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SubjectRe: [PATCH 1/4 v5] livepatch: add old_sympos as disambiguator field to klp_func
On Thu, 12 Nov 2015, Chris J Arges wrote:

> diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
> index 31db7a0..3d18dff 100644
> --- a/include/linux/livepatch.h
> +++ b/include/linux/livepatch.h
> @@ -37,8 +37,9 @@ enum klp_state {
> * struct klp_func - function structure for live patching
> * @old_name: name of the function to be patched
> * @new_func: pointer to the patched function code
> - * @old_addr: a hint conveying at what address the old function
> - * can be found (optional, vmlinux patches only)
> + * @old_sympos: a hint indicating which symbol position the old function
> + * can be found (optional)
> + * @old_addr: the address of the function being patched
> * @kobj: kobject for sysfs resources
> * @state: tracks function-level patch application state
> * @stack_node: list node for klp_ops func_stack list
> @@ -47,17 +48,18 @@ struct klp_func {
> /* external */
> const char *old_name;
> void *new_func;
> +

A nit, but this new empty line is not necessary. Let's keep all the
external stuff in one pack.

> /*
> - * The old_addr field is optional and can be used to resolve
> - * duplicate symbol names in the vmlinux object. If this
> - * information is not present, the symbol is located by name
> - * with kallsyms. If the name is not unique and old_addr is
> - * not provided, the patch application fails as there is no
> - * way to resolve the ambiguity.
> + * The old_sympos field is optional and can be used to resolve
> + * duplicate symbol names in livepatch objects. If this field is zero,
> + * it is expected the symbol is unique, otherwise patching fails. If
> + * this value is greater than zero then that occurrence of the symbol
> + * in kallsyms for the given object is used.
> */


> @@ -749,8 +733,13 @@ static int klp_init_object_loaded(struct klp_patch *patch,
> return ret;
> }
>
> + /*
> + * Verify the symbol, find old_addr, and write it to the structure.
> + */

It is not verification anymore. I think a comment here is not necessary.
It is quite clear what klp_find_object_symbol does.

> klp_for_each_func(obj, func) {
> - ret = klp_find_verify_func_addr(obj, func);
> + ret = klp_find_object_symbol(obj->name, func->old_name,
> + &func->old_addr,
> + func->old_sympos);
> if (ret)
> return ret;
> }

Thanks,
Miroslav


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