Re: [PATCH 2/4] extable: Consolidate *kernel_text_address() functions

Paul E. McKenney
2017-09-22T22:40:18Z

On Fri, Sep 22, 2017 at 06:15:45PM -0400, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.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@linux.vnet.ibm.com>
> Cc: stable@vger.kernel.org
> Fixes: 0be964be0 ("module: Sanitize RCU usage and locking")
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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

Acked-by: Paul E. McKenney <paulmck@linux.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
>
>