SPARC64's crt1.o is wrongly compiled with -fPIC

[Rui Ueyama]

Ubuntu 22's libc6-dev-sparc64-cross package (version 2.35-0ubuntu3cross4) seems to contain a mis-configured crt1.o file. It looks like the file was wrongly compiled with -fPIC option. As a result, you can only cross-build position-independent executables for SPARC64.

  $ sparc64-linux-gnu-gcc-12 -o hello hello.c -fPIC -pie
  $ qemu-sparc64 -L /usr/sparc64-linux-gnu ./hello
  Hello world

  $ sparc64-linux-gnu-gcc-12 -o hello hello.c -fno-PIC -no-pie
  $ qemu-sparc64 -L /usr/sparc64-linux-gnu ./hello
  Illegal instruction (core dumped)

Here is the content of the correct crt1.o file (taken from Debian):

  $ sparc64-linux-gnu-objdump -dr /usr/sparc64-linux-gnu/lib/crt1.o
  /usr/sparc64-linux-gnu/lib/crt1.o: file format elf64-sparc
  Disassembly of section .text:

  0000000000000000 <_start>:
     0: bc 10 00 00 mov %g0, %fp
     4: 9c 23 a0 30 sub %sp, 0x30, %sp
     8: d2 5b a8 af ldx [ %sp + 0x8af ], %o1
     c: 94 03 a8 b7 add %sp, 0x8b7, %o2
    10: 11 00 00 00 sethi %hi(0), %o0
                          10: R_SPARC_HI22 main
    14: 17 00 00 00 sethi %hi(0), %o3
                          14: R_SPARC_HI22 __libc_csu_init
    18: 19 00 00 00 sethi %hi(0), %o4
                          18: R_SPARC_HI22 __libc_csu_fini
    1c: 90 12 20 00 mov %o0, %o0
                          1c: R_SPARC_LO10 main
    20: 96 12 e0 00 mov %o3, %o3
                          20: R_SPARC_LO10 __libc_csu_init
    24: 98 13 20 00 mov %o4, %o4
                          24: R_SPARC_LO10 __libc_csu_fini
    28: 9a 10 00 01 mov %g1, %o5
    2c: 40 00 00 00 call 2c <_start+0x2c>
                          2c: R_SPARC_WDISP30 __libc_start_main
    30: 01 00 00 00 nop
    34: 00 00 00 00 illtrap 0

This is a dump of Ubuntu's bad crt1.o file.

  $ sparc64-linux-gnu-objdump -dr /usr/sparc64-linux-gnu/lib/crt1.o
  /usr/sparc64-linux-gnu/lib/crt1.o: file format elf64-sparc
  Disassembly of section .text:

  0000000000000000 <_start>:
     0: 2f 00 00 00 sethi %hi(0), %l7
                          0: R_SPARC_HI22 _GLOBAL_OFFSET_TABLE_-0x4
     4: 40 00 00 00 call 4 <_start+0x4>
                          4: R_SPARC_WDISP30 __sparc_get_pc_thunk.l7
     8: ae 15 e0 00 mov %l7, %l7 ! 0 <_start>
                          8: R_SPARC_LO10 _GLOBAL_OFFSET_TABLE_+0x4
     c: bc 10 00 00 mov %g0, %fp
    10: 9c 23 a0 30 sub %sp, 0x30, %sp
    14: d2 5b a8 af ldx [ %sp + 0x8af ], %o1
    18: 94 03 a8 b7 add %sp, 0x8b7, %o2
    1c: 11 00 00 00 sethi %hi(0), %o0
                          1c: R_SPARC_GOTDATA_OP_HIX22 main
    20: 90 1a 20 00 xor %o0, 0, %o0
                          20: R_SPARC_GOTDATA_OP_LOX10 main
    24: d0 5d c0 08 ldx [ %l7 + %o0 ], %o0
                          24: R_SPARC_GOTDATA_OP main
    28: 96 10 20 00 clr %o3
    2c: 98 10 20 00 clr %o4
    30: 9a 10 00 01 mov %g1, %o5
    34: 40 00 00 00 call 34 <_start+0x34>
                          34: R_SPARC_WDISP30 __libc_start_main
    38: 01 00 00 00 nop
    3c: 00 00 00 00 illtrap 0