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Sender: Guenter Roeck <groeck7@gmail.com>
From:   Guenter Roeck <linux@roeck-us.net>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Richard Henderson <rth@twiddle.net>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
        Matt Turner <mattst88@gmail.com>,
        "James E . J . Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, linux-alpha@vger.kernel.org,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org,
        netdev@vger.kernel.org, linux-sparse@vger.kernel.org,
        Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH 0/4] Introduce and use absolute_pointer macro
Date:   Sun, 12 Sep 2021 09:01:45 -0700
Message-Id: <20210912160149.2227137-1-linux@roeck-us.net>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Kernel test builds currently fail for several architectures with error
messages such as the following.

drivers/net/ethernet/i825xx/82596.c: In function 'i82596_probe':
./arch/m68k/include/asm/string.h:72:25: error:
	'__builtin_memcpy' reading 6 bytes from a region of size 0
		[-Werror=stringop-overread]

Such warnings may be reported by gcc 11.x for string and memory operations
on fixed addresses.

This patch series introduces absolute_pointer() to fix the problem.
absolute_pointer() disassociates a pointer from its originating symbol
type and context, and thus prevents gcc from making assumptions about
pointers passed to memory operations.

----------------------------------------------------------------
Guenter Roeck (4):
      compiler.h: Introduce absolute_pointer macro
      net: i825xx: Use absolute_pointer for memcpy on fixed memory location
      parisc: Use absolute_pointer for memcmp on fixed memory location
      alpha: Use absolute_pointer for strcmp on fixed memory location

 arch/alpha/kernel/setup.c           | 2 +-
 arch/parisc/kernel/setup.c          | 2 +-
 drivers/net/ethernet/i825xx/82596.c | 2 +-
 include/linux/compiler.h            | 2 ++
 4 files changed, 5 insertions(+), 3 deletions(-)