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

From: Palmer Dabbelt
Date: Tue Mar 20 2018 - 13:11:52 EST


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.