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From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH bpf-next 3/3] libbpf: Fix dumping __int128
Date: Tue, 12 Oct 2021 04:32:18 +0200	[thread overview]
Message-ID: <20211012023218.399568-4-iii@linux.ibm.com> (raw)
In-Reply-To: <20211012023218.399568-1-iii@linux.ibm.com>

On s390 __int128 can be 8-byte aligned, therefore in libbpf will
occasionally consider variables of this type non-aligned and try to
dump them as a bitfield, which is supported for at most 64-bit
integers.

Fix by using the same trick as btf_dump_float_data(): copy non-aligned
values to the local buffer.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 tools/lib/bpf/btf_dump.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index ab45771d0cb4..d8264c1762e8 100644
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -1672,9 +1672,10 @@ static int btf_dump_int_data(struct btf_dump *d,
 {
 	__u8 encoding = btf_int_encoding(t);
 	bool sign = encoding & BTF_INT_SIGNED;
+	char buf[16] __aligned(16);
 	int sz = t->size;
 
-	if (sz == 0) {
+	if (sz == 0 || sz > sizeof(buf)) {
 		pr_warn("unexpected size %d for id [%u]\n", sz, type_id);
 		return -EINVAL;
 	}
@@ -1682,8 +1683,10 @@ static int btf_dump_int_data(struct btf_dump *d,
 	/* handle packed int data - accesses of integers not aligned on
 	 * int boundaries can cause problems on some platforms.
 	 */
-	if (!ptr_is_aligned(data, sz))
-		return btf_dump_bitfield_data(d, t, data, 0, 0);
+	if (!ptr_is_aligned(data, sz)) {
+		memcpy(buf, data, sz);
+		data = buf;
+	}
 
 	switch (sz) {
 	case 16: {
-- 
2.31.1


  parent reply	other threads:[~2021-10-12  2:32 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-12  2:32 [PATCH bpf-next 0/3] btf_dump fixes for s390 Ilya Leoshkevich
2021-10-12  2:32 ` [PATCH bpf-next 1/3] selftests/bpf: Use cpu_number only on arches that have it Ilya Leoshkevich
2021-10-12  3:56   ` Andrii Nakryiko
2021-10-12 11:02     ` Ilya Leoshkevich
2021-10-20 18:32       ` Andrii Nakryiko
2021-10-12  2:32 ` [PATCH bpf-next 2/3] libbpf: Fix dumping big-endian bitfields Ilya Leoshkevich
2021-10-12  4:03   ` Andrii Nakryiko
2021-10-12 11:43     ` Ilya Leoshkevich
2021-10-12  2:32 ` Ilya Leoshkevich [this message]
2021-10-12  3:52   ` [PATCH bpf-next 3/3] libbpf: Fix dumping __int128 Andrii Nakryiko
2021-10-12 11:44     ` Ilya Leoshkevich

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