mm: move get_user_pages()-related code to separate file (4bbd4c77) · Commits · e / devices / android_kernel_teracube_emerald

mm/Makefile

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -3,7 +3,7 @@
	#		#

	mmu-y := nommu.o		mmu-y := nommu.o
	mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \		mmu-$(CONFIG_MMU) := fremap.o gup.o highmem.o madvise.o memory.o mincore.o \
	mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \		mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
	vmalloc.o pagewalk.o pgtable-generic.o		vmalloc.o pagewalk.o pgtable-generic.o

mm/gup.c

0 → 100644

+649 −0

Original line number	Original line	Diff line number	Diff line
			#include <linux/kernel.h>
			#include <linux/errno.h>
			#include <linux/err.h>
			#include <linux/spinlock.h>

			#include <linux/hugetlb.h>
			#include <linux/mm.h>
			#include <linux/pagemap.h>
			#include <linux/rmap.h>
			#include <linux/swap.h>
			#include <linux/swapops.h>

			#include "internal.h"

			/**
			* follow_page_mask - look up a page descriptor from a user-virtual address
			* @vma: vm_area_struct mapping @address
			* @address: virtual address to look up
			* @flags: flags modifying lookup behaviour
			* @page_mask: on output, *page_mask is set according to the size of the page
			*
			* @flags can have FOLL_ flags set, defined in <linux/mm.h>
			*
			* Returns the mapped (struct page *), %NULL if no mapping exists, or
			* an error pointer if there is a mapping to something not represented
			* by a page descriptor (see also vm_normal_page()).
			*/
			struct page follow_page_mask(struct vm_area_struct vma,
			unsigned long address, unsigned int flags,
			unsigned int *page_mask)
			{
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *ptep, pte;
			spinlock_t *ptl;
			struct page *page;
			struct mm_struct *mm = vma->vm_mm;

			*page_mask = 0;

			page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
			if (!IS_ERR(page)) {
			BUG_ON(flags & FOLL_GET);
			goto out;
			}

			page = NULL;
			pgd = pgd_offset(mm, address);
			if (pgd_none(pgd) \|\| unlikely(pgd_bad(pgd)))
			goto no_page_table;

			pud = pud_offset(pgd, address);
			if (pud_none(*pud))
			goto no_page_table;
			if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
			if (flags & FOLL_GET)
			goto out;
			page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
			goto out;
			}
			if (unlikely(pud_bad(*pud)))
			goto no_page_table;

			pmd = pmd_offset(pud, address);
			if (pmd_none(*pmd))
			goto no_page_table;
			if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
			page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
			if (flags & FOLL_GET) {
			/*
			* Refcount on tail pages are not well-defined and
			* shouldn't be taken. The caller should handle a NULL
			* return when trying to follow tail pages.
			*/
			if (PageHead(page))
			get_page(page);
			else {
			page = NULL;
			goto out;
			}
			}
			goto out;
			}
			if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
			goto no_page_table;
			if (pmd_trans_huge(*pmd)) {
			if (flags & FOLL_SPLIT) {
			split_huge_page_pmd(vma, address, pmd);
			goto split_fallthrough;
			}
			ptl = pmd_lock(mm, pmd);
			if (likely(pmd_trans_huge(*pmd))) {
			if (unlikely(pmd_trans_splitting(*pmd))) {
			spin_unlock(ptl);
			wait_split_huge_page(vma->anon_vma, pmd);
			} else {
			page = follow_trans_huge_pmd(vma, address,
			pmd, flags);
			spin_unlock(ptl);
			*page_mask = HPAGE_PMD_NR - 1;
			goto out;
			}
			} else
			spin_unlock(ptl);
			/* fall through */
			}
			split_fallthrough:
			if (unlikely(pmd_bad(*pmd)))
			goto no_page_table;

			ptep = pte_offset_map_lock(mm, pmd, address, &ptl);

			pte = *ptep;
			if (!pte_present(pte)) {
			swp_entry_t entry;
			/*
			* KSM's break_ksm() relies upon recognizing a ksm page
			* even while it is being migrated, so for that case we
			* need migration_entry_wait().
			*/
			if (likely(!(flags & FOLL_MIGRATION)))
			goto no_page;
			if (pte_none(pte) \|\| pte_file(pte))
			goto no_page;
			entry = pte_to_swp_entry(pte);
			if (!is_migration_entry(entry))
			goto no_page;
			pte_unmap_unlock(ptep, ptl);
			migration_entry_wait(mm, pmd, address);
			goto split_fallthrough;
			}
			if ((flags & FOLL_NUMA) && pte_numa(pte))
			goto no_page;
			if ((flags & FOLL_WRITE) && !pte_write(pte))
			goto unlock;

