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(-)
>
On Fri, 2022-07-29 at 10:23 +0800, Youling Tang wrote:
> 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.
>
Retroactively, append the changes from v1 to v2:
- Fix a stupid programming error (confusion between the number of PLT
entries and the number of GOT entries). (Bug spotted by Youling).
- Synthesize the _GLOBAL_OFFSET_TABLE_ symbol with module.lds, instead
of faking it at runtime. The 3rd patch from V1 is now merged into
the 1st patch because it would be a one-line change. (Suggested by
Jinyang).
- Keep reloc_rela_handlers[] ordered by the relocation type ID.
(Suggested by Youling).
- Remove -fplt along with -Wa,-mla-* options because it's the default.
(Suggested by Youling).
--
Xi Ruoyao <[email protected]>
School of Aerospace Science and Technology, Xidian University