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From:   Khem Raj <raj.khem@gmail.com>
To:     linux-kernel@vger.kernel.org
Cc:     Khem Raj <raj.khem@gmail.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Kees Cook <keescook@chromium.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>, x86-ml <x86@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH] x86/boot/compressed/64: Define __force_order only when CONFIG_RANDOMIZE_BASE is unset
Date:   Sat, 21 Dec 2019 07:18:13 -0800
Message-Id: <20191221151813.1573450-1-raj.khem@gmail.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

kaslr_64.c also defines the same variable, however when both files are
included into final link, linker complains about multiple definition of
`__force_order' which is coming from kaslr_64.o and pgtable_64.o, its
possible that kaslr_64.o is disabled via CONFIG_RANDOMIZE_BASE config
option, therefore define it conditionally only when
CONFIG_RANDOMIZE_BASE is not set

Since arch/x86/boot/compressed/Makefile overrides global CFLAGS it loses
-fno-common option which would have caught this

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
---
 arch/x86/boot/compressed/pgtable_64.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index c8862696a47b..077d19268b0b 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -12,7 +12,9 @@
  * It is not referenced from the code, but GCC < 5 with -fPIE would fail
  * due to an undefined symbol. Define it to make these ancient GCCs work.
  */
+#ifndef CONFIG_RANDOMIZE_BASE
 unsigned long __force_order;
+#endif
 
 #define BIOS_START_MIN		0x20000U	/* 128K, less than this is insane */
 #define BIOS_START_MAX		0x9f000U	/* 640K, absolute maximum */
-- 
2.24.1