Commit f75298f5 authored Jul 29, 2015 by Michael Holzheu Committed by David S. Miller Jul 29, 2015

s390/bpf: clear correct BPF accumulator register



Currently we assumed the following BPF to eBPF register mapping:

 - BPF_REG_A -> BPF_REG_7
 - BPF_REG_X -> BPF_REG_8

Unfortunately this mapping is wrong. The correct mapping is:

 - BPF_REG_A -> BPF_REG_0
 - BPF_REG_X -> BPF_REG_7

So clear the correct registers and use the BPF_REG_A and BPF_REG_X
macros instead of BPF_REG_0/7.

Fixes: 05462310 ("s390/bpf: Add s390x eBPF JIT compiler backend")
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 35e455f4

arch/s390/net/bpf_jit_comp.c

+7 −7

Original line number	Diff line number	Diff line
		@@ -448,13 +448,13 @@ static void bpf_jit_prologue(struct bpf_jit *jit)
		EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
		BPF_REG_1, offsetof(struct sk_buff, data));
		}
		/* BPF compatibility: clear A (%b7) and X (%b8) registers */
		if (REG_SEEN(BPF_REG_7))
		/* lghi %b7,0 */
		EMIT4_IMM(0xa7090000, BPF_REG_7, 0);
		if (REG_SEEN(BPF_REG_8))
		/* lghi %b8,0 */
		EMIT4_IMM(0xa7090000, BPF_REG_8, 0);
		/* BPF compatibility: clear A (%b0) and X (%b7) registers */
		if (REG_SEEN(BPF_REG_A))
		/* lghi %ba,0 */
		EMIT4_IMM(0xa7090000, BPF_REG_A, 0);
		if (REG_SEEN(BPF_REG_X))
		/* lghi %bx,0 */
		EMIT4_IMM(0xa7090000, BPF_REG_X, 0);
		}

		/*