[RTEMS Project] #3740: Libld does not load incrementially linked object file

[RTEMS trac]

#3740: Libld does not load incrementially linked object file
--------------------------+-------------------------
  Reporter:  Chris Johns  |      Owner:  Chris Johns
      Type:  defect       |     Status:  assigned
  Priority:  normal       |  Milestone:  5.1
 Component:  lib/dl       |    Version:  5
  Severity:  normal       |   Keywords:
Blocked By:               |   Blocking:
--------------------------+-------------------------
 If separate object files have the same local symbol and are incrementally
 linked `libdl` only uses the first symbol found.

 The issue has been raised by Peter in a post to `devel`:

  https://lists.rtems.org/pipermail/devel/2019-April/025623.html

 The issue can be shown with:
 {{{
 $ cat foo.c
 #include <stdio.h>

 extern void foo(void);
 void foo(void)
 {
     printf("FOO %s\n", "Foo 1");
 }
 $ cat bar.c
 #include <stdio.h>

 extern void bar(void);
 void bar(void)
 {
     printf("BAR %s\n", "Bar 1");
 }
 $ arm-rtems5-gcc -march=armv7-a -mthumb -c foo.c
 $ arm-rtems5-gcc -march=armv7-a -mthumb -c bar.c
 $ arm-rtems5-ld -r -o fubar bar.o foo.o
 $ arm-rtems5-readelf -s fubar

 Symbol table '.symtab' contains 20 entries:
    Num:    Value  Size Type    Bind   Vis      Ndx Name
      0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
      1: 00000000     0 SECTION LOCAL  DEFAULT    1
      2: 00000000     0 SECTION LOCAL  DEFAULT    3
      3: 00000000     0 SECTION LOCAL  DEFAULT    4
      4: 00000000     0 SECTION LOCAL  DEFAULT    5
      5: 00000000     0 SECTION LOCAL  DEFAULT    6
      6: 00000000     0 SECTION LOCAL  DEFAULT    7
      7: 00000000     0 FILE    LOCAL  DEFAULT  ABS bar.c
      8: 00000000     0 NOTYPE  LOCAL  DEFAULT    3 $d
      9: 00000000     0 NOTYPE  LOCAL  DEFAULT    3 .LC0
     10: 00000008     0 NOTYPE  LOCAL  DEFAULT    3 .LC1
     11: 00000000     0 NOTYPE  LOCAL  DEFAULT    1 $t
     12: 00000000     0 FILE    LOCAL  DEFAULT  ABS foo.c
     13: 00000010     0 NOTYPE  LOCAL  DEFAULT    3 $d
     14: 00000010     0 NOTYPE  LOCAL  DEFAULT    3 .LC0
     15: 00000018     0 NOTYPE  LOCAL  DEFAULT    3 .LC1
     16: 0000001c     0 NOTYPE  LOCAL  DEFAULT    1 $t
     17: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND printf
     18: 0000001d    28 FUNC    GLOBAL DEFAULT    1 foo
     19: 00000001    28 FUNC    GLOBAL DEFAULT    1 bar
 $ arm-rtems5-objdump --disassemble --source fubar

 fubar:     file format elf32-littlearm

 Disassembly of section .text:

 00000000 <bar>:
    0:   b580            push    {r7, lr}
    2:   af00            add     r7, sp, #0
    4:   f240 0100       movw    r1, #0
    8:   f2c0 0100       movt    r1, #0
    c:   f240 0000       movw    r0, #0
   10:   f2c0 0000       movt    r0, #0
   14:   f7ff fffe       bl      0 <printf>
   18:   bf00            nop
   1a:   bd80            pop     {r7, pc}

 0000001c <foo>:
   1c:   b580            push    {r7, lr}
   1e:   af00            add     r7, sp, #0
   20:   f240 0100       movw    r1, #0
   24:   f2c0 0100       movt    r1, #0
   28:   f240 0000       movw    r0, #0
   2c:   f2c0 0000       movt    r0, #0
   30:   f7ff fffe       bl      0 <printf>
   34:   bf00            nop
   36:   bd80            pop     {r7, pc}
 }}}

--
Ticket URL: <http://devel.rtems.org/ticket/3740>
RTEMS Project <http://www.rtems.org/>
RTEMS Project