Merge branch 'objtool/core' of https://git.kernel.org/pub/scm/linux/kernel/git/jpoimboe/linux

This series introduces new objtool features and a klp-build script to
generate livepatch modules using a source .patch as input.

This builds on concepts from the longstanding out-of-tree kpatch [1]
project which began in 2012 and has been used for many years to generate
livepatch modules for production kernels.  However, this is a complete
rewrite which incorporates hard-earned lessons from 12+ years of
maintaining kpatch.

Key improvements compared to kpatch-build:

  - Integrated with objtool: Leverages objtool's existing control-flow
    graph analysis to help detect changed functions.

  - Works on vmlinux.o: Supports late-linked objects, making it
    compatible with LTO, IBT, and similar.

  - Simplified code base: ~3k fewer lines of code.

  - Upstream: No more out-of-tree #ifdef hacks, far less cruft.

  - Cleaner internals: Vastly simplified logic for symbol/section/reloc
    inclusion and special section extraction.

  - Robust __LINE__ macro handling: Avoids false positive binary diffs
    caused by the __LINE__ macro by introducing a fix-patch-lines script
    which injects #line directives into the source .patch to preserve
    the original line numbers at compile time.

The primary user interface is the klp-build script which does the
following:

  - Builds an original kernel with -function-sections and
    -fdata-sections, plus objtool function checksumming.

  - Applies the .patch file and rebuilds the kernel using the same
    options.

  - Runs 'objtool klp diff' to detect changed functions and generate
    intermediate binary diff objects.

  - Builds a kernel module which links the diff objects with some
    livepatch module init code (scripts/livepatch/init.c).

  - Finalizes the livepatch module (aka work around linker wreckage)
    using 'objtool klp post-link'.

I've tested with a variety of patches on defconfig and Fedora-config
kernels with both GCC and Clang.

1 files changed, 3 insertions, 3 deletions

diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index 2e555c4060c5..0115b97c526b 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -7,7 +7,7 @@
 #include <linux/objtool_types.h>
 #include <arch/elf.h>
 
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
 {
 	return !strcmp(name, "_mcount");
 }
@@ -17,9 +17,9 @@ unsigned long arch_jump_destination(struct instruction *insn)
 	return insn->offset + (insn->immediate << 2);
 }
 
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 {
-	return addend;
+	return reloc_addend(reloc);
 }
 
 bool arch_pc_relative_reloc(struct reloc *reloc)