On 24/6/26 06:45, Andrii Nakryiko wrote: > On Mon, Jun 22, 2026 at 7:37 AM Leon Hwang <[email protected]> wrote: [...] >> @@ -5353,6 +5387,13 @@ bpf_object__populate_internal_map(struct bpf_object >> *obj, struct bpf_map *map) >> return err; >> } >> map->mmaped = mmaped; >> + } else if (is_percpu) { >> + if (mprotect(map->mmaped, mmap_sz, PROT_READ)) { >> + err = -errno; >> + pr_warn("map '%s': failed to mprotect() contents: >> %s\n", >> + bpf_map__name(map), errstr(err)); >> + return err; >> + } > > hm... do we need to do this? what happens for LIBBPF_MAP_KCONFIG, do > we just null out the initial image? should we just do that here? > Basically what I am asking is how important it is to access initial > per-CPU image after load? What's the realistic use case for that? >
This was suggested by you in v3: https://lore.kernel.org/bpf/caef4bzy9keveo2+6ht1v3rl6udwnxabzcsk1oz_sd8qhpyz...@mail.gmail.com/ >> } else if (map->mmaped) { >> munmap(map->mmaped, mmap_sz); >> map->mmaped = NULL; >> @@ -10806,16 +10847,19 @@ int bpf_map__fd(const struct bpf_map *map) >> >> static bool map_uses_real_name(const struct bpf_map *map) >> { >> - /* Since libbpf started to support custom .data.* and .rodata.* maps, >> - * their user-visible name differs from kernel-visible name. Users >> see >> - * such map's corresponding ELF section name as a map name. >> - * This check distinguishes .data/.rodata from .data.* and .rodata.* >> - * maps to know which name has to be returned to the user. >> + /* >> + * Since libbpf started to support custom .data.*, .rodata.* and >> + * .percpu.* maps, their user-visible name differs from >> + * kernel-visible name. Users see such map's corresponding ELF >> section >> + * name as a map name. This check distinguishes plain >> .data/.rodata/.percpu >> + * from .data.*, .rodata.* and .percpu.* to choose which name to >> return. >> */ >> if (map->libbpf_type == LIBBPF_MAP_DATA && strcmp(map->real_name, >> DATA_SEC) != 0) >> return true; >> if (map->libbpf_type == LIBBPF_MAP_RODATA && strcmp(map->real_name, >> RODATA_SEC) != 0) >> return true; >> + if (map->libbpf_type == LIBBPF_MAP_PERCPU && strcmp(map->real_name, >> PERCPU_SEC) != 0) >> + return true; > > um... this is extra logic for DATA/RODATA is supposed to be backwards > compatible legacy stuff. We shouldn't need this for PERCPU_SEC. It > should actually be called just ".percpu", not "<object_name>.percpu". > Understand the backwards compatibility after reading the comment in internal_map_name(). Will drop this hunk, and set "map->name" as ".percpu" in bpf_object__init_internal_map(). Thanks, Leon
