btf: ice: implement finding BTF type id

Function btf_get_type_id is needed to get correct BTF id to fill metadata by driver. BTF id is obtained while loading XDP program and saved in ring structure to be available in irq. Calling btf_get_type_id with null pointer as module will result in searching for BTF id in vmlinux. Also cleanup sample code to print id from metadata and from libbpf. Moving btf_id in generic metadata structure is temporary solution. Signed-off-by: Ederson de Souza <[email protected]> Signed-off-by: Michal Swiatkowski <[email protected]>
alobakin · Sep 23, 2021 · 36335fe · 36335fe
1 parent f1a04d2
commit 36335fe
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Showing 9 changed files with 76 additions and 14 deletions.
diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
@@ -38,6 +38,7 @@
 #include <linux/avf/virtchnl.h>
 #include <linux/cpu_rmap.h>
 #include <linux/dim.h>
+#include <linux/btf.h>
 #include <net/devlink.h>
 #include <net/ipv6.h>
 #include <net/xdp_sock.h>
@@ -350,6 +351,7 @@ struct ice_vsi {
 	u8 xdp_mapping_mode;		 /* ICE_MAP_MODE_[CONTIG|SCATTER] */
 
 	bool xdp_metadata_support;	 /* true if VSI should support xdp meta */
+	s32 btf_id;
 
 	/* setup back reference, to which aggregator node this VSI
 	 * corresponds to

diff --git a/drivers/net/ethernet/intel/ice/ice_main.c b/drivers/net/ethernet/intel/ice/ice_main.c
@@ -2423,11 +2423,15 @@ static void ice_xdp_rings_set_metadata(struct ice_vsi *vsi)
 {
 	int i;
 
-	ice_for_each_rxq(vsi, i)
+	ice_for_each_rxq(vsi, i) {
 		vsi->rx_rings[i]->xdp_metadata_support = vsi->xdp_metadata_support;
+		vsi->rx_rings[i]->btf_id = vsi->btf_id;
+	}
 
-	for (i = 0; i < vsi->num_xdp_txq; i++)
+	for (i = 0; i < vsi->num_xdp_txq; i++) {
 		vsi->xdp_rings[i]->xdp_metadata_support = vsi->xdp_metadata_support;
+		vsi->xdp_rings[i]->btf_id = vsi->btf_id;
+	}
 }
 
 /**
@@ -2646,8 +2650,10 @@ ice_xdp_setup_prog(struct ice_vsi *vsi, struct bpf_prog *prog,
 		}
 	}
 
-	if (flags & XDP_FLAGS_USE_METADATA)
+	if (flags & XDP_FLAGS_USE_METADATA) {
 		vsi->xdp_metadata_support = true;
+		vsi->btf_id = btf_get_type_id(THIS_MODULE, "xdp_meta_generic", BTF_KIND_STRUCT);
+	}	
 
 	if (!ice_is_xdp_ena_vsi(vsi) && prog) {
 		vsi->num_xdp_txq = vsi->alloc_rxq;

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.c b/drivers/net/ethernet/intel/ice/ice_txrx.c
@@ -1137,7 +1137,8 @@ int ice_clean_rx_irq(struct ice_ring *rx_ring, int budget)
 		xdp_prepare_buff(&xdp, hard_start, offset, size, true);
 
 		if (likely(rx_ring->xdp_metadata_support))
-			ice_xdp_set_meta(&xdp, rx_desc);
+			ice_xdp_set_meta(&xdp, rx_desc, rx_ring->btf_id);
+
 #if (PAGE_SIZE > 4096)
 		/* At larger PAGE_SIZE, frame_sz depend on len size */
 		xdp.frame_sz = ice_rx_frame_truesize(rx_ring, size);

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx.h b/drivers/net/ethernet/intel/ice/ice_txrx.h
@@ -302,6 +302,7 @@ struct ice_ring {
 	/* CL3 - 3rd cacheline starts here */
 	struct xdp_rxq_info xdp_rxq;
 	struct sk_buff *skb;
+	s32 btf_id;
 
 
 	/* CLX - the below items are only accessed infrequently and should be

diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.h b/drivers/net/ethernet/intel/ice/ice_txrx_lib.h
@@ -46,14 +46,24 @@ static inline void ice_xdp_ring_update_tail(struct ice_ring *xdp_ring)
 	writel_relaxed(xdp_ring->next_to_use, xdp_ring->tail);
 }
 
