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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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029223d301
Livepatch identifies a duplicate-named symbol by its position (sympos) among same-named kallsyms entries, which for vmlinux are counted in ascending address order in the final linked kernel. That order can't be reliably derived from vmlinux.o: the final link reorders sub-sections (.text.unlikely*, .data..*, etc). Bridge the gap with a new .klp.symid section which can be used to correlate symbols between vmlinux.o and vmlinux so that klp-diff can reliably determine the sympos. The table can't survive --gc-sections: keeping it alive would keep every duplicate-named symbol's section alive, so the reference kernel would stop matching the one which ships. klp-build rejects CONFIG_LD_DEAD_CODE_DATA_ELIMINATION instead. Nothing is lost today: x86_64 is the only HAVE_KLP_BUILD arch and doesn't select HAVE_LD_DEAD_CODE_DATA_ELIMINATION, arm64 and s390 have never selected it either, and on powerpc, it's still EXPERIMENTAL and disabled by every distro kernel. This is the build-time half of reliable vmlinux sympos computation; "objtool klp diff" will consume the table in a subsequent commit. Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: live-patching@vger.kernel.org Link: https://patch.msgid.link/64d50f077b569f47883c015cdb7079edb068efe8.1785727106.git.jpoimboe@kernel.org
39 lines
900 B
Plaintext
39 lines
900 B
Plaintext
objtool-y += arch/$(SRCARCH)/
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objtool-y += weak.o
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objtool-y += check.o
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objtool-y += special.o
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objtool-y += builtin-check.o
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objtool-y += elf.o
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objtool-y += klp-symid.o
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objtool-y += objtool.o
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objtool-$(BUILD_DISAS) += disas.o
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objtool-$(BUILD_DISAS) += trace.o
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objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o
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objtool-$(BUILD_KLP) += builtin-klp.o klp-checksum.o klp-diff.o klp-post-link.o
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objtool-y += libstring.o
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objtool-y += libctype.o
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objtool-y += str_error_r.o
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objtool-y += librbtree.o
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objtool-y += signal.o
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$(OUTPUT)libstring.o: ../lib/string.c FORCE
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$(call rule_mkdir)
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$(call if_changed_dep,cc_o_c)
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$(OUTPUT)libctype.o: ../lib/ctype.c FORCE
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$(call rule_mkdir)
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$(call if_changed_dep,cc_o_c)
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$(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
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$(call rule_mkdir)
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$(call if_changed_dep,cc_o_c)
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$(OUTPUT)librbtree.o: ../lib/rbtree.c FORCE
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$(call rule_mkdir)
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$(call if_changed_dep,cc_o_c)
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