linux-kernel - [PATCH v6 25/29] x86/build: Warn on orphan section placement

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Message-Id: <20200821194310.3089815-26-keescook@chromium.org>
Date:   Fri, 21 Aug 2020 12:43:06 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Peter Collingbourne <pcc@...gle.com>,
        James Morse <james.morse@....com>,
        Borislav Petkov <bp@...e.de>, Ingo Molnar <mingo@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>, x86@...nel.org,
        clang-built-linux@...glegroups.com, linux-arch@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v6 25/29] x86/build: Warn on orphan section placement

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@...omium.org>
---
 arch/x86/Makefile | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 4346ffb2e39f..ccacbf808552 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 += --orphan-handling=warn
+
 archscripts: scripts_basic
 	$(Q)$(MAKE) $(build)=arch/x86/tools relocs
 
-- 
2.25.1