Commit b8dce5ad authored by Tom Stellard's avatar Tom Stellard
Browse files

Merging r343668: 

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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
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llvm-svn: 344925
parent 8e5d7e51

lld/ELF/Symbols.cpp

+1 −1
Original line number Diff line number Diff line
@@ -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;

lld/test/ELF/local-ver-preemptible.s

0 → 100644
+21 −0
Original line number Diff line number Diff line 
# 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