linux-kernel - Re: [PATCH v1 2/5] livepatch: Add klp-convert tool

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Date: Fri, 5 Jan 2024 16:01:48 +0100
From: Petr Mladek <pmladek@...e.com>
To: Lukas Hruska <lhruska@...e.cz>
Cc: Miroslav Benes <mbenes@...e.cz>, Josh Poimboeuf <jpoimboe@...nel.org>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-kbuild@...r.kernel.org,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH v1 2/5] livepatch: Add klp-convert tool

On Mon 2023-11-06 17:25:10, Lukas Hruska wrote:
> Livepatches need to access external symbols which can't be handled
> by the normal relocation mechanism. It is needed for two types
> of symbols:
> 
> --- /dev/null
> +++ b/scripts/livepatch/klp-convert.c
> @@ -0,0 +1,283 @@
[...]
> +/*
> + * Formats name of klp rela symbol based on another given section (@oldsec)
> + * and object (@obj_name) name, then returns it
> + */
> +static char *alloc_klp_rela_name(struct section *oldsec,
> +		char *target_objname, struct elf *klp_elf)
> +{

Nit: Please, use @lp_obj_name instead of @target_objname.
     It would make it consistent with the caller:

	klp_rela_name = alloc_klp_rela_name(oldsec, lp_obj_name, klp_elf);

and also with

#define KLP_RELOC_SYMBOL_POS(LP_OBJ_NAME, SYM_OBJ_NAME, SYM_NAME, SYM_POS)


> +	char *klp_rela_name;
> +	unsigned int length;
> +	int err;

Just for record. The name "lp_obj_name" came from a discussion between
me and Lukas about the KLP_RELOC_SYMBOL_POS() parameter names.

The macro has two object name parameters. And LP_OBJ_NAME aka
LivePatched_OBJ_NAME looked better than TARGET_OBJ_NAME.
The name "TARGET" is too ambiguous to me.

Best Regards,
Petr