6.16-stable review patch. If anyone has any objections, please let me know.
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From: Tiezhu Yang yangtiezhu@loongson.cn
commit 74f8295c6fb8436bec9995baf6ba463151b6fb68 upstream.
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-zYrfpris... Suggested-by: WANG Rui wangrui@loongson.cn Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/loongarch/Kconfig | 4 ++++ arch/loongarch/Makefile | 5 +++++ 2 files changed, 9 insertions(+)
--- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -301,6 +301,10 @@ config AS_HAS_LVZ_EXTENSION config CC_HAS_ANNOTATE_TABLEJUMP def_bool $(cc-option,-mannotate-tablejump)
+config RUSTC_HAS_ANNOTATE_TABLEJUMP + depends on RUST + def_bool $(rustc-option,-Cllvm-args=--loongarch-annotate-tablejump) + menu "Kernel type and options"
source "kernel/Kconfig.hz" --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -106,6 +106,11 @@ KBUILD_CFLAGS += -mannotate-tablejump else KBUILD_CFLAGS += -fno-jump-tables # keep compatibility with older compilers endif +ifdef CONFIG_RUSTC_HAS_ANNOTATE_TABLEJUMP +KBUILD_RUSTFLAGS += -Cllvm-args=--loongarch-annotate-tablejump +else +KBUILD_RUSTFLAGS += -Zno-jump-tables # keep compatibility with older compilers +endif ifdef CONFIG_LTO_CLANG # The annotate-tablejump option can not be passed to LLVM backend when LTO is enabled. # Ensure it is aware of linker with LTO, '--loongarch-annotate-tablejump' also needs to