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Martin KaFai Lau 569c484f99 bpf: Limit static tcp-cc functions in the .BTF_ids list to x86 
During the discussion in [0]. It was pointed out that static functions
in ppc64 is prefixed with ".". For example, the 'readelf -s vmlinux.ppc':

  89326: c000000001383280    24 NOTYPE  LOCAL  DEFAULT   31 cubictcp_init
  89327: c000000000c97c50   168 FUNC    LOCAL  DEFAULT    2 .cubictcp_init

The one with FUNC type is ".cubictcp_init" instead of "cubictcp_init".
The "." seems to be done by arch/powerpc/include/asm/ppc_asm.h.

This caused that pahole cannot generate the BTF for these tcp-cc kernel
functions because pahole only captures the FUNC type and "cubictcp_init"
is not. It then failed the kernel compilation in ppc64.

This behavior is only reported in ppc64 so far. I tried arm64, s390,
and sparc64 and did not observe this "." prefix and NOTYPE behavior.

Since the kfunc call is only supported in the x86_64 and x86_32 JIT,
this patch limits those tcp-cc functions to x86 only to avoid unnecessary
compilation issue in other ARCHs. In the future, we can examine if it
is better to change all those functions from static to extern.

  [0] https://lore.kernel.org/bpf/4e051459-8532-7b61-c815-f3435767f8a0@kernel.org/

Fixes: e78aea8b21 ("bpf: tcp: Put some tcp cong functions in allowlist for bpf-tcp-cc")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Michal Suchánek <msuchanek@suse.de>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/bpf/20210508005011.3863757-1-kafai@fb.com
2021-05-11 23:23:07 +02:00
arch
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Documentation bpf: Add kconfig knob for disabling unpriv bpf by default 2021-05-11 13:56:16 -07:00
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init bpf, kconfig: Add consolidated menu entry for bpf with core options 2021-05-11 13:56:16 -07:00
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kernel bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers 2021-05-11 14:02:33 -07:00
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net bpf: Limit static tcp-cc functions in the .BTF_ids list to x86 2021-05-11 23:23:07 +02:00
samples samples/bpf: Consider frame size in tx_only of xdpsock sample 2021-05-07 01:19:55 +02:00
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tools selftests/bpf: Rewrite test_tc_redirect.sh as prog_tests/tc_redirect.c 2021-05-11 23:15:43 +02:00
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