linux.git/tools/objtool/klp-diff.c, branch v7.1-rc2

Merge tag 'objtool-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2026-04-14T20:00:04+00:00

Pull objtool updates from Ingo Molnar:

 - KLP support updates and fixes (Song Liu)

 - KLP-build script updates and fixes (Joe Lawrence)

 - Support Clang RAX DRAP sequence, to address clang false positive
   (Josh Poimboeuf)

 - Reorder ORC register numbering to match regular x86 register
   numbering (Josh Poimboeuf)

 - Misc cleanups (Wentong Tian, Song Liu)

* tag 'objtool-core-2026-04-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool/x86: Reorder ORC register numbering
  objtool: Support Clang RAX DRAP sequence
  livepatch/klp-build: report patch validation fuzz
  livepatch/klp-build: add terminal color output
  livepatch/klp-build: provide friendlier error messages
  livepatch/klp-build: improve short-circuit validation
  livepatch/klp-build: fix shellcheck complaints
  livepatch/klp-build: add Makefile with check target
  livepatch/klp-build: add grep-override function
  livepatch/klp-build: switch to GNU patch and recountdiff
  livepatch/klp-build: support patches that add/remove files
  objtool/klp: Correlate locals to globals
  objtool/klp: Match symbols based on demangled_name for global variables
  objtool/klp: Remove .llvm suffix in demangle_name()
  objtool/klp: Also demangle global objects
  objtool/klp: Use sym->demangled_name for symbol_name hash
  objtool/klp: Remove trailing '_' in demangle_name()
  objtool/klp: Remove redundant strcmp() in correlate_symbols()
  objtool: Use section/symbol type helpers

objtool/klp: fix data alignment in __clone_symbol()

2026-03-16T19:39:45+00:00

Commit 356e4b2f5b80 ("objtool: Fix data alignment in elf_add_data()")
corrected the alignment of data within a section (honoring the section's
sh_addralign).  Apply the same alignment when klp-diff mode clones a
symbol, adjusting the new symbol's offset for the output section's
sh_addralign.

Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Signed-off-by: Joe Lawrence 
Link: https://patch.msgid.link/20260310203751.1479229-2-joe.lawrence@redhat.com
Signed-off-by: Josh Poimboeuf

objtool/klp: Correlate locals to globals

2026-03-06T16:08:34+00:00

Allow correlating original locals to patched globals, and vice versa.
This is needed when:

1. User adds/removes "static" for a function.
2. CONFIG_LTO_CLANG_THIN promotes local functions and objects to global
   and add .llvm. suffix.

Signed-off-by: Song Liu 
Link: https://patch.msgid.link/20260305231531.3847295-8-song@kernel.org
Signed-off-by: Josh Poimboeuf

objtool/klp: Match symbols based on demangled_name for global variables

2026-03-06T16:08:33+00:00

correlate_symbols() will always try to match full name first. If there is
no match, try match only demangled_name.

In very rare cases, it is possible to have multiple foo.llvm. in
the same kernel. Whenever there is ambiguity like this, fail the klp diff.

Signed-off-by: Song Liu 
Link: https://patch.msgid.link/20260305231531.3847295-7-song@kernel.org
Signed-off-by: Josh Poimboeuf

objtool/klp: Remove redundant strcmp() in correlate_symbols()

2026-03-06T16:08:23+00:00

find_global_symbol_by_name() already compares names of the two symbols,
so there is no need to compare them again.

Signed-off-by: Song Liu 
Link: https://patch.msgid.link/20260305231531.3847295-2-song@kernel.org
Signed-off-by: Josh Poimboeuf

objtool: Use section/symbol type helpers

2026-03-06T16:08:19+00:00

Commit 25eac74b6bdb ("objtool: Add section/symbol type helpers")
introduced several helper macros to improve code readability.

Update the remaining open-coded checks in check.c, disas.c, elf.c,
and klp-diff.c to use these new helpers.

Signed-off-by: Wentong Tian 
Link: https://patch.msgid.link/20260122144404.40602-1-tianwentong2000@gmail.com
Signed-off-by: Josh Poimboeuf

objtool/klp: Avoid NULL pointer dereference when printing code symbol name

2026-03-06T15:47:11+00:00

Fix a hypothetical NULL pointer defereference of the 'code_sym'
variable.  In theory this should never happen.

Reviewed-and-tested-by: Song Liu 
Link: https://patch.msgid.link/64116517bc93851a98fe366ea0a4d807f4c70aab.1770759954.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf

objtool/klp: Disable unsupported pr_debug() usage

2026-03-06T15:47:11+00:00

Instead of erroring out on unsupported pr_debug() (e.g., when patching a
module), issue a warning and make it inert, similar to how unsupported
tracepoints are currently handled.

Reviewed-and-tested-by: Song Liu 
Link: https://patch.msgid.link/3a7db3a5b7d4abf9b2534803a74e2e7231322738.1770759954.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf

objtool/klp: Fix detection of corrupt static branch/call entries

2026-03-06T15:47:10+00:00

Patching a function which references a static key living in a kernel
module is unsupported due to ordering issues inherent to late module
patching:

  1) Load a livepatch module which has a __jump_table entry which needs
     a klp reloc to reference static key K which lives in module M.

  2) The __jump_table klp reloc does *not* get resolved because module M
     is not yet loaded.

  3) jump_label_add_module() corrupts memory (or causes a panic) when
     dereferencing the uninitialized pointer to key K.

validate_special_section_klp_reloc() intends to prevent that from ever
happening by catching it at build time.  However, it incorrectly assumes
the special section entry's reloc symbol references have already been
converted from section symbols to object symbols, causing the validation
to miss corruption in extracted static branch/call table entries.

Make sure the references have been properly converted before doing the
validation.

Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Reported-by: Song Liu 
Reviewed-and-tested-by: Song Liu 
Link: https://patch.msgid.link/124ad747b751df0df1725eff89de8332e3fb26d6.1770759954.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf

objtool/klp: Fix symbol correlation for orphaned local symbols

2026-02-05T16:00:45+00:00

When compiling with CONFIG_LTO_CLANG_THIN, vmlinux.o has
__irf_[start|end] before the first FILE entry:

  $ readelf -sW vmlinux.o
  Symbol table '.symtab' contains 597706 entries:
     Num:    Value          Size Type    Bind   Vis      Ndx Name
       0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
       1: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT   18 __irf_start
       2: 0000000000000200     0 NOTYPE  LOCAL  DEFAULT   18 __irf_end
       3: 0000000000000000     0 SECTION LOCAL  DEFAULT   17 .text
       4: 0000000000000000     0 SECTION LOCAL  DEFAULT   18 .init.ramfs

This causes klp-build warnings like:

  vmlinux.o: warning: objtool: no correlation: __irf_start
  vmlinux.o: warning: objtool: no correlation: __irf_end

The problem is that Clang LTO is stripping the initramfs_data.o FILE
symbol, causing those two symbols to be orphaned and not noticed by
klp-diff's correlation logic.  Add a loop to correlate any symbols found
before the first FILE symbol.

Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Reported-by: Song Liu 
Acked-by: Song Liu 
Link: https://patch.msgid.link/e21ec1141fc749b5f538d7329b531c1ab63a6d1a.1770055235.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf