The offset must be multiplied by 4 to be sure to access the correct
32bit word in the stack scratch space.

For instance, a store at scratch memory cell #1 was generating the
following:

st	r4, [sp, #1]

While the correct code for this is:

st	r4, [sp, #4]

To reproduce the bug (assuming your system has a NIC with the mac
address 52:54:00:12:34:56):

echo 0 > /proc/sys/net/core/bpf_jit_enable
tcpdump -ni eth0 "ether[1] + ether[2] - ether[3] * ether[4] - ether[5] \
	== -0x3AA" # this will capture packets as expected

echo 1 > /proc/sys/net/core/bpf_jit_enable
tcpdump -ni eth0 "ether[1] + ether[2] - ether[3] * ether[4] - ether[5] \
	== -0x3AA" # this will not.

This bug was present since the original inclusion of bpf_jit for ARM
(ddecdfce: ARM: 7259/3: net: JIT compiler for packet filters).
Signed-off-by: NNicolas Schichan <nschichan@freebox.fr>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Official prototype for kzalloc is:

void *kzalloc(size_t, gfp_t);

The ARM bpf_jit code was having the assumption that it was:

void *kzalloc(gfp_t, size);

This was resulting the use of some random GFP flags depending on the
size requested and some random overflows once the really needed size
was more than the value of GFP_KERNEL.

This bug was present since the original inclusion of bpf_jit for ARM
(ddecdfce: ARM: 7259/3: net: JIT compiler for packet filters).
Signed-off-by: NNicolas Schichan <nschichan@freebox.fr>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

JIT support for the XOR operation introduced by the commit
ffe06c17.
Signed-off-by: NMircea Gherzan <mgherzan@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Based of Matt Evans's PPC64 implementation.

The compiler generates ARM instructions but interworking is
supported for Thumb2 kernels.

Supports both little and big endian. Unaligned loads are emitted
for ARMv6+. Not all the BPF opcodes that deal with ancillary data
are supported. The scratch memory of the filter lives on the stack.
Hardware integer division is used if it is available.

Enabled in the same way as for x86-64 and PPC64:

	echo 1 > /proc/sys/net/core/bpf_jit_enable

A value greater than 1 enables opcode output.
Signed-off-by: NMircea Gherzan <mgherzan@gmail.com>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Acked-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>