From 940713b0a5f595a894d1cd37c36dfaa7f2108ae4 Mon Sep 17 00:00:00 2001 From: maoxiaochuan Date: Sat, 23 Aug 2025 09:43:55 +0800 Subject: [PATCH] LoongArch: Pass annotate-tablejump option if LTO is enabled When compiling with LLVM and CONFIG_LTO_CLANG is set, there exist many objtool warnings "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. It needs to do something on the LLVM side to make sure that there is the relocation section '.rela.discard.tablejump_annotate' if LTO is enabled, but in order to maintain compatibility for the current LLVM compiler, this can be done in the kernel Makefile for now. Ensure it is aware of linker with LTO, '--loongarch-annotate-tablejump' needs to be passed via '-mllvm' to ld.lld. Note that it should also pass the compiler option -mannotate-tablejump rather than only pass '-mllvm --loongarch-annotate-tablejump' to ld.lld if LTO is enabled, otherwise there are no jump info for some table jump instructions. Fixes: e20ab7d454ee ("LoongArch: Enable jump table for objtool") Closes: https://lore.kernel.org/loongarch/20250731175655.GA1455142@ax162/ Reported-by: Nathan Chancellor Tested-by: Nathan Chancellor Co-developed-by: WANG Rui Signed-off-by: WANG Rui Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen Signed-off-by: maoxiaochuan --- arch/loongarch/Makefile | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index 64801db4a..40ec900ff 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -103,7 +103,13 @@ KBUILD_CFLAGS += $(call cc-option,-mthin-add-sub) $(call cc-option,-Wa$(comma) ifdef CONFIG_OBJTOOL ifdef CONFIG_CC_HAS_ANNOTATE_TABLEJUMP -KBUILD_CFLAGS += $(call cc-option,-mannotate-tablejump) +# 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 +# be passed via '-mllvm' to ld.lld. +KBUILD_CFLAGS += -mannotate-tablejump +ifdef CONFIG_LTO_CLANG +KBUILD_LDFLAGS += -mllvm --loongarch-annotate-tablejump +endif else KBUILD_CFLAGS += -fno-jump-tables # keep compatibility with older compilers endif