On 1/19/26 11:19 PM, Joe Lawrence wrote: > On Wed, Jan 14, 2026 at 01:29:53PM +0100, Petr Pavlu wrote: >> The linker script scripts/module.lds.S specifies that all input >> __klp_objects sections should be consolidated into an output section of >> the same name, and start/stop symbols should be created to enable >> scripts/livepatch/init.c to locate this data. >> >> This start/stop pattern is not ideal for modules because the symbols are >> created even if no __klp_objects input sections are present. >> Consequently, a dummy __klp_objects section also appears in the >> resulting module. This unnecessarily pollutes non-livepatch modules. >> >> Instead, since modules are relocatable files, the usual method for >> locating consolidated data in a module is to read its section table. >> This approach avoids the aforementioned problem. >> >> The klp_modinfo already stores a copy of the entire section table with >> the final addresses. Introduce a helper function that >> scripts/livepatch/init.c can call to obtain the location of the >> __klp_objects section from this data. >> >> Signed-off-by: Petr Pavlu <[email protected]> >> --- >> include/linux/livepatch.h | 3 +++ >> kernel/livepatch/core.c | 20 ++++++++++++++++++++ >> scripts/livepatch/init.c | 17 ++++++----------- >> scripts/module.lds.S | 7 +------ >> 4 files changed, 30 insertions(+), 17 deletions(-) >> >> diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h >> index 772919e8096a..ca90adbe89ed 100644 >> --- a/include/linux/livepatch.h >> +++ b/include/linux/livepatch.h >> @@ -175,6 +175,9 @@ int klp_enable_patch(struct klp_patch *); >> int klp_module_coming(struct module *mod); >> void klp_module_going(struct module *mod); >> >> +struct klp_object_ext *klp_build_locate_init_objects(const struct module >> *mod, >> + unsigned int *nr_objs); >> + >> void klp_copy_process(struct task_struct *child); >> void klp_update_patch_state(struct task_struct *task); >> >> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c >> index 9917756dae46..4e0ac47b3623 100644 >> --- a/kernel/livepatch/core.c >> +++ b/kernel/livepatch/core.c >> @@ -1356,6 +1356,26 @@ void klp_module_going(struct module *mod) >> mutex_unlock(&klp_mutex); >> } >> >> +struct klp_object_ext *klp_build_locate_init_objects(const struct module >> *mod, >> + unsigned int *nr_objs) >> +{ >> + struct klp_modinfo *info = mod->klp_info; >> + >> + for (int i = 1; i < info->hdr.e_shnum; i++) { >> + Elf_Shdr *shdr = &info->sechdrs[i]; >> + >> + if (strcmp(info->secstrings + shdr->sh_name, "__klp_objects")) >> + continue; >> + > > Since this function is doing a string comparision to find the ELF > section, would it make sense to open up the API by allowing to caller to > specify the sh_name? That would give scripts/livepatch/init.c future > flexibility in finding similarly crafted data structures. Disregard if > there is already a pattern of doing it this way :)
Makes sense. I'll change the function signature to: void *klp_locate_section_objs(const struct module *mod, const char *name, size_t object_size, unsigned int *nr_objs); -- Thanks, Petr
