[llvm-objdump] Teach llvm-objdump dump dynamic symbols.

Summary: This patch is to teach `llvm-objdump` dump dynamic symbols (`-T` and `--dynamic-syms`). Currently, this patch is not fully compatible with `gnu-objdump`, but I would like to continue working on this in next few patches. It has two issues. 1. Some symbols shouldn't be marked as global(g). (`-t/--syms` has same issue as well) (Fixed by D75659) 2. `gnu-objdump` can dump version information and *dynamically* insert before symbol name field. `objdump -T a.out` gives: ``` DYNAMIC SYMBOL TABLE: 0000000000000000 w D *UND* 0000000000000000 _ITM_deregisterTMCloneTable 0000000000000000 DF *UND* 0000000000000000 GLIBC_2.2.5 printf 0000000000000000 DF *UND* 0000000000000000 GLIBC_2.2.5 __libc_start_main 0000000000000000 w D *UND* 0000000000000000 __gmon_start__ 0000000000000000 w D *UND* 0000000000000000 _ITM_registerTMCloneTable 0000000000000000 w DF *UND* 0000000000000000 GLIBC_2.2.5 __cxa_finalize ``` `llvm-objdump -T a.out` gives: ``` DYNAMIC SYMBOL TABLE: 0000000000000000 w D *UND* 0000000000000000 _ITM_deregisterTMCloneTable 0000000000000000 g DF *UND* 0000000000000000 printf 0000000000000000 g DF *UND* 0000000000000000 __libc_start_main 0000000000000000 w D *UND* 0000000000000000 __gmon_start__ 0000000000000000 w D *UND* 0000000000000000 _ITM_registerTMCloneTable 0000000000000000 w DF *UND* 0000000000000000 __cxa_finalize ``` Reviewers: jhenderson, grimar, MaskRay, espindola Reviewed By: jhenderson, grimar Subscribers: emaste, rupprecht, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D75756
llvm · Apr 5, 2020 · 948ef5b · 948ef5b
1 parent 5aacce3
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diff --git a/llvm/docs/CommandGuide/llvm-objdump.rst b/llvm/docs/CommandGuide/llvm-objdump.rst
@@ -85,6 +85,10 @@ combined with other commands:
 
   Display the symbol table.
 
+.. option:: -T, --dynamic-syms
+
+  Display the contents of the dynamic symbol table.
+
 .. option:: -u, --unwind-info
 
   Display the unwind info of the input(s).

