[llvm-readobj] - Teach readobj to print PT_OPENBSD_RANDOMIZE/PT_OPENBSD_WXNEEDED headers.

[grimar]

Summary

These are OpenBSD specific program headers and
currently we support them in LLD.

Description of headers (just in case) available here:
http://man.openbsd.org/OpenBSD-current/man5/elf.5

OpenBSD commits were:
For PT_OPENBSD_RANDOMIZE:
https://github.com/openbsd/src/commit/c494713c450d98da3f2e1451ee8c7fb675a7c461
For PT_OPENBSD_WXNEEDED:
https://github.com/openbsd/src/commit/2a5a8fc7e30928c2cff57cfe5fb491c90d8478ad

[emaste]

For reference I have now also added them to ELF Tool Chain's readelf in r3496.

tools/llvm-readobj/ELFDumper.cpp

1157–1160 ↗

(On Diff #74678)

The grouping seems a bit odd in this switch?

[davide]

test/tools/llvm-readobj/program-headers.test

9 ↗

(On Diff #74678)

You should add a comment explaining how you're generating this code, so that if we need to regenerate in the future we don't have to randomly guess.

154 ↗

(On Diff #74678)

Remove the (0x4), here and in other parts of the patch.

tools/llvm-readobj/ELFDumper.cpp

1157–1160 ↗

(On Diff #74678)

Agree.

[grimar]

• Addressed review comments.

test/tools/llvm-readobj/program-headers.test

9 ↗

(On Diff #74678)

Done.

154 ↗

(On Diff #74678)

Ok, though it is not consistent with other places in this file. I also removed all values checking, as
intention of testcase is to check string name of PHDR and nothing else.

tools/llvm-readobj/ELFDumper.cpp

1157–1160 ↗

(On Diff #74678)

It is grouped (and sorted) at the same way as done in ELF.h:

PT_NULL    = 0, // Unused segment.
PT_LOAD    = 1, // Loadable segment.
PT_DYNAMIC = 2, // Dynamic linking information.
PT_INTERP  = 3, // Interpreter pathname.
PT_NOTE    = 4, // Auxiliary information.
PT_SHLIB   = 5, // Reserved.
PT_PHDR    = 6, // The program header table itself.
PT_TLS     = 7, // The thread-local storage template.
PT_LOOS    = 0x60000000, // Lowest operating system-specific pt entry type.
PT_HIOS    = 0x6fffffff, // Highest operating system-specific pt entry type.
PT_LOPROC  = 0x70000000, // Lowest processor-specific program hdr entry type.
PT_HIPROC  = 0x7fffffff, // Highest processor-specific program hdr entry type.

// x86-64 program header types.
// These all contain stack unwind tables.
PT_GNU_EH_FRAME  = 0x6474e550,
PT_SUNW_EH_FRAME = 0x6474e550,
PT_SUNW_UNWIND   = 0x6464e550,

PT_GNU_STACK = 0x6474e551, // Indicates stack executability.
PT_GNU_RELRO = 0x6474e552, // Read-only after relocation.

PT_OPENBSD_RANDOMIZE = 0x65a3dbe6, // Fill with random data.
PT_OPENBSD_WXNEEDED  = 0x65a3dbe7, // Program does W^X violations.

[davide]

LGTM modulo nit.

test/tools/llvm-readobj/program-headers.test

14 ↗

(On Diff #74820)

test.s is an empty file.
linker.script:

154 ↗

(On Diff #74678)

cool.

llvm/trunk/test/tools/llvm-readobj/program-headers.test

 RUN: llvm-readobj -program-headers %p/../../Object/Inputs/program-headers.elf-i386 \
 RUN:     | FileCheck %s -check-prefix ELF-I386
 RUN: llvm-readobj -program-headers %p/../../Object/Inputs/program-headers.elf-x86-64 \
 RUN:     | FileCheck %s -check-prefix ELF-X86-64
 RUN: llvm-readobj -program-headers %p/../../Object/Inputs/program-headers.mips \
 RUN:     | FileCheck %s -check-prefix ELF-MIPS
 RUN: llvm-readobj -program-headers %p/../../Object/Inputs/program-headers.mips64 \
 RUN:     | FileCheck %s -check-prefix ELF-MIPS64
 
