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authorDaniel Borkmann <daniel@iogearbox.net>2020-10-21 22:32:57 +0200
committerDaniel Borkmann <daniel@iogearbox.net>2020-10-22 01:46:52 +0200
commit3652c9a1b1fe6cbdd4510eb220db548bff8704ae (patch)
tree588bd4e33e618b033bad20f117759795ac4c3a45 /samples/bpf
parentadfd272c4ccbe43d9761bb17dd8a4387d7815382 (diff)
downloadlinux-stericsson-3652c9a1b1fe6cbdd4510eb220db548bff8704ae.tar.gz
bpf, libbpf: Guard bpf inline asm from bpf_tail_call_static
Yaniv reported a compilation error after pulling latest libbpf: [...] ../libbpf/src/root/usr/include/bpf/bpf_helpers.h:99:10: error: unknown register name 'r0' in asm : "r0", "r1", "r2", "r3", "r4", "r5"); [...] The issue got triggered given Yaniv was compiling tracing programs with native target (e.g. x86) instead of BPF target, hence no BTF generated vmlinux.h nor CO-RE used, and later llc with -march=bpf was invoked to compile from LLVM IR to BPF object file. Given that clang was expecting x86 inline asm and not BPF one the error complained that these regs don't exist on the former. Guard bpf_tail_call_static() with defined(__bpf__) where BPF inline asm is valid to use. BPF tracing programs on more modern kernels use BPF target anyway and thus the bpf_tail_call_static() function will be available for them. BPF inline asm is supported since clang 7 (clang <= 6 otherwise throws same above error), and __bpf_unreachable() since clang 8, therefore include the latter condition in order to prevent compilation errors for older clang versions. Given even an old Ubuntu 18.04 LTS has official LLVM packages all the way up to llvm-10, I did not bother to special case the __bpf_unreachable() inside bpf_tail_call_static() further. Also, undo the sockex3_kern's use of bpf_tail_call_static() sample given they still have the old hacky way to even compile networking progs with native instead of BPF target so bpf_tail_call_static() won't be defined there anymore. Fixes: 0e9f6841f664 ("bpf, libbpf: Add bpf_tail_call_static helper for bpf programs") Reported-by: Yaniv Agman <yanivagman@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Tested-by: Yaniv Agman <yanivagman@gmail.com> Link: https://lore.kernel.org/bpf/CAMy7=ZUk08w5Gc2Z-EKi4JFtuUCaZYmE4yzhJjrExXpYKR4L8w@mail.gmail.com Link: https://lore.kernel.org/bpf/20201021203257.26223-1-daniel@iogearbox.net
Diffstat (limited to 'samples/bpf')
-rw-r--r--samples/bpf/sockex3_kern.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/samples/bpf/sockex3_kern.c b/samples/bpf/sockex3_kern.c
index 8142d02b33e6..b363503357e5 100644
--- a/samples/bpf/sockex3_kern.c
+++ b/samples/bpf/sockex3_kern.c
@@ -44,17 +44,17 @@ static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto)
switch (proto) {
case ETH_P_8021Q:
case ETH_P_8021AD:
- bpf_tail_call_static(skb, &jmp_table, PARSE_VLAN);
+ bpf_tail_call(skb, &jmp_table, PARSE_VLAN);
break;
case ETH_P_MPLS_UC:
case ETH_P_MPLS_MC:
- bpf_tail_call_static(skb, &jmp_table, PARSE_MPLS);
+ bpf_tail_call(skb, &jmp_table, PARSE_MPLS);
break;
case ETH_P_IP:
- bpf_tail_call_static(skb, &jmp_table, PARSE_IP);
+ bpf_tail_call(skb, &jmp_table, PARSE_IP);
break;
case ETH_P_IPV6:
- bpf_tail_call_static(skb, &jmp_table, PARSE_IPV6);
+ bpf_tail_call(skb, &jmp_table, PARSE_IPV6);
break;
}
}