On 3/12/24 17:27, Andrii Nakryiko wrote:
On Tue, Mar 12, 2024 at 5:08 PM Kui-Feng Lee <sinquersw@xxxxxxxxx> wrote:
On 3/12/24 15:47, Andrii Nakryiko wrote:
On Mon, Mar 11, 2024 at 6:38 PM Kui-Feng Lee <thinker.li@xxxxxxxxx> wrote:
According to a report, skeletons fail to assign shadow pointers when being
compiled with C++ programs. Unlike C doing implicit casting for void
pointers, C++ requires an explicit casting.
To support C++, we do explicit casting for each shadow pointer.
Cc: yhs@xxxxxxxx
Signed-off-by: Kui-Feng Lee <thinker.li@xxxxxxxxx>
---
tools/bpf/bpftool/gen.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index 4fa4ade1ce74..dedafea0c127 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -1131,7 +1131,7 @@ static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj)
continue;
codegen("\
\n\
- obj->struct_ops.%1$s = bpf_map__initial_value(obj->maps.%1$s, NULL);\n\
+ obj->struct_ops.%1$s = (typeof(obj->struct_ops.%1$s))bpf_map__initial_value(obj->maps.%1$s, NULL);\n\
Given we have a named struct type for this and we use explicit type
names in other parts of generated skeleton code, let's maybe use
"struct %s__%s__%s" explicitly here (passing in obj_name, ident,
type_name)?
I have considered about this solution. But, C++ works differently. It
has nested namespaces. That means it should be referred as
"XXX_skeleton::OOO_st_ops_map" in C++. Then, we need #if #else #endif
directives to provide two separated casting.
we cast to (struct <skeleton> *) by name of the skeleton, so it should
be fine, I don't see why we'd need to do something C++ specific here
The skeleton looks like
struct struct_ops_module {
......
struct {
struct
struct_ops_module__testmod_zeroed__bpf_testmod_ops___zeroed {
....
} testmod_zeroed;
} struct_ops;
};
struct struct_ops_module__testmod_zeroed__bpf_testmod_ops___zeroed is
inside of struct struct_ops_module. In C++, it should be referred as
"struct_ops_module::struct_ops_module__testmod_zeroed__bpf_testmod_ops___zeroed".
The other option is moving definitions of these types to the top scope.
No strong preferences, but feels like a consistent approach here would be nice.
\n\
", ident);
}
--
2.34.1
