32-bit powerpc and powerpc64 kernel relocation types when built via system-clang-8 and devel/powerpc64-binutils: a few R_PPC*_ADDR32 mixed in with the R_PPC*_RELATIVE

[Mark Millard]

I'm not sure if getting a few R_PPC_ADDR32/R_PPC64_ADDR64
in the kernel is expected or not.

This was a amd64 -> powerpc cross build from/for:

# uname -apKU
FreeBSD FBSDFSSD 13.0-CURRENT FreeBSD 13.0-CURRENT #20 r347549M: Fri May 31 17:00:45 PDT 2019     markmi at FBSDFSSD:/usr/obj/amd64_clang/amd64.amd64/usr/src/amd64.amd64/sys/GENERIC-NODBG  amd64 amd64 1300025 1300025

system clang was used for the build but devel/powerpc64-binutils was used.

# readelf -asW /usr/obj/DESTDIRs/clang-powerpc-installkernel_altbinutils/boot/kernel/kernel | grep -v R_PPC_RELATIVE | less
. . .
Relocation section with addend (.rela.dyn):
r_offset r_info   r_type              st_value st_name + r_addend
00da1744 00275101 R_PPC_ADDR32        00000000 uart_quicc_class + 0

Relocation section with addend (.rela.text):
r_offset r_info   r_type              st_value st_name + r_addend

Relocation section with addend (.rela.data):
r_offset r_info   r_type              st_value st_name + r_addend

Relocation section with addend (.rela.got):
r_offset r_info   r_type              st_value st_name + r_addend

Relocation section with addend (.rela.got2):
r_offset r_info   r_type              st_value st_name + r_addend
00e646d0 00117401 R_PPC_ADDR32        00000000 mfs_root_end + 0
00e646d4 002d7c01 R_PPC_ADDR32        00000000 mfs_root + 0
00e67c94 002b3a01 R_PPC_ADDR32        00000000 __stop_set_uart_fdt_class_set + 0
00e67c98 00210301 R_PPC_ADDR32        00000000 __start_set_uart_fdt_class_set + 0

. . .


# readelf -asW /usr/obj/DESTDIRs/clang-powerpc64-installkernel_altbinutils/boot/kernel/kernel | grep -v R_PPC64_RELATIVE | less
. . .
Relocation section with addend (.rela.dyn):
r_offset         r_info           r_type                   st_value         st_name + r_addend
000000000130c360 00002d2800000026 R_PPC64_ADDR64           0000000000000000 uart_quicc_class + 0
0000000001362008 0000143600000026 R_PPC64_ADDR64           0000000000000000 mfs_root_end + 0
0000000001362010 0000343300000026 R_PPC64_ADDR64           0000000000000000 mfs_root + 0
0000000001362018 000031a000000026 R_PPC64_ADDR64           0000000000000000 __stop_set_uart_fdt_class_set + 0
0000000001362020 000025fd00000026 R_PPC64_ADDR64           0000000000000000 __start_set_uart_fdt_class_set + 0

Relocation section with addend (.rela.text):
r_offset         r_info           r_type                   st_value         st_name + r_addend

Relocation section with addend (.rela.data):
r_offset         r_info           r_type                   st_value         st_name + r_addend

. . .

So it is always:

uart_quicc_class
mfs_root_end
mfs_root
__stop_set_uart_fdt_class_set
__start_set_uart_fdt_class_set

but the .rela.got2 vs. .rela.dyn status varies for all
but uart_quicc_class in my context.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)