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SubjectRe: [PATCH 2/3 v8] livepatch: add sympos as disambiguator field to klp_reloc
On Fri, 20 Nov 2015, Chris J Arges wrote:

[...]

> @@ -272,6 +233,7 @@ static int klp_write_object_relocations(struct module *pmod,
> struct klp_object *obj)
> {
> int ret;
> + unsigned long val;
> struct klp_reloc *reloc;
>
> if (WARN_ON(!klp_is_object_loaded(obj)))
> @@ -281,29 +243,26 @@ static int klp_write_object_relocations(struct module *pmod,
> return -EINVAL;
>
> for (reloc = obj->relocs; reloc->name; reloc++) {
> - if (!klp_is_module(obj)) {
> - ret = klp_verify_vmlinux_symbol(reloc->name,
> - reloc->val);
> - if (ret)
> - return ret;
> - } else {
> - /* module, reloc->val needs to be discovered */
> - if (reloc->external)
> - ret = klp_find_external_symbol(pmod,
> - reloc->name,
> - &reloc->val);
> - else
> - ret = klp_find_object_symbol(obj->mod->name,
> - reloc->name,
> - 0, &reloc->val);
> - if (ret)
> - return ret;
> - }
> + /* discover the address of the referenced symbol */
> + if (reloc->external) {
> + if (reloc->sympos > 0) {
> + pr_err("non-zero sympos for external reloc symbol '%s' is not supported\n",
> + reloc->name);
> + return -EINVAL;
> + }
> + ret = klp_find_external_symbol(pmod, reloc->name, &val);
> + } else
> + ret = klp_find_object_symbol(obj->mod->name,
> + reloc->name,
> + reloc->sympos,
> + &val);

I think this will cause an unwanted effect if a relocation is for vmlinux
symbol. obj->mod is NULL in that case. So obj->name should be there. Can
you test it with kpatch, Chris, please? If that is possible.

Thanks,
Miroslav


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