On Thu, Mar 21, 2024 at 8:16 AM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> Noticed on several perf container builds:
>
> perfbuilder@number:~$ grep -B1 -A2 "cast to pointer" dm.log/*\:*
> dm.log/ubuntu:18.04-x-arm-libbpf.c: In function 'bpf_object__create_maps':
> dm.log/ubuntu:18.04-x-arm:libbpf.c:5355:24: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> dm.log/ubuntu:18.04-x-arm- map->mmaped = mmap((void *)map->map_extra, bpf_map_mmap_sz(map),
> dm.log/ubuntu:18.04-x-arm- ^
> --
> dm.log/ubuntu:18.04-x-powerpc-libbpf.c: In function 'bpf_object__create_maps':
> dm.log/ubuntu:18.04-x-powerpc:libbpf.c:5355:24: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> dm.log/ubuntu:18.04-x-powerpc- map->mmaped = mmap((void *)map->map_extra, bpf_map_mmap_sz(map),
> dm.log/ubuntu:18.04-x-powerpc- ^
> --
> dm.log/ubuntu:18.04-x-sh4-libbpf.c: In function 'bpf_object__create_maps':
> dm.log/ubuntu:18.04-x-sh4:libbpf.c:5355:24: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
> dm.log/ubuntu:18.04-x-sh4- map->mmaped = mmap((void *)map->map_extra, bpf_map_mmap_sz(map),
> dm.log/ubuntu:18.04-x-sh4- ^
> perfbuilder@number:~$
>
> I think Namhyung mentioned as well on a chat conversation about noticing
> this on a 32-bit build on Debian.
>
> Fixes: 79ff13e99169ddb0 ("libbpf: Add support for bpf_arena.")
> Reported-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
> Cc: Andrii Nakryiko <andrii@xxxxxxxxxx>
> Cc: Ian Rogers <irogers@xxxxxxxxxx>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> ---
> tools/lib/bpf/libbpf.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
We've already landed a similar fix in the bpf tree, see [0].
[0] https://patchwork.kernel.org/project/netdevbpf/patch/20240319215143.1279312-1-andrii@xxxxxxxxxx/
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index efab29b8935bd9f7..af0b0e24978558f8 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -14,6 +14,7 @@
> #define _GNU_SOURCE
> #endif
> #include <stdlib.h>
> +#include <stdint.h>
> #include <stdio.h>
> #include <stdarg.h>
> #include <libgen.h>
> @@ -5352,7 +5353,7 @@ bpf_object__create_maps(struct bpf_object *obj)
> goto err_out;
> }
> if (map->def.type == BPF_MAP_TYPE_ARENA) {
> - map->mmaped = mmap((void *)map->map_extra, bpf_map_mmap_sz(map),
> + map->mmaped = mmap((void *)(uintptr_t)map->map_extra, bpf_map_mmap_sz(map),
> PROT_READ | PROT_WRITE,
> map->map_extra ? MAP_SHARED | MAP_FIXED : MAP_SHARED,
> map->fd, 0);
> --
> 2.44.0
