From a47bc954cf0eb51f2828e1607d169d487df7f11f Mon Sep 17 00:00:00 2001 From: Tiezhu Yang Date: Wed, 20 Aug 2025 22:23:15 +0800 Subject: [PATCH] objtool/LoongArch: Get table size correctly 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. Before doing the above changes, it should handle the special case of the relocation section '.rela.discard.tablejump_annotate' to get the correct table size first, otherwise there are many objtool warnings and errors if LTO is enabled. There are many different rodata for each function if LTO is enabled, it is necessary to enhance get_rodata_table_size_by_table_annotate(). Fixes: b95f852d3af2 ("objtool/LoongArch: Add support for switch table") Closes: https://lore.kernel.org/loongarch/20250731175655.GA1455142@ax162/ Reported-by: Nathan Chancellor Tested-by: Nathan Chancellor Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen --- tools/objtool/arch/loongarch/special.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/tools/objtool/arch/loongarch/special.c b/tools/objtool/arch/loongarch/special.c index e39f86d97002b..a80b75f7b061f 100644 --- a/tools/objtool/arch/loongarch/special.c +++ b/tools/objtool/arch/loongarch/special.c @@ -27,6 +27,7 @@ static void get_rodata_table_size_by_table_annotate(struct objtool_file *file, struct table_info *next_table; unsigned long tmp_insn_offset; unsigned long tmp_rodata_offset; + bool is_valid_list = false; rsec = find_section_by_name(file->elf, ".rela.discard.tablejump_annotate"); if (!rsec) @@ -35,6 +36,12 @@ static void get_rodata_table_size_by_table_annotate(struct objtool_file *file, INIT_LIST_HEAD(&table_list); for_each_reloc(rsec, reloc) { + if (reloc->sym->sec->rodata) + continue; + + if (strcmp(insn->sec->name, reloc->sym->sec->name)) + continue; + orig_table = malloc(sizeof(struct table_info)); if (!orig_table) { WARN("malloc failed"); @@ -49,6 +56,22 @@ static void get_rodata_table_size_by_table_annotate(struct objtool_file *file, if (reloc_idx(reloc) + 1 == sec_num_entries(rsec)) break; + + if (strcmp(insn->sec->name, (reloc + 1)->sym->sec->name)) { + list_for_each_entry(orig_table, &table_list, jump_info) { + if (orig_table->insn_offset == insn->offset) { + is_valid_list = true; + break; + } + } + + if (!is_valid_list) { + list_del_init(&table_list); + continue; + } + + break; + } } list_for_each_entry(orig_table, &table_list, jump_info) { -- 2.51.0