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

[Shea Levy]

Hi Palmer, Zong,

Palmer Dabbelt <palmer@xxxxxxxxxx> writes:

> On Thu, 15 Mar 2018 01:50:40 PDT (-0700), zong@xxxxxxxxxxxxx wrote:
>> 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
>
> Thanks!  I've added this to our for-next branch, so it should start to get a
> bit more testing soon.  I've had a bit of the flu and am therefor a bit out of
> it, so I'll try to look closer before the next merge window.
>

I've updated my kernel to point to riscv-all, and now I'm getting:

scsi_mod: target ffffffe000029a80 can not be addressed by the 32-bit offset from PC = 00000000fe3be867

Any idea why this might be? My patchset had a patch [1] to ensure
modules were loaded within a 32 bit offset of the kernel text, do we
need to include that?

Thanks,
Shea

[1] http://lists.infradead.org/pipermail/linux-riscv/2018-February/000083.html

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