[PATCH] D35724: [ELF] - Fix missing relocation when linking executable with --unresolved-symbols=ignore-all

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 108331.
grimar added a comment.

- Addressed review comments.
- Added testcase with protected symbol. In that case we fail to link it with  --unresolved-symbols=ignore-all. That behavior is natural and matches both bfd and gold. See no reasons to change it atm.


https://reviews.llvm.org/D35724

Files:
  ELF/Symbols.cpp
  test/ELF/executable-undefined-ignoreall.s
  test/ELF/executable-undefined-protected-ignoreall.s
  test/ELF/no-inhibit-exec.s


Index: test/ELF/no-inhibit-exec.s
===================================================================
--- test/ELF/no-inhibit-exec.s
+++ test/ELF/no-inhibit-exec.s
@@ -2,11 +2,15 @@
 # RUN: not ld.lld %t -o %t2
 # RUN: ld.lld %t --noinhibit-exec -o %t2
 # RUN: llvm-objdump -d %t2 | FileCheck %s
+# RUN: llvm-readobj -r %t2 | FileCheck %s --check-prefix=RELOC
 # REQUIRES: x86
 
 # CHECK: Disassembly of section .text:
 # CHECK-NEXT: _start
-# CHECK-NEXT: 201000: {{.*}} callq -2101253
+# CHECK-NEXT: 201000: {{.*}} callq 0
+
+# RELOC: Relocations [
+# RELOC: ]
 
 # next code will not link without noinhibit-exec flag
 # because of undefined symbol _bar
Index: test/ELF/executable-undefined-protected-ignoreall.s
===================================================================
--- test/ELF/executable-undefined-protected-ignoreall.s
+++ test/ELF/executable-undefined-protected-ignoreall.s
@@ -0,0 +1,8 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: not ld.lld %t -o %tout --unresolved-symbols=ignore-all -pie 2>&1 | FileCheck %s
+# CHECK: error: undefined symbol: foo
+
+.protected foo
+_start:
+callq foo at PLT
Index: test/ELF/executable-undefined-ignoreall.s
===================================================================
--- test/ELF/executable-undefined-ignoreall.s
+++ test/ELF/executable-undefined-ignoreall.s
@@ -0,0 +1,13 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: ld.lld %t -o %tout --unresolved-symbols=ignore-all -pie
+# RUN: llvm-readobj -r %tout | FileCheck %s
+
+# CHECK:      Relocations [
+# CHECK-NEXT:   Section ({{.*}}) .rela.plt {
+# CHECK-NEXT:     0x2018 R_X86_64_JUMP_SLOT foo 0x0
+# CHECK-NEXT:   }
+# CHECK-NEXT: ]
+
+_start:
+callq foo at PLT
Index: ELF/Symbols.cpp
===================================================================
--- ELF/Symbols.cpp
+++ ELF/Symbols.cpp
@@ -141,18 +141,20 @@
   if (isShared())
     return !NeedsCopy && !NeedsPltAddr;
 
-  // That's all that can be preempted in a non-DSO.
-  if (!Config->Shared)
-    return false;
-
   // Only symbols that appear in dynsym can be preempted.
   if (!symbol()->includeInDynsym())
     return false;
 
   // Only default visibility symbols can be preempted.
   if (symbol()->Visibility != STV_DEFAULT)
     return false;
 
+  // Undefined external symbols in a non-DSO usually reported by linker and link
+  // fails, but together with --unresolved-symbols=ignore-all link succeeds and
+  // runtime linker should take care about them during execution.
+  if (!Config->Shared)
+    return isUndefined();
+
   // -Bsymbolic means that definitions are not preempted.
   if (Config->Bsymbolic || (Config->BsymbolicFunctions && isFunc()))
     return !isDefined();
@@ -357,8 +359,11 @@
 bool Symbol::includeInDynsym() const {
   if (computeBinding() == STB_LOCAL)
     return false;
-  return ExportDynamic || body()->isShared() ||
-         (body()->isUndefined() && Config->Shared);
+  if (ExportDynamic || body()->isShared())
+    return true;
+  if (!body()->isUndefined())
+    return false;
+  return Config->Shared || !body()->symbol()->isWeak();
 }
 
 // Print out a log message for --trace-symbol.


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