OSchip
/
llvm-project
mirror of https://github.com/THU-DSP-LAB/llvm-project.git
13
0
Fork 2
Code Issues Packages Projects Releases Wiki Activity

[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

llvm-svn: 343668
This commit is contained in:
George Rimar 2018-10-03 09:33:00 +00:00
parent 3832d7c25d
commit f79a8ef2ae
2 changed files with 22 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
lld/ELF/Symbols.cpp
View File

@ -225,7 +225,7 @@ 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;

21
lld/test/ELF/local-ver-preemptible.s Normal file
View File

@ -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 0x288 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