Subject: Re: [PATCH] powerpc: Remove flush_HPTE()

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 10 Dec 2008 19:34:57 +1100

On Wed, 2008-12-10 at 17:08 +1100, Benjamin Herrenschmidt wrote:
> The function flush_HPTE() is used in only one place, the implementation
> of DEBUG_PAGEALLOC on ppc32.
> 
> It's actually a dup of flush_tlb_page() though it's -slightly- more
> efficient on hash based processors. We remove it and replace it by
> a direct call to the hash flush code on those processors and to
> flush_tlb_page() for everybody else.
> 
> Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
> ---

Actually, patch is bogus, it will break on 603. I'll fix that tomorrow
by just calling flush_tlb_page().

Cheers,
Ben.

>  arch/powerpc/mm/mmu_decl.h   |   17 -----------------
>  arch/powerpc/mm/pgtable_32.c |    6 +++++-
>  2 files changed, 5 insertions(+), 18 deletions(-)
> 
> --- linux-work.orig/arch/powerpc/mm/mmu_decl.h	2008-12-10 17:01:18.000000000 +1100
> +++ linux-work/arch/powerpc/mm/mmu_decl.h	2008-12-10 17:01:35.000000000 +1100
> @@ -58,17 +58,14 @@ extern phys_addr_t lowmem_end_addr;
>   * architectures.  -- Dan
>   */
>  #if defined(CONFIG_8xx)
> -#define flush_HPTE(X, va, pg)	_tlbie(va, 0 /* 8xx doesn't care about PID */)
>  #define MMU_init_hw()		do { } while(0)
>  #define mmu_mapin_ram()		(0UL)
>  
>  #elif defined(CONFIG_4xx)
> -#define flush_HPTE(pid, va, pg)	_tlbie(va, pid)
>  extern void MMU_init_hw(void);
>  extern unsigned long mmu_mapin_ram(void);
>  
>  #elif defined(CONFIG_FSL_BOOKE)
> -#define flush_HPTE(pid, va, pg)	_tlbie(va, pid)
>  extern void MMU_init_hw(void);
>  extern unsigned long mmu_mapin_ram(void);
>  extern void adjust_total_lowmem(void);
> @@ -77,18 +74,4 @@ extern void adjust_total_lowmem(void);
>  /* anything 32-bit except 4xx or 8xx */
>  extern void MMU_init_hw(void);
>  extern unsigned long mmu_mapin_ram(void);
> -
> -/* Be careful....this needs to be updated if we ever encounter 603 SMPs,
> - * which includes all new 82xx processors.  We need tlbie/tlbsync here
> - * in that case (I think). -- Dan.
> - */
> -static inline void flush_HPTE(unsigned context, unsigned long va,
> -			      unsigned long pdval)
> -{
> -	if ((Hash != 0) &&
> -	    mmu_has_feature(MMU_FTR_HPTE_TABLE))
> -		flush_hash_pages(0, va, pdval, 1);
> -	else
> -		_tlbie(va);
> -}
>  #endif
> Index: linux-work/arch/powerpc/mm/pgtable_32.c
> ===================================================================
> --- linux-work.orig/arch/powerpc/mm/pgtable_32.c	2008-12-10 17:01:49.000000000 +1100
> +++ linux-work/arch/powerpc/mm/pgtable_32.c	2008-12-10 17:04:36.000000000 +1100
> @@ -342,7 +342,11 @@ static int __change_page_attr(struct pag
>  		return -EINVAL;
>  	set_pte_at(&init_mm, address, kpte, mk_pte(page, prot));
>  	wmb();
> -	flush_HPTE(0, address, pmd_val(*kpmd));
> +#ifdef CONFIG_PPC_STD_MMU
> +	flush_hash_pages(0, address, pmd_val(*kpmd), 1);
> +#else
> +	flush_tlb_page(NULL, address);
> +#endif
>  	pte_unmap(kpte);
>  
>  	return 0;
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