linux-kernel - Re: [PATCH 2/4] extable: Consolidate *kernel_text

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Message-Id: <20170922224014.GY3521@linux.vnet.ibm.com>
Date:   Fri, 22 Sep 2017 15:40:14 -0700
From:   "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, ngo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH 2/4] extable: Consolidate *kernel_text_address() functions

On Fri, Sep 22, 2017 at 06:15:45PM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
> 
> The functionality between kernel_text_address() and _kernel_text_address()
> is the same except that _kernel_text_address() does a little more (that
> function needs a rename, but that can be done another time). Instead of
> having duplicate code in both, simply have _kernel_text_address() calls
> kernel_text_address() instead.
> 
> This is marked for stable because there's an RCU bug that can happen if
> one of these functions gets called while RCU is not watching. That fix
> depends on this fix to keep from having to write the fix twice.
> 
> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: stable@...r.kernel.org
> Fixes: 0be964be0 ("module: Sanitize RCU usage and locking")
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>

Not my area, but straightforward transformation and nice reduction
in code size.

Acked-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>

> ---
>  kernel/extable.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/kernel/extable.c b/kernel/extable.c
> index 38c2412401a1..a7024a494faf 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -102,15 +102,7 @@ int core_kernel_data(unsigned long addr)
> 
>  int __kernel_text_address(unsigned long addr)
>  {
> -	if (core_kernel_text(addr))
> -		return 1;
> -	if (is_module_text_address(addr))
> -		return 1;
> -	if (is_ftrace_trampoline(addr))
> -		return 1;
> -	if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
> -		return 1;
> -	if (is_bpf_text_address(addr))
> +	if (kernel_text_address(addr))
>  		return 1;
>  	/*
>  	 * There might be init symbols in saved stacktraces.
> -- 
> 2.13.2
> 
>