Merge tag 'objtool-core-2026-10-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

- Add unit test suite for objtool klp functionality and
known

Merge tag 'objtool-core-2026-10-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

- Add unit test suite for objtool klp functionality and
known failure modes (by Song Liu and Puranjay Mohan,
with fixes by Joe Lawrence)

* tag 'objtool-core-2026-10-18' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (58 commits)
objtool/klp: Add test for ThinLTO symbols sharing a demangled name
objtool/klp: Add test for Clang switch jump tables
objtool/klp: Add test for UBSAN metadata in an unchanged function
objtool/klp: Add test for absolute and __ADDRESSABLE symbols
objtool/klp: Add test for a patch which strips a data annotation
objtool/klp: Add test for the alignment of cloned data sections
objtool/klp: Add test for alternative replacement code in checksums
objtool/klp: Add test for instruction operand checksums
objtool/klp: Add test for a static call introduced by the patch
objtool/klp: Add test for tracepoint and pr_debug static branch keys
objtool/klp: Add test for a static branch introduced by the patch
objtool/klp: Add test for symbols with no checksum entry of their own
objtool/klp: Add test for data object checksums
objtool/klp: Test text annotations on alternative replacements
objtool/klp: Test a hand-built livepatch module's static call keys
objtool/klp: Test rejection of a file-local static branch key
objtool/klp: Add test for symbols whose linkage the patch changes
objtool/klp: Add test for kCFI prefix symbols and traps
objtool/klp: Add test for __bug_table, __ex_table and __mcount_loc extraction
objtool/klp: Add test for static locals which must not be correlated
...

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objtool/klp: Add test for instruction operand checksums

checksum_update_insn() hashes an instruction's bytes and then what any
relocation on it refers to: a string section contributes the string's
c

objtool/klp: Add test for instruction operand checksums

checksum_update_insn() hashes an instruction's bytes and then what any
relocation on it refers to: a string section contributes the string's
contents, anything else the target symbol's name and adjusted addend, with
a reference to a static resolved through its section symbol first.

None of that shows up in the bytes. A rel32 operand is zero in the object
and supplied by the relocation, so calling a different function, editing a
literal the code passes, or reading a different index of an array all leave
the encoded instruction byte-identical. A checksum stopping at the bytes
reports the function unchanged and the patch silently does not contain the
fix.

test-checksum-position is the other half: what must *not* change the
checksum when a function merely moves.

Each of the four is verified by sabotaging the line it covers. The static
case needed a writer the compiler cannot see through -- without one it
proves the array is never written, folds every read to zero, and emits no
relocation at all, so the reference under test does not exist and the
variant passes having compared two identical objects.

Assisted-by: Claude:claude-opus-4
Based-on-test-by: Joe Lawrence <joe.lawrence@redhat.com>
Assisted-by: Claude:claude-opus-5
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20260916184351.2720310-52-song@kernel.org

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