -0,0 +1,14 @@
+## Position independent executables require dynamic
+## relocations for references to non-absolute script
+## symbols so that their values are correct at runtime.
+
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "foo = .;" > %t.script
+# RUN: ld.lld -pie -o %t --script %t.script %t.o
+# RUN: llvm-readelf -r %t | FileCheck %s
+
+# CHECK: Relocation section '.rela.dyn' at offset {{.*}} contains 1 entries:
+
+.data
+.quad foo
Index: lld/ELF/Relocations.cpp
===================================================================
--- lld/ELF/Relocations.cpp
+++ lld/ELF/Relocations.cpp
@@ -421,11 +421,6 @@
   if (E == R_SIZE)
     return true;
 
-  // We set the final symbols values for linker script defined symbols later.
-  // They always can be computed as a link time constant.
-  if (Sym.ScriptDefined)
-    return true;
-
   // For the target and the relocation, we want to know if they are
   // absolute or relative.
   bool AbsVal = isAbsoluteValue(Sym);
@@ -449,6 +444,11 @@
   if (Sym.isUndefWeak())
     return true;
 
+  // We set the final symbols values for linker script defined symbols later.
+  // They always can be computed as a link time constant.
+  if (Sym.ScriptDefined)
+      return true;
+
   error("relocation " + toString(Type) + " cannot refer to absolute symbol: " +
         toString(Sym) + getLocation(S, Sym, RelOff));
   return true;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D61298.197280.patch
Type: text/x-patch
Size: 1624 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190430/e86c36f9/attachment.bin>