examples/l3fwd: fix crash with unaligned L2 header

l3fwd app expects PMDs to return packets whose L2 header is
16-byte aligned due to usage of _mm_load_si128()/_mm_store_si128()
intrinsics in the app. However, most of the protocol stacks expects
packets such that its IP/L3 header be aligned on a 16-byte boundary.

Based on the recommendations received on dpdk-dev, we are changing
the l3fwd app to use _mm_loadu_si128()/_mm_loadu_si128() so that the
address need not be 16-byte aligned and thereby preventing crash.
We have tested that there is no performance impact due to this
change.

Signed-off-by: Harish Patil <harish.patil@qlogic.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

diff --git a/examples/l3fwd/main.c b/examples/l3fwd/main.c
index 91a0f58..5b0c2dd 100644 (file)
--- a/examples/l3fwd/main.c
+++ b/examples/l3fwd/main.c
@@ -1220,14 +1220,14 @@ process_packet(struct lcore_conf *qconf, struct rte_mbuf *pkt,
        dst_ipv4 = rte_be_to_cpu_32(dst_ipv4);
        dp = get_dst_port(qconf, pkt, dst_ipv4, portid);
 
-       te = _mm_load_si128((__m128i *)eth_hdr);
+       te = _mm_loadu_si128((__m128i *)eth_hdr);
        ve = val_eth[dp];
 
        dst_port[0] = dp;
        rfc1812_process(ipv4_hdr, dst_port, pkt->packet_type);
 
        te =  _mm_blend_epi16(te, ve, MASK_ETH);
-       _mm_store_si128((__m128i *)eth_hdr, te);
+       _mm_storeu_si128((__m128i *)eth_hdr, te);
 }
 
 /*
@@ -1313,16 +1313,16 @@ processx4_step3(struct rte_mbuf *pkt[FWDSTEP], uint16_t dst_port[FWDSTEP])
        p[3] = rte_pktmbuf_mtod(pkt[3], __m128i *);
 
        ve[0] = val_eth[dst_port[0]];
-       te[0] = _mm_load_si128(p[0]);
+       te[0] = _mm_loadu_si128(p[0]);
 
        ve[1] = val_eth[dst_port[1]];
-       te[1] = _mm_load_si128(p[1]);
+       te[1] = _mm_loadu_si128(p[1]);
 
        ve[2] = val_eth[dst_port[2]];
-       te[2] = _mm_load_si128(p[2]);
+       te[2] = _mm_loadu_si128(p[2]);
 
        ve[3] = val_eth[dst_port[3]];
-       te[3] = _mm_load_si128(p[3]);
+       te[3] = _mm_loadu_si128(p[3]);
 
        /* Update first 12 bytes, keep rest bytes intact. */
        te[0] =  _mm_blend_epi16(te[0], ve[0], MASK_ETH);
@@ -1330,10 +1330,10 @@ processx4_step3(struct rte_mbuf *pkt[FWDSTEP], uint16_t dst_port[FWDSTEP])
        te[2] =  _mm_blend_epi16(te[2], ve[2], MASK_ETH);
        te[3] =  _mm_blend_epi16(te[3], ve[3], MASK_ETH);
 
-       _mm_store_si128(p[0], te[0]);
-       _mm_store_si128(p[1], te[1]);
-       _mm_store_si128(p[2], te[2]);
-       _mm_store_si128(p[3], te[3]);
+       _mm_storeu_si128(p[0], te[0]);
+       _mm_storeu_si128(p[1], te[1]);
+       _mm_storeu_si128(p[2], te[2]);
+       _mm_storeu_si128(p[3], te[3]);
 
        rfc1812_process((struct ipv4_hdr *)((struct ether_hdr *)p[0] + 1),
                &dst_port[0], pkt[0]->packet_type);