42dcb0a374
[ Upstream commit 0568b6f0d863643db2edcc7be31165740c89fa82 ]
IPv6 checksum tests with unaligned addresses on 64-bit builds result
in unexpected failures.
Expected expected == csum_result, but
expected == 46591 (0xb5ff)
csum_result == 46381 (0xb52d)
with alignment offset 1
Oddly enough, the problem disappeared after adding test code into
the beginning of csum_ipv6_magic().
As it turns out, the 'sum' parameter of csum_ipv6_magic() is declared as
__wsum, which is a 32-bit variable. However, it is treated as 64-bit
variable in the 64-bit assembler code. Tests showed that the upper 32 bit
of the register used to pass the variable are _not_ cleared when entering
the function. This can result in checksum calculation errors.
Clearing the upper 32 bit of 'sum' as first operation in the assembler
code fixes the problem.
Acked-by: Helge Deller <deller@gmx.de>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.