			page = vm_normal_page(vma, address, pte);
			if (unlikely(!page)) {
			if ((flags & FOLL_DUMP) \|\|
			!is_zero_pfn(pte_pfn(pte)))
			goto bad_page;
			page = pte_page(pte);
			}

			if (flags & FOLL_GET)
			get_page_foll(page);
			if (flags & FOLL_TOUCH) {
			if ((flags & FOLL_WRITE) &&
			!pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
			/*
			* pte_mkyoung() would be more correct here, but atomic care
			* is needed to avoid losing the dirty bit: it is easier to use
			* mark_page_accessed().
			*/
			mark_page_accessed(page);
			}
			if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
			/*
			* The preliminary mapping check is mainly to avoid the
			* pointless overhead of lock_page on the ZERO_PAGE
			* which might bounce very badly if there is contention.
			*
			* If the page is already locked, we don't need to
			* handle it now - vmscan will handle it later if and
			* when it attempts to reclaim the page.
			*/
			if (page->mapping && trylock_page(page)) {
			lru_add_drain(); /* push cached pages to LRU */
			/*
			* Because we lock page here, and migration is
			* blocked by the pte's page reference, and we
			* know the page is still mapped, we don't even
			* need to check for file-cache page truncation.
			*/
			mlock_vma_page(page);
			unlock_page(page);
			}
			}
			unlock:
			pte_unmap_unlock(ptep, ptl);
			out:
			return page;

			bad_page:
			pte_unmap_unlock(ptep, ptl);
			return ERR_PTR(-EFAULT);

			no_page:
			pte_unmap_unlock(ptep, ptl);
			if (!pte_none(pte))
			return page;

			no_page_table:
			/*
			* When core dumping an enormous anonymous area that nobody
			* has touched so far, we don't want to allocate unnecessary pages or
			* page tables. Return error instead of NULL to skip handle_mm_fault,
			* then get_dump_page() will return NULL to leave a hole in the dump.
			* But we can only make this optimization where a hole would surely
			* be zero-filled if handle_mm_fault() actually did handle it.
			*/
			if ((flags & FOLL_DUMP) &&
			(!vma->vm_ops \|\| !vma->vm_ops->fault))
			return ERR_PTR(-EFAULT);
			return page;
			}

			static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
			{
			return stack_guard_page_start(vma, addr) \|\|
			stack_guard_page_end(vma, addr+PAGE_SIZE);
			}

			/**
			* __get_user_pages() - pin user pages in memory
			* @tsk: task_struct of target task
			* @mm: mm_struct of target mm
			* @start: starting user address
			* @nr_pages: number of pages from start to pin
			* @gup_flags: flags modifying pin behaviour
			* @pages: array that receives pointers to the pages pinned.
			* Should be at least nr_pages long. Or NULL, if caller
			* only intends to ensure the pages are faulted in.
			* @vmas: array of pointers to vmas corresponding to each page.
			* Or NULL if the caller does not require them.
			* @nonblocking: whether waiting for disk IO or mmap_sem contention
			*
			* Returns number of pages pinned. This may be fewer than the number
			* requested. If nr_pages is 0 or negative, returns 0. If no pages
			* were pinned, returns -errno. Each page returned must be released
			* with a put_page() call when it is finished with. vmas will only
			* remain valid while mmap_sem is held.
			*
			* Must be called with mmap_sem held for read or write.
			*
			* __get_user_pages walks a process's page tables and takes a reference to
			* each struct page that each user address corresponds to at a given
			* instant. That is, it takes the page that would be accessed if a user
			* thread accesses the given user virtual address at that instant.
			*
			* This does not guarantee that the page exists in the user mappings when
			* __get_user_pages returns, and there may even be a completely different
			* page there in some cases (eg. if mmapped pagecache has been invalidated
			* and subsequently re faulted). However it does guarantee that the page
			* won't be freed completely. And mostly callers simply care that the page
			* contains data that was valid at some point in time. Typically, an IO
			* or similar operation cannot guarantee anything stronger anyway because
			* locks can't be held over the syscall boundary.
			*
			* If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
			* the page is written to, set_page_dirty (or set_page_dirty_lock, as
			* appropriate) must be called after the page is finished with, and
			* before put_page is called.
			*
			* If @nonblocking != NULL, __get_user_pages will not wait for disk IO
			* or mmap_sem contention, and if waiting is needed to pin all pages,
			* *@nonblocking will be set to 0.
			*
			* In most cases, get_user_pages or get_user_pages_fast should be used
			* instead of __get_user_pages. __get_user_pages should be used only if
			* you need some special @gup_flags.
			*/
			long __get_user_pages(struct task_struct tsk, struct mm_struct mm,
			unsigned long start, unsigned long nr_pages,
			unsigned int gup_flags, struct page **pages,
			struct vm_area_struct *vmas, int nonblocking)
			{
			long i;
			unsigned long vm_flags;
			unsigned int page_mask;

			if (!nr_pages)
			return 0;

			VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));

			/*
			* If FOLL_FORCE is set then do not force a full fault as the hinting
			* fault information is unrelated to the reference behaviour of a task
			* using the address space
			*/
			if (!(gup_flags & FOLL_FORCE))
			gup_flags \|= FOLL_NUMA;

			i = 0;

			do {
			struct vm_area_struct *vma;

			vma = find_extend_vma(mm, start);
			if (!vma && in_gate_area(mm, start)) {
			unsigned long pg = start & PAGE_MASK;
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;

			/* user gate pages are read-only */
			if (gup_flags & FOLL_WRITE)
			goto efault;
			if (pg > TASK_SIZE)
			pgd = pgd_offset_k(pg);
			else
			pgd = pgd_offset_gate(mm, pg);
			BUG_ON(pgd_none(*pgd));
			pud = pud_offset(pgd, pg);
			BUG_ON(pud_none(*pud));
			pmd = pmd_offset(pud, pg);
			if (pmd_none(*pmd))
			goto efault;
			VM_BUG_ON(pmd_trans_huge(*pmd));
			pte = pte_offset_map(pmd, pg);
			if (pte_none(*pte)) {
			pte_unmap(pte);
			goto efault;
			}
			vma = get_gate_vma(mm);
			if (pages) {
			struct page *page;

			page = vm_normal_page(vma, start, *pte);
			if (!page) {
			if (!(gup_flags & FOLL_DUMP) &&
			is_zero_pfn(pte_pfn(*pte)))
			page = pte_page(*pte);
			else {
			pte_unmap(pte);
			goto efault;
			}
			}
			pages[i] = page;
			get_page(page);
			}
			pte_unmap(pte);
			page_mask = 0;
			goto next_page;
			}

			if (!vma)
			goto efault;
			vm_flags = vma->vm_flags;
			if (vm_flags & (VM_IO \| VM_PFNMAP))
			goto efault;

			if (gup_flags & FOLL_WRITE) {
			if (!(vm_flags & VM_WRITE)) {
			if (!(gup_flags & FOLL_FORCE))
			goto efault;
			/*
			* We used to let the write,force case do COW
			* in a VM_MAYWRITE VM_SHARED !VM_WRITE vma, so
			* ptrace could set a breakpoint in a read-only
			* mapping of an executable, without corrupting
			* the file (yet only when that file had been
			* opened for writing!). Anon pages in shared
			* mappings are surprising: now just reject it.
			*/
			if (!is_cow_mapping(vm_flags)) {
			WARN_ON_ONCE(vm_flags & VM_MAYWRITE);
			goto efault;
			}
			}
			} else {
			if (!(vm_flags & VM_READ)) {
			if (!(gup_flags & FOLL_FORCE))
			goto efault;
			/*
			* Is there actually any vma we can reach here
			* which does not have VM_MAYREAD set?
			*/
			if (!(vm_flags & VM_MAYREAD))
			goto efault;
			}
			}

			if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
			&start, &nr_pages, i, gup_flags);
			continue;
			}

			do {
			struct page *page;
			unsigned int foll_flags = gup_flags;
			unsigned int page_increm;

			/*
			* If we have a pending SIGKILL, don't keep faulting
			* pages and potentially allocating memory.
			*/
			if (unlikely(fatal_signal_pending(current)))
			return i ? i : -ERESTARTSYS;

			cond_resched();
			while (!(page = follow_page_mask(vma, start,
			foll_flags, &page_mask))) {
			int ret;
			unsigned int fault_flags = 0;

