Re: [v5 4/6] extable: Add function to search only kernel exception table

[Nicholas Piggin]

Santosh Sivaraj's on July 9, 2019 10:15 pm:
> In real mode, the search_exception tables cannot be called because
> it also searches the module exception tables if entry is not found
> in the kernel exception tables.

This is a patch for generic kernel code, it may not go through
powerpc tree and someone doing git blame or something won't have
any idea what this changelog means.

Can you re-word this and just say something like, "certain architecture
$specific operating modes (e.g., in powerpc machine check handler that
is unable to access vmalloc memory)."

> 
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> Signed-off-by: Santosh Sivaraj <santosh@xxxxxxxxxx>
> ---
>  include/linux/extable.h |  2 ++
>  kernel/extable.c        | 16 +++++++++++++---
>  2 files changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/extable.h b/include/linux/extable.h
> index 41c5b3a25f67..0c2819ba67f0 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);
>  
>  #ifdef CONFIG_MODULES
>  /* For extable.c to search modules' exception tables. */
> diff --git a/kernel/extable.c b/kernel/extable.c
> index e23cce6e6092..6d544cb79fff 100644
> --- a/kernel/extable.c
> +++ b/kernel/extable.c
> @@ -40,13 +40,23 @@ void __init sort_main_extable(void)
>  	}
>  }
>  
> -/* Given an address, look for it in the exception tables. */
> +/* For the given address, look for it in the kernel exception table */

Nitpick, no reason to vary the structure of the comment.

Code wise it looks fine, so with the comments and changelog fixed,

Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>

> +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 kernel and the module 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;
> -- 
> 2.20.1
> 
>