kernel modules can't be loaded if build with 2019.03-rc1 toolchain

[evgeniy-paltsev]

If we build kernel with 2019.03-rc1 toolchain we get errors on modules loading.

I.E:

insmod ./lib/modules/4.19.9/kernel/net/ipv6/ipv6.ko
ipv6: unknown relocation: 82
insmod: ERROR: could not insert module ./lib/modules/4.19.9/kernel/net/ipv6/ipv6.ko: Invalid module format

Everything works fine with previous toolchain (2018.09).
This issue can be reproduced on different versions of kernel (I've tried 4.19.9, 4.20)

[evgeniy-paltsev]

CC @vineetgarc @abrodkin

[evgeniy-paltsev]

BTW, it's enough to build only modules with 2019.03-rc1 toolchain to reproduce this issue.
(I.E. build modules with 2019.03-rc1, build the rest of the kernel with 2018.09)

[evgeniy-paltsev]

Ok, it's new R_ARC_S8H_PCREL type of relocation.
We need to add support of this relocation type to the our module.c

[claziss]

No need to do such an operation for the time being. The following relocs have being introduced to support linker-time relaxation:

Enum	ELF Reloc Type	Description	Details
80	R_ARC_S9H_PCREL	PC-relative	bits9 = ME ( ( ( ( S + A ) - P ) >> 1 ) ) )
81	R_ARC_S7H_PCREL	PC-relative	bits7 = (( S + A ) - P ) >> 1
82	R_ARC_S8H_PCREL	PC-relative	disp8h = (( S + A ) - P ) >> 1
83	R_ARC_S10H_PCREL	PC-relative	bits10 = (( S + A ) - P ) >> 1
84	R_ARC_S13H_PCREL	PC-relative	bits13 = ME ( ( ( ( S + A ) - P ) >> 1 ) ) )
85	R_ARC_ALIGN	Alignment statement
86	R_ARC_ADD8	8-bit label addition	word8 = S + A
87	R_ARC_ADD16	16-bit label addition	word16 = S + A
88	R_ARC_SUB8	8-bit label subtraction	word8 = S - A
89	R_ARC_SUB16	16-bit label subtraction	word16 = S - A
90	R_ARC_SUB32	32-bit label subtraction	word32 = S - A

A binutils patch will be added to make the tools to behave as "before" when the linker relaxation is not required.

[evgeniy-paltsev]

Kernel nodules loading works fine if we build modules with 2019.03-rc2 toolchain.