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author | Yonghong Song <yhs@fb.com> | 2022-11-20 22:54:37 +0300 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2022-11-21 02:45:26 +0300 |
commit | a35b9af4ec2c7f69286ef861fd2074a577e354cb (patch) | |
tree | 260c91a59720dc30887556f629b4851af8efedcb /tools | |
parent | fd264ca020948a743e4c36731dfdecc4a812153c (diff) | |
download | linux-a35b9af4ec2c7f69286ef861fd2074a577e354cb.tar.xz |
bpf: Add a kfunc for generic type cast
Implement bpf_rdonly_cast() which tries to cast the object
to a specified type. This tries to support use case like below:
#define skb_shinfo(SKB) ((struct skb_shared_info *)(skb_end_pointer(SKB)))
where skb_end_pointer(SKB) is a 'unsigned char *' and needs to
be casted to 'struct skb_shared_info *'.
The signature of bpf_rdonly_cast() looks like
void *bpf_rdonly_cast(void *obj, __u32 btf_id)
The function returns the same 'obj' but with PTR_TO_BTF_ID with
btf_id. The verifier will ensure btf_id being a struct type.
Since the supported type cast may not reflect what the 'obj'
represents, the returned btf_id is marked as PTR_UNTRUSTED, so
the return value and subsequent pointer chasing cannot be
used as helper/kfunc arguments.
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221120195437.3114585-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools')
0 files changed, 0 insertions, 0 deletions