			/* For mlock, just skip the stack guard page. */
			if (foll_flags & FOLL_MLOCK) {
			if (stack_guard_page(vma, start))
			goto next_page;
			}
			if (foll_flags & FOLL_WRITE)
			fault_flags \|= FAULT_FLAG_WRITE;
			if (nonblocking)
			fault_flags \|= FAULT_FLAG_ALLOW_RETRY;
			if (foll_flags & FOLL_NOWAIT)
			fault_flags \|= (FAULT_FLAG_ALLOW_RETRY \| FAULT_FLAG_RETRY_NOWAIT);

			ret = handle_mm_fault(mm, vma, start,
			fault_flags);

			if (ret & VM_FAULT_ERROR) {
			if (ret & VM_FAULT_OOM)
			return i ? i : -ENOMEM;
			if (ret & (VM_FAULT_HWPOISON \|
			VM_FAULT_HWPOISON_LARGE)) {
			if (i)
			return i;
			else if (gup_flags & FOLL_HWPOISON)
			return -EHWPOISON;
			else
			return -EFAULT;
			}
			if (ret & VM_FAULT_SIGBUS)
			goto efault;
			BUG();
			}

			if (tsk) {
			if (ret & VM_FAULT_MAJOR)
			tsk->maj_flt++;
			else
			tsk->min_flt++;
			}

			if (ret & VM_FAULT_RETRY) {
			if (nonblocking)
			*nonblocking = 0;
			return i;
			}

			/*
			* The VM_FAULT_WRITE bit tells us that
			* do_wp_page has broken COW when necessary,
			* even if maybe_mkwrite decided not to set
			* pte_write. We can thus safely do subsequent
			* page lookups as if they were reads. But only
			* do so when looping for pte_write is futile:
			* in some cases userspace may also be wanting
			* to write to the gotten user page, which a
			* read fault here might prevent (a readonly
			* page might get reCOWed by userspace write).
			*/
			if ((ret & VM_FAULT_WRITE) &&
			!(vma->vm_flags & VM_WRITE))
			foll_flags &= ~FOLL_WRITE;

			cond_resched();
			}
			if (IS_ERR(page))
			return i ? i : PTR_ERR(page);
			if (pages) {
			pages[i] = page;

			flush_anon_page(vma, page, start);
			flush_dcache_page(page);
			page_mask = 0;
			}
			next_page:
			if (vmas) {
			vmas[i] = vma;
			page_mask = 0;
			}
			page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
			if (page_increm > nr_pages)
			page_increm = nr_pages;
			i += page_increm;
			start += page_increm * PAGE_SIZE;
			nr_pages -= page_increm;
			} while (nr_pages && start < vma->vm_end);
			} while (nr_pages);
			return i;
			efault:
			return i ? : -EFAULT;
			}
			EXPORT_SYMBOL(__get_user_pages);

			/*
			* fixup_user_fault() - manually resolve a user page fault
			* @tsk: the task_struct to use for page fault accounting, or
			* NULL if faults are not to be recorded.
			* @mm: mm_struct of target mm
			* @address: user address
			* @fault_flags:flags to pass down to handle_mm_fault()
			*
			* This is meant to be called in the specific scenario where for locking reasons
			* we try to access user memory in atomic context (within a pagefault_disable()
			* section), this returns -EFAULT, and we want to resolve the user fault before
			* trying again.
			*
			* Typically this is meant to be used by the futex code.
			*
			* The main difference with get_user_pages() is that this function will
			* unconditionally call handle_mm_fault() which will in turn perform all the
			* necessary SW fixup of the dirty and young bits in the PTE, while
			* handle_mm_fault() only guarantees to update these in the struct page.
			*
			* This is important for some architectures where those bits also gate the
			* access permission to the page because they are maintained in software. On
			* such architectures, gup() will not be enough to make a subsequent access
			* succeed.
			*
			* This should be called with the mm_sem held for read.
			*/
			int fixup_user_fault(struct task_struct tsk, struct mm_struct mm,
			unsigned long address, unsigned int fault_flags)
			{
			struct vm_area_struct *vma;
			vm_flags_t vm_flags;
			int ret;

			vma = find_extend_vma(mm, address);
			if (!vma \|\| address < vma->vm_start)
			return -EFAULT;

			vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ;
			if (!(vm_flags & vma->vm_flags))
			return -EFAULT;

			ret = handle_mm_fault(mm, vma, address, fault_flags);
			if (ret & VM_FAULT_ERROR) {
			if (ret & VM_FAULT_OOM)
			return -ENOMEM;
			if (ret & (VM_FAULT_HWPOISON \| VM_FAULT_HWPOISON_LARGE))
			return -EHWPOISON;
			if (ret & VM_FAULT_SIGBUS)
			return -EFAULT;
			BUG();
			}
			if (tsk) {
			if (ret & VM_FAULT_MAJOR)
			tsk->maj_flt++;
			else
			tsk->min_flt++;
			}
			return 0;
			}

