On Tue, Jun 18, 2024 at 5:43 AM Jiri Olsa olsajiri@gmail.com wrote:
On Mon, Jun 17, 2024 at 03:25:53PM -0700, Andrii Nakryiko wrote:
On Mon, Jun 10, 2024 at 6:04 AM Jiri Olsa olsajiri@gmail.com wrote:
On Sat, Jun 08, 2024 at 03:16:02PM -0600, Daniel Xu wrote:
The prototype defined in bpf_kfuncs.h was not in line with how the actual kfunc was defined. This causes compilation errors when kfunc prototypes are generated from BTF.
Fix by aligning with actual kfunc definition.
Signed-off-by: Daniel Xu dxu@dxuuu.xyz
tools/testing/selftests/bpf/bpf_kfuncs.h | 2 +- tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h index be91a6919315..3b6675ab4086 100644 --- a/tools/testing/selftests/bpf/bpf_kfuncs.h +++ b/tools/testing/selftests/bpf/bpf_kfuncs.h @@ -77,5 +77,5 @@ extern int bpf_verify_pkcs7_signature(struct bpf_dynptr *data_ptr, struct bpf_key *trusted_keyring) __ksym;
extern bool bpf_session_is_return(void) __ksym __weak; -extern long *bpf_session_cookie(void) __ksym __weak; +extern __u64 *bpf_session_cookie(void) __ksym __weak;
the original intent was to expose long instead of __u64 :-\
Cookies internally are always u64 (8 byte values). Marking them internally in the kernel as long could lead to problems on 32-bit architectures, potentially (it still needs to be 64-bit value according to BPF contract, but we'll allocate only 4 bytes for them).
It seems better and safer to be explicit with __u64/u64 for cookies everywhere.
hum, I based that on what we did for kprobe session, but I guess it makes sense just for bpf side:
yep, exactly, long is 64-bit only for BPF "architecture", but internally it will be 4 bytes for 32-bit architectures, which will potentially lead to problems. With recent kfunc vmlinux.h generation, it's probably better to stick to explicitly sized types.
https://lore.kernel.org/bpf/CAEf4BzbyQpKvZS-mUECLRq3gyBJbsqQghOKyAbutoB76mJM...
jirka
What am I missing?
could we rather change the bpf_session_cookie function to return long? should be just return value type change
thanks, jirka
#endif diff --git a/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c b/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c index d49070803e22..0835b5edf685 100644 --- a/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c +++ b/tools/testing/selftests/bpf/progs/kprobe_multi_session_cookie.c @@ -25,7 +25,7 @@ int BPF_PROG(trigger)
static int check_cookie(__u64 val, __u64 *result) {
long *cookie;
__u64 *cookie; if (bpf_get_current_pid_tgid() >> 32 != pid) return 1;-- 2.44.0