-static inline void ice_xdp_set_meta(struct xdp_buff *xdp, union ice_32b_rx_flex_desc *desc)
+static inline void ice_xdp_set_meta(struct xdp_buff *xdp, union ice_32b_rx_flex_desc *desc, s32 btf_id)
 {
 	struct ice_32b_rx_flex_desc_nic *flex = (struct ice_32b_rx_flex_desc_nic *)desc;
 	struct xdp_meta_generic *md = xdp->data - sizeof(struct xdp_meta_generic);
 
-	xdp->data_meta = md;
 	md->rxcvid = le16_to_cpu(flex->flex_ts.flex.vlan_id);
 	md->hash = le32_to_cpu(flex->rss_hash);
+
+	md->flags = 0;
+	md->free_slot = 0;
+	md->csum_off = 0;
+	md->txcvid = 0;
+	md->csum = 0;
+	md->tstamp = 0;
+
+	md->btf_id = btf_id;
+
+	xdp->data_meta = md;
 }
 
 void ice_finalize_xdp_rx(struct ice_ring *rx_ring, unsigned int xdp_res);

diff --git a/include/linux/btf.h b/include/linux/btf.h
@@ -94,6 +94,7 @@ u32 btf_obj_id(const struct btf *btf);
 bool btf_is_kernel(const struct btf *btf);
 bool btf_is_module(const struct btf *btf);
 struct module *btf_try_get_module(const struct btf *btf);
+s32 btf_get_type_id(const struct module *mod, char *name, u32 kind);
 u32 btf_nr_types(const struct btf *btf);
 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
 			   const struct btf_member *m,

diff --git a/include/net/xdp.h b/include/net/xdp.h
@@ -77,6 +77,9 @@ struct xdp_buff {
 };
 
 struct xdp_meta_generic {
+	// BTF ID
+	u32        btf_id;
+
 	// Tx part
 	u32        flags;
 	u16        free_slot;
@@ -88,9 +91,6 @@ struct xdp_meta_generic {
 	u32        csum;
 	u32        hash;
 	u64        tstamp;
-
-	// BTF ID
-	u32        btf_id;
 } __packed __aligned(8);
 static_assert(sizeof(struct xdp_meta_generic) == 32);
 

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
@@ -6152,6 +6152,43 @@ struct module *btf_try_get_module(const struct btf *btf)
 	return res;
 }
 
+struct btf *btf_get_from_module(const struct module *module)
+{
+	struct btf *res = NULL;
+#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
+	struct btf_module *btf_mod, *tmp;
+
+	mutex_lock(&btf_module_mutex);
+	list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
+		if (btf_mod->module != module)
+			continue;
+
+		res = btf_mod->btf;
+
+		break;
+	}
+	mutex_unlock(&btf_module_mutex);
+#endif
+
+	return res;
+}
+
+s32 btf_get_type_id(const struct module *mod, char *name, u32 kind)
+{
+	struct btf *btf;
+
+	if (mod)
+		btf = btf_get_from_module(mod);
+	else
+		btf = bpf_get_btf_vmlinux();
+
+	if (!btf)
+		return 0;
+
+	return btf_find_by_name_kind(btf, name, kind);
+}
+EXPORT_SYMBOL_GPL(btf_get_type_id);
+
 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
 {
 	struct btf *btf;

diff --git a/samples/bpf/xdp_meta.bpf.c b/samples/bpf/xdp_meta.bpf.c
@@ -8,17 +8,18 @@
 #include <bpf/bpf_core_read.h>
 #include <bpf/bpf_helpers.h>
 
-struct xdp_meta_generic___empty {
-	u32 btf_id;
+struct xdp_meta_generic___btf {
+	u32        btf_id;
 };
 
 SEC("xdp")
 int xdp_meta_prog(struct xdp_md *ctx)
 {
-	struct xdp_meta_generic___empty *data_meta =
+	struct xdp_meta_generic___btf *data_meta =
 		(void *)(long)ctx->data_meta;
 	void *data_end = (void *)(long)ctx->data_end;
 	void *data = (void *)(long)ctx->data;
+	u32 *btf_id = (void *)((long)ctx->data - 4);
 	struct ethhdr *eth = data;
 	u64 nh_off;
 	int id;
@@ -31,8 +32,11 @@ int xdp_meta_prog(struct xdp_md *ctx)
 	if (data_meta + 1 > data)
 		return XDP_DROP;
 
-	id = bpf_core_type_id_kernel(struct xdp_meta_generic___empty);
-	bpf_printk("id is %d\n", id);
+	id = bpf_core_type_id_kernel(struct xdp_meta_generic___btf);
+	bpf_printk("id from libbpf %d, id from hints metadata %d\n", id, data_meta->btf_id);
+
+	if (id && id == data_meta->btf_id)
+		bpf_printk("hints match btf_id\n");
 
 	return XDP_PASS;
 }