On Thu, Feb 8, 2024 at 8:07 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> From: Alexei Starovoitov <ast@xxxxxxxxxx>
>
> __uint() macro that is used to specify map attributes like:
> __uint(type, BPF_MAP_TYPE_ARRAY);
> __uint(map_flags, BPF_F_MMAPABLE);
> is limited to 32-bit, since BTF_KIND_ARRAY has u32 "number of elements" field.
>
> Introduce __ulong() macro that allows specifying values bigger than 32-bit.
> In map definition "map_extra" is the only u64 field.
>
> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
> ---
> tools/lib/bpf/bpf_helpers.h | 5 +++++
> tools/lib/bpf/libbpf.c | 44 ++++++++++++++++++++++++++++++++++---
> 2 files changed, 46 insertions(+), 3 deletions(-)
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index 9c777c21da28..0aeac8ea7af2 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -13,6 +13,11 @@
> #define __uint(name, val) int (*name)[val]
> #define __type(name, val) typeof(val) *name
> #define __array(name, val) typeof(val) *name[]
> +#ifndef __PASTE
> +#define ___PASTE(a,b) a##b
> +#define __PASTE(a,b) ___PASTE(a,b)
> +#endif
we already have ___bpf_concat defined further in this file (it's macro
so ordering shouldn't matter), let's just use that instead of adding
another variant
> +#define __ulong(name, val) enum { __PASTE(__unique_value, __COUNTER__) = val } name
>
> /*
> * Helper macro to place programs, maps, license in
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 4880d623098d..f8158e250327 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -2243,6 +2243,39 @@ static bool get_map_field_int(const char *map_name, const struct btf *btf,
> return true;
> }
>
> +static bool get_map_field_long(const char *map_name, const struct btf *btf,
> + const struct btf_member *m, __u64 *res)
> +{
> + const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
> + const char *name = btf__name_by_offset(btf, m->name_off);
> +
> + if (btf_is_ptr(t))
> + return false;
It's not great that anyone that uses __uint(map_extra, ...) would get
warnings now.
Let's just teach get_map_field_long to recognize __uint vs __ulong?
Let's call into get_map_field_int() here if we have a pointer, and
then upcast u32 into u64?
> +
> + if (!btf_is_enum(t) && !btf_is_enum64(t)) {
> + pr_warn("map '%s': attr '%s': expected enum or enum64, got %s.\n",
seems like get_map_field_int() is using "PTR" and "ARRAY" all caps
spelling in warnings, let's use ENUM and ENUM64 for consistency?
> + map_name, name, btf_kind_str(t));
> + return false;
> + }
> +
> + if (btf_vlen(t) != 1) {
> + pr_warn("map '%s': attr '%s': invalid __ulong\n",
> + map_name, name);
> + return false;
> + }
> +
> + if (btf_is_enum(t)) {
> + const struct btf_enum *e = btf_enum(t);
> +
> + *res = e->val;
> + } else {
> + const struct btf_enum64 *e = btf_enum64(t);
> +
> + *res = btf_enum64_value(e);
> + }
> + return true;
> +}
> +
> static int pathname_concat(char *buf, size_t buf_sz, const char *path, const char *name)
> {
> int len;
> @@ -2476,10 +2509,15 @@ int parse_btf_map_def(const char *map_name, struct btf *btf,
> map_def->pinning = val;
> map_def->parts |= MAP_DEF_PINNING;
> } else if (strcmp(name, "map_extra") == 0) {
> - __u32 map_extra;
> + __u64 map_extra;
>
> - if (!get_map_field_int(map_name, btf, m, &map_extra))
> - return -EINVAL;
> + if (!get_map_field_long(map_name, btf, m, &map_extra)) {
> + __u32 map_extra_u32;
> +
> + if (!get_map_field_int(map_name, btf, m, &map_extra_u32))
> + return -EINVAL;
> + map_extra = map_extra_u32;
> + }
with the above change it would be a simple
s/get_map_field_int/get_map_field_long/ (and __u32 -> __u64, of
course)
> map_def->map_extra = map_extra;
> map_def->parts |= MAP_DEF_MAP_EXTRA;
> } else {
> --
> 2.34.1
>
