linux-kernel - Re: [RFC PATCH 02/10] objtool, x86: add several functions and files to the objtool whitelist

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Date:   Wed, 14 Jun 2017 09:24:39 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC PATCH 02/10] objtool, x86: add several functions and files
 to the objtool whitelist

On 06/01/2017, 07:44 AM, Josh Poimboeuf wrote:
...
> --- a/arch/x86/kernel/kprobes/opt.c
> +++ b/arch/x86/kernel/kprobes/opt.c
> @@ -28,6 +28,7 @@
>  #include <linux/kdebug.h>
>  #include <linux/kallsyms.h>
>  #include <linux/ftrace.h>
> +#include <linux/frame.h>
>  
>  #include <asm/text-patching.h>
>  #include <asm/cacheflush.h>
> @@ -94,6 +95,7 @@ static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
>  }
>  
>  asm (
> +			"optprobe_template_func:\n"

Why do you add another symbol here? What's wrong with
optprobe_template_entry?

>  			".global optprobe_template_entry\n"
>  			"optprobe_template_entry:\n"
>  #ifdef CONFIG_X86_64
> @@ -131,7 +133,12 @@ asm (
>  			"	popf\n"
>  #endif
>  			".global optprobe_template_end\n"
> -			"optprobe_template_end:\n");
> +			"optprobe_template_end:\n"
> +			".type optprobe_template_func, @function\n"
> +			".size optprobe_template_func, .-optprobe_template_func\n");
> +
> +void optprobe_template_func(void);
> +STACK_FRAME_NON_STANDARD(optprobe_template_func);
>  
>  #define TMPL_MOVE_IDX \
>  	((long)&optprobe_template_val - (long)&optprobe_template_entry)

thanks,
-- 
js
suse labs