			/*
			* get_user_pages() - pin user pages in memory
			* @tsk: the task_struct to use for page fault accounting, or
			* NULL if faults are not to be recorded.
			* @mm: mm_struct of target mm
			* @start: starting user address
			* @nr_pages: number of pages from start to pin
			* @write: whether pages will be written to by the caller
			* @force: whether to force access even when user mapping is currently
			* protected (but never forces write access to shared mapping).
			* @pages: array that receives pointers to the pages pinned.
			* Should be at least nr_pages long. Or NULL, if caller
			* only intends to ensure the pages are faulted in.
			* @vmas: array of pointers to vmas corresponding to each page.
			* Or NULL if the caller does not require them.
			*
			* Returns number of pages pinned. This may be fewer than the number
			* requested. If nr_pages is 0 or negative, returns 0. If no pages
			* were pinned, returns -errno. Each page returned must be released
			* with a put_page() call when it is finished with. vmas will only
			* remain valid while mmap_sem is held.
			*
			* Must be called with mmap_sem held for read or write.
			*
			* get_user_pages walks a process's page tables and takes a reference to
			* each struct page that each user address corresponds to at a given
			* instant. That is, it takes the page that would be accessed if a user
			* thread accesses the given user virtual address at that instant.
			*
			* This does not guarantee that the page exists in the user mappings when
			* get_user_pages returns, and there may even be a completely different
			* page there in some cases (eg. if mmapped pagecache has been invalidated
			* and subsequently re faulted). However it does guarantee that the page
			* won't be freed completely. And mostly callers simply care that the page
			* contains data that was valid at some point in time. Typically, an IO
			* or similar operation cannot guarantee anything stronger anyway because
			* locks can't be held over the syscall boundary.
			*
			* If write=0, the page must not be written to. If the page is written to,
			* set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
			* after the page is finished with, and before put_page is called.
			*
			* get_user_pages is typically used for fewer-copy IO operations, to get a
			* handle on the memory by some means other than accesses via the user virtual
			* addresses. The pages may be submitted for DMA to devices or accessed via
			* their kernel linear mapping (via the kmap APIs). Care should be taken to
			* use the correct cache flushing APIs.
			*
			* See also get_user_pages_fast, for performance critical applications.
			*/
			long get_user_pages(struct task_struct tsk, struct mm_struct mm,
			unsigned long start, unsigned long nr_pages, int write,
			int force, struct page pages, struct vm_area_struct vmas)
			{
			int flags = FOLL_TOUCH;

			if (pages)
			flags \|= FOLL_GET;
			if (write)
			flags \|= FOLL_WRITE;
			if (force)
			flags \|= FOLL_FORCE;

			return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
			NULL);
			}
			EXPORT_SYMBOL(get_user_pages);

			/**
			* get_dump_page() - pin user page in memory while writing it to core dump
			* @addr: user address
			*
			* Returns struct page pointer of user page pinned for dump,
			* to be freed afterwards by page_cache_release() or put_page().
			*
			* Returns NULL on any kind of failure - a hole must then be inserted into
			* the corefile, to preserve alignment with its headers; and also returns
			* NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
			* allowing a hole to be left in the corefile to save diskspace.
			*
			* Called without mmap_sem, but after all other threads have been killed.
			*/
			#ifdef CONFIG_ELF_CORE
			struct page *get_dump_page(unsigned long addr)
			{
			struct vm_area_struct *vma;
			struct page *page;

			if (__get_user_pages(current, current->mm, addr, 1,
			FOLL_FORCE \| FOLL_DUMP \| FOLL_GET, &page, &vma,
			NULL) < 1)
			return NULL;
			flush_cache_page(vma, addr, page_to_pfn(page));
			return page;
			}
			#endif /* CONFIG_ELF_CORE */

mm/internal.h

+5 −0

Original line number	Original line	Diff line number	Diff line
	@@ -169,6 +169,11 @@ static inline unsigned long page_order(struct page *page)
	return page_private(page);		return page_private(page);
	}		}

			static inline bool is_cow_mapping(vm_flags_t flags)
			{
			return (flags & (VM_SHARED \| VM_MAYWRITE)) == VM_MAYWRITE;
			}

	/* mm/util.c */		/* mm/util.c */
	void __vma_link_list(struct mm_struct mm, struct vm_area_struct vma,		void __vma_link_list(struct mm_struct mm, struct vm_area_struct vma,
	struct vm_area_struct prev, struct rb_node rb_parent);		struct vm_area_struct prev, struct rb_node rb_parent);

mm/memory.c

+0 −641

File changed.

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