kernel/git/stable/linux.git/tools/objtool/builtin-check.c, branch master

objtool/klp: Add .klp.symid for sympos disambiguation

2026-08-03T05:12:39+00:00

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 Signed-off-by: Ingo Molnar Cc: live-patching@vger.kernel.org Link: https://patch.msgid.link/64d50f077b569f47883c015cdb7079edb068efe8.1785727106.git.jpoimboe@kernel.org

objtool: Grow __cfi_* prefix symbols for all CFI+CALL_PADDING

2026-05-05T04:16:07+00:00

For all CONFIG_CFI+CONFIG_CALL_PADDING configs, for C functions, the __cfi_ symbols only cover the 5-byte kCFI type hash. After that there also N bytes of NOP padding between the hash and the function entry which aren't associated with any symbol. The NOPs can be replaced with actual code at runtime. Without a symbol, unwinders and tooling have no way of knowing where those bytes belong. Grow the existing __cfi_* symbols to fill that gap. Note that assembly functions with SYM_TYPED_FUNC_START() aren't affected by this issue, their __cfi_ symbols also cover the padding. Also, CONFIG_PREFIX_SYMBOLS has no reason to exist: CONFIG_CALL_PADDING is what causes the compiler to emit NOP padding before function entry (via -fpatchable-function-entry), so it's the right condition for creating prefix symbols. Remove CONFIG_PREFIX_SYMBOLS, as it's no longer needed. Simplify the LONGEST_SYM_KUNIT_TEST dependency accordingly. Rework objtool's arguments a bit to handle the variety of prefix/cfi-related cases. Suggested-by: Peter Zijlstra Signed-off-by: Josh Poimboeuf

objtool/klp: Remove "objtool --checksum"

2026-05-05T04:16:05+00:00

The checksum functionality has been moved to "objtool klp checksum" which is now used by klp-build. Remove the now-dead --checksum and --debug-checksum options from the default objtool command. Acked-by: Song Liu Signed-off-by: Josh Poimboeuf

objtool: Add wide output for disassembly

2025-11-24T19:40:48+00:00

Add the --wide option to provide a wide output when disassembling. With this option, the disassembly of alternatives is displayed side-by-side instead of one above the other. Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-30-alexandre.chartre@oracle.com

objtool: Add the --disas= action

2025-11-21T14:30:12+00:00

Add the --disas= actions to disassemble the specified functions. The function pattern can be a single function name (e.g. --disas foo to disassemble the function with the name "foo"), or a shell wildcard pattern (e.g. --disas foo* to disassemble all functions with a name starting with "foo"). Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-18-alexandre.chartre@oracle.com

objtool: Add option to trace function validation

2025-11-21T14:30:09+00:00

Add an option to trace and have information during the validation of specified functions. Functions are specified with the --trace option which can be a single function name (e.g. --trace foo to trace the function with the name "foo"), or a shell wildcard pattern (e.g. --trace foo* to trace all functions with a name starting with "foo"). Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://patch.msgid.link/20251121095340.464045-11-alexandre.chartre@oracle.com

objtool: Set minimum xxhash version to 0.8

2025-11-18T08:59:25+00:00

XXH3 is only supported starting with xxhash 0.8. Enforce that. Fixes: 0d83da43b1e1 ("objtool/klp: Add --checksum option to generate per-function checksums") Closes: https://lore.kernel.org/SN6PR02MB41579B83CD295C9FEE40EED6D4FCA@SN6PR02MB4157.namprd02.prod.outlook.com Reported-by: Michael Kelley Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Michael Kelley Tested-by: Michael Kelley Link: https://patch.msgid.link/7227c94692a3a51840278744c7af31b4797c6b96.1762990139.git.jpoimboe@kernel.org

objtool/klp: Add the debian-based package name of xxhash to the hint

2025-10-22T11:51:11+00:00

Add the debian package name for the devel version of the xxHash package "libxxhash-dev". Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251017194732.7713-1-bp@kernel.org

objtool/klp: Add --debug-checksum= to show per-instruction checksums

2025-10-14T21:50:18+00:00

Add a --debug-checksum= option to the check subcommand to print the calculated checksum of each instruction in the given functions. This is useful for determining where two versions of a function begin to diverge. Acked-by: Petr Mladek Tested-by: Joe Lawrence Signed-off-by: Josh Poimboeuf

objtool/klp: Add --checksum option to generate per-function checksums

2025-10-14T21:50:17+00:00

In preparation for the objtool klp diff subcommand, add a command-line option to generate a unique checksum for each function. This will enable detection of functions which have changed between two versions of an object file. Acked-by: Petr Mladek Tested-by: Joe Lawrence Signed-off-by: Josh Poimboeuf