s390/bpf,jit: add pkt_type support

s390 version of 3b58908a "x86: bpf_jit_comp: add pkt_type support".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 788e22395acd..d5f10a43a58f 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -10,6 +10,7 @@
 #include <linux/if_vlan.h>
 #include <linux/filter.h>
 #include <linux/random.h>
+#include <linux/init.h>
 #include <asm/cacheflush.h>
 #include <asm/processor.h>
 #include <asm/facility.h>
@@ -222,6 +223,37 @@ static void bpf_jit_epilogue(struct bpf_jit *jit)
         EMIT2(0x07fe);
 }
 
+/* Helper to find the offset of pkt_type in sk_buff
+ * Make sure its still a 3bit field starting at the MSBs within a byte.
+ */
+#define PKT_TYPE_MAX 0xe0
+static int pkt_type_offset;
+
+static int __init bpf_pkt_type_offset_init(void)
+{
+        struct sk_buff skb_probe = {
+                .pkt_type = ~0,
+        };
+        char *ct = (char *)&skb_probe;
+        int off;
+
+        pkt_type_offset = -1;
+        for (off = 0; off < sizeof(struct sk_buff); off++) {
+                if (!ct[off])
+                        continue;
+                if (ct[off] == PKT_TYPE_MAX)
+                        pkt_type_offset = off;
+                else {
+                        /* Found non matching bit pattern, fix needed. */
+                        WARN_ON_ONCE(1);
+                        pkt_type_offset = -1;
+                        return -1;
+                }
+        }
+        return 0;
+}
+device_initcall(bpf_pkt_type_offset_init);
+
 /*
  * make sure we dont leak kernel information to user
  */
@@ -721,6 +753,16 @@ call_fn:	/* lg %r1,<d(function)>(%r13) */
                         EMIT4_DISP(0x88500000, 12);
                 }
                 break;
+        case BPF_S_ANC_PKTTYPE:
+                if (pkt_type_offset < 0)
+                        goto out;
+                /* lhi %r5,0 */
+                EMIT4(0xa7580000);
+                /* ic %r5,<d(pkt_type_offset)>(%r2) */
+                EMIT4_DISP(0x43502000, pkt_type_offset);
+                /* srl %r5,5 */
+                EMIT4_DISP(0x88500000, 5);
+                break;
         case BPF_S_ANC_CPU: /* A = smp_processor_id() */
 #ifdef CONFIG_SMP
                 /* l %r5,<d(cpu_nr)> */