[PATCH] D60250: [llvm-objdump] Allow -dynamic-reloc on ET_EXEC files

[Chih-Mao Chen via Phabricator via llvm-commits]

PkmX updated this revision to Diff 195300.
PkmX marked 8 inline comments as done.
PkmX set the repository for this revision to rG LLVM Github Monorepo.
PkmX added a comment.

- `-R` now only checks for the presence of `SHT_DYNAMIC` section.
- Reduce dynamic test case: remove unnecessary fields and use `R_X86_64_RELATIVE` so we don't even need a symbol table.
- Clarify the test for no `SHT_DYNAMIC` section case.
- Use `llvm::any_of` as suggested by @grimar.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60250/new/

https://reviews.llvm.org/D60250

Files:
  llvm/include/llvm/Object/ELFObjectFile.h
  llvm/test/tools/llvm-objdump/dynamic-reloc-dyn.test
  llvm/test/tools/llvm-objdump/dynamic-reloc-not-dyn.test
  llvm/tools/llvm-objdump/llvm-objdump.cpp


Index: llvm/tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1475,13 +1475,19 @@
   }
 }
 
+static bool hasDynamicSection(const ELFObjectFileBase &Elf) {
+  return llvm::any_of(Elf.sections(), [](const ELFSectionRef Sec) {
+    return Sec.getType() == ELF::SHT_DYNAMIC;
+  });
+}
+
 void llvm::printDynamicRelocations(const ObjectFile *Obj) {
   // For the moment, this option is for ELF only
   if (!Obj->isELF())
     return;
 
   const auto *Elf = dyn_cast<ELFObjectFileBase>(Obj);
-  if (!Elf || Elf->getEType() != ELF::ET_DYN) {
+  if (!Elf || !hasDynamicSection(*Elf)) {
     error("not a dynamic object");
     return;
   }
Index: llvm/test/tools/llvm-objdump/dynamic-reloc-not-dyn.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/dynamic-reloc-not-dyn.test
@@ -0,0 +1,13 @@
+# Check that -R errors out if there is no dynamic section.
+#
+# RUN: yaml2obj %s > %t
+# RUN: not llvm-objdump -R %t 2>&1 | FileCheck %s
+# CHECK: error: not a dynamic object
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_EXEC
+  Machine:         EM_X86_64
+...
Index: llvm/test/tools/llvm-objdump/dynamic-reloc-dyn.test
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/dynamic-reloc-dyn.test
@@ -0,0 +1,31 @@
+# RUN: yaml2obj %s > %t.dyn
+# RUN: llvm-objdump -R %t.dyn | FileCheck %s
+#
+# CHECK:      DYNAMIC RELOCATION RECORDS
+# CHECK-NEXT: 0000000000000000 R_X86_64_RELATIVE *ABS*
+
+--- !ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  Type:            ET_DYN
+  Machine:         EM_X86_64
+Sections:
+  - Name:            .rela.dyn
+    Type:            SHT_RELA
+    Info:            0
+    Flags:           [ SHF_ALLOC ]
+    Address:         0x1000
+    Relocations:
+      - Offset:          0x0
+        Type:            R_X86_64_RELATIVE
+  - Name:            .dynamic
+    Type:            SHT_DYNAMIC
+    Flags:           [ SHF_WRITE, SHF_ALLOC ]
+    Address:         0x2000
+    Entries:
+      - Tag:             DT_RELA
+        Value:           0x1000
+      - Tag:             DT_NULL
+        Value:           0x0
+...
Index: llvm/include/llvm/Object/ELFObjectFile.h
===================================================================
--- llvm/include/llvm/Object/ELFObjectFile.h
+++ llvm/include/llvm/Object/ELFObjectFile.h
@@ -771,7 +771,7 @@
     }
   }
   for (const Elf_Shdr &Sec : *SectionsOrErr) {
-    if (is_contained(Offsets, Sec.sh_offset))
+    if (is_contained(Offsets, Sec.sh_addr))
       Res.emplace_back(toDRI(&Sec), this);
   }
   return Res;


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