mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 19:29:37 +00:00
![Aili Yao](/assets/img/avatar_default.png)
When we do coredump for user process signal, this may be an SIGBUS signal with BUS_MCEERR_AR or BUS_MCEERR_AO code, which means this signal is resulted from ECC memory fail like SRAR or SRAO, we expect the memory recovery work is finished correctly, then the get_dump_page() will not return the error page as its process pte is set invalid by memory_failure(). But memory_failure() may fail, and the process's related pte may not be correctly set invalid, for current code, we will return the poison page, get it dumped, and then lead to system panic as its in kernel code. So check the poison status in get_dump_page(), and if TRUE, return NULL. There maybe other scenario that is also better to check the posion status and not to panic, so make a wrapper for this check, Thanks to David's suggestion(<david@redhat.com>). [akpm@linux-foundation.org: s/0/false/] [yaoaili@kingsoft.com: is_page_poisoned() arg cannot be null, per Matthew] Link: https://lkml.kernel.org/r/20210322115233.05e4e82a@alex-virtual-machine Link: https://lkml.kernel.org/r/20210319104437.6f30e80d@alex-virtual-machine Signed-off-by: Aili Yao <yaoaili@kingsoft.com> Cc: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Aili Yao <yaoaili@kingsoft.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2875 lines
81 KiB
C
2875 lines
81 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
#include <linux/kernel.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/err.h>
|
|
#include <linux/spinlock.h>
|
|
|
|
#include <linux/mm.h>
|
|
#include <linux/memremap.h>
|
|
#include <linux/pagemap.h>
|
|
#include <linux/rmap.h>
|
|
#include <linux/swap.h>
|
|
#include <linux/swapops.h>
|
|
|
|
#include <linux/sched/signal.h>
|
|
#include <linux/rwsem.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <linux/migrate.h>
|
|
#include <linux/mm_inline.h>
|
|
#include <linux/sched/mm.h>
|
|
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
#include "internal.h"
|
|
|
|
struct follow_page_context {
|
|
struct dev_pagemap *pgmap;
|
|
unsigned int page_mask;
|
|
};
|
|
|
|
static void hpage_pincount_add(struct page *page, int refs)
|
|
{
|
|
VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
|
|
VM_BUG_ON_PAGE(page != compound_head(page), page);
|
|
|
|
atomic_add(refs, compound_pincount_ptr(page));
|
|
}
|
|
|
|
static void hpage_pincount_sub(struct page *page, int refs)
|
|
{
|
|
VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
|
|
VM_BUG_ON_PAGE(page != compound_head(page), page);
|
|
|
|
atomic_sub(refs, compound_pincount_ptr(page));
|
|
}
|
|
|
|
/*
|
|
* Return the compound head page with ref appropriately incremented,
|
|
* or NULL if that failed.
|
|
*/
|
|
static inline struct page *try_get_compound_head(struct page *page, int refs)
|
|
{
|
|
struct page *head = compound_head(page);
|
|
|
|
if (WARN_ON_ONCE(page_ref_count(head) < 0))
|
|
return NULL;
|
|
if (unlikely(!page_cache_add_speculative(head, refs)))
|
|
return NULL;
|
|
return head;
|
|
}
|
|
|
|
/*
|
|
* try_grab_compound_head() - attempt to elevate a page's refcount, by a
|
|
* flags-dependent amount.
|
|
*
|
|
* "grab" names in this file mean, "look at flags to decide whether to use
|
|
* FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.
|
|
*
|
|
* Either FOLL_PIN or FOLL_GET (or neither) must be set, but not both at the
|
|
* same time. (That's true throughout the get_user_pages*() and
|
|
* pin_user_pages*() APIs.) Cases:
|
|
*
|
|
* FOLL_GET: page's refcount will be incremented by 1.
|
|
* FOLL_PIN: page's refcount will be incremented by GUP_PIN_COUNTING_BIAS.
