bpftool: Make skeleton C++ compatible with explicit casts #10607
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Author
|
Upstream branch: a069190 |
Fix C++ compilation errors in generated skeleton by adding explicit
pointer casts and using integer subtraction for offset calculation.
Use struct outer::inner syntax under __cplusplus to access nested skeleton map
structs, ensuring C++ compilation compatibility while preserving C support
error: invalid conversion from 'void*' to '<obj_name>*' [-fpermissive]
| skel = skel_alloc(sizeof(*skel));
| ~~~~~~~~~~^~~~~~~~~~~~~~~
| |
| void*
error: arithmetic on pointers to void
| skel->ctx.sz = (void *)&skel->links - (void *)skel;
| ~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~
error: assigning to 'struct <obj_name>__<ident> *' from incompatible type 'void *'
| skel-><ident> = skel_prep_map_data((void *)data, 4096,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| sizeof(data) - 1);
| ~~~~~~~~~~~~~~~~~
error: assigning to 'struct <obj_name>__<ident> *' from incompatible type 'void *'
| skel-><ident> = skel_finalize_map_data(&skel->maps.<ident>.initial_value,
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| 4096, PROT_READ | PROT_WRITE, skel->maps.<ident>.map_fd);
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Minimum reproducer:
$ cat test.bpf.c
int val; // placed in .bss section
#include "vmlinux.h"
#include <bpf/bpf_helpers.h>
SEC("raw_tracepoint/sched_wakeup_new") int handle(void *ctx) { return 0; }
$ cat test.cpp
#include <cerrno>
extern "C" {
#include "test.bpf.skel.h"
}
$ bpftool btf dump file /sys/kernel/btf/vmlinux format c > vmlinux.h
$ clang -g -O2 -target bpf -c test.bpf.c -o test.bpf.o
$ bpftool gen skeleton test.bpf.o -L > test.bpf.skel.h
$ g++ -c test.cpp -I.
Signed-off-by: WanLi Niu <niuwl1@chinatelecom.cn>
Co-developed-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Acked-by: Quentin Monnet <qmo@kernel.org>
Author
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Upstream branch: a069190 |
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Pull request for series with
subject: bpftool: Make skeleton C++ compatible with explicit casts
version: 4
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1038349