diff --git a/llvm/test/tools/llvm-objdump/X86/elf-dynamic-symbols.test b/llvm/test/tools/llvm-objdump/X86/elf-dynamic-symbols.test
@@ -0,0 +1,107 @@
+## Test that llvm-objdump can dump dynamic symbols.
+# RUN: yaml2obj --docnum=1 %s -o %t1
+# RUN: llvm-objdump --dynamic-syms %t1 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=DYNSYM
+# RUN: llvm-objdump -T %t1 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=DYNSYM
+
+#       DYNSYM:DYNAMIC SYMBOL TABLE:
+#  DYNSYM-NEXT:0000000000000000 l    DO .data	0000000000000000 localsym
+#  DYNSYM-NEXT:0000000000000000 g    DO .data	0000000000000000 globalsym
+#  DYNSYM-NEXT:0000000000000000 u    DO .data	0000000000000000 uniqueglobalsym
+#  DYNSYM-NEXT:0000000000000000  w   DO .data	0000000000000000 weaksym
+#  DYNSYM-NEXT:0000000000000000 g    Df .data	0000000000000000 filesym
+#  DYNSYM-NEXT:0000000000000000 g    DF .data	0000000000000000 funcsym
+# DYNSYM-EMPTY:
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:  .data
+    Type:  SHT_PROGBITS
+    Flags: [ SHF_ALLOC, SHF_WRITE ]
+DynamicSymbols:
+  - Name:    localsym
+    Type:    STT_OBJECT
+    Section: .data
+    Binding: STB_LOCAL
+  - Name:    globalsym
+    Type:    STT_OBJECT
+    Section: .data
+    Binding: STB_GLOBAL
+  - Name:    uniqueglobalsym
+    Type:    STT_OBJECT
+    Section: .data
+    Binding: STB_GNU_UNIQUE
+  - Name:    weaksym
+    Type:    STT_OBJECT
+    Section: .data
+    Binding: STB_WEAK
+  - Name:    filesym
+    Type:    STT_FILE
+    Section: .data
+    Binding: STB_GLOBAL
+  - Name:    funcsym
+    Type:    STT_FUNC
+    Section: .data
+    Binding: STB_GLOBAL
+
+## Test dumping ELF files with no .dynsym section.
+# RUN: yaml2obj --docnum=2 %s -o %t2
+# RUN: llvm-objdump --dynamic-syms %t2 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=NODYNSYM
+# RUN: llvm-objdump -T %t2 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=NODYNSYM
+
+#       NODYNSYM:DYNAMIC SYMBOL TABLE:
+# NODYNSYM-EMPTY:
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+
+## Test dumping ELF files with logically empty .dynsym section (only has a 0-index NULL symbol).
+# RUN: yaml2obj --docnum=3 %s -o %t3
+# RUN: llvm-objdump --dynamic-syms %t3 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=ONLY-NULL
+# RUN: llvm-objdump -T %t3 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=ONLY-NULL
+
+#       ONLY-NULL:DYNAMIC SYMBOL TABLE:
+# ONLY-NULL-EMPTY:
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+DynamicSymbols: []
+
+## Test dumping ELF files with truly empty .dynsym section (size of .dynsym section is 0).
+# RUN: yaml2obj --docnum=4 %s -o %t4
+# RUN: llvm-objdump --dynamic-syms %t4 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=EMPTY
+# RUN: llvm-objdump -T %t4 | \
+# RUN:   FileCheck %s --match-full-lines --strict-whitespace --check-prefix=EMPTY
+
+#       EMPTY:DYNAMIC SYMBOL TABLE:
+# EMPTY-EMPTY:
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name: .dynsym
+    Type: SHT_DYNSYM
+    Size: 0
diff --git a/llvm/test/tools/llvm-objdump/unimplemented-features.test b/llvm/test/tools/llvm-objdump/unimplemented-features.test
@@ -0,0 +1,31 @@
+## Test dumping dynamic symbols reports a warning if the operation is unsupported for the file format.
+# RUN: yaml2obj %s --docnum=1 -o %t.macho.o
+# RUN: llvm-objdump --dynamic-syms %t.macho.o 2>&1 | \
+# RUN:   FileCheck %s -DFILE=%t.macho.o
+# RUN: yaml2obj %s --docnum=2 -o %t.coff.o
+# RUN: llvm-objdump --dynamic-syms %t.coff.o 2>&1 | \
+# RUN:   FileCheck %s -DFILE=%t.coff.o
+# RUN: llvm-objdump --dynamic-syms %p/XCOFF/Inputs/xcoff-section-headers.o 2>&1 | \
+# RUN:   FileCheck %s -DFILE=%p/XCOFF/Inputs/xcoff-section-headers.o
+
+#       CHECK:DYNAMIC SYMBOL TABLE:
+#  CHECK-NEXT:{{.*}}llvm-objdump: warning: '[[FILE]]': this operation is not currently supported for this file format
+# CHECK-EMPTY:
+
+--- !mach-o
+FileHeader:      
+  magic:      0xFEEDFACF
+  cputype:    0x01000007
+  cpusubtype: 0x80000003
+  filetype:   0x00000002
+  ncmds:      0
+  sizeofcmds: 0
+  flags:      0x00218085
+  reserved:   0x00000000
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections: []
+symbols:  []