Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Alexei Starovoitov says:

====================
pull-request: bpf 2020-09-29

The following pull-request contains BPF updates for your *net* tree.

We've added 7 non-merge commits during the last 14 day(s) which contain
a total of 7 files changed, 28 insertions(+), 8 deletions(-).

The main changes are:

1) fix xdp loading regression in libbpf for old kernels, from Andrii.

2) Do not discard packet when NETDEV_TX_BUSY, from Magnus.

3) Fix corner cases in libbpf related to endianness and kconfig, from Tony.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/powerpc/net/bpf_jit_comp.c

@@ -475,7 +475,6 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 		case BPF_JMP | BPF_JSET | BPF_K:
 		case BPF_JMP | BPF_JSET | BPF_X:
 			true_cond = COND_NE;
-			fallthrough;
 		cond_branch:
 			/* same targets, can avoid doing the test :) */
 			if (filter[i].jt == filter[i].jf) {

include/asm-generic/vmlinux.lds.h

@@ -661,7 +661,7 @@
 #define BTF								\
 	.BTF : AT(ADDR(.BTF) - LOAD_OFFSET) {				\
 		__start_BTF = .;					\
-		*(.BTF)							\
+		KEEP(*(.BTF))						\
 		__stop_BTF = .;						\
 	}								\
 	. = ALIGN(4);							\

kernel/bpf/sysfs_btf.c

@@ -30,15 +30,15 @@ static struct kobject *btf_kobj;
 
 static int __init btf_vmlinux_init(void)
 {
-	if (!__start_BTF)
+	bin_attr_btf_vmlinux.size = __stop_BTF - __start_BTF;
+
+	if (!__start_BTF || bin_attr_btf_vmlinux.size == 0)
 		return 0;
 
 	btf_kobj = kobject_create_and_add("btf", kernel_kobj);
 	if (!btf_kobj)
 		return -ENOMEM;
 
-	bin_attr_btf_vmlinux.size = __stop_BTF - __start_BTF;
-
 	return sysfs_create_bin_file(btf_kobj, &bin_attr_btf_vmlinux);
 }
 

net/xdp/xsk.c

@@ -377,15 +377,30 @@ static int xsk_generic_xmit(struct sock *sk)
 		skb_shinfo(skb)->destructor_arg = (void *)(long)desc.addr;
 		skb->destructor = xsk_destruct_skb;
 
+		/* Hinder dev_direct_xmit from freeing the packet and
+		 * therefore completing it in the destructor
+		 */
+		refcount_inc(&skb->users);
 		err = dev_direct_xmit(skb, xs->queue_id);
+		if  (err == NETDEV_TX_BUSY) {
+			/* Tell user-space to retry the send */
+			skb->destructor = sock_wfree;
+			/* Free skb without triggering the perf drop trace */
+			consume_skb(skb);
+			err = -EAGAIN;
+			goto out;
+		}
+
 		xskq_cons_release(xs->tx);
 		/* Ignore NET_XMIT_CN as packet might have been sent */
-		if (err == NET_XMIT_DROP || err == NETDEV_TX_BUSY) {
+		if (err == NET_XMIT_DROP) {
 			/* SKB completed but not sent */
+			kfree_skb(skb);
 			err = -EBUSY;
 			goto out;
 		}
 
+		consume_skb(skb);
 		sent_frame = true;
 	}
 

tools/bpf/bpftool/Makefile

@@ -25,7 +25,7 @@ endif
 
 LIBBPF = $(LIBBPF_PATH)libbpf.a
 
-BPFTOOL_VERSION := $(shell make -rR --no-print-directory -sC ../../.. kernelversion)
+BPFTOOL_VERSION ?= $(shell make -rR --no-print-directory -sC ../../.. kernelversion)
 
 $(LIBBPF): FORCE
 	$(if $(LIBBPF_OUTPUT),@mkdir -p $(LIBBPF_OUTPUT))

tools/lib/bpf/btf.c

@@ -659,6 +659,12 @@ struct btf *btf__parse_raw(const char *path)
 		err = -EIO;
 		goto err_out;
 	}
+	if (magic == __bswap_16(BTF_MAGIC)) {
+		/* non-native endian raw BTF */
+		pr_warn("non-native BTF endianness is not supported\n");
+		err = -LIBBPF_ERRNO__ENDIAN;
+		goto err_out;
+	}
 	if (magic != BTF_MAGIC) {
 		/* definitely not a raw BTF */
 		err = -EPROTO;

tools/lib/bpf/libbpf.c

@@ -6925,7 +6925,7 @@ static const struct bpf_sec_def section_defs[] = {
 						BPF_XDP_DEVMAP),
 	BPF_EAPROG_SEC("xdp_cpumap/",		BPF_PROG_TYPE_XDP,
 						BPF_XDP_CPUMAP),
-	BPF_EAPROG_SEC("xdp",			BPF_PROG_TYPE_XDP,
+	BPF_APROG_SEC("xdp",			BPF_PROG_TYPE_XDP,
 						BPF_XDP),
 	BPF_PROG_SEC("perf_event",		BPF_PROG_TYPE_PERF_EVENT),
 	BPF_PROG_SEC("lwt_in",			BPF_PROG_TYPE_LWT_IN),