]> www.infradead.org Git - users/jedix/linux-maple.git/commit
s390/bpf: Fix backward jumps
authorMichael Holzheu <holzheu@linux.vnet.ibm.com>
Thu, 21 May 2015 13:39:31 +0000 (15:39 +0200)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Fri, 10 Jul 2015 16:49:36 +0000 (09:49 -0700)
commit17de07163877d0f1fdd9185130ac4111f5f340f7
treec4d00bdc9d3bcdcbdba6522af40cd9cacf3ae798
parent534c9f9886c25221d4f4dd396cd78b67214c1796
s390/bpf: Fix backward jumps

commit b035b60ded132592055c0f9bd1cc280259c7de4b upstream.

Currently all backward jumps crash for JITed s390x eBPF programs
with an illegal instruction program check and kernel panic. Because
for negative values the opcode of the jump instruction is overriden
by the negative branch offset an illegal instruction is generated
by the JIT:

 000003ff802da378c01100000002   lgfi    %r1,2
 000003ff802da37efffffff52065   unknown <-- illegal instruction
 000003ff802da384b904002e       lgr     %r2,%r14

So fix this and mask the offset in order not to damage the opcode.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
arch/s390/net/bpf_jit_comp.c