Merge tag 'objtool-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - The biggest change is the new option to automatically fail the build
   on objtool warnings: CONFIG_OBJTOOL_WERROR.

   While there are no currently known unfixed false positives left, such
   an expansion in the severity of objtool warnings inevitably creates a
   risk of build failures, so it's disabled by default and depends on
   !COMPILE_TEST, so it shouldn't be enabled on
   allyesconfig/allmodconfig builds and won't be forced on people who
   just accept build-time defaults in 'make oldconfig'.

   While the option is strongly recommended, only people who enable it
   explicitly should see it.

   (Josh Poimboeuf)

 - Disable branch profiling in noinstr code with a broad brush that
   includes all of arch/x86/ and kernel/sched/. (Josh Poimboeuf)

 - Create backup object files on objtool errors and print exact objtool
   arguments to make failure analysis easier (Josh Poimboeuf)

 - Improve noreturn handling (Josh Poimboeuf)

 - Improve rodata handling (Tiezhu Yang)

 - Support jump tables, switch tables and goto tables on LoongArch
   (Tiezhu Yang)

 - Misc cleanups and fixes (Josh Poimboeuf, David Engraf, Ingo Molnar)

* tag 'objtool-core-2025-03-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (22 commits)
  tracing: Disable branch profiling in noinstr code
  objtool: Use O_CREAT with explicit mode mask
  objtool: Add CONFIG_OBJTOOL_WERROR
  objtool: Create backup on error and print args
  objtool: Change "warning:" to "error:" for --Werror
  objtool: Add --Werror option
  objtool: Add --output option
  objtool: Upgrade "Linked object detected" warning to error
  objtool: Consolidate option validation
  objtool: Remove --unret dependency on --rethunk
  objtool: Increase per-function WARN_FUNC() rate limit
  objtool: Update documentation
  objtool: Improve __noreturn annotation warning
  objtool: Fix error handling inconsistencies in check()
  x86/traps: Make exc_double_fault() consistently noreturn
  LoongArch: Enable jump table for objtool
  objtool/LoongArch: Add support for goto table
  objtool/LoongArch: Add support for switch table
  objtool: Handle PC relative relocation type
  objtool: Handle different entry size of rodata
  ...

2 files changed, 16 insertions, 0 deletions

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 70c6298c281e..c3004032c3ed 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -545,6 +545,17 @@ config FRAME_POINTER
 config OBJTOOL
 	bool
 
+config OBJTOOL_WERROR
+	bool "Upgrade objtool warnings to errors"
+	depends on OBJTOOL && !COMPILE_TEST
+	help
+	  Fail the build on objtool warnings.
+
+	  Objtool warnings can indicate kernel instability, including boot
+	  failures.  This option is highly recommended.
+
+	  If unsure, say Y.
+
 config STACK_VALIDATION
 	bool "Compile-time stack metadata validation"
 	depends on HAVE_STACK_VALIDATION && UNWINDER_FRAME_POINTER
diff --git a/lib/Makefile b/lib/Makefile
index 89b8a4bce108..6de467a02b03 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -5,6 +5,11 @@
 
 ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
 
+# Branch profiling isn't noinstr-safe
+ifdef CONFIG_TRACE_BRANCH_PROFILING
+CFLAGS_smp_processor_id.o += -DDISABLE_BRANCH_PROFILING
+endif
+
 # These files are disabled because they produce lots of non-interesting and/or
 # flaky coverage that is not a function of syscall inputs. For example,
 # rbtree can be global and individual rotations don't correlate with inputs.