Re: [PATCH] powerpc/tm: Clean up duplication of code

[Balbir Singh <bsingharora@gmail.com>]

On 11/05/16 14:55, Rashmica Gupta wrote:
> The same logic for tm_abort appears twice, so pull it out into a
> function.
> 
> Signed-off-by: Rashmica Gupta <rashmicy@gmail.com>
> ---
>  arch/powerpc/mm/hash_utils_64.c | 47 ++++++++++++++++++-----------------------
>  1 file changed, 21 insertions(+), 26 deletions(-)
> 
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index 7635b1c6b5da..1cef8f5aee9b 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -1318,6 +1318,25 @@ out_exit:
>  	local_irq_restore(flags);
>  }
>  
> +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
> +	/* Transactions are not aborted by tlbiel, only tlbie.
> +	 * Without, syncing a page back to a block device w/ PIO could pick up
> +	 * transactional data (bad!) so we force an abort here.  Before the
> +	 * sync the page will be made read-only, which will flush_hash_page.
> +	 * BIG ISSUE here: if the kernel uses a page from userspace without
> +	 * unmapping it first, it may see the speculated version.
> +	 */
> +static inline void abort_tm(int local)
> +{
> +	if (local && cpu_has_feature(CPU_FTR_TM) &&
> +	    current->thread.regs &&
> +	    MSR_TM_ACTIVE(current->thread.regs->msr)) {
> +		tm_enable();
> +		tm_abort(TM_CAUSE_TLBI);
> +	}
> +}

While your at this do

#else

static inline void abort_tm(int local)
{
}

> +#endif
> +
>  /* WARNING: This is called from hash_low_64.S, if you change this prototype,
>   *          do not forget to update the assembly call site !
>   */
> @@ -1344,19 +1363,7 @@ void flush_hash_page(unsigned long vpn, real_pte_t pte, int psize, int ssize,
>  	} pte_iterate_hashed_end();
>  
>  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
Then remove these extra #ifdef
> -	/* Transactions are not aborted by tlbiel, only tlbie.
> -	 * Without, syncing a page back to a block device w/ PIO could pick up
> -	 * transactional data (bad!) so we force an abort here.  Before the
> -	 * sync the page will be made read-only, which will flush_hash_page.
> -	 * BIG ISSUE here: if the kernel uses a page from userspace without
> -	 * unmapping it first, it may see the speculated version.
> -	 */
> -	if (local && cpu_has_feature(CPU_FTR_TM) &&
> -	    current->thread.regs &&
> -	    MSR_TM_ACTIVE(current->thread.regs->msr)) {
> -		tm_enable();
> -		tm_abort(TM_CAUSE_TLBI);
> -	}
> +	abort_tm(local);
>  #endif
>  }
>  
> @@ -1415,19 +1422,7 @@ void flush_hash_hugepage(unsigned long vsid, unsigned long addr,
>  	}
>  tm_abort:
>  #ifdef CONFIG_PPC_TRANSACTIONAL_MEM

Then remove these extra #ifdef
> -	/* Transactions are not aborted by tlbiel, only tlbie.
> -	 * Without, syncing a page back to a block device w/ PIO could pick up
> -	 * transactional data (bad!) so we force an abort here.  Before the
> -	 * sync the page will be made read-only, which will flush_hash_page.
> -	 * BIG ISSUE here: if the kernel uses a page from userspace without
> -	 * unmapping it first, it may see the speculated version.
> -	 */
> -	if (local && cpu_has_feature(CPU_FTR_TM) &&
> -	    current->thread.regs &&
> -	    MSR_TM_ACTIVE(current->thread.regs->msr)) {
> -		tm_enable();
> -		tm_abort(TM_CAUSE_TLBI);
> -	}
> +	abort_tm(local);
>  #endif
>  	return;
>  }
>