Re: [PATCH v9 4/7] extable: Add function to search only kernel exception table

[Balbir Singh]

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@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> Signed-off-by: Santosh Sivaraj <santosh@xxxxxxxxxx>
> Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>
> ---
>  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;
>