path: root/include/math-emu
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authorJohn Fastabend <john.fastabend@gmail.com>2020-06-24 15:20:39 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2020-06-25 16:17:05 +0200
commita9b59159d338d414acaa8e2f569d129d51c76452 (patch)
treeb02a3af3bee5967515fb0ca85d736b83b975f897 /include/math-emu
parentbpf: Fix formatting in documentation for BPF helpers (diff)
bpf: Do not allow btf_ctx_access with __int128 types
To ensure btf_ctx_access() is safe the verifier checks that the BTF arg type is an int, enum, or pointer. When the function does the BTF arg lookup it uses the calculation 'arg = off / 8' using the fact that registers are 8B. This requires that the first arg is in the first reg, the second in the second, and so on. However, for __int128 the arg will consume two registers by default LLVM implementation. So this will cause the arg layout assumed by the 'arg = off / 8' calculation to be incorrect. Because __int128 is uncommon this patch applies the easiest fix and will force int types to be sizeof(u64) or smaller so that they will fit in a single register. v2: remove unneeded parens per Andrii's feedback Fixes: 9e15db66136a1 ("bpf: Implement accurate raw_tp context access via BTF") Signed-off-by: John Fastabend <john.fastabend@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/159303723962.11287.13309537171132420717.stgit@john-Precision-5820-Tower
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