Subject: Re: [PATCH v1 2/8] powerpc/signal64: Untangle setup_tm_sigcontexts() and user_access_begin()

From: David Laight <[email-masked]>
Date: Fri, 22 May 2026 12:12:37 +0100

On Fri, 22 May 2026 11:56:02 +0200
"Christophe Leroy (CS GROUP)" <[email-masked]> wrote:

> Call setup_tm_sigcontexts() before opening user access to avoid
> having to close and open again.
> 
> Signed-off-by: Christophe Leroy (CS GROUP) <[email-masked]>
> ---
>  arch/powerpc/kernel/signal_64.c | 22 +++++++++-------------
>  1 file changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
> index 86bb5bb4c143..3849af21e1d8 100644
> --- a/arch/powerpc/kernel/signal_64.c
> +++ b/arch/powerpc/kernel/signal_64.c
> @@ -873,6 +873,15 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
>  	if (!MSR_TM_ACTIVE(msr))
>  		prepare_setup_sigcontext(tsk);
>  
> +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> +	if (MSR_TM_ACTIVE(msr))

Can't that be done without the ugly #ifdef?
I assume MSR_TM_ACTIVE() will be zero - so it will all get optimised away.

-- David

> +		err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
> +					    &frame->uc_transact.uc_mcontext,
> +					    tsk, ksig->sig, NULL,
> +					    (unsigned long)ksig->ka.sa.sa_handler,
> +					    msr);
> +
> +#endif
>  	if (!user_write_access_begin(frame, sizeof(*frame)))
>  		goto badframe;
>  
> @@ -889,19 +898,6 @@ int handle_rt_signal64(struct ksignal *ksig, sigset_t *set,
>  		 * ucontext_t (for transactional state) with its uc_link ptr.
>  		 */
>  		unsafe_put_user(&frame->uc_transact, &frame->uc.uc_link, badframe_block);
> -
> -		user_write_access_end();
> -
> -		err |= setup_tm_sigcontexts(&frame->uc.uc_mcontext,
> -					    &frame->uc_transact.uc_mcontext,
> -					    tsk, ksig->sig, NULL,
> -					    (unsigned long)ksig->ka.sa.sa_handler,
> -					    msr);
> -
> -		if (!user_write_access_begin(&frame->uc.uc_sigmask,
> -					     sizeof(frame->uc.uc_sigmask)))
> -			goto badframe;
> -
>  #endif
>  	} else {
>  		unsafe_put_user(0, &frame->uc.uc_link, badframe_block);