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bb1f85d604
Similar as other architectures such as arm64, x86 and so on, use
offsets relative to the exception table entry values rather than
absolute addresses for both the exception locationand the fixup.
However, RISCV label difference will actually produce two relocations,
a pair of R_RISCV_ADD32 and R_RISCV_SUB32. Take below simple code for
example:
$ cat test.S
.section .text
1:
nop
.section __ex_table,"a"
.balign 4
.long (1b - .)
.previous
$ riscv64-linux-gnu-gcc -c test.S
$ riscv64-linux-gnu-readelf -r test.o
Relocation section '.rela__ex_table' at offset 0x100 contains 2 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000000 000600000023 R_RISCV_ADD32 0000000000000000 .L1^B1 + 0
000000000000 000500000027 R_RISCV_SUB32 0000000000000000 .L0 + 0
The modpost will complain the R_RISCV_SUB32 relocation, so we need to
patch modpost.c to skip this relocation for .rela__ex_table section.
After this patch, the __ex_table section size of defconfig vmlinux is
reduced from 7072 Bytes to 3536 Bytes.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.