Re: [PATCH v2 00/11] RISC-V: Resolve the issue of loadable module on 64-bit

[Zong Li]

2018-03-15 16:50 GMT+08:00 Zong Li <zong@xxxxxxxxxxxxx>:
> These patches resolve the some issues of loadable module.
>   - symbol out of ranges
>   - unknown relocation types
>
> The reference of external variable and function symbols
> cannot exceed 32-bit offset ranges in kernel module.
> The module only can work on the 32-bit OS or the 64-bit
> OS with sv32 virtual addressing.
>
> These patches will generate the .got, .got.plt and
> .plt sections during loading module, let it can refer
> to the symbol which locate more than 32-bit offset.
> These sections depend on the relocation types:
>  - R_RISCV_GOT_HI20
>  - R_RISCV_CALL_PLT
>
> These patches also support more relocation types
>  - R_RISCV_CALL
>  - R_RISCV_HI20
>  - R_RISCV_LO12_I
>  - R_RISCV_LO12_S
>  - R_RISCV_RVC_BRANCH
>  - R_RISCV_RVC_JUMP
>  - R_RISCV_ALIGN
>  - R_RISCV_ADD32
>  - R_RISCV_SUB32
>
> This is the list of testing modules:
> # lsmod
> btrfs 7876158 0 - Live 0xffffffd00745d000
> ramoops 90806 0 - Live 0xffffffd0024b8000
> lzo 10554 0 - Live 0xffffffd002050000
> zstd_decompress 567575 1 btrfs, Live 0xffffffd00238b000
> zstd_compress 1543837 1 btrfs, Live 0xffffffd002211000
> zram 101300 0 - Live 0xffffffd0021b8000
> xxhash 62254 2 zstd_decompress,zstd_compress, Live 0xffffffd0020cf000
> xor 33246 1 btrfs, Live 0xffffffd002042000
> xfs 4395343 0 - Live 0xffffffd00399e000
> tun 252041 0 - Live 0xffffffd0038e0000
> test_user_copy 5265 0 - Live 0xffffffd003783000
> test_static_keys 19606 0 - Live 0xffffffd003717000
> test_static_key_base 7374 1 test_static_keys, Live 0xffffffd0036dc000
> test_printf 7804 0 [permanent], Live 0xffffffd00369c000
> test_module 1557 0 - Live 0xffffffd003646000
> test_kmod 49100 0 - Live 0xffffffd0035f2000
> test_bpf 1599301 0 - Live 0xffffffd003000000
> test_bitmap 4403 0 - Live 0xffffffd002dd8000
> reed_solomon 38866 1 ramoops, Live 0xffffffd002d86000
> raid6_pq 161872 1 btrfs, Live 0xffffffd002b9e000
> netdevsim 65401 0 - Live 0xffffffd002910000
>
> Signed-off-by: Zong Li <zong@xxxxxxxxxxxxx>
> ---
> Change in v2:
>  - Add compile option 'mno-relax' for build kernel module
>  - Just fail on ALIGN type, this is unexpected type with mno-relax.
>
> Zong Li (11):
>   RISC-V: Add sections of PLT and GOT for kernel module
>   RISC-V: Add section of GOT.PLT for kernel module
>   RISC-V: Support GOT_HI20/CALL_PLT relocation type in kernel module
>   RISC-V: Support CALL relocation type in kernel module
>   RISC-V: Support HI20/LO12_I/LO12_S relocation type in kernel module
>   RISC-V: Support RVC_BRANCH/JUMP relocation type in kernel modulewq
>   RISC-V: Support ALIGN relocation type in kernel module
>   RISC-V: Support ADD32 relocation type in kernel module
>   RISC-V: Support SUB32 relocation type in kernel module
>   RISC-V: Enable module support in defconfig
>   RISC-V: Add definition of relocation types
>
>  arch/riscv/Kconfig                  |   5 +
>  arch/riscv/Makefile                 |   5 +
>  arch/riscv/configs/defconfig        |   2 +
>  arch/riscv/include/asm/module.h     | 113 +++++++++++++++++++++++
>  arch/riscv/include/uapi/asm/elf.h   |   7 ++
>  arch/riscv/kernel/Makefile          |   1 +
>  arch/riscv/kernel/module-sections.c | 156 +++++++++++++++++++++++++++++++
>  arch/riscv/kernel/module.c          | 179 ++++++++++++++++++++++++++++++++++--
>  arch/riscv/kernel/module.lds        |   8 ++
>  9 files changed, 470 insertions(+), 6 deletions(-)
>  create mode 100644 arch/riscv/include/asm/module.h
>  create mode 100644 arch/riscv/kernel/module-sections.c
>  create mode 100644 arch/riscv/kernel/module.lds
>
> --
> 2.16.1
>

Hi,

The ALIGN relocation type is just fail and print the error message on
v2 version,
Because I think that it will not exist in module which building with
'mno-relax ' option,
The behavior of check alignment will become a redundant thing.

Thanks a lot.