Messages in this thread | | | Subject | Re: [PATCH v2 09/17] powerpc/mm: Add new hash_page_mm() | From | Michael Neuling <> | Date | Thu, 02 Oct 2014 17:10:04 +1000 |
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On Wed, 2014-10-01 at 15:13 +0530, Aneesh Kumar K.V wrote: > Michael Neuling <mikey@neuling.org> writes: > > > From: Ian Munsie <imunsie@au1.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. > > It would be nice to document the rules here. So when we try to add a hash > page entry, and if that result in demotion of the segment are we suppose to > flush slbs ?
Yeah, we found it sucky to understand. The current documentation is "buy benh a beer and ask him" which doesn't scale very well unless you're benh and you like beer.
> Also why would one want to hash anything other > than current->mm ? How will this get called ?
We are calling this on behalf of a co-processor (eg cxl). The mm this is currently associated with may not be running on a cpu.
> May be they are explained in later patches. But can we also explain it > here.
Ok, I'll add something (mpe had the same question).
Mikey > > > > > Signed-off-by: Ian Munsie <imunsie@au1.ibm.com> > > Signed-off-by: Michael Neuling <mikey@neuling.org> > > --- > > arch/powerpc/include/asm/mmu-hash64.h | 1 + > > arch/powerpc/mm/hash_utils_64.c | 22 ++++++++++++++-------- > > 2 files changed, 15 insertions(+), 8 deletions(-) > > > > diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h > > index 6d0b7a2..f84e5a5 100644 > > --- a/arch/powerpc/include/asm/mmu-hash64.h > > +++ b/arch/powerpc/include/asm/mmu-hash64.h > > @@ -322,6 +322,7 @@ 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..0a5c8c0 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(); > > } > > @@ -989,26 +989,24 @@ 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; > > int rc, user_region = 0, local = 0; > > int psize, ssize; > > > > - DBG_LOW("hash_page(ea=%016lx, access=%lx, trap=%lx\n", > > - ea, access, trap); > > + DBG_LOW("%s(ea=%016lx, access=%lx, trap=%lx\n", > > + __func__, ea, access, trap); > > > > /* Get region & vsid */ > > 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; > > @@ -1104,7 +1102,8 @@ 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 +1144,8 @@ 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 +1180,12 @@ 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) > > +{ > > + return hash_page_mm(current->mm, ea, access, trap); > > +} > > EXPORT_SYMBOL_GPL(hash_page); > > > > void hash_preload(struct mm_struct *mm, unsigned long ea, > > -- > > 1.9.1 > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Please read the FAQ at http://www.tux.org/lkml/ >
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