linux-kernel - [PATCH v3 2/4] libbpf: add support for ints larger than 128 bits

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Message-Id: <3d3f8d4cc59b61d42e05d5f66d7b29fc7eb20cfa.1609855479.git.sean@mess.org>
Date:   Tue,  5 Jan 2021 14:45:32 +0000
From:   Sean Young <sean@...s.org>
To:     Yonghong Song <yhs@...com>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Quentin Monnet <quentin@...valent.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        linux-doc@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: [PATCH v3 2/4] libbpf: add support for ints larger than 128 bits

clang supports arbitrary length ints using the _ExtInt extension. This
can be useful to hold very large values, e.g. 256 bit or 512 bit types.

This requires the _ExtInt extension enabled in clang, which is under
review.

Link: https://clang.llvm.org/docs/LanguageExtensions.html#extended-integer-types
Link: https://reviews.llvm.org/D93103

Signed-off-by: Sean Young <sean@...s.org>
---
 tools/lib/bpf/btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 3c3f2bc6c652..a676373f052b 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1722,7 +1722,7 @@ int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding
 	if (!name || !name[0])
 		return -EINVAL;
 	/* byte_sz must be power of 2 */
-	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
+	if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 64)
 		return -EINVAL;
 	if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
 		return -EINVAL;
-- 
2.29.2