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, 6 insertions, 3 deletions

diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 922e6aac7cea..1045e1380ffd 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -12,7 +12,6 @@
 #include <objtool/check.h>
 #include <objtool/orc.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 struct orc_list_entry {
 	struct list_head list;
@@ -57,7 +56,7 @@ int orc_create(struct objtool_file *file)
 
 	/* Build a deduplicated list of ORC entries: */
 	INIT_LIST_HEAD(&orc_list);
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		struct orc_entry orc, prev_orc = {0};
 		struct instruction *insn;
 		bool empty = true;
@@ -127,7 +126,11 @@ int orc_create(struct objtool_file *file)
 		return -1;
 	}
 	orc_sec = elf_create_section(file->elf, ".orc_unwind",
-				     sizeof(struct orc_entry), nr);
+				     nr * sizeof(struct orc_entry),
+				     sizeof(struct orc_entry),
+				     SHT_PROGBITS,
+				     1,
+				     SHF_ALLOC);
 	if (!orc_sec)
 		return -1;