On Wed, Aug 26, 2020 at 9:08 AM Alexei Starovoitov
[off-list ref] wrote:

On Tue, Aug 25, 2020 at 08:09:21PM -0700, Andrii Nakryiko wrote:

quoted

Add __pu64 and __ps64 (sort of like "printf u64 and s64") for libbpf-internal
use only in printf-like situations to avoid compilation warnings due to
%lld/%llu mismatch with a __u64/__s64 due to some architecture defining the
latter as either `long` or `long long`. Use that on all %lld/%llu cases in
libbpf.c.

Reported-by: Naresh Kamboju <redacted>
Fixes: eacaaed784e2 ("libbpf: Implement enum value-based CO-RE relocations")
Fixes: 50e09460d9f8 ("libbpf: Skip well-known ELF sections when iterating ELF")
Signed-off-by: Andrii Nakryiko <redacted>
---
 tools/lib/bpf/libbpf.c          | 15 ++++++++-------
 tools/lib/bpf/libbpf_internal.h | 11 +++++++++++
 2 files changed, 19 insertions(+), 7 deletions(-)

[...]

quoted

+/* These types are for casting 64-bit arguments of printf-like functions to
+ * avoid compiler warnings on various architectures that define size_t, __u64,
+ * uint64_t, etc as either unsigned long or unsigned long long (similarly for
+ * signed variants). Use these typedefs only for these purposes. Alternative
+ * is PRIu64 (and similar) macros, requiring stitching printf format strings
+ * which are extremely ugly and should be avoided in libbpf code base. With
+ * arguments casted to __pu64/__ps64, always use %llu/%lld in format string.
+ */
+typedef unsigned long long __pu64;
+typedef long long __ps64;

I think these extra typedefs will cause confusion. Original approach
of open coding type casts to long long and unsigned long long is imo cleaner.

Fair enough. Sent v2 with just direct "unsigned long long" casts.