From 7fd24723f1601340ee09bca93989bd1fb4515783 Mon Sep 17 00:00:00 2001 From: Puranjay Mohan Date: Wed, 16 Sep 2026 11:43:17 -0700 Subject: objtool/klp: Add test for correlation across ThinLTO name mangling ThinLTO promotes the file-local symbols an imported function touches, renaming them name.llvm.. The hash is content derived, so it changes whenever the module does: original: counter.llvm.13663304415433785070 patched: counter.llvm.10543383937958011340 Correlating the two objects therefore requires demangling the suffix; matching raw names would see two unrelated symbols and treat the variable as new. The resulting klp relocation also has to name the original symbol, since that is the one in the running kernel's kallsyms. Naming the patched build's symbol produces a relocation which can never be resolved. ThinLTO is a clang feature, so the test declares itself clang-only. It also needs an lld from the same LLVM release as $CC; a mismatched pair fails with "Invalid summary version", which reads like a broken test rather than a broken environment, so probe for a working lld and skip if there is none. Signed-off-by: Puranjay Mohan Signed-off-by: Song Liu Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Assisted-by: Claude:claude-opus-5 Link: https://patch.msgid.link/20260916184351.2720310-25-song@kernel.org --- .../objtool/tests/generic/fixtures/thinlto_local.c | 39 ++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 tools/objtool/tests/generic/fixtures/thinlto_local.c (limited to 'tools/objtool/tests/generic/fixtures/thinlto_local.c') diff --git a/tools/objtool/tests/generic/fixtures/thinlto_local.c b/tools/objtool/tests/generic/fixtures/thinlto_local.c new file mode 100644 index 000000000000..fe9f9e6bf44f --- /dev/null +++ b/tools/objtool/tests/generic/fixtures/thinlto_local.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Two translation units (TU_B selects the second) linked with ThinLTO. + * Importing bump() promotes the file-local counter, renaming it + * counter.llvm.. The hash is content derived, so it differs between the + * original and patched builds. + */ + +#ifdef TU_B + +extern int bump(void); + +int other_entry(void) +{ + return bump() + bump(); +} + +#else + +static const char __modinfo[] + __attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux"; + +static int counter; + +int bump(void) +{ + return ++counter; +} + +int target(void) +{ +#ifdef PATCHED + return counter + 1; +#else + return counter; +#endif +} + +#endif -- cgit v1.2.3