linux-kernel - [PATCH 5.4 61/62] vmlinux.lds.h: Handle clangs module.{c,d}tor sections

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Message-Id: <20210816125430.316622916@linuxfoundation.org>
Date:   Mon, 16 Aug 2021 15:02:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Fangrui Song <maskray@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH 5.4 61/62] vmlinux.lds.h: Handle clangs module.{c,d}tor sections

From: Nathan Chancellor <nathan@...nel.org>

commit 848378812e40152abe9b9baf58ce2004f76fb988 upstream.

A recent change in LLVM causes module_{c,d}tor sections to appear when
CONFIG_K{A,C}SAN are enabled, which results in orphan section warnings
because these are not handled anywhere:

ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_ctor) is being placed in '.text.asan.module_ctor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_dtor) is being placed in '.text.asan.module_dtor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor'

Fangrui explains: "the function asan.module_ctor has the SHF_GNU_RETAIN
flag, so it is in a separate section even with -fno-function-sections
(default)".

Place them in the TEXT_TEXT section so that these technologies continue
to work with the newer compiler versions. All of the KASAN and KCSAN
KUnit tests continue to pass after this change.

Cc: stable@...r.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1432
Link: https://github.com/llvm/llvm-project/commit/7b789562244ee941b7bf2cefeb3fc08a59a01865
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Reviewed-by: Fangrui Song <maskray@...gle.com>
Acked-by: Marco Elver <elver@...gle.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Link: https://lore.kernel.org/r/20210731023107.1932981-1-nathan@kernel.org
[nc: Resolve conflict due to lack of cf68fffb66d60]
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 include/asm-generic/vmlinux.lds.h |    1 +
 1 file changed, 1 insertion(+)

--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -536,6 +536,7 @@
 		NOINSTR_TEXT						\
 		*(.text..refcount)					\
 		*(.ref.text)						\
+		*(.text.asan.* .text.tsan.*)				\
 	MEM_KEEP(init.text*)						\
 	MEM_KEEP(exit.text*)						\