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SubjectRe: [PATCH 2/3 v7] livepatch: add sympos as disambiguator field to klp_reloc
On Mon, 16 Nov 2015, Chris J Arges wrote:

> @@ -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;
> + if (reloc->sympos && (reloc->sympos != 1)) {
> + pr_err("symbol '%s' is external and has sympos %lu\n",
> + reloc->name, reloc->sympos);
> + return -EINVAL;
> }

Oh, this check should not be here, right? I think it needs to be under 'if
(reloc->external) {'.

And

if (reloc->sympos && (reloc->sympos != 1)) {

can be written as

if (reloc->sympos > 1) {

Anyway, I am not sure if this is the right thing to do. I know Petr
suggested it, but maybe it would be sufficient just to error out when
reloc->sympos is specified for external symbols. Despite there is a valid
value (== 1). Like it had been done before. Josh came up with the issue.
So what is your opinion, Josh? It is a nitpick, but nevertheless.

Miroslav

> + /* discover the address of the referenced symbol */
> + if (reloc->external) {
> + ret = klp_find_external_symbol(pmod, reloc->name, &val);
> + } else
> + ret = klp_find_object_symbol(obj->mod->name,
> + reloc->name,
> + reloc->sympos,
> + &val);
> + if (ret)
> + return ret;
> ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
> - reloc->val + reloc->addend);
> + val + reloc->addend);
> if (ret) {
> pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n",
> - reloc->name, reloc->val, ret);
> + reloc->name, val, ret);
> return ret;
> }
> }
>



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