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Subject: Re: [PATCH v9 4/7] extable: Add function to search only kernel
 exception table
To:     Santosh Sivaraj <santosh@fossix.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>
Cc:     "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Mahesh Salgaonkar <mahesh@linux.ibm.com>,
        Reza Arbab <arbab@linux.ibm.com>,
        Chandan Rajendra <chandan@linux.vnet.ibm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Nicholas Piggin <npiggin@gmail.com>,
        christophe leroy <christophe.leroy@c-s.fr>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>
References: <20190812092236.16648-1-santosh@fossix.org>
 <20190812092236.16648-5-santosh@fossix.org>
From:   Balbir Singh <bsingharora@gmail.com>
Message-ID: <916d5741-a0bd-8860-4a38-7a5ef677214a@gmail.com>
Date:   Wed, 14 Aug 2019 19:22:00 +1000
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On 12/8/19 7:22 pm, Santosh Sivaraj wrote:
> Certain architecture specific operating modes (e.g., in powerpc machine
> check handler that is unable to access vmalloc memory), the
> search_exception_tables cannot be called because it also searches the
> module exception tables if entry is not found in the kernel exception
> table.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
> Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  include/linux/extable.h |  2 ++
>  kernel/extable.c        | 11 +++++++++--
>  2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/extable.h b/include/linux/extable.h
> index 41c5b3a25f67..81ecfaa83ad3 100644
> --- a/include/linux/extable.h
> +++ b/include/linux/extable.h
> @@ -19,6 +19,8 @@ void trim_init_extable(struct module *m);
>  
>  /* Given an address, look for it in the exception tables */
>  const struct exception_table_entry *search_exception_tables(unsigned long add);
> +const struct exception_table_entry *
> +search_kernel_exception_table(unsigned long addr);
> 

Can we find a better name search_kernel still sounds like all of the kernel.
Can we rename it to search_kernel_linear_map_extable?

 
>  #ifdef CONFIG_MODULES
>  /* For extable.c to search modules' exception tables. */
> diff --git a/kernel/extable.c b/kernel/extable.c
> index e23cce6e6092..f6c9406eec7d 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -40,13 +40,20 @@ void __init sort_main_extable(void)
>  	}
>  }
>  
> +/* Given an address, look for it in the kernel exception table */
> +const
> +struct exception_table_entry *search_kernel_exception_table(unsigned long addr)
> +{
> +	return search_extable(__start___ex_table,
> +			      __stop___ex_table - __start___ex_table, addr);
> +}
> +
>  /* Given an address, look for it in the exception tables. */
>  const struct exception_table_entry *search_exception_tables(unsigned long addr)
>  {
>  	const struct exception_table_entry *e;
>  
> -	e = search_extable(__start___ex_table,
> -			   __stop___ex_table - __start___ex_table, addr);
> +	e = search_kernel_exception_table(addr);
>  	if (!e)
>  		e = search_module_extables(addr);
>  	return e;
>