|
|
*
|
|
* Return: head page (with refcount appropriately incremented) for success, or
|
|
* NULL upon failure. If neither FOLL_GET nor FOLL_PIN was set, that's
|
|
* considered failure, and furthermore, a likely bug in the caller, so a warning
|
|
* is also emitted.
|
|
*/
|
|
__maybe_unused struct page *try_grab_compound_head(struct page *page,
|
|
int refs, unsigned int flags)
|
|
{
|
|
if (flags & FOLL_GET)
|
|
return try_get_compound_head(page, refs);
|
|
else if (flags & FOLL_PIN) {
|
|
int orig_refs = refs;
|
|
|
|
/*
|
|
* Can't do FOLL_LONGTERM + FOLL_PIN with CMA in the gup fast
|
|
* path, so fail and let the caller fall back to the slow path.
|
|
*/
|
|
if (unlikely(flags & FOLL_LONGTERM) &&
|
|
is_migrate_cma_page(page))
|
|
return NULL;
|
|
|
|
/*
|
|
* When pinning a compound page of order > 1 (which is what
|
|
* hpage_pincount_available() checks for), use an exact count to
|
|
* track it, via hpage_pincount_add/_sub().
|
|
*
|
|
* However, be sure to *also* increment the normal page refcount
|
|
* field at least once, so that the page really is pinned.
|
|
*/
|
|
if (!hpage_pincount_available(page))
|
|
refs *= GUP_PIN_COUNTING_BIAS;
|
|
|
|
page = try_get_compound_head(page, refs);
|
|
if (!page)
|
|
return NULL;
|
|
|
|
if (hpage_pincount_available(page))
|
|
hpage_pincount_add(page, refs);
|
|
|
|
mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED,
|
|
orig_refs);
|
|
|
|
return page;
|
|
}
|
|
|
|
WARN_ON_ONCE(1);
|
|
return NULL;
|
|
}
|
|
|
|
static void put_compound_head(struct page *page, int refs, unsigned int flags)
|
|
{
|
|
if (flags & FOLL_PIN) {
|
|
mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED,
|
|
refs);
|
|
|
|
if (hpage_pincount_available(page))
|
|
hpage_pincount_sub(page, refs);
|
|
else
|
|
refs *= GUP_PIN_COUNTING_BIAS;
|
|
}
|
|
|
|
VM_BUG_ON_PAGE(page_ref_count(page) < refs, page);
|
|
/*
|
|
* Calling put_page() for each ref is unnecessarily slow. Only the last
|
|
* ref needs a put_page().
|
|
*/
|
|
if (refs > 1)
|
|
page_ref_sub(page, refs - 1);
|
|
put_page(page);
|
|
}
|
|
|
|
/**
|
|
* try_grab_page() - elevate a page's refcount by a flag-dependent amount
|
|
*
|
|
* This might not do anything at all, depending on the flags argument.
|
|
*
|
|
* "grab" names in this file mean, "look at flags to decide whether to use
|
|
* FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.
|
|
*
|
|
* @page: pointer to page to be grabbed
|
|
* @flags: gup flags: these are the FOLL_* flag values.
|
|
*
|
|
* Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same
|
|
* time. Cases:
|
|
*
|
|
* FOLL_GET: page's refcount will be incremented by 1.
|
|
* FOLL_PIN: page's refcount will be incremented by GUP_PIN_COUNTING_BIAS.
|
|
*
|
|
* Return: true for success, or if no action was required (if neither FOLL_PIN
|
|
* nor FOLL_GET was set, nothing is done). False for failure: FOLL_GET or
|
|
* FOLL_PIN was set, but the page could not be grabbed.
|
|
*/
|
|
bool __must_check try_grab_page(struct page *page, unsigned int flags)
|
|
{
|
|
WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN));
|
|
|
|
if (flags & FOLL_GET)
|
|
return try_get_page(page);
|
|
else if (flags & FOLL_PIN) {
|
|
int refs = 1;
|
|
|
|
page = compound_head(page);
|
|
|
|
if (WARN_ON_ONCE(page_ref_count(page) <= 0))
|
|
return false;
|
|
|
|
if (hpage_pincount_available(page))
|
|
hpage_pincount_add(page, 1);
|
|
else
|
|
refs = GUP_PIN_COUNTING_BIAS;
|
|
|
|
/*
|
|
* Similar to try_grab_compound_head(): even if using the
|
|
* hpage_pincount_add/_sub() routines, be sure to
|
|
* *also* increment the normal page refcount field at least
|
|
* once, so that the page really is pinned.
