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This patch updates csum_ipv6_magic so that it correctly recognizes that
protocol is a unsigned 8 bit value.
This will allow us to better understand what limitations may or may not be
present in how we handle the data. For example there are a number of
places that call htonl on the protocol value. This is likely not necessary
and can be replaced with a multiplication by ntohl(1) which will be
converted to a shift by the compiler.
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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This patch updates all instances of csum_tcpudp_magic and
csum_tcpudp_nofold to reflect the types that are usually used as the source
inputs. For example the protocol field is populated based on nexthdr which
is actually an unsigned 8 bit value. The length is usually populated based
on skb->len which is an unsigned integer.
This addresses an issue in which the IPv6 function csum_ipv6_magic was
generating a checksum using the full 32b of skb->len while
csum_tcpudp_magic was only using the lower 16 bits. As a result we could
run into issues when attempting to adjust the checksum as there was no
protocol agnostic way to update it.
With this change the value is still truncated as many architectures use
"(len + proto) << 8", however this truncation only occurs for values
greater than 16776960 in length and as such is unlikely to occur as we stop
the inner headers at ~64K in size.
I did have to make a few minor changes in the arm, mn10300, nios2, and
score versions of the function in order to support these changes as they
were either using things such as an OR to combine the protocol and length,
or were using ntohs to convert the length which would have truncated the
value.
I also updated a few spots in terms of whitespace and type differences for
the addresses. Most of this was just to make sure all of the definitions
were in sync going forward.
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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There is a miscompilation of csum_tcpudp_magic() due to the way we pass
the asm() operands in. Fortunately, this doesn't affect the IP code,
but can affect anyone who passes ntohs(udp->len) as the length argument,
or protocols with more than 8 bits.
The problem stems from passing 16-bit operands into an asm() - GCC makes
no guarantees about what may be in the high 16-bits of such a register
passed into assembly which is in the "HI" machine mode.
Address this by changing the way we handle the 16-bit arguments - since
accumulating the protocol and length can never overflow, we can delegate
this to the compiler to perform, and then accumulate it into the
checksum inside the asm(), taking account of the endian-ness via an
appropriate 32-bit rotation.
While we are here, also realise that there's a chance to optimise this
a little: several callers from IP code pass a constant zero as the
initial sum. This is wasteful - if we detect this condition, we can
optimise away one instruction.
Tested-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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