On Thu, Jul 21, 2022 at 03:42:34PM +0200, Kumar Kartikeya Dwivedi wrote:
> A flag is a 4-byte symbol that may follow a BTF ID in a set8. This is
> used in the kernel to tag kfuncs in BTF sets with certain flags. Add
> support to adjust the sorting code so that it passes size as 8 bytes
> for 8-byte BTF sets.
>
> Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
jirka
> ---
> tools/bpf/resolve_btfids/main.c | 40 ++++++++++++++++++++++++++++-----
> 1 file changed, 34 insertions(+), 6 deletions(-)
>
> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> index 5d26f3c6f918..80cd7843c677 100644
> --- a/tools/bpf/resolve_btfids/main.c
> +++ b/tools/bpf/resolve_btfids/main.c
> @@ -45,6 +45,19 @@
> * .zero 4
> * __BTF_ID__func__vfs_fallocate__4:
> * .zero 4
> + *
> + * set8 - store symbol size into first 4 bytes and sort following
> + * ID list
> + *
> + * __BTF_ID__set8__list:
> + * .zero 8
> + * list:
> + * __BTF_ID__func__vfs_getattr__3:
> + * .zero 4
> + * .word (1 << 0) | (1 << 2)
> + * __BTF_ID__func__vfs_fallocate__5:
> + * .zero 4
> + * .word (1 << 3) | (1 << 1) | (1 << 2)
> */
>
> #define _GNU_SOURCE
> @@ -72,6 +85,7 @@
> #define BTF_TYPEDEF "typedef"
> #define BTF_FUNC "func"
> #define BTF_SET "set"
> +#define BTF_SET8 "set8"
>
> #define ADDR_CNT 100
>
> @@ -84,6 +98,7 @@ struct btf_id {
> };
> int addr_cnt;
> bool is_set;
> + bool is_set8;
> Elf64_Addr addr[ADDR_CNT];
> };
>
> @@ -231,14 +246,14 @@ static char *get_id(const char *prefix_end)
> return id;
> }
>
> -static struct btf_id *add_set(struct object *obj, char *name)
> +static struct btf_id *add_set(struct object *obj, char *name, bool is_set8)
> {
> /*
> * __BTF_ID__set__name
> * name = ^
> * id = ^
> */
> - char *id = name + sizeof(BTF_SET "__") - 1;
> + char *id = name + (is_set8 ? sizeof(BTF_SET8 "__") : sizeof(BTF_SET "__")) - 1;
> int len = strlen(name);
>
> if (id >= name + len) {
> @@ -444,9 +459,21 @@ static int symbols_collect(struct object *obj)
> } else if (!strncmp(prefix, BTF_FUNC, sizeof(BTF_FUNC) - 1)) {
> obj->nr_funcs++;
> id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
> + /* set8 */
> + } else if (!strncmp(prefix, BTF_SET8, sizeof(BTF_SET8) - 1)) {
> + id = add_set(obj, prefix, true);
> + /*
> + * SET8 objects store list's count, which is encoded
> + * in symbol's size, together with 'cnt' field hence
> + * that - 1.
> + */
> + if (id) {
> + id->cnt = sym.st_size / sizeof(uint64_t) - 1;
> + id->is_set8 = true;
> + }
> /* set */
> } else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
> - id = add_set(obj, prefix);
> + id = add_set(obj, prefix, false);
> /*
> * SET objects store list's count, which is encoded
> * in symbol's size, together with 'cnt' field hence
> @@ -571,7 +598,8 @@ static int id_patch(struct object *obj, struct btf_id *id)
> int *ptr = data->d_buf;
> int i;
>
> - if (!id->id && !id->is_set)
> + /* For set, set8, id->id may be 0 */
> + if (!id->id && !id->is_set && !id->is_set8)
> pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
>
> for (i = 0; i < id->addr_cnt; i++) {
> @@ -643,13 +671,13 @@ static int sets_patch(struct object *obj)
> }
>
> idx = idx / sizeof(int);
> - base = &ptr[idx] + 1;
> + base = &ptr[idx] + (id->is_set8 ? 2 : 1);
> cnt = ptr[idx];
>
> pr_debug("sorting addr %5lu: cnt %6d [%s]\n",
> (idx + 1) * sizeof(int), cnt, id->name);
>
> - qsort(base, cnt, sizeof(int), cmp_id);
> + qsort(base, cnt, id->is_set8 ? sizeof(uint64_t) : sizeof(int), cmp_id);
>
> next = rb_next(next);
> }
> --
> 2.34.1
>
