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When compiling with LLVM and CONFIG_RUST is set, there exist objtool
warnings in rust/core.o and rust/kernel.o, like this:
rust/core.o: warning: objtool:
_RNvXs1_NtNtCs5QSdWC790r4_4core5ascii10ascii_charNtB5_9AsciiCharNtNtB9_3fmt5Debug3fmt+0x54:
sibling call from callable instruction with modified stack frame
For this special case, the related object file shows that there is no
generated relocation section '.rela.discard.tablejump_annotate' for the
table jump instruction jirl, thus objtool can not know that what is the
actual destination address.
If rustc has the option "-Cllvm-args=--loongarch-annotate-tablejump",
pass the option to enable jump tables for objtool, otherwise it should
pass "-Zno-jump-tables" to keep compatibility with older rustc.
How to test:
$ rustup component add rust-src
$ make LLVM=1 rustavailable
$ make ARCH=loongarch LLVM=1 clean defconfig
$ scripts/config -d MODVERSIONS \
-e RUST -e SAMPLES -e SAMPLES_RUST \
-e SAMPLE_RUST_CONFIGFS -e SAMPLE_RUST_MINIMAL \
-e SAMPLE_RUST_MISC_DEVICE -e SAMPLE_RUST_PRINT \
-e SAMPLE_RUST_DMA -e SAMPLE_RUST_DRIVER_PCI \
-e SAMPLE_RUST_DRIVER_PLATFORM -e SAMPLE_RUST_DRIVER_FAUX \
-e SAMPLE_RUST_DRIVER_AUXILIARY -e SAMPLE_RUST_HOSTPROGS
$ make ARCH=loongarch LLVM=1 olddefconfig all
Cc: stable@vger.kernel.org
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Closes: https://lore.kernel.org/rust-for-linux/CANiq72mNeCuPkCDrG2db3w=AX+O-zYrfprisDPmRac_qh65Dmg@mail.gmail.com/
Suggested-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
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 reStructuredText 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.