|
|
*/
|
|
page_ref_add(page, refs);
|
|
|
|
mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED, 1);
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* unpin_user_page() - release a dma-pinned page
|
|
* @page: pointer to page to be released
|
|
*
|
|
* Pages that were pinned via pin_user_pages*() must be released via either
|
|
* unpin_user_page(), or one of the unpin_user_pages*() routines. This is so
|
|
* that such pages can be separately tracked and uniquely handled. In
|
|
* particular, interactions with RDMA and filesystems need special handling.
|
|
*/
|
|
void unpin_user_page(struct page *page)
|
|
{
|
|
put_compound_head(compound_head(page), 1, FOLL_PIN);
|
|
}
|
|
EXPORT_SYMBOL(unpin_user_page);
|
|
|
|
/**
|
|
* unpin_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages
|
|
* @pages: array of pages to be maybe marked dirty, and definitely released.
|
|
* @npages: number of pages in the @pages array.
|
|
* @make_dirty: whether to mark the pages dirty
|
|
*
|
|
* "gup-pinned page" refers to a page that has had one of the get_user_pages()
|
|
* variants called on that page.
|
|
*
|
|
* For each page in the @pages array, make that page (or its head page, if a
|
|
* compound page) dirty, if @make_dirty is true, and if the page was previously
|
|
* listed as clean. In any case, releases all pages using unpin_user_page(),
|
|
* possibly via unpin_user_pages(), for the non-dirty case.
|
|
*
|
|
* Please see the unpin_user_page() documentation for details.
|
|
*
|
|
* set_page_dirty_lock() is used internally. If instead, set_page_dirty() is
|
|
* required, then the caller should a) verify that this is really correct,
|
|
* because _lock() is usually required, and b) hand code it:
|
|
* set_page_dirty_lock(), unpin_user_page().
|
|
*
|
|
*/
|
|
void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
|
|
bool make_dirty)
|
|
{
|
|
unsigned long index;
|
|
|
|
/*
|
|
* TODO: this can be optimized for huge pages: if a series of pages is
|
|
* physically contiguous and part of the same compound page, then a
|
|
* single operation to the head page should suffice.
|
|
*/
|
|
|
|
if (!make_dirty) {
|
|
unpin_user_pages(pages, npages);
|
|
return;
|
|
}
|
|
|
|
for (index = 0; index < npages; index++) {
|
|
struct page *page = compound_head(pages[index]);
|
|
/*
|
|
* Checking PageDirty at this point may race with
|
|
* clear_page_dirty_for_io(), but that's OK. Two key
|
|
* cases:
|
|
*
|
|
* 1) This code sees the page as already dirty, so it
|
|
* skips the call to set_page_dirty(). That could happen
|
|
* because clear_page_dirty_for_io() called
|
|
* page_mkclean(), followed by set_page_dirty().
|
|
* However, now the page is going to get written back,
|
|
* which meets the original intention of setting it
|
|
* dirty, so all is well: clear_page_dirty_for_io() goes
|
|
* on to call TestClearPageDirty(), and write the page
|
|
* back.
|
|
*
|
|
* 2) This code sees the page as clean, so it calls
|
|
* set_page_dirty(). The page stays dirty, despite being
|
|
* written back, so it gets written back again in the
|
|
* next writeback cycle. This is harmless.
|
|
*/
|
|
if (!PageDirty(page))
|
|
set_page_dirty_lock(page);
|
|
unpin_user_page(page);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(unpin_user_pages_dirty_lock);
|
|
|
|
/**
|
|
* unpin_user_pages() - release an array of gup-pinned pages.
|
|
* @pages: array of pages to be marked dirty and released.
|
|
* @npages: number of pages in the @pages array.
|
|
*
|
|
* For each page in the @pages array, release the page using unpin_user_page().
|
|
*
|
|
* Please see the unpin_user_page() documentation for details.
|
|
*/
|
|
void unpin_user_pages(struct page **pages, unsigned long npages)
|
|
{
|
|
unsigned long index;
|
|
|
|
/*
|
|
* If this WARN_ON() fires, then the system *might* be leaking pages (by
|
|
* leaving them pinned), but probably not. More likely, gup/pup returned
|
|
* a hard -ERRNO error to the caller, who erroneously passed it here.
|
|
*/
|
|
if (WARN_ON(IS_ERR_VALUE(npages)))
|
|
return;
|
|
/*
|
|
* TODO: this can be optimized for huge pages: if a series of pages is
|
|
* physically contiguous and part of the same compound page, then a
|
|
* single operation to the head page should suffice.
|
|
*/
|
|
for (index = 0; index < npages; index++)
|
|
unpin_user_page(pages[index]);
|
|
}
|
|
EXPORT_SYMBOL(unpin_user_pages);
|
|
|
|
#ifdef CONFIG_MMU
|
|
static struct page *no_page_table(struct vm_area_struct *vma,
|
|
unsigned int flags)
|
|
{
|
|
/*
|
|
* 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_is_anonymous(vma) || !vma->vm_ops->fault))
|
|
return ERR_PTR(-EFAULT);
|
|
return NULL;
|
|
}
|
|
|
|
static int follow_pfn_pte(struct vm_area_struct *vma, unsigned long address,
|
|
pte_t *pte, unsigned int flags)
|
|
{
|
|
/* No page to get reference */
|
|
if (flags & FOLL_GET)
|
|
return -EFAULT;
|
|
|
|
if (flags & FOLL_TOUCH) {
|
|
pte_t entry = *pte;
|
|
|
|
if (flags & FOLL_WRITE)
|
|
entry = pte_mkdirty(entry);
|
|
entry = pte_mkyoung(entry);
|
|
|
|
if (!pte_same(*pte, entry)) {
|
|
set_pte_at(vma->vm_mm, address, pte, entry);
|
|
update_mmu_cache(vma, address, pte);
|
|
}
|
|
}
|
|
|
|
/* Proper page table entry exists, but no corresponding struct page */
|
|
return -EEXIST;
|
|
}
|
|
|
|
/*
|
|
* FOLL_FORCE can write to even unwritable pte's, but only
|
|
* after we've gone through a COW cycle and they are dirty.
|
|
*/
|
|
static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
|
|
{
|
|
return pte_write(pte) ||
|
|
((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
|
|
}
|
|
|
|
static struct page *follow_page_pte(struct vm_area_struct *vma,
|
|
unsigned long address, pmd_t *pmd, unsigned int flags,
|
|
struct dev_pagemap **pgmap)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *page;
|
|
spinlock_t *ptl;
|
|
pte_t *ptep, pte;
|
|
int ret;
|
|
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE((flags & (FOLL_PIN | FOLL_GET)) ==
|
|
(FOLL_PIN | FOLL_GET)))
|
|
return ERR_PTR(-EINVAL);
|
|
retry:
|
|
if (unlikely(pmd_bad(*pmd)))
|
|
return no_page_table(vma, flags);
|
|
|
|
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))
|
|
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 retry;
|
|
}
|
|
if ((flags & FOLL_NUMA) && pte_protnone(pte))
|
|
goto no_page;
|
|
if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags)) {
|
|
pte_unmap_unlock(ptep, ptl);
|
|
return NULL;
|
|
}
|
|
|
|
page = vm_normal_page(vma, address, pte);
|
|
if (!page && pte_devmap(pte) && (flags & (FOLL_GET | FOLL_PIN))) {
|
|
/*
|
|
* Only return device mapping pages in the FOLL_GET or FOLL_PIN
|
|
* case since they are only valid while holding the pgmap
|
|
* reference.
|
|
*/
|
|
*pgmap = get_dev_pagemap(pte_pfn(pte), *pgmap);
|
|
if (*pgmap)
|
|
page = pte_page(pte);
|
|
else
|
|
goto no_page;
|
|
} else if (unlikely(!page)) {
|
|
if (flags & FOLL_DUMP) {
|
|
/* Avoid special (like zero) pages in core dumps */
|
|
page = ERR_PTR(-EFAULT);
|
|
goto out;
|
|
}
|
|
|
|
if (is_zero_pfn(pte_pfn(pte))) {
|
|
page = pte_page(pte);
|
|
} else {
|
|
ret = follow_pfn_pte(vma, address, ptep, flags);
|
|
page = ERR_PTR(ret);
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
if (flags & FOLL_SPLIT && PageTransCompound(page)) {
|
|
get_page(page);
|
|
pte_unmap_unlock(ptep, ptl);
|
|
lock_page(page);
|
|
ret = split_huge_page(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
if (ret)
|
|
return ERR_PTR(ret);
|
|
goto retry;
|
|
}
|
|
|
|
/* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */
|
|
if (unlikely(!try_grab_page(page, flags))) {
|
|
page = ERR_PTR(-ENOMEM);
|
|
goto out;
|
|
}
|
|
/*
|
|
* We need to make the page accessible if and only if we are going
|
|
* to access its content (the FOLL_PIN case). Please see
|
|
* Documentation/core-api/pin_user_pages.rst for details.
|
|
*/
|
|
if (flags & FOLL_PIN) {
|
|
ret = arch_make_page_accessible(page);
|
|
if (ret) {
|
|
unpin_user_page(page);
|
|
page = ERR_PTR(ret);
|
|
goto out;
|
|
}
|
|
}
|
|
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)) {
|
|
/* Do not mlock pte-mapped THP */
|
|
if (PageTransCompound(page))
|
|
goto out;
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
}
|
|
out:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
return page;
|
|
no_page:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
if (!pte_none(pte))
|
|
return NULL;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
|
|
static struct page *follow_pmd_mask(struct vm_area_struct *vma,
|
|
unsigned long address, pud_t *pudp,
|
|
unsigned int flags,
|
|
struct follow_page_context *ctx)
|
|
{
|
|
pmd_t *pmd, pmdval;
|
|
spinlock_t *ptl;
|
|
struct page *page;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
pmd = pmd_offset(pudp, address);
|
|
/*
|
|
* The READ_ONCE() will stabilize the pmdval in a register or
|
|
* on the stack so that it will stop changing under the code.
|
|
*/
|
|
pmdval = READ_ONCE(*pmd);
|
|
if (pmd_none(pmdval))
|
|
return no_page_table(vma, flags);
|
|
if (pmd_huge(pmdval) && is_vm_hugetlb_page(vma)) {
|
|
page = follow_huge_pmd(mm, address, pmd, flags);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
if (is_hugepd(__hugepd(pmd_val(pmdval)))) {
|
|
page = follow_huge_pd(vma, address,
|
|
__hugepd(pmd_val(pmdval)), flags,
|
|
PMD_SHIFT);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
retry:
|
|
if (!pmd_present(pmdval)) {
|
|
if (likely(!(flags & FOLL_MIGRATION)))
|
|
return no_page_table(vma, flags);
|
|
VM_BUG_ON(thp_migration_supported() &&
|
|
!is_pmd_migration_entry(pmdval));
|
|
if (is_pmd_migration_entry(pmdval))
|
|
pmd_migration_entry_wait(mm, pmd);
|
|
pmdval = READ_ONCE(*pmd);
|
|
/*
|
|
* MADV_DONTNEED may convert the pmd to null because
|
|
* mmap_lock is held in read mode
|
|
*/
|
|
if (pmd_none(pmdval))
|
|
return no_page_table(vma, flags);
|
|
goto retry;
|
|
}
|
|
if (pmd_devmap(pmdval)) {
|
|
ptl = pmd_lock(mm, pmd);
|
|
page = follow_devmap_pmd(vma, address, pmd, flags, &ctx->pgmap);
|
|
spin_unlock(ptl);
|
|
if (page)
|
|
return page;
|
|
}
|
|
if (likely(!pmd_trans_huge(pmdval)))
|
|
return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
|
|
|
|
if ((flags & FOLL_NUMA) && pmd_protnone(pmdval))
|
|
return no_page_table(vma, flags);
|
|
|
|
retry_locked:
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (unlikely(pmd_none(*pmd))) {
|
|
spin_unlock(ptl);
|
|
return no_page_table(vma, flags);
|
|
}
|
|
if (unlikely(!pmd_present(*pmd))) {
|
|
spin_unlock(ptl);
|
|
if (likely(!(flags & FOLL_MIGRATION)))
|
|
return no_page_table(vma, flags);
|
|
pmd_migration_entry_wait(mm, pmd);
|
|
goto retry_locked;
|
|
}
|
|
if (unlikely(!pmd_trans_huge(*pmd))) {
|
|
spin_unlock(ptl);
|
|
return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
|
|
}
|
|
if (flags & (FOLL_SPLIT | FOLL_SPLIT_PMD)) {
|
|
int ret;
|
|
page = pmd_page(*pmd);
|
|
if (is_huge_zero_page(page)) {
|
|
spin_unlock(ptl);
|
|
ret = 0;
|
|
split_huge_pmd(vma, pmd, address);
|
|
if (pmd_trans_unstable(pmd))
|
|
ret = -EBUSY;
|
|
} else if (flags & FOLL_SPLIT) {
|
|
if (unlikely(!try_get_page(page))) {
|
|
spin_unlock(ptl);
|
|
return ERR_PTR(-ENOMEM);
|
|
}
|
|
spin_unlock(ptl);
|
|
lock_page(page);
|
|
ret = split_huge_page(page);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
if (pmd_none(*pmd))
|
|
return no_page_table(vma, flags);
|
|
} else { /* flags & FOLL_SPLIT_PMD */
|
|
spin_unlock(ptl);
|
|
split_huge_pmd(vma, pmd, address);
|
|
ret = pte_alloc(mm, pmd) ? -ENOMEM : 0;
|
|
}
|
|
|
|
return ret ? ERR_PTR(ret) :
|
|
follow_page_pte(vma, address, pmd, flags, &ctx->pgmap);
|
|
}
|
|
page = follow_trans_huge_pmd(vma, address, pmd, flags);
|
|
spin_unlock(ptl);
|
|
ctx->page_mask = HPAGE_PMD_NR - 1;
|
|
return page;
|
|
}
|
|
|
|
static struct page *follow_pud_mask(struct vm_area_struct *vma,
|
|
unsigned long address, p4d_t *p4dp,
|
|
unsigned int flags,
|
|
struct follow_page_context *ctx)
|
|
{
|
|
pud_t *pud;
|
|
spinlock_t *ptl;
|
|
struct page *page;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
pud = pud_offset(p4dp, address);
|
|
if (pud_none(*pud))
|
|
return no_page_table(vma, flags);
|
|
if (pud_huge(*pud) && is_vm_hugetlb_page(vma)) {
|
|
page = follow_huge_pud(mm, address, pud, flags);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
if (is_hugepd(__hugepd(pud_val(*pud)))) {
|
|
page = follow_huge_pd(vma, address,
|
|
__hugepd(pud_val(*pud)), flags,
|
|
PUD_SHIFT);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
if (pud_devmap(*pud)) {
|
|
ptl = pud_lock(mm, pud);
|
|
page = follow_devmap_pud(vma, address, pud, flags, &ctx->pgmap);
|
|
spin_unlock(ptl);
|
|
if (page)
|
|
return page;
|
|
}
|
|
if (unlikely(pud_bad(*pud)))
|
|
return no_page_table(vma, flags);
|
|
|
|
return follow_pmd_mask(vma, address, pud, flags, ctx);
|
|
}
|
|
|
|
static struct page *follow_p4d_mask(struct vm_area_struct *vma,
|
|
unsigned long address, pgd_t *pgdp,
|
|
unsigned int flags,
|
|
struct follow_page_context *ctx)
|
|
{
|
|
p4d_t *p4d;
|
|
struct page *page;
|
|
|
|
p4d = p4d_offset(pgdp, address);
|
|
if (p4d_none(*p4d))
|
|
return no_page_table(vma, flags);
|
|
BUILD_BUG_ON(p4d_huge(*p4d));
|
|
if (unlikely(p4d_bad(*p4d)))
|
|
return no_page_table(vma, flags);
|
|
|
|
if (is_hugepd(__hugepd(p4d_val(*p4d)))) {
|
|
page = follow_huge_pd(vma, address,
|
|
__hugepd(p4d_val(*p4d)), flags,
|
|
P4D_SHIFT);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
return follow_pud_mask(vma, address, p4d, flags, ctx);
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
* @ctx: contains dev_pagemap for %ZONE_DEVICE memory pinning and a
|
|
* pointer to output page_mask
|
|
*
|
|
* @flags can have FOLL_ flags set, defined in <linux/mm.h>
|
|
*
|
|
* When getting pages from ZONE_DEVICE memory, the @ctx->pgmap caches
|
|
* the device's dev_pagemap metadata to avoid repeating expensive lookups.
|
|
*
|
|
* On output, the @ctx->page_mask is set according to the size of the page.
|
|
*
|
|
* Return: 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()).
|
|
*/
|
|
static struct page *follow_page_mask(struct vm_area_struct *vma,
|
|
unsigned long address, unsigned int flags,
|
|
struct follow_page_context *ctx)
|
|
{
|
|
pgd_t *pgd;
|
|
struct page *page;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
ctx->page_mask = 0;
|
|
|
|
/* make this handle hugepd */
|
|
page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
|
|
if (!IS_ERR(page)) {
|
|
WARN_ON_ONCE(flags & (FOLL_GET | FOLL_PIN));
|
|
return page;
|
|
}
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
|
|
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
|
|
return no_page_table(vma, flags);
|
|
|
|
if (pgd_huge(*pgd)) {
|
|
page = follow_huge_pgd(mm, address, pgd, flags);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
if (is_hugepd(__hugepd(pgd_val(*pgd)))) {
|
|
page = follow_huge_pd(vma, address,
|
|
__hugepd(pgd_val(*pgd)), flags,
|
|
PGDIR_SHIFT);
|
|
if (page)
|
|
return page;
|
|
return no_page_table(vma, flags);
|
|
}
|
|
|
|
return follow_p4d_mask(vma, address, pgd, flags, ctx);
|
|
}
|
|
|
|
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned int foll_flags)
|
|
{
|
|
struct follow_page_context ctx = { NULL };
|
|
struct page *page;
|
|
|
|
page = follow_page_mask(vma, address, foll_flags, &ctx);
|
|
if (ctx.pgmap)
|
|
put_dev_pagemap(ctx.pgmap);
|
|
return page;
|
|
}
|
|
|
|
static int get_gate_page(struct mm_struct *mm, unsigned long address,
|
|
unsigned int gup_flags, struct vm_area_struct **vma,
|
|
struct page **page)
|
|
{
|
|
pgd_t *pgd;
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
pte_t *pte;
|
|
int ret = -EFAULT;
|
|
|
|
/* user gate pages are read-only */
|
|
if (gup_flags & FOLL_WRITE)
|
|
return -EFAULT;
|
|
if (address > TASK_SIZE)
|
|
pgd = pgd_offset_k(address);
|
|
else
|
|
pgd = pgd_offset_gate(mm, address);
|
|
if (pgd_none(*pgd))
|
|
return -EFAULT;
|
|
p4d = p4d_offset(pgd, address);
|
|
if (p4d_none(*p4d))
|
|
return -EFAULT;
|
|
pud = pud_offset(p4d, address);
|
|
if (pud_none(*pud))
|
|
return -EFAULT;
|
|
pmd = pmd_offset(pud, address);
|
|
if (!pmd_present(*pmd))
|
|
return -EFAULT;
|
|
VM_BUG_ON(pmd_trans_huge(*pmd));
|
|
pte = pte_offset_map(pmd, address);
|
|
if (pte_none(*pte))
|
|
goto unmap;
|
|
*vma = get_gate_vma(mm);
|
|
if (!page)
|
|
goto out;
|
|
*page = vm_normal_page(*vma, address, *pte);
|
|
if (!*page) {
|
|
if ((gup_flags & FOLL_DUMP) || !is_zero_pfn(pte_pfn(*pte)))
|
|
goto unmap;
|
|
*page = pte_page(*pte);
|
|
}
|
|
if (unlikely(!try_grab_page(*page, gup_flags))) {
|
|
ret = -ENOMEM;
|
|
goto unmap;
|
|
}
|
|
out:
|
|
ret = 0;
|
|
unmap:
|
|
pte_unmap(pte);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* mmap_lock must be held on entry. If @locked != NULL and *@flags
|
|
* does not include FOLL_NOWAIT, the mmap_lock may be released. If it
|
|
* is, *@locked will be set to 0 and -EBUSY returned.
|
|
*/
|
|
static int faultin_page(struct vm_area_struct *vma,
|
|
unsigned long address, unsigned int *flags, int *locked)
|
|
{
|
|
unsigned int fault_flags = 0;
|
|
vm_fault_t ret;
|
|
|
|
/* mlock all present pages, but do not fault in new pages */
|
|
if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK)
|
|
return -ENOENT;
|
|
if (*flags & FOLL_WRITE)
|
|
fault_flags |= FAULT_FLAG_WRITE;
|
|
if (*flags & FOLL_REMOTE)
|
|
fault_flags |= FAULT_FLAG_REMOTE;
|
|
if (locked)
|
|
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
|
|
if (*flags & FOLL_NOWAIT)
|
|
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
|
|
if (*flags & FOLL_TRIED) {
|
|
/*
|
|
* Note: FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_TRIED
|
|
* can co-exist
|
|
*/
|
|
fault_flags |= FAULT_FLAG_TRIED;
|
|
}
|
|
|
|
ret = handle_mm_fault(vma, address, fault_flags, NULL);
|
|
if (ret & VM_FAULT_ERROR) {
|
|
int err = vm_fault_to_errno(ret, *flags);
|
|
|
|
if (err)
|
|
return err;
|
|
BUG();
|
|
}
|
|
|
|
if (ret & VM_FAULT_RETRY) {
|
|
if (locked && !(fault_flags & FAULT_FLAG_RETRY_NOWAIT))
|
|
*locked = 0;
|
|
return -EBUSY;
|
|
}
|
|
|
|
/*
|
|
* 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))
|
|
*flags |= FOLL_COW;
|
|
return 0;
|
|
}
|
|
|
|
static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
|
|
{
|
|
vm_flags_t vm_flags = vma->vm_flags;
|
|
int write = (gup_flags & FOLL_WRITE);
|
|
int foreign = (gup_flags & FOLL_REMOTE);
|
|
|
|
if (vm_flags & (VM_IO | VM_PFNMAP))
|
|
return -EFAULT;
|
|
|
|
if (gup_flags & FOLL_ANON && !vma_is_anonymous(vma))
|
|
return -EFAULT;
|
|
|
|
if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma))
|
|
return -EOPNOTSUPP;
|
|
|
|
if (write) {
|
|
if (!(vm_flags & VM_WRITE)) {
|
|
if (!(gup_flags & FOLL_FORCE))
|
|
return -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))
|
|
return -EFAULT;
|
|
}
|
|
} else if (!(vm_flags & VM_READ)) {
|
|
if (!(gup_flags & FOLL_FORCE))
|
|
return -EFAULT;
|
|
/*
|
|
* Is there actually any vma we can reach here which does not
|
|
* have VM_MAYREAD set?
|
|
*/
|
|
if (!(vm_flags & VM_MAYREAD))
|
|
