iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

libbpf: Simplify BPF_CORE_READ_BITFIELD_PROBED usage

Browse Source 
Streamline BPF_CORE_READ_BITFIELD_PROBED interface to follow
BPF_CORE_READ_BITFIELD (direct) and BPF_CORE_READ, in general, i.e., just
return read result or 0, if underlying bpf_probe_read() failed.

In practice, real applications rarely check bpf_probe_read() result, because
it has to always work or otherwise it's a bug. So propagating internal
bpf_probe_read() error from this macro hurts usability without providing real
benefits in practice. This patch fixes the issue and simplifies usage,
noticeable even in selftest itself.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20191106201500.2582438-1-andriin@fb.com
This commit is contained in:
Andrii Nakryiko
2019-11-06 12:15:00 -08:00
committed by Alexei Starovoitov
parent 65a052d537
commit ed57802121
2 changed files with 18 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
tools/testing/selftests/bpf/progs/test_core_reloc_bitfields_probed.c
View File

@@ -37,11 +37,6 @@ struct core_reloc_bitfields_output {
int64_t s32;
};
#define TRANSFER_BITFIELD(in, out, field) \
if (BPF_CORE_READ_BITFIELD_PROBED(in, field, &res)) \
return 1; \
out->field = res
SEC("raw_tracepoint/sys_enter")
int test_core_bitfields(void *ctx)
{
@@ -49,13 +44,13 @@ int test_core_bitfields(void *ctx)
struct core_reloc_bitfields_output *out = (void *)&data.out;
uint64_t res;
TRANSFER_BITFIELD(in, out, ub1);
TRANSFER_BITFIELD(in, out, ub2);
TRANSFER_BITFIELD(in, out, ub7);
TRANSFER_BITFIELD(in, out, sb4);
TRANSFER_BITFIELD(in, out, sb20);
TRANSFER_BITFIELD(in, out, u32);
TRANSFER_BITFIELD(in, out, s32);
out->ub1 = BPF_CORE_READ_BITFIELD_PROBED(in, ub1);
out->ub2 = BPF_CORE_READ_BITFIELD_PROBED(in, ub2);
out->ub7 = BPF_CORE_READ_BITFIELD_PROBED(in, ub7);
out->sb4 = BPF_CORE_READ_BITFIELD_PROBED(in, sb4);
out->sb20 = BPF_CORE_READ_BITFIELD_PROBED(in, sb20);
out->u32 = BPF_CORE_READ_BITFIELD_PROBED(in, u32);
out->s32 = BPF_CORE_READ_BITFIELD_PROBED(in, s32);
return 0;
}