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| author | Yonghong Song <yhs@fb.com> | 2023-04-25 22:50:30 -0700 |
|---|---|---|
| committer | Matthias Maennich <maennich@google.com> | 2023-05-02 16:16:36 +0100 |
| commit | ea353ab8f68b23b5b5df9048beec26e3e3660680 (patch) | |
| tree | 953a14df1e3aba8165f79062aa101cde9beaa713 | |
| parent | ebe1755fff7972edf58b96695e0ba489133465b6 (diff) | |
| download | dwarves-ea353ab8f68b23b5b5df9048beec26e3e3660680.tar.gz | |
btf_encoder: Fix a dwarf type DW_ATE_unsigned_1024 to btf encoding issue
Nick Desaulniers reported an issue ([1]) where an 128-byte sized type
(DW_ATE_unsigned_1024) cannot be encoded into BTF with failure message
likes below:
$ pahole -J reduced.o
[2] INT DW_ATE_unsigned_1024 Error emitting BTF type
Encountered error while encoding BTF.
See [1] for how to reproduce the issue.
The failure is due to currently BTF int type only supports upto 16
bytes (__int128) and in this case the dwarf int type is 128-byte.
The DW_ATE_unsigned_1024 is not a normal type for variable/func
declaration etc. It is used in DW_AT_location. There are two
ways to resolve this issue.
(1). If btf encoding is expected, remove all dwarf int types
where btf encoding will failure, e.g., non-power-of-2
bytes, or greater than 16 bytes.
(2). do a sanitization in btf_encoder ([2]).
This patch uses method (2) since it is a simple fix in btf_encoder.
I checked my local built vmlinux with latest
bpf-next. There is only one instance of DW_ATE_unsigned_24 (used in
DW_AT_location) so I expect irregular int types should be very rare.
[1] https://github.com/libbpf/libbpf/pull/680
[2] commit 7d8e829f636f ("btf_encoder: Sanitize non-regular int base type")
Bug: 279144929
Change-Id: Ie93d2b0cc5a232cb1853f44dbe395ad3c95210a3
Signed-off-by: Yonghong Song <yhs@fb.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Matthias Maennich <maennich@google.com>
| -rw-r--r-- | btf_encoder.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/btf_encoder.c b/btf_encoder.c index 9d015f3..154d679 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -353,7 +353,7 @@ static int32_t btf_encoder__add_base_type(struct btf_encoder *encoder, const str * these non-regular int types to avoid libbpf/kernel complaints. */ byte_sz = BITS_ROUNDUP_BYTES(bt->bit_size); - if (!byte_sz || (byte_sz & (byte_sz - 1))) { + if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16) { name = "__SANITIZED_FAKE_INT__"; byte_sz = 4; } |