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From:   Nathan Chancellor <nathan@kernel.org>
Date:   Wed, 19 Apr 2023 11:42:54 -0700
Subject: [PATCH] MIPS: Mark check_bugs{,_early}() as __init
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Message-Id: <20230419-mips-check_bugs-init-attribute-v1-1-91e6eed55b89@kernel.org>
To:     tsbogend@alpha.franken.de
Cc:     ndesaulniers@google.com, jpoimboe@kernel.org, peterz@infradead.org,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev, patches@lists.linux.dev,
        Nathan Chancellor <nathan@kernel.org>
Precedence: bulk

After commit ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING
forcibly"), a compiler may choose not to inline a function marked with
just 'inline'. If check_bugs() is not inlined into start_kernel(), which
occurs when building with clang after commit 9ea7e6b62c2b ("init: Mark
[arch_call_]rest_init() __noreturn"), modpost complains with:

  WARNING: modpost: vmlinux.o: section mismatch in reference: check_bugs (section: .text) -> check_bugs32 (section: .init.text)

check_bugs() is only called from start_kernel(), which itself is marked
__init, so mark check_bugs() as __init as well to clear up the warning
and make everything work properly.

While there is currently no warning about check_bugs_early(), it could
have the same problem, as it is called from arch_setup() and calls
check_bugs64_early(), both marked __init. Mark it as __init for the same
reason as above.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
NOTE: This is based on v6.3-rc7, as the issue shows up due to a patch in
the tip tree, but this appears to be an ancient issue that could have
showed up at any point (hence why no explicit Fixes tag), so I chose a
base that should allow either the MIPS or tip folks to apply this patch.

Additionally, I was tempted to remove the explicit 'inline' since the
compiler is free to do whatever it wants anyways but this is a static
function in a header so we would need to add '__maybe_unused', which is
already added with 'inline' in a normal build so I just left it alone.
---
 arch/mips/include/asm/bugs.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/bugs.h b/arch/mips/include/asm/bugs.h
index d72dc6e1cf3c..9b9bf9bc7d24 100644
--- a/arch/mips/include/asm/bugs.h
+++ b/arch/mips/include/asm/bugs.h
@@ -24,13 +24,13 @@ extern void check_bugs64_early(void);
 extern void check_bugs32(void);
 extern void check_bugs64(void);
 
-static inline void check_bugs_early(void)
+static inline void __init check_bugs_early(void)
 {
 	if (IS_ENABLED(CONFIG_CPU_R4X00_BUGS64))
 		check_bugs64_early();
 }
 
-static inline void check_bugs(void)
+static inline void __init check_bugs(void)
 {
 	unsigned int cpu = smp_processor_id();
 

---
base-commit: 6a8f57ae2eb07ab39a6f0ccad60c760743051026
change-id: 20230419-mips-check_bugs-init-attribute-026103bdb255

Best regards,
-- 
Nathan Chancellor <nathan@kernel.org>