From: Alexei Starovoitov <ast@plumgrid.com>
Date: Sat, 29 Nov 2014 22:46:13 +0000 (-0800)
Subject: bpf: x86: fix epilogue generation for eBPF programs
X-Git-Tag: omap-for-v3.19/fixes-rc1~125^2~10^2~24
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=769e0de6475e5512f88bfb4dbf6d6323fd23514f;p=pandora-kernel.git

bpf: x86: fix epilogue generation for eBPF programs

classic BPF has a restriction that last insn is always BPF_RET.
eBPF doesn't have BPF_RET instruction and this restriction.
It has BPF_EXIT insn which can appear anywhere in the program
one or more times and it doesn't have to be last insn.
Fix eBPF JIT to emit epilogue when first BPF_EXIT is seen
and all other BPF_EXIT instructions will be emitted as jump.

Since jump offset to epilogue is computed as:
jmp_offset = ctx->cleanup_addr - addrs[i]
we need to change type of cleanup_addr to signed to compute the offset as:
(long long) ((int)20 - (int)30)
instead of:
(long long) ((unsigned int)20 - (int)30)

Fixes: 622582786c9e ("net: filter: x86: internal BPF JIT")
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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