Re: [linux-next][41e83b9][gcc 4.8.5] make modules fail at net/netfilter/xt_bpf.ko

Al Viro
2017-12-05T18:07:00Z

On Tue, Dec 05, 2017 at 08:13:11PM +0530, Abdul Haleem wrote:
> Hi Al Viro,
>
> Today's next kernel build failed with commit 41e83b9: fix "netfilter:
> xt_bpf: Fix XT_BPF_MODE_FD_PINNED
>
> Machine Type: Power 7
> kernel version: 4.15.0-rc2-next-20171204
> kernel config: attached
> test: 'make modules'
>
> ERROR: ".bpf_prog_get_type_path" [net/netfilter/xt_bpf.ko] undefined!
>
> Kernel built fine when bad commit is reverted.

In the same commit there's

+EXPORT_SYMBOL(bpf_prog_get_type_path);

so I really wonder WTF is going on...

Oh, I see. !BPF_SYSCALL and NETFILTER_XT_MATCH_BPF in .config triggers
that. Incremental (to be folded into the commit in question) follows:

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index a7000e4775e7..571450f98006 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -419,6 +419,8 @@ static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
attr->numa_node : NUMA_NO_NODE;
}

+struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type);
+
#else /* !CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get(u32 ufd)
{
@@ -506,6 +508,12 @@ static inline int cpu_map_enqueue(struct bpf_cpu_map_entry *rcpu,
{
return 0;
}
+
+static inline struct bpf_prog *bpf_prog_get_type_path(const char *name,
+ enum bpf_prog_type type)
+{
+ return -EOPNOTSUPP;
+}
#endif /* CONFIG_BPF_SYSCALL */

static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
@@ -514,7 +522,6 @@ static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
return bpf_prog_get_type_dev(ufd, type, false);
}

-struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type);
bool bpf_prog_get_ok(struct bpf_prog *, enum bpf_prog_type *, bool);

int bpf_prog_offload_compile(struct bpf_prog *prog);