diff options
| -rw-r--r-- | arch/powerpc/include/asm/pgtable-ppc64.h | 2 | ||||
| -rw-r--r-- | arch/powerpc/mm/init_64.c | 51 | ||||
| -rw-r--r-- | include/linux/mm.h | 14 | ||||
| -rw-r--r-- | include/linux/page-flags.h | 4 |
4 files changed, 69 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h index 46db09414a10..4a191c472867 100644 --- a/arch/powerpc/include/asm/pgtable-ppc64.h +++ b/arch/powerpc/include/asm/pgtable-ppc64.h @@ -394,6 +394,8 @@ static inline void mark_hpte_slot_valid(unsigned char *hpte_slot_array, hpte_slot_array[index] = hidx << 4 | 0x1 << 3; } +struct page *realmode_pfn_to_page(unsigned long pfn); + static inline char *get_hpte_slot_array(pmd_t *pmdp) { /* diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c index 8ed035d2edb5..e3734edffa69 100644 --- a/arch/powerpc/mm/init_64.c +++ b/arch/powerpc/mm/init_64.c @@ -304,5 +304,54 @@ void register_page_bootmem_memmap(unsigned long section_nr, struct page *start_page, unsigned long size) { } -#endif /* CONFIG_SPARSEMEM_VMEMMAP */ +/* + * We do not have access to the sparsemem vmemmap, so we fallback to + * walking the list of sparsemem blocks which we already maintain for + * the sake of crashdump. In the long run, we might want to maintain + * a tree if performance of that linear walk becomes a problem. + * + * realmode_pfn_to_page functions can fail due to: + * 1) As real sparsemem blocks do not lay in RAM continously (they + * are in virtual address space which is not available in the real mode), + * the requested page struct can be split between blocks so get_page/put_page + * may fail. + * 2) When huge pages are used, the get_page/put_page API will fail + * in real mode as the linked addresses in the page struct are virtual + * too. + */ +struct page *realmode_pfn_to_page(unsigned long pfn) +{ + struct vmemmap_backing *vmem_back; + struct page *page; + unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift; + unsigned long pg_va = (unsigned long) pfn_to_page(pfn); + + for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) { + if (pg_va < vmem_back->virt_addr) + continue; + + /* Check that page struct is not split between real pages */ + if ((pg_va + sizeof(struct page)) > + (vmem_back->virt_addr + page_size)) + return NULL; + + page = (struct page *) (vmem_back->phys + pg_va - + vmem_back->virt_addr); + return page; + } + + return NULL; +} +EXPORT_SYMBOL_GPL(realmode_pfn_to_page); + +#elif defined(CONFIG_FLATMEM) + +struct page *realmode_pfn_to_page(unsigned long pfn) +{ + struct page *page = pfn_to_page(pfn); + return page; +} +EXPORT_SYMBOL_GPL(realmode_pfn_to_page); + +#endif /* CONFIG_SPARSEMEM_VMEMMAP/CONFIG_FLATMEM */ diff --git a/include/linux/mm.h b/include/linux/mm.h index 8b6e55ee8855..1a0668e5a4ee 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -297,12 +297,26 @@ static inline int put_page_testzero(struct page *page) /* * Try to grab a ref unless the page has a refcount of zero, return false if * that is the case. + * This can be called when MMU is off so it must not access + * any of the virtual mappings. */ static inline int get_page_unless_zero(struct page *page) { return atomic_inc_not_zero(&page->_count); } +/* + * Try to drop a ref unless the page has a refcount of one, return false if + * that is the case. + * This is to make sure that the refcount won't become zero after this drop. + * This can be called when MMU is off so it must not access + * any of the virtual mappings. + */ +static inline int put_page_unless_one(struct page *page) +{ + return atomic_add_unless(&page->_count, -1, 1); +} + extern int page_is_ram(unsigned long pfn); /* Support for virtually mapped pages */ diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 6d53675c2b54..98ada58f9942 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -329,7 +329,9 @@ static inline void set_page_writeback(struct page *page) * System with lots of page flags available. This allows separate * flags for PageHead() and PageTail() checks of compound pages so that bit * tests can be used in performance sensitive paths. PageCompound is - * generally not used in hot code paths. + * generally not used in hot code paths except arch/powerpc/mm/init_64.c + * and arch/powerpc/kvm/book3s_64_vio_hv.c which use it to detect huge pages + * and avoid handling those in real mode. */ __PAGEFLAG(Head, head) CLEARPAGEFLAG(Head, head) __PAGEFLAG(Tail, tail) |