Subject: Re: [PATCH] powerpc, mm: Fix build failure due to CONFIG_PPC_TRANSACTIONAL_MEM

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 21 Apr 2015 20:09:32 +0530

Anshuman Khandual <[email-masked]> writes:

> The function flush_hash_page fails to compile when the transaction memory
> config option is turned off because there is a label at end of compound
> statement. This patch moves the code block into a function tm_abort_tlbi
> and calls it after the label thus fixing the build problem.
>
> Signed-off-by: Anshuman Khandual <[email-masked]>
> ---
> arch/powerpc/mm/hash_utils_64.c: In function ‘flush_hash_hugepage’:
> arch/powerpc/mm/hash_utils_64.c:1381:1: error: label at end of compound statement
>  tm_abort:
>  ^
> make[1]: *** [arch/powerpc/mm/hash_utils_64.o] Error 1
> make: *** [arch/powerpc/mm] Error 2
>
>  arch/powerpc/mm/hash_utils_64.c | 35 ++++++++++++++++++++---------------
>  1 file changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index 2c2022d..b30b2b5 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -1326,6 +1326,25 @@ void flush_hash_page(unsigned long vpn, real_pte_t pte, int psize, int ssize,
>  }
>
>  #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +static void tm_abort_tlbi(int local)
> +{
> +#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.
> +	 */
> +	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);
> +	}
> +#endif
> +}
> +
>  void flush_hash_hugepage(unsigned long vsid, unsigned long addr,
>  			 pmd_t *pmdp, unsigned int psize, int ssize,
>  			 unsigned long flags)
> @@ -1379,21 +1398,7 @@ void flush_hash_hugepage(unsigned long vsid, unsigned long addr,
>  				       MMU_PAGE_16M, ssize, local);
>  	}
>  tm_abort:
> -#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.
> -	 */
> -	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);
> -	}
> -#endif
> +	tm_abort_tlbi(local);
>  }
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>
> -- 

Why not just do ?. I will send a seperate patch 

commit 52b6dcc8fe34b9d05b8a0f14d45fcdc3bef6c84f
Author: Aneesh Kumar K.V <[email-masked]>
Date:   Tue Apr 21 19:51:10 2015 +0530

    powerpc/mm: Fix build error with CONFIG_PPC_TRANSACTIONAL_MEM disabled
    
    This fix the below build error
    
    arch/powerpc/mm/hash_utils_64.c: In function ‘flush_hash_hugepage’:
    arch/powerpc/mm/hash_utils_64.c:1381:1: error: label at end of compound statement
     tm_abort:
     ^
    make[1]: *** [arch/powerpc/mm/hash_utils_64.o] Error 1
    
    Reported-by: Anshuman Khandual <[email-masked]>
    Signed-off-by: Aneesh Kumar K.V <[email-masked]>

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 2c2022d16059..ac5c4373cd8b 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1394,6 +1394,7 @@ tm_abort:
 		tm_abort(TM_CAUSE_TLBI);
 	}
 #endif
+	return;
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */