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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
64 lines
1.0 KiB
C
64 lines
1.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* Copyright (C) 2015 Josh Poimboeuf <jpoimboe@redhat.com>
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*/
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#ifndef _BUILTIN_H
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#define _BUILTIN_H
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#include <subcmd/parse-options.h>
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struct opts {
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/* actions: */
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bool checksum;
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const char *disas;
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bool dump_orc;
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bool hack_jump_label;
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bool hack_noinstr;
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bool hack_skylake;
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bool ibt;
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bool klp_symids;
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bool mcount;
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bool noabs;
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bool noinstr;
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bool orc;
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int prefix;
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bool retpoline;
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bool rethunk;
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bool unret;
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bool sls;
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bool stackval;
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bool static_call;
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bool uaccess;
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/* options: */
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bool backtrace;
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bool backup;
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bool cfi;
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const char *debug_checksum;
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bool dryrun;
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bool fineibt;
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bool link;
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bool mnop;
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bool module;
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bool no_unreachable;
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const char *output;
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bool sec_address;
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bool stats;
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const char *trace;
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bool verbose;
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bool werror;
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bool wide;
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};
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extern struct opts opts;
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int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
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int objtool_run(int argc, const char **argv);
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int make_backup(void);
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int cmd_klp(int argc, const char **argv);
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#endif /* _BUILTIN_H */
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