Re: [PATCH v3 1/4] rethook: use preempt_{disable, enable}_notrace in rethook_trampoline_handler

[Google]

Hi Ze Gao,

On Wed, 17 May 2023 11:45:06 +0800
Ze Gao <zegao2021@xxxxxxxxx> wrote:

> This patch replaces preempt_{disable, enable} with its corresponding
> notrace version in rethook_trampoline_handler so no worries about stack
> recursion or overflow introduced by preempt_count_{add, sub} under
> fprobe + rethook context.
> 
> Fixes: 54ecbe6f1ed5 ("rethook: Add a generic return hook")
> Signed-off-by: Ze Gao <zegao@xxxxxxxxxxx>
> Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/linux-trace-kernel/20230516071830.8190-2-zegao@xxxxxxxxxxx

Note that you don't need to add Link tag of the previous version for each patch.
I'll add it when I pick it :)

Thank you,

> ---
>  kernel/trace/rethook.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/rethook.c b/kernel/trace/rethook.c
> index 32c3dfdb4d6a..60f6cb2b486b 100644
> --- a/kernel/trace/rethook.c
> +++ b/kernel/trace/rethook.c
> @@ -288,7 +288,7 @@ unsigned long rethook_trampoline_handler(struct pt_regs *regs,
>  	 * These loops must be protected from rethook_free_rcu() because those
>  	 * are accessing 'rhn->rethook'.
>  	 */
> -	preempt_disable();
> +	preempt_disable_notrace();
>  
>  	/*
>  	 * Run the handler on the shadow stack. Do not unlink the list here because
> @@ -321,7 +321,7 @@ unsigned long rethook_trampoline_handler(struct pt_regs *regs,
>  		first = first->next;
>  		rethook_recycle(rhn);
>  	}
> -	preempt_enable();
> +	preempt_enable_notrace();
>  
>  	return correct_ret_addr;
>  }
> -- 
> 2.40.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>