[PATCH v3 16/26] scripts: Fix the inclusion order in modpost

From: Vincenzo Frascino <vincenzo.frascino@arm.com>
To: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
	clang-built-linux@googlegroups.com, x86@kernel.org
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
	Russell King <linux@armlinux.org.uk>,
	Paul Burton <paul.burton@mips.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>, Stephen Boyd <sboyd@kernel.org>,
	Mark Salyzyn <salyzyn@android.com>,
	Kees Cook <keescook@chromium.org>,
	Peter Collingbourne <pcc@google.com>,
	Dmitry Safonov <0x7f454c46@gmail.com>,
	Andrei Vagin <avagin@openvz.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Marc Zyngier <maz@kernel.org>,
	Mark Rutland <Mark.Rutland@arm.com>,
	kbuild test robot <lkp@intel.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>
Subject: [PATCH v3 16/26] scripts: Fix the inclusion order in modpost
Date: Fri, 13 Mar 2020 15:43:35 +0000	[thread overview]
Message-ID: <20200313154345.56760-17-vincenzo.frascino@arm.com> (raw)
In-Reply-To: <20200313154345.56760-1-vincenzo.frascino@arm.com>

In the process of creating the source file of a module modpost injects a
set of includes that are not required if the compilation unit is
statically built into the kernel.

The order of inclusion of the headers can cause redefinition problems
(e.g.):

   In file included from include/linux/elf.h:5:0,
                    from include/linux/module.h:18,
                    from crypto/arc4.mod.c:2:
>> arch/parisc/include/asm/elf.h:324:0: warning: "ELF_OSABI" redefined
    #define ELF_OSABI  ELFOSABI_LINUX

   In file included from include/linux/elfnote.h:62:0,
                    from include/linux/build-salt.h:4,
                    from crypto/arc4.mod.c:1:
   include/uapi/linux/elf.h:363:0: note: this is the location of
   the previous definition
    #define ELF_OSABI ELFOSABI_NONE

The issue was exposed during the development of the series [1].

[1] https://lore.kernel.org/lkml/20200306133242.26279-1-vincenzo.frascino@arm.com/

Reported-by: kbuild test robot <lkp@intel.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
 scripts/mod/modpost.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 7edfdb2f4497..0f354b1ee2aa 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -2251,8 +2251,12 @@ static int check_modname_len(struct module *mod)
  **/
 static void add_header(struct buffer *b, struct module *mod)
 {
-	buf_printf(b, "#include <linux/build-salt.h>\n");
 	buf_printf(b, "#include <linux/module.h>\n");
+	/*
+	 * Include build-salt.h after module.h in order to
+	 * inherit the definitions.
+	 */
+	buf_printf(b, "#include <linux/build-salt.h>\n");
 	buf_printf(b, "#include <linux/vermagic.h>\n");
 	buf_printf(b, "#include <linux/compiler.h>\n");
 	buf_printf(b, "\n");
-- 
2.25.1

