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From: Arvind Sankar <nivedita@alum.mit.edu>
To: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@suse.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Peter Collingbourne <pcc@google.com>,
	James Morse <james.morse@arm.com>, Ingo Molnar <mingo@redhat.com>,
	Russell King <linux@armlinux.org.uk>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>,
	x86@kernel.org, clang-built-linux@googlegroups.com,
	linux-arch@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 4/5] x86/build: Warn on orphan section placement
Date: Sat, 5 Sep 2020 18:48:35 -0400	[thread overview]
Message-ID: <20200905224835.GA1500331@rani.riverdale.lan> (raw)
In-Reply-To: <20200902025347.2504702-5-keescook@chromium.org>

On Tue, Sep 01, 2020 at 07:53:46PM -0700, Kees Cook wrote:
> We don't want to depend on the linker's orphan section placement
> heuristics as these can vary between linkers, and may change between
> versions. All sections need to be explicitly handled in the linker script.
> 
> Now that all sections are explicitly handled, enable orphan section
> warnings.
> 
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>  arch/x86/Makefile | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index 4346ffb2e39f..154259f18b8b 100644
> --- a/arch/x86/Makefile
> +++ b/arch/x86/Makefile
> @@ -209,6 +209,10 @@ ifdef CONFIG_X86_64
>  LDFLAGS_vmlinux += -z max-page-size=0x200000
>  endif
>  
> +# We never want expected sections to be placed heuristically by the
> +# linker. All sections should be explicitly named in the linker script.
> +LDFLAGS_vmlinux += $(call ld-option, --orphan-handling=warn)
> +
>  archscripts: scripts_basic
>  	$(Q)$(MAKE) $(build)=arch/x86/tools relocs
>  
> -- 
> 2.25.1
> 

With LLVM=1 and GCOV_KERNEL/GCOV_PROFILE_ALL enabled, there are
.eh_frame sections created. I see that KASAN and KCSAN currently discard
them. Does GCOV actually need them or should it also discard?

Thanks.

  reply	other threads:[~2020-09-05 22:48 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-02  2:53 [PATCH v7 0/5] Warn on orphan section placement Kees Cook
2020-09-02  2:53 ` [PATCH v7 1/5] arm64/build: " Kees Cook
2020-09-07  6:05   ` [tip: core/build] " tip-bot2 for Kees Cook
2020-09-02  2:53 ` [PATCH v7 2/5] arm/build: " Kees Cook
2020-09-07  6:05   ` [tip: core/build] " tip-bot2 for Kees Cook
2020-09-02  2:53 ` [PATCH v7 3/5] arm/boot: " Kees Cook
2020-09-07  6:05   ` [tip: core/build] " tip-bot2 for Kees Cook
2020-09-02  2:53 ` [PATCH v7 4/5] x86/build: " Kees Cook
2020-09-05 22:48   ` Arvind Sankar [this message]
2020-09-08 20:17     ` Arvind Sankar
2020-09-07  6:05   ` [tip: core/build] " tip-bot2 for Kees Cook
2020-09-02  2:53 ` [PATCH v7 5/5] x86/boot/compressed: " Kees Cook
2020-09-07  6:05   ` [tip: core/build] " tip-bot2 for Kees Cook
2020-09-02 19:04 ` [PATCH v7 0/5] " Nick Desaulniers
2020-09-04  5:58   ` Ingo Molnar
2020-09-04 18:20     ` Kees Cook
2020-09-06  7:24       ` Ingo Molnar

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