Messages in this thread | | | Subject | Re: [PATCH bpf-next v3 4/6] libbpf: Unify memory address casting operation style | From | Pu Lehui <> | Date | Thu, 7 Jul 2022 20:23:00 +0800 |
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On 2022/6/4 5:03, Andrii Nakryiko wrote: > On Mon, May 30, 2022 at 2:03 PM Daniel Borkmann <daniel@iogearbox.net> wrote: >> >> On 5/30/22 11:28 AM, Pu Lehui wrote: >>> The members of bpf_prog_info, which are line_info, jited_line_info, >>> jited_ksyms and jited_func_lens, store u64 address pointed to the >>> corresponding memory regions. Memory addresses are conceptually >>> unsigned, (unsigned long) casting makes more sense, so let's make >>> a change for conceptual uniformity. >>> >>> Signed-off-by: Pu Lehui <pulehui@huawei.com> >>> --- >>> tools/lib/bpf/bpf_prog_linfo.c | 9 +++++---- >>> 1 file changed, 5 insertions(+), 4 deletions(-) >>> >>> diff --git a/tools/lib/bpf/bpf_prog_linfo.c b/tools/lib/bpf/bpf_prog_linfo.c >>> index 5c503096ef43..7beb060d0671 100644 >>> --- a/tools/lib/bpf/bpf_prog_linfo.c >>> +++ b/tools/lib/bpf/bpf_prog_linfo.c >>> @@ -127,7 +127,8 @@ struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info) >>> prog_linfo->raw_linfo = malloc(data_sz); >>> if (!prog_linfo->raw_linfo) >>> goto err_free; >>> - memcpy(prog_linfo->raw_linfo, (void *)(long)info->line_info, data_sz); >>> + memcpy(prog_linfo->raw_linfo, (void *)(unsigned long)info->line_info, >>> + data_sz); >> >> Took in patch 1-3, lgtm, thanks! My question around the cleanups in patch 4-6 ... >> there are various other such cases e.g. in libbpf, perhaps makes sense to clean all >> of them up at once and not just the 4 locations in here. > > if (void *)(long) pattern is wrong, then I guess the best replacement > should be (void *)(uintptr_t) ? >
I also think that (void *)(uintptr_t) would be the best replacement. I applied the changes to kernel/bpf and samples/bpf, and it worked fine. But in selftests/bpf, the following similar error occur at compile time:
progs/test_cls_redirect.c:504:11: error: cast to 'uint8_t *' (aka 'unsigned char *') from smaller integer type 'uintptr_t' (aka 'unsigned int') [-Werror,-Wint-to-pointer-cast] .head = (uint8_t *)(uintptr_t)skb->data,
I take clang to compile with the front and back end separation, like samples/bpf, and it works. It seems that the all-in-one clang has problems handling the uintptr_t.
>> >> Thanks, >> Daniel > . >
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