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Date: Thu, 09 Oct 2014 20:58:32 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: Michael Neuling <mikey@...ling.org>, greg@...ah.com, arnd@...db.de,
mpe@...erman.id.au, benh@...nel.crashing.org
Cc: mikey@...ling.org, anton@...ba.org, linux-kernel@...r.kernel.org,
linuxppc-dev@...abs.org, jk@...abs.org, imunsie@....ibm.com,
cbe-oss-dev@...ts.ozlabs.org
Subject: Re: [PATCH v4 09/16] powerpc/mm: Add new hash_page_mm()
Michael Neuling <mikey@...ling.org> writes:
> From: Ian Munsie <imunsie@....ibm.com>
>
> This adds a new function hash_page_mm() based on the existing hash_page().
> This version allows any struct mm to be passed in, rather than assuming
> current. This is useful for servicing co-processor faults which are not in the
> context of the current running process.
>
> We need to be careful here as the current hash_page() assumes current in a few
> places.
if you move cxl_slbia patch before this, then we could add additonal
information here.
1) We use this to insert hpte entries on-behalf of co-processor.
2) we don't need to flush cpu slb entries when adding new hpte entries
3) We do flush the co-processor slb cache, if adding hpte entry result
in a segement demotion or have mmu_ci_restrictions enabled.
4) We do update the slice array to indicate the new base page size
5) w.r.t co-processor on segment miss we look at slice array and add new slb entry
using newly added copro_calculate_slb "powerpc/cell: Move data segment faulting code out of cell platform"
>
> Signed-off-by: Ian Munsie <imunsie@....ibm.com>
> Signed-off-by: Michael Neuling <mikey@...ling.org>
> ---
> arch/powerpc/include/asm/mmu-hash64.h | 1 +
> arch/powerpc/mm/hash_utils_64.c | 24 +++++++++++++++++-------
> 2 files changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
> index aeabd02..764e141 100644
> --- a/arch/powerpc/include/asm/mmu-hash64.h
> +++ b/arch/powerpc/include/asm/mmu-hash64.h
> @@ -324,6 +324,7 @@ extern int __hash_page_64K(unsigned long ea, unsigned long access,
> unsigned int local, int ssize);
> struct mm_struct;
> unsigned int hash_page_do_lazy_icache(unsigned int pp, pte_t pte, int trap);
> +extern int hash_page_mm(struct mm_struct *mm, unsigned long ea, unsigned long access, unsigned long trap);
> extern int hash_page(unsigned long ea, unsigned long access, unsigned long trap);
> int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
> pte_t *ptep, unsigned long trap, int local, int ssize,
> diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
> index bbdb054..698834d 100644
> --- a/arch/powerpc/mm/hash_utils_64.c
> +++ b/arch/powerpc/mm/hash_utils_64.c
> @@ -904,7 +904,7 @@ void demote_segment_4k(struct mm_struct *mm, unsigned long addr)
> return;
> slice_set_range_psize(mm, addr, 1, MMU_PAGE_4K);
> copro_flush_all_slbs(mm);
> - if (get_paca_psize(addr) != MMU_PAGE_4K) {
> + if ((get_paca_psize(addr) != MMU_PAGE_4K) && (current->mm == mm)) {
> get_paca()->context = mm->context;
> slb_flush_and_rebolt();
> }
> @@ -989,12 +989,11 @@ static void check_paca_psize(unsigned long ea, struct mm_struct *mm,
> * -1 - critical hash insertion error
> * -2 - access not permitted by subpage protection mechanism
> */
> -int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> +int hash_page_mm(struct mm_struct *mm, unsigned long ea, unsigned long access, unsigned long trap)
> {
> enum ctx_state prev_state = exception_enter();
> pgd_t *pgdir;
> unsigned long vsid;
> - struct mm_struct *mm;
> pte_t *ptep;
> unsigned hugeshift;
> const struct cpumask *tmp;
> @@ -1008,7 +1007,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> switch (REGION_ID(ea)) {
> case USER_REGION_ID:
> user_region = 1;
> - mm = current->mm;
> if (! mm) {
> DBG_LOW(" user region with no mm !\n");
> rc = 1;
> @@ -1019,7 +1017,6 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> vsid = get_vsid(mm->context.id, ea, ssize);
> break;
> case VMALLOC_REGION_ID:
> - mm = &init_mm;
> vsid = get_kernel_vsid(ea, mmu_kernel_ssize);
> if (ea < VMALLOC_END)
> psize = mmu_vmalloc_psize;
> @@ -1104,7 +1101,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> WARN_ON(1);
> }
> #endif
> - check_paca_psize(ea, mm, psize, user_region);
> + if (current->mm == mm)
> + check_paca_psize(ea, mm, psize, user_region);
>
> goto bail;
> }
> @@ -1145,7 +1143,8 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> }
> }
>
> - check_paca_psize(ea, mm, psize, user_region);
> + if (current->mm == mm)
> + check_paca_psize(ea, mm, psize, user_region);
> #endif /* CONFIG_PPC_64K_PAGES */
>
> #ifdef CONFIG_PPC_HAS_HASH_64K
> @@ -1180,6 +1179,17 @@ bail:
> exception_exit(prev_state);
> return rc;
> }
> +EXPORT_SYMBOL_GPL(hash_page_mm);
> +
> +int hash_page(unsigned long ea, unsigned long access, unsigned long trap)
> +{
> + struct mm_struct *mm = current->mm;
> +
> + if (REGION_ID(ea) == VMALLOC_REGION_ID)
> + mm = &init_mm;
> +
> + return hash_page_mm(mm, ea, access, trap);
> +}
> EXPORT_SYMBOL_GPL(hash_page);
>
> void hash_preload(struct mm_struct *mm, unsigned long ea,
> --
> 1.9.1
>
> --
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