[PATCH] D42486: [ELF][MIPS] Ignore incorrect version definition index for _gp_disp symbol

[Simon Atanasyan via Phabricator via llvm-commits]

atanasyan created this revision.
atanasyan added a reviewer: rafael.
atanasyan added a project: lld.
Herald added subscribers: arichardson, emaste.

MIPS BFD linker puts _gp_disp symbol into DSO files and assigns zero version definition index to it. This value means 'unversioned local symbol' while _gp_disp is a section global symbol. We have to handle this bug in the LLD because BFD linker is used for building MIPS toolchain libraries.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D42486

Files:
  ELF/InputFiles.cpp
  test/ELF/Inputs/mips-gp-dips-corrupt-ver.s
  test/ELF/Inputs/mips-gp-dips-corrupt-ver.so
  test/ELF/mips-gp-disp-ver.s


Index: test/ELF/mips-gp-disp-ver.s
===================================================================
--- /dev/null
+++ test/ELF/mips-gp-disp-ver.s
@@ -0,0 +1,13 @@
+# MIPS BFD linker puts _gp_disp symbol into DSO files and assigns zero
+# version definition index to it. This value means 'unversioned local symbol'
+# while _gp_disp is a section global symbol. We have to handle this bug
+# in the LLD because BFD linker is used for building MIPS toolchain
+# libraries. This test checks such handling.
+
+# RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o %S/Inputs/mips-gp-dips-corrupt-ver.so
+
+  .global __start
+  .text
+__start:
+  lw     $t0, %got(foo)($gp)
Index: test/ELF/Inputs/mips-gp-dips-corrupt-ver.s
===================================================================
--- /dev/null
+++ test/ELF/Inputs/mips-gp-dips-corrupt-ver.s
@@ -0,0 +1,14 @@
+# Source file for mips-gp-dips-corrupt-ver.so
+#
+# % cat gpdisp.ver
+# LLD_1.0.0 { global: foo; };
+#
+# % as mips-gp-dips-corrupt-ver.s -o mips-gp-dips-corrupt-ver.o
+# % ld -shared -o mips-gp-dips-corrupt-ver.so \
+#      --version-script gpdisp.ver mips-gp-dips-corrupt-ver.o
+
+  .global foo
+  .text
+foo:
+  lui    $t0, %hi(_gp_disp)
+  addi   $t0, $t0, %lo(_gp_disp)
Index: ELF/InputFiles.cpp
===================================================================
--- ELF/InputFiles.cpp
+++ ELF/InputFiles.cpp
@@ -856,6 +856,14 @@
       continue;
     }
 
+    if (Config->EMachine == EM_MIPS) {
+      // MIPS BFD linker puts _gp_disp symbol into DSO files and incorrectly
+      // assigns VER_NDX_LOCAL to this section global symbol.
+      // Here is a workaround for this bug.
+      if (Versym && VersymIndex == VER_NDX_LOCAL && Name == "_gp_disp")
+        continue;
+    }
+
     const Elf_Verdef *Ver = nullptr;
     if (VersymIndex != VER_NDX_GLOBAL) {
       if (VersymIndex >= Verdefs.size() || VersymIndex == VER_NDX_LOCAL) {


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