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

From: Jiri Slaby <jslaby@suse.cz>
To: Josh Poimboeuf <jpoimboe@redhat.com>, x86@kernel.org
Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH 02/10] objtool, x86: add several functions and files to the objtool whitelist
Date: Wed, 14 Jun 2017 09:24:39 +0200	[thread overview]
Message-ID: <b380123a-aefd-45cd-ada4-ae9aeda96f82@suse.cz> (raw)
In-Reply-To: <1c982a42e4d2b9b3a4aa76bf0a0437842bbdf718.1496293620.git.jpoimboe@redhat.com>

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