linux-kernel - Re: [PATCH v2 11/24] powerpc/mm: don't use _PAGE_EXEC for calling hash

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Message-Id: <87workh7wb.fsf@linux.ibm.com>
Date:   Mon, 17 Sep 2018 13:29:00 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Geoff Levand <geoff@...radead.org>,
        Jens Axboe <axboe@...nel.dk>,
        Kumar Gala <galak@...nel.crashing.org>,
        Li Yang <leoyang.li@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        Scott Wood <oss@...error.net>, aneesh.kumar@...ux.vnet.ibm.com
Cc:     linux-arm-kernel@...ts.infradead.org, linux-block@...r.kernel.org,
        linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v2 11/24] powerpc/mm: don't use _PAGE_EXEC for calling hash_preload()

Christophe Leroy <christophe.leroy@....fr> writes:

> The 'access' parameter of hash_preload() is either 0 or _PAGE_EXEC.
> Among the two versions of hash_preload(), only the PPC64 one is
> doing something with this 'access' parameter.
>
> In order to remove the use of _PAGE_EXEC outside platform code,
> 'access' parameter is replaced by 'is_exec' which will be either
> true of false, and the PPC64 version of hash_preload() creates
> the access flag based on 'is_exec'.
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com>

> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>  arch/powerpc/mm/hash_utils_64.c | 3 ++-
>  arch/powerpc/mm/mem.c           | 9 +++++----
>  arch/powerpc/mm/mmu_decl.h      | 2 +-
>  arch/powerpc/mm/pgtable_32.c    | 2 +-
>  arch/powerpc/mm/ppc_mmu_32.c    | 2 +-
>  5 files changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index f23a89d8e4ce..b8ce0e8cc608 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -1482,7 +1482,7 @@ static bool should_hash_preload(struct mm_struct *mm, unsigned long ea)
>  #endif
>  
>  void hash_preload(struct mm_struct *mm, unsigned long ea,
> -		  unsigned long access, unsigned long trap)
> +		  bool is_exec, unsigned long trap)
>  {
>  	int hugepage_shift;
>  	unsigned long vsid;
> @@ -1490,6 +1490,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea,
>  	pte_t *ptep;
>  	unsigned long flags;
>  	int rc, ssize, update_flags = 0;
> +	unsigned long access = _PAGE_PRESENT | _PAGE_READ | (is_exec ? _PAGE_EXEC : 0);
>  
>  	BUG_ON(REGION_ID(ea) != USER_REGION_ID);
>  
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 31bd9b53c358..0ba0cdb3f759 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -507,7 +507,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
>  	 * We don't need to worry about _PAGE_PRESENT here because we are
>  	 * called with either mm->page_table_lock held or ptl lock held
>  	 */
> -	unsigned long access, trap;
> +	unsigned long trap;
> +	bool is_exec;
>  
>  	if (radix_enabled()) {
>  		prefetch((void *)address);
> @@ -529,16 +530,16 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
>  	trap = current->thread.regs ? TRAP(current->thread.regs) : 0UL;
>  	switch (trap) {
>  	case 0x300:
> -		access = 0UL;
> +		is_exec = false;
>  		break;
>  	case 0x400:
> -		access = _PAGE_EXEC;
> +		is_exec = true;
>  		break;
>  	default:
>  		return;
>  	}
>  
> -	hash_preload(vma->vm_mm, address, access, trap);
> +	hash_preload(vma->vm_mm, address, is_exec, trap);
>  #endif /* CONFIG_PPC_STD_MMU */
>  #if (defined(CONFIG_PPC_BOOK3E_64) || defined(CONFIG_PPC_FSL_BOOK3E)) \
>  	&& defined(CONFIG_HUGETLB_PAGE)
> diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
> index e5d779eed181..dd7f9b951d25 100644
> --- a/arch/powerpc/mm/mmu_decl.h
> +++ b/arch/powerpc/mm/mmu_decl.h
> @@ -82,7 +82,7 @@ static inline void _tlbivax_bcast(unsigned long address, unsigned int pid,
>  #else /* CONFIG_PPC_MMU_NOHASH */
>  
>  extern void hash_preload(struct mm_struct *mm, unsigned long ea,
> -			 unsigned long access, unsigned long trap);
> +			 bool is_exec, unsigned long trap);
>  
>  
>  extern void _tlbie(unsigned long address);
> diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
> index 0bbc7b7d8a05..01f348938328 100644
> --- a/arch/powerpc/mm/pgtable_32.c
> +++ b/arch/powerpc/mm/pgtable_32.c
> @@ -261,7 +261,7 @@ static void __init __mapin_ram_chunk(unsigned long offset, unsigned long top)
>  		map_kernel_page(v, p, ktext ? PAGE_KERNEL_TEXT : PAGE_KERNEL);
>  #ifdef CONFIG_PPC_STD_MMU_32
>  		if (ktext)
> -			hash_preload(&init_mm, v, 0, 0x300);
> +			hash_preload(&init_mm, v, false, 0x300);
>  #endif
>  		v += PAGE_SIZE;
>  		p += PAGE_SIZE;
> diff --git a/arch/powerpc/mm/ppc_mmu_32.c b/arch/powerpc/mm/ppc_mmu_32.c
> index bea6c544e38f..38a793bfca37 100644
> --- a/arch/powerpc/mm/ppc_mmu_32.c
> +++ b/arch/powerpc/mm/ppc_mmu_32.c
> @@ -163,7 +163,7 @@ void __init setbat(int index, unsigned long virt, phys_addr_t phys,
>   * Preload a translation in the hash table
>   */
>  void hash_preload(struct mm_struct *mm, unsigned long ea,
> -		  unsigned long access, unsigned long trap)
> +		  bool is_exec, unsigned long trap)
>  {
>  	pmd_t *pmd;
>  
> -- 
> 2.13.3