pussuw commented on PR #12853:
URL: https://github.com/apache/nuttx/pull/12853#issuecomment-2270842965
I would appreciate if someone who actually knows the elf file format better
could chime in on this.
When building nsh (used as init) as a relocatable elf file, this is what the
linker produces when using the nuttx gnu-elf.ld linker script:
```ville@workpc:~/Desktop/Kernelmode/cxx_bad_relocation$ objdump -hw init
objdump: Warning: Bogus end-of-siblings marker detected at offset 3e9 in
.debug_info section
objdump: Warning: Bogus end-of-siblings marker detected at offset 403 in
.debug_info section
objdump: Warning: Bogus end-of-siblings marker detected at offset 404 in
.debug_info section
objdump: Warning: Further warnings about bogus end-of-sibling markers
suppressed
objdump: Warning: DIE at offset 0x433 refers to abbreviation number 955
which does not exist
init: file format elf64-little
Sections:
Idx Name Size VMA LMA
File off Algn Flags
0 .text 0000adde 0000000000000000 0000000000000000
00000040 2**1 CONTENTS, ALLOC, LOAD, RELOC, READONLY, CODE
1 .rodata 0000234c 000000000000ade0 000000000000ade0
0000ae20 2**3 CONTENTS, ALLOC, LOAD, RELOC, READONLY, DATA
2 .srodata.g_nullstring 00000009 0000000000000000 0000000000000000
0000d170 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .srodata.cst8 00000030 0000000000000000 0000000000000000
0000d180 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .srodata.g_arg_separator 00000003 0000000000000000 0000000000000000
0000d1b0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .srodata.g_exitstatus 00000002 0000000000000000 0000000000000000
0000d1b8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .srodata.g_failure 00000002 0000000000000000 0000000000000000
0000d1c0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .srodata.g_line_separator 00000006 0000000000000000 0000000000000000
0000d1c8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .srodata.g_quote_separator 00000004 0000000000000000 0000000000000000
0000d1d0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .srodata.g_redirect1 00000002 0000000000000000 0000000000000000
0000d1d8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
10 .srodata.g_redirect2 00000003 0000000000000000 0000000000000000
0000d1e0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
11 .srodata.g_success 00000002 0000000000000000 0000000000000000
0000d1e8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
12 .srodata.g_token_separator 00000004 0000000000000000 0000000000000000
0000d1f0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
13 .srodata.g_erasetoeol 00000003 0000000000000000 0000000000000000
0000d1f8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
14 .srodata.g_home 00000002 0000000000000000 0000000000000000
0000d200 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
15 .srodata.g_oldpwd 00000007 0000000000000000 0000000000000000
0000d208 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
16 .srodata.g_pwd 00000004 0000000000000000 0000000000000000
0000d210 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
17 .srodata.cst4 0000000c 0000000000000000 0000000000000000
0000d214 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA
18 .srodata.g_flags 00000007 0000000000000000 0000000000000000
0000d220 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
19 .srodata.g_groupid 00000007 0000000000000000 0000000000000000
0000d228 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
20 .srodata.g_state 00000007 0000000000000000 0000000000000000
0000d230 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
21 .srodata.g_type 00000006 0000000000000000 0000000000000000
0000d238 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
22 .srodata.g_unknown 00000008 0000000000000000 0000000000000000
0000d240 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
23 .data 00000048 0000000000000008 0000000000000008
0000d248 2**3 CONTENTS, ALLOC, LOAD, DATA
24 .sdata.__dso_handle 00000008 0000000000000000 0000000000000000
0000d290 2**3 CONTENTS, ALLOC, LOAD, RELOC, DATA
25 .sdata.g_syslog_mask 00000001 0000000000000000 0000000000000000
0000d298 2**0 CONTENTS, ALLOC, LOAD, DATA
26 .ctors 00000000 0000000000000001 0000000000000001
0000d299 2**0 CONTENTS
27 .dtors 00000000 0000000000000001 0000000000000001
0000d299 2**0 CONTENTS
28 .bss 0000054c 0000000000000008 0000000000000008
0000d2a0 2**3 ALLOC
29 .tdata 00000000 0000000000000554 0000000000000554
0000d2a0 2**0 CONTENTS, ALLOC, LOAD, DATA, THREAD_LOCAL
30 .tbss 00000000 0000000000000554 0000000000000554
0000d2a0 2**0 ALLOC, THREAD_LOCAL
31 .comment 000023cb 0000000000000000 0000000000000000
0000d2a0 2**0 CONTENTS, READONLY
32 .riscv.attributes 00000035 0000000000000000 0000000000000000
0000f66b 2**0 CONTENTS, READONLY
33 .debug_abbrev 0000f594 0000000000000000 0000000000000000
0000f6a0 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
34 .debug_info 00037cd9 0000000000000000 0000000000000000
0001ec34 2**0 CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
35 .debug_line 000282b5 0000000000000000 0000000000000000
0005690d 2**0 CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
36 .debug_aranges 00002d40 0000000000000000 0000000000000000
0007ebd0 2**4 CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
37 .debug_loc 00020cae 0000000000000000 0000000000000000
00081910 2**0 CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
38 .debug_ranges 00003ac0 0000000000000000 0000000000000000
000a25be 2**0 CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
39 .debug_str 00036e1b 0000000000000000 0000000000000000
000a607e 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
40 .debug_frame 00004598 0000000000000000 0000000000000000
000dcea0 2**3 CONTENTS, RELOC, READONLY, DEBUGGING, OCTETS
```
As can be seen, the .ctor and .dtor sections are empty, and not allocated. I
think this is expected.
If I use the RISC-V GNU toolchain to do final linking, it assigns LMA and
VMA addresses for .ctors and .dtors. This is why nsh works as init with e.g.
our qemu rv-virt:knsh targets; the VMA address is set!
```
ville@workpc:~/Desktop/Kernelmode/cxx_bad_relocation$ objdump -hw a.out
a.out: file format elf64-little
Sections:
Idx Name Size VMA LMA
File off Algn Flags
0 .text 00009db8 00000000c0000000 00000000c0000000
00001000 2**1 CONTENTS, ALLOC, LOAD, READONLY, CODE
1 .rodata 0000234c 00000000c0009db8 00000000c0009db8
0000adb8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .srodata.g_nullstring 00000009 00000000c000c108 00000000c000c108
0000d108 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .srodata.cst8 00000030 00000000c000c118 00000000c000c118
0000d118 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .srodata.g_arg_separator 00000003 00000000c000c148 00000000c000c148
0000d148 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .srodata.g_exitstatus 00000002 00000000c000c150 00000000c000c150
0000d150 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .srodata.g_failure 00000002 00000000c000c158 00000000c000c158
0000d158 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .srodata.g_line_separator 00000006 00000000c000c160 00000000c000c160
0000d160 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .srodata.g_quote_separator 00000004 00000000c000c168 00000000c000c168
0000d168 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .srodata.g_redirect1 00000002 00000000c000c170 00000000c000c170
0000d170 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
10 .srodata.g_redirect2 00000003 00000000c000c178 00000000c000c178
0000d178 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
11 .srodata.g_success 00000002 00000000c000c180 00000000c000c180
0000d180 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
12 .srodata.g_token_separator 00000004 00000000c000c188 00000000c000c188
0000d188 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
13 .srodata.g_erasetoeol 00000003 00000000c000c190 00000000c000c190
0000d190 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
14 .srodata.g_home 00000002 00000000c000c198 00000000c000c198
0000d198 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
15 .srodata.g_oldpwd 00000007 00000000c000c1a0 00000000c000c1a0
0000d1a0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
16 .srodata.g_pwd 00000004 00000000c000c1a8 00000000c000c1a8
0000d1a8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
17 .srodata.cst4 0000000c 00000000c000c1ac 00000000c000c1ac
0000d1ac 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA
18 .srodata.g_flags 00000007 00000000c000c1b8 00000000c000c1b8
0000d1b8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
19 .srodata.g_groupid 00000007 00000000c000c1c0 00000000c000c1c0
0000d1c0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
20 .srodata.g_state 00000007 00000000c000c1c8 00000000c000c1c8
0000d1c8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
21 .srodata.g_type 00000006 00000000c000c1d0 00000000c000c1d0
0000d1d0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
22 .srodata.g_unknown 00000008 00000000c000c1d8 00000000c000c1d8
0000d1d8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
23 .data 00000048 00000000c000c1e0 00000000c000c1e0
0000d1e0 2**3 CONTENTS, ALLOC, LOAD, DATA
24 .sdata.__dso_handle 00000008 00000000c000c228 00000000c000c228
0000d228 2**3 CONTENTS, ALLOC, LOAD, DATA
25 .sdata.g_syslog_mask 00000001 00000000c000c230 00000000c000c230
0000d230 2**0 CONTENTS, ALLOC, LOAD, DATA
26 .ctors 00000000 00000000c000c231 00000000c000c231
0000d784 2**0 CONTENTS
27 .dtors 00000000 00000000c000c231 00000000c000c231
0000d784 2**0 CONTENTS
28 .bss 0000054c 00000000c000c238 00000000c000c238
0000d231 2**3 ALLOC
29 .tdata 00000000 00000000c000c784 00000000c000c784
0000d784 2**0 CONTENTS, ALLOC, LOAD, DATA, THREAD_LOCAL
30 .tbss 00000000 00000000c000c784 00000000c000c784
0000d784 2**0 ALLOC, THREAD_LOCAL
31 .comment 00000030 0000000000000000 0000000000000000
0000d784 2**0 CONTENTS, READONLY
32 .riscv.attributes 00000035 0000000000000000 0000000000000000
0000d7b4 2**0 CONTENTS, READONLY
33 .debug_abbrev 0000f594 0000000000000000 0000000000000000
0000d7e9 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
34 .debug_info 00037cd9 0000000000000000 0000000000000000
0001cd7d 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
35 .debug_line 000282b5 0000000000000000 0000000000000000
00054a56 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
36 .debug_aranges 00002d40 0000000000000000 0000000000000000
0007cd10 2**4 CONTENTS, READONLY, DEBUGGING, OCTETS
37 .debug_loc 00020cae 0000000000000000 0000000000000000
0007fa50 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
38 .debug_ranges 00003ac0 0000000000000000 0000000000000000
000a06fe 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
39 .debug_str 000046ab 0000000000000000 0000000000000000
000a41be 2**0 CONTENTS, READONLY, DEBUGGING, OCTETS
40 .debug_frame 00004598 0000000000000000 0000000000000000
000a8870 2**3 CONTENTS, READONLY, DEBUGGING, OCTETS
```
However, prior to this patch, the VMA address was _not_ set by the nuttx
binfmt elfloader, which causes a the crash mentioned in the commit message.
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