+## openbsd-phdrs.elf-x86-64 was generated using GNU ld (GNU Binutils for Ubuntu) 2.26.1.
+## llvm-mc -filetype=obj -triple=x86_64-pc-linux test.s -o main.o
+## ld -script linker.script main.o -o openbsd-phdrs.elf-x86-64
+##
+## test.s is an empty file.
+## linker.script:
+## PHDRS { text PT_LOAD FILEHDR PHDRS; foo 0x65a3dbe6; bar 0x65a3dbe7; }
+## SECTIONS { . = SIZEOF_HEADERS; .all : { *(.*) } : text }
+RUN: llvm-readobj -program-headers %p/../../Object/Inputs/openbsd-phdrs.elf-x86-64 \
+RUN:     | FileCheck %s -check-prefix OPENBSD-X86-64
+
 ELF-I386:      ProgramHeaders [
 ELF-I386-NEXT:   ProgramHeader {
 ELF-I386-NEXT:     Type: PT_LOAD (0x1)
 ELF-I386-NEXT:     Offset: 0x0
 ELF-I386-NEXT:     VirtualAddress: 0x8048000
 ELF-I386-NEXT:     PhysicalAddress: 0x8048000
 ELF-I386-NEXT:     FileSize: 308
 ELF-I386-NEXT:     MemSize: 308

 ELF-MIPS64-NEXT:     MemSize: 136
 ELF-MIPS64-NEXT:     Flags [ (0x5)
 ELF-MIPS64-NEXT:       PF_R (0x4)
 ELF-MIPS64-NEXT:       PF_X (0x1)
 ELF-MIPS64-NEXT:     ]
 ELF-MIPS64-NEXT:     Alignment: 65536
 ELF-MIPS64-NEXT:   }
 ELF-MIPS64-NEXT: ]
+
+OPENBSD-X86-64:      ProgramHeaders [
+OPENBSD-X86-64:        ProgramHeader {
+OPENBSD-X86-64:          Type:  PT_OPENBSD_RANDOMIZE
+OPENBSD-X86-64-NEXT:     Offset:
+OPENBSD-X86-64-NEXT:     VirtualAddress:
+OPENBSD-X86-64-NEXT:     PhysicalAddress:
+OPENBSD-X86-64-NEXT:     FileSize:
+OPENBSD-X86-64-NEXT:     MemSize:
+OPENBSD-X86-64-NEXT:     Flags [
+OPENBSD-X86-64-NEXT:     ]
+OPENBSD-X86-64-NEXT:     Alignment:
+OPENBSD-X86-64-NEXT:   }
+OPENBSD-X86-64-NEXT:   ProgramHeader {
+OPENBSD-X86-64-NEXT:     Type:  PT_OPENBSD_WXNEEDED
+OPENBSD-X86-64-NEXT:     Offset:
+OPENBSD-X86-64-NEXT:     VirtualAddress:
+OPENBSD-X86-64-NEXT:     PhysicalAddress:
+OPENBSD-X86-64-NEXT:     FileSize:
+OPENBSD-X86-64-NEXT:     MemSize:
+OPENBSD-X86-64-NEXT:     Flags [
+OPENBSD-X86-64-NEXT:     ]
+OPENBSD-X86-64-NEXT:     Alignment:
+OPENBSD-X86-64-NEXT:   }

llvm/trunk/tools/llvm-readobj/ELFDumper.cpp

static const char *getElfSegmentType(unsigned Arch, unsigned Type) {
   LLVM_READOBJ_ENUM_CASE(ELF, PT_PHDR   );
   LLVM_READOBJ_ENUM_CASE(ELF, PT_TLS    );
 
   LLVM_READOBJ_ENUM_CASE(ELF, PT_GNU_EH_FRAME);
   LLVM_READOBJ_ENUM_CASE(ELF, PT_SUNW_UNWIND);
 
   LLVM_READOBJ_ENUM_CASE(ELF, PT_GNU_STACK);
   LLVM_READOBJ_ENUM_CASE(ELF, PT_GNU_RELRO);
+
+  LLVM_READOBJ_ENUM_CASE(ELF, PT_OPENBSD_RANDOMIZE);
+  LLVM_READOBJ_ENUM_CASE(ELF, PT_OPENBSD_WXNEEDED);
+
   default: return "";
   }
 }
 
 static std::string getElfPtType(unsigned Arch, unsigned Type) {
   switch (Type) {
     LLVM_READOBJ_PHDR_ENUM(ELF, PT_NULL)
     LLVM_READOBJ_PHDR_ENUM(ELF, PT_LOAD)