Re: [PATCH v3 0/4] LoongArch: Support new relocation types

From: Youling Tang
Date: Thu Jul 28 2022 - 22:23:36 EST


Hi, Ruoyao

On 07/29/2022 10:07 AM, Xi Ruoyao wrote:
The version 2.00 of LoongArch ELF ABI specification introduced new
relocation types, and the development tree of Binutils and GCC has
started to use them. If the kernel is built with the latest snapshot of
Binutils or GCC, it will fail to load the modules because of unrecognized
relocation types in modules.

Add support for GOT and new relocation types for the module loader, so
the kernel (with modules) can be built with the "normal" code model and
function properly.

This series does not break the compatibility with old toolchain using
stack-based relocation types, so with the patches applied the kernel can
be be built with both old and new toolchains.

Tested by building the kernel with both Binutils & GCC master branch and
my system Binutils & GCC (without new relocation type support), running
both the builds with 35 in-tree modules loaded, and loading one module
with 20 GOT loads (loaded addresses verified by comparing with
/proc/kallsyms).

Changes from v2 to v3:

- Use `union loongarch_instruction` instead of explicit bit shifts
applying the relocation. Suggested by Youling.
- For R_LARCH_B26, move the alignment check before the range check to be
consistent with stack pop relocations. Suggested by Youling.
- Reword the commit message of the 3rd patch. Suggested by Huacai.

The log of changes from v1 to v2 should be preserved.

Thanks,
Youling

Xi Ruoyao (4):
LoongArch: Add section of GOT for kernel module
LoongArch: Support R_LARCH_SOP_PUSH_GPREL relocation type in kernel
module
LoongArch: Remove -fplt and -Wa,-mla-* from CFLAGS
LoongArch: Support modules with new relocation types

arch/loongarch/Makefile | 4 --
arch/loongarch/include/asm/elf.h | 37 ++++++++++
arch/loongarch/include/asm/module.h | 23 ++++++
arch/loongarch/include/asm/module.lds.h | 1 +
arch/loongarch/kernel/head.S | 10 +--
arch/loongarch/kernel/module-sections.c | 51 +++++++++++--
arch/loongarch/kernel/module.c | 96 +++++++++++++++++++++++++
7 files changed, 209 insertions(+), 13 deletions(-)