[llvm] 30718f3 - [llvm-objcopy] --weaken-symbol/--weaken: weaken STB_GNU_UNIQUE symbols

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2022-03-16T09:48:19-07:00
New Revision: 30718f3aa62b81c2814564d2ca08888435202655

URL: https://github.com/llvm/llvm-project/commit/30718f3aa62b81c2814564d2ca08888435202655
DIFF: https://github.com/llvm/llvm-project/commit/30718f3aa62b81c2814564d2ca08888435202655.diff

LOG: [llvm-objcopy] --weaken-symbol/--weaken: weaken STB_GNU_UNIQUE symbols

STB_GNU_UNIQUE is like STB_GLOBAL with extra semantics:

* gold and ld.lld: changed to STB_GLOBAL if --no-gnu-unique is specified
* glibc: unique even with dlopen `RTLD_LOCAL`, implies DF_1_NODELETE

Therefore, I think it makes sense for --weaken-symbol/--weaken-symbols/--weaken
to change STB_GNU_UNIQUE symbols.

binutils 2.39 will have the same behavior: https://sourceware.org/bugzilla/show_bug.cgi?id=28926

Reviewed By: jhenderson

Differential Revision: https://reviews.llvm.org/D120638

Added: 
    

Modified: 
    llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
    llvm/test/tools/llvm-objcopy/ELF/weaken-all.test
    llvm/test/tools/llvm-objcopy/ELF/weaken.test

Removed: 
    


################################################################################
diff  --git a/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp b/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
index bbbbd9f990073..f759fac5ac111 100644
--- a/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
+++ b/llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp
@@ -302,10 +302,11 @@ static Error updateAndRemoveSymbols(const CommonConfig &Config,
         Sym.getShndx() != SHN_UNDEF)
       Sym.Binding = STB_GLOBAL;
 
-    if (Config.SymbolsToWeaken.matches(Sym.Name) && Sym.Binding == STB_GLOBAL)
+    // SymbolsToWeaken applies to both STB_GLOBAL and STB_GNU_UNIQUE.
+    if (Config.SymbolsToWeaken.matches(Sym.Name) && Sym.Binding != STB_LOCAL)
       Sym.Binding = STB_WEAK;
 
-    if (Config.Weaken && Sym.Binding == STB_GLOBAL &&
+    if (Config.Weaken && Sym.Binding != STB_LOCAL &&
         Sym.getShndx() != SHN_UNDEF)
       Sym.Binding = STB_WEAK;
 

diff  --git a/llvm/test/tools/llvm-objcopy/ELF/weaken-all.test b/llvm/test/tools/llvm-objcopy/ELF/weaken-all.test
index 6fd8b64715f91..69f4ebc6f0a46 100644
--- a/llvm/test/tools/llvm-objcopy/ELF/weaken-all.test
+++ b/llvm/test/tools/llvm-objcopy/ELF/weaken-all.test
@@ -44,6 +44,10 @@ Symbols:
     Section:  .text
     Value:    0x1010
     Binding:  STB_WEAK
+  - Name:     GnuUnique
+    Section:  .text
+    Value:    0x1010
+    Binding:  STB_GNU_UNIQUE
 
 #CHECK: Symbols [
 #CHECK-NEXT:  Symbol {
@@ -91,4 +95,13 @@ Symbols:
 #CHECK-NEXT:    Other: 0
 #CHECK-NEXT:    Section: .text
 #CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: GnuUnique
+#CHECK-NEXT:    Value: 0x1010
+#CHECK-NEXT:    Size: 0
+#CHECK-NEXT:    Binding: Weak
+#CHECK-NEXT:    Type: None
+#CHECK-NEXT:    Other: 0
+#CHECK-NEXT:    Section: .text
+#CHECK-NEXT:  }
 #CHECK-NEXT:]

diff  --git a/llvm/test/tools/llvm-objcopy/ELF/weaken.test b/llvm/test/tools/llvm-objcopy/ELF/weaken.test
index a23a4fc0fbc81..107c5a03521ef 100644
--- a/llvm/test/tools/llvm-objcopy/ELF/weaken.test
+++ b/llvm/test/tools/llvm-objcopy/ELF/weaken.test
@@ -1,17 +1,19 @@
 # RUN: yaml2obj %s -o %t
-# RUN: llvm-objcopy --weaken-symbol Global -W Local -W Weak -W Missing %t %t2
+# RUN: llvm-objcopy --weaken-symbol Global -W Local -W Weak -W GnuUnique -W Missing %t %t2
 # RUN: llvm-readobj --symbols %t2 | FileCheck %s
 # RUN: llvm-objcopy --regex --weaken-symbol='[LGW].*' %t %t3
 # RUN: cmp %t2 %t3
 # RUN: echo "  Global  # comment" > %t-list.txt
 # RUN: echo "Local" >> %t-list.txt
 # RUN: echo "Weak" >> %t-list.txt
+# RUN: echo "GnuUnique" >> %t-list.txt
 # RUN: echo "Missing" >> %t-list.txt
 # RUN: echo " # comment" >> %t-list.txt
 # RUN: llvm-objcopy --weaken-symbols %t-list.txt %t %t4
 # RUN: cmp %t2 %t4
 # RUN: echo ".*al # Global + Local == .*al" > %t-list2.txt
 # RUN: echo "Weak # weak" >> %t-list2.txt
+# RUN: echo " Gnu.*" >> %t-list2.txt
 # RUN: llvm-objcopy --regex --weaken-symbols %t-list2.txt %t %t5
 # RUN: cmp %t2 %t5
 
@@ -46,6 +48,9 @@ Symbols:
     Section:  .text
     Value:    0x1008
     Binding:  STB_WEAK
+  - Name:     GnuUnique
+    Section:  .text
+    Binding:  STB_GNU_UNIQUE
   - Name:     Unspecified
     Section:  .text
     Binding:  STB_GLOBAL
@@ -88,6 +93,15 @@ Symbols:
 #CHECK-NEXT:    Section: .text
 #CHECK-NEXT:  }
 #CHECK-NEXT:  Symbol {
+#CHECK-NEXT:    Name: GnuUnique
+#CHECK-NEXT:    Value: 0x0
+#CHECK-NEXT:    Size: 0
+#CHECK-NEXT:    Binding: Weak
+#CHECK-NEXT:    Type: None
+#CHECK-NEXT:    Other: 0
+#CHECK-NEXT:    Section: .text
+#CHECK-NEXT:  }
+#CHECK-NEXT:  Symbol {
 #CHECK-NEXT:    Name: Unspecified
 #CHECK-NEXT:    Value: 0x0
 #CHECK-NEXT:    Size: 0