[Bug ld/23428] New: ld does not put program headers in a load segment when static linking an executable

[nszabolcs at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=23428

            Bug ID: 23428
           Summary: ld does not put program headers in a load segment when
                    static linking an executable
           Product: binutils
           Version: 2.31
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: nszabolcs at gmail dot com
  Target Milestone: ---

simple static linking with is broken with 2.31 ld because it does not put
program headers into a load section unless there is some other read only
loaded section.

$ ld --version
GNU ld (GNU Binutils) 2.31.1.20180718
Copyright (C) 2018 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) a later version.
This program has absolutely no warranty.
$ cat t.s
.globl _start
_start:
        xor %rdi,%rdi
        mov $0xe7,%eax
        syscall
$ as -o t.o t.s
$ ld -static t.o
$ readelf -aW a.out
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           Advanced Micro Devices X86-64
  Version:                           0x1
  Entry point address:               0x401000
  Start of program headers:          64 (bytes into file)
  Start of section headers:          4320 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           56 (bytes)
  Number of program headers:         1
  Size of section headers:           64 (bytes)
  Number of section headers:         5
  Section header string table index: 4

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg
Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 000000 00     
0   0  0
  [ 1] .text             PROGBITS        0000000000401000 001000 00000a 00  AX 
0   0  1
  [ 2] .symtab           SYMTAB          0000000000000000 001010 000090 18     
3   2  8
  [ 3] .strtab           STRTAB          0000000000000000 0010a0 000019 00     
0   0  1
  [ 4] .shstrtab         STRTAB          0000000000000000 0010b9 000021 00     
0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  l (large), p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset   VirtAddr           PhysAddr           FileSiz  MemSiz
  Flg Align
  LOAD           0x001000 0x0000000000401000 0x0000000000401000 0x00000a
0x00000a R E 0x1000

 Section to Segment mapping:
  Segment Sections...
   00     .text 

There is no dynamic section in this file.

There are no relocations in this file.

The decoding of unwind sections for machine type Advanced Micro Devices X86-64
is not currently supported.

Symbol table '.symtab' contains 6 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 0000000000401000     0 SECTION LOCAL  DEFAULT    1 
     2: 0000000000401000     0 NOTYPE  GLOBAL DEFAULT    1 _start
     3: 0000000000402000     0 NOTYPE  GLOBAL DEFAULT    1 __bss_start
     4: 0000000000402000     0 NOTYPE  GLOBAL DEFAULT    1 _edata
     5: 0000000000402000     0 NOTYPE  GLOBAL DEFAULT    1 _end

No version information found in this file.
$ ./a.out
$


Note that the program headers (starting at 0x400000 + 64) are not in a load
segment, so if the executable tries to access it (based on the program header
address the kernel passed in auxv) then it will be a runtime fault.
(reading program headers is e.g. needed to support tls in static executables)

if i add a readonly note section then program headers are correctly loaded:

$ ld --build-id -static t.o
$ readelf -lW a.out

Elf file type is EXEC (Executable file)
Entry point 0x401000
There are 3 program headers, starting at offset 64

Program Headers:
  Type           Offset   VirtAddr           PhysAddr           FileSiz  MemSiz
  Flg Align
  LOAD           0x000000 0x0000000000400000 0x0000000000400000 0x00010c
0x00010c R   0x1000
  LOAD           0x001000 0x0000000000401000 0x0000000000401000 0x00000a
0x00000a R E 0x1000
  NOTE           0x0000e8 0x00000000004000e8 0x00000000004000e8 0x000024
0x000024 R   0x4

 Section to Segment mapping:
  Segment Sections...
   00     .note.gnu.build-id 
   01     .text 
   02     .note.gnu.build-id 
$


with a 2.30 ld, the program headers are part of the same segment as .text so it
is loaded (and executable):

$ readelf -lW a.out

Elf file type is EXEC (Executable file)
Entry point 0x400078
There is 1 program header, starting at offset 64

Program Headers:
  Type           Offset   VirtAddr           PhysAddr           FileSiz  MemSiz
  Flg Align
  LOAD           0x000000 0x0000000000400000 0x0000000000400000 0x000082
0x000082 R E 0x200000

 Section to Segment mapping:
  Segment Sections...
   00     .text 
$

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