[llvm-readelf] - Allow dumping of the .dynamic section even if there is no PT_DYNAMIC...

It is now possible after D61937 was landed and was discussed
in it's review comments. It is not consistent with GNU, which
does not output .dynamic section content in this case for
no visible reason.

Differential revision: https://reviews.llvm.org/D62179

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@361630 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test b/test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
index 3ef293714a89779caa9100e3b2000bcbf3eceb37..5a03d04ab4d5406e67f896019e5e106a299b26be 100644 (file)
--- a/test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
+++ b/test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
@@ -1,16 +1,23 @@
-# Show that no dumping occurs if there is no PT_DYNAMIC header.
+## Show that dumping occurs even if there is no PT_DYNAMIC header.
+## This is inconsistent with the GNU behavior, but seems to be more reasonable.
 # RUN: yaml2obj %s -o %t.no-phdr
 # RUN: llvm-readobj --dynamic-table %t.no-phdr | FileCheck %s --check-prefix=LLVM
-# RUN: llvm-readelf --dynamic-table %t.no-phdr | FileCheck %s --check-prefix=GNU --allow-empty
+# RUN: llvm-readelf --dynamic-table %t.no-phdr | FileCheck %s --check-prefix=GNU
 
 # LLVM:      File: {{.*}}.no-phdr
 # LLVM-NEXT: Format: ELF64-x86-64
 # LLVM-NEXT: Arch: x86_64
 # LLVM-NEXT: AddressSize: 64bit
 # LLVM-NEXT: LoadName:{{ *}}
-# LLVM-NOT:  {{.}}
+# LLVM-NEXT: DynamicSection [ (1 entries)
+# LLVM-NEXT:   Tag                Type Name/Value
+# LLVM-NEXT:   0x0000000000000000 NULL 0x0
+# LLVM-NEXT: ]
 
-# GNU-NOT: {{.}}
+# GNU:      DynamicSection [ (1 entries)
+# GNU-NEXT:   Tag                Type Name/Value
+# GNU-NEXT:   0x0000000000000000 NULL 0x0
+# GNU-NEXT: ]
 
 --- !ELF
 FileHeader:

diff --git a/tools/llvm-readobj/ELFDumper.cpp b/tools/llvm-readobj/ELFDumper.cpp
index 159e300de305851b59bd0d96ae51b4f795e15776..b86a6c192cab3756ea5551f70ada96aea7eb8faf 100644 (file)
--- a/tools/llvm-readobj/ELFDumper.cpp
+++ b/tools/llvm-readobj/ELFDumper.cpp
@@ -1331,6 +1331,7 @@ static const char *getElfMipsOptionsOdkType(unsigned Odk) {
 
 template <typename ELFT>
 void ELFDumper<ELFT>::loadDynamicTable(const ELFFile<ELFT> *Obj) {
+  // Try to locate the PT_DYNAMIC header.
   const Elf_Phdr *DynamicPhdr = nullptr;
   for (const Elf_Phdr &Phdr : unwrapOrError(Obj->program_headers())) {
     if (Phdr.p_type != ELF::PT_DYNAMIC)
@@ -1339,11 +1340,6 @@ void ELFDumper<ELFT>::loadDynamicTable(const ELFFile<ELFT> *Obj) {
     break;
   }
 
-  // We do not want to dump dynamic section if we have no PT_DYNAMIC header.
-  // This matches GNU's behavior.
-  if (!DynamicPhdr)
-    return;
-
   // Try to locate the .dynamic section in the sections header table.
   const Elf_Shdr *DynamicSec = nullptr;
   for (const Elf_Shdr &Sec : unwrapOrError(Obj->sections())) {
@@ -1358,9 +1354,16 @@ void ELFDumper<ELFT>::loadDynamicTable(const ELFFile<ELFT> *Obj) {
   // Ignore sh_entsize and use the expected value for entry size explicitly.
   // This allows us to dump the dynamic sections with a broken sh_entsize
   // field.
-  if (DynamicSec)
+  if (DynamicSec) {
     DynamicTable = checkDRI({ObjF->getELFFile()->base() + DynamicSec->sh_offset,
                              DynamicSec->sh_size, sizeof(Elf_Dyn)});
+    parseDynamicTable();
+  }
+
+  // If we have a PT_DYNAMIC header, we will either check the found dynamic
+  // section or take the dynamic table data directly from the header.
+  if (!DynamicPhdr)
+    return;
 
   if (DynamicPhdr->p_offset + DynamicPhdr->p_filesz >
       ObjF->getMemoryBufferRef().getBufferSize())
@@ -1374,7 +1377,6 @@ void ELFDumper<ELFT>::loadDynamicTable(const ELFFile<ELFT> *Obj) {
   }
 
   StringRef Name = unwrapOrError(Obj->getSectionName(DynamicSec));
-
   if (DynamicSec->sh_addr + DynamicSec->sh_size >
           DynamicPhdr->p_vaddr + DynamicPhdr->p_memsz ||
       DynamicSec->sh_addr < DynamicPhdr->p_vaddr)
@@ -1386,8 +1388,6 @@ void ELFDumper<ELFT>::loadDynamicTable(const ELFFile<ELFT> *Obj) {
     reportWarning("The SHT_DYNAMIC section '" + Name +
                   "' is not at the start of "
                   "PT_DYNAMIC segment");
-
-  parseDynamicTable();
 }
 
 template <typename ELFT>