[llvm-branch-commits] [lld] r344925 - Merging r343668:

[Tom Stellard via llvm-branch-commits]

Author: tstellar
Date: Mon Oct 22 10:44:17 2018
New Revision: 344925

URL: http://llvm.org/viewvc/llvm-project?rev=344925&view=rev
Log:
Merging r343668:

------------------------------------------------------------------------
r343668 | grimar | 2018-10-03 02:33:00 -0700 (Wed, 03 Oct 2018) | 20 lines

[ELF] - Do not forget to include to .dymsym symbols that were converted to Defined.

This is the fix for
"Bug 39104 - LLD links incorrect ELF executable if version script contains "local: *;"
(https://bugs.llvm.org/show_bug.cgi?id=39104).

The issue happens when we have non-PIC program call to function in a shared library.
(for example, the PR above has R_X86_64_PC32 relocation against __libc_start_main)

LLD converts symbol to Defined in that case with the use of replaceWithDefined()

The issue is that after above we create a broken relocation because do not
include the symbol into .dynsym.

That happens when the version script is used because we treat the symbol as
STB_LOCAL if the following condition match:
VersionId == VER_NDX_LOCAL && isDefined() and do not include it to
.dynsym because of that. Patch fixes the issue.

Differential revision: https://reviews.llvm.org/D52724
------------------------------------------------------------------------

Added:
    lld/branches/release_70/test/ELF/local-ver-preemptible.s
Modified:
    lld/branches/release_70/ELF/Symbols.cpp

Modified: lld/branches/release_70/ELF/Symbols.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/branches/release_70/ELF/Symbols.cpp?rev=344925&r1=344924&r2=344925&view=diff
==============================================================================
--- lld/branches/release_70/ELF/Symbols.cpp (original)
+++ lld/branches/release_70/ELF/Symbols.cpp Mon Oct 22 10:44:17 2018
@@ -209,7 +209,7 @@ uint8_t Symbol::computeBinding() const {
     return Binding;
   if (Visibility != STV_DEFAULT && Visibility != STV_PROTECTED)
     return STB_LOCAL;
-  if (VersionId == VER_NDX_LOCAL && isDefined())
+  if (VersionId == VER_NDX_LOCAL && isDefined() && !IsPreemptible)
     return STB_LOCAL;
   if (!Config->GnuUnique && Binding == STB_GNU_UNIQUE)
     return STB_GLOBAL;

Added: lld/branches/release_70/test/ELF/local-ver-preemptible.s
URL: http://llvm.org/viewvc/llvm-project/lld/branches/release_70/test/ELF/local-ver-preemptible.s?rev=344925&view=auto
==============================================================================
--- lld/branches/release_70/test/ELF/local-ver-preemptible.s (added)
+++ lld/branches/release_70/test/ELF/local-ver-preemptible.s Mon Oct 22 10:44:17 2018
@@ -0,0 +1,21 @@
+# REQUIRES: x86
+# RUN: echo '.global foo; .type foo, @function; foo:' | \
+# RUN:   llvm-mc -filetype=obj -triple=x86_64-unknown-linux - -o %t.so.o
+# RUN: ld.lld %t.so.o -o %t.so -shared
+
+# RUN: echo "{ global: main; local: *; };" > %t.script
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: ld.lld %t.o %t.so -o %t -version-script %t.script
+# RUN: llvm-readelf -r --symbols %t | FileCheck %s
+
+# CHECK:      Relocation section '.rela.plt' at offset 0x290 contains 1 entries:
+# CHECK:        R_X86_64_JUMP_SLOT 0000000000201020 foo + 0
+
+# CHECK:      Symbol table '.dynsym' contains 2 entries:
+# CHECK-NEXT:   Num:    Value          Size Type    Bind   Vis      Ndx Name
+# CHECK-NEXT:     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND @
+# CHECK-NEXT:     1: 0000000000201020     0 FUNC    GLOBAL DEFAULT  UND foo@
+
+_start:
+  movl $foo - ., %eax