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Peter Anvin" , Paolo Bonzini , Mike Rapoport , Vitaly Kuznetsov , Henrique de Moraes Holschuh , Hans de Goede , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , "Rafael J. Wysocki" , Len Brown , Masami Hiramatsu , Michal Wilczynski , Juergen Gross , Andy Shevchenko , "Kirill A. Shutemov" , Roger Pau Monne , David Woodhouse , Usama Arif , "Guilherme G. Piccoli" , Thomas Huth , Brian Gerst , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Hou Wenlong , Andrew Morton , Masahiro Yamada , "Peter Zijlstra (Intel)" , Luis Chamberlain , Sami Tolvanen , Christophe Leroy , Nathan Chancellor , Nicolas Schier , "Gustavo A. R. Silva" , Andy Lutomirski , Baoquan He , Alexander Graf , Changyuan Lyu , Paul Moore , James Morris , "Serge E. Hallyn" , Nick Desaulniers , Bill Wendling , Justin Stitt , Jan Beulich , Boqun Feng , Viresh Kumar , "Paul E. McKenney" , Bibo Mao , linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, ibm-acpi-devel@lists.sourceforge.net, platform-driver-x86@vger.kernel.org, linux-acpi@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, linux-kbuild@vger.kernel.org, linux-hardening@vger.kernel.org, kexec@lists.infradead.org, linux-security-module@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH v4 1/4] arm64: Handle KCOV __init vs inline mismatches Message-ID: References: <20250724054419.it.405-kees@kernel.org> <20250724055029.3623499-1-kees@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250724055029.3623499-1-kees@kernel.org> X-Stat-Signature: rf9xkx3gm18oerc7u5iuioj7rjifz3iz X-Rspamd-Queue-Id: 5E3D14000F X-Rspamd-Server: rspam10 X-Rspam-User: X-HE-Tag: 1753776673-28953 X-HE-Meta: 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 NJbeXxPc 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 23, 2025 at 10:50:25PM -0700, Kees Cook wrote: > GCC appears to have kind of fragile inlining heuristics, in the > sense that it can change whether or not it inlines something based on > optimizations. It looks like the kcov instrumentation being added (or in > this case, removed) from a function changes the optimization results, > and some functions marked "inline" are _not_ inlined. In that case, > we end up with __init code calling a function not marked __init, and we > get the build warnings I'm trying to eliminate in the coming patch that > adds __no_sanitize_coverage to __init functions: > > WARNING: modpost: vmlinux: section mismatch in reference: acpi_get_enable_method+0x1c (section: .text.unlikely) -> acpi_psci_present (section: .init.text) > > This problem is somewhat fragile (though using either __always_inline > or __init will deterministically solve it), but we've tripped over > this before with GCC and the solution has usually been to just use > __always_inline and move on. > > For arm64 this requires forcing one ACPI function to be inlined with > __always_inline. > > Signed-off-by: Kees Cook > --- > Cc: Will Deacon > Cc: Ard Biesheuvel > Cc: Catalin Marinas > Cc: Jonathan Cameron > Cc: Gavin Shan > Cc: "Russell King (Oracle)" > Cc: James Morse > Cc: Oza Pawandeep > Cc: Anshuman Khandual > Cc: > --- > arch/arm64/include/asm/acpi.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h > index a407f9cd549e..c07a58b96329 100644 > --- a/arch/arm64/include/asm/acpi.h > +++ b/arch/arm64/include/asm/acpi.h > @@ -150,7 +150,7 @@ acpi_set_mailbox_entry(int cpu, struct acpi_madt_generic_interrupt *processor) > {} > #endif > > -static inline const char *acpi_get_enable_method(int cpu) > +static __always_inline const char *acpi_get_enable_method(int cpu) > { > if (acpi_psci_present()) > return "psci"; Thanks for improving the commit message: Acked-by: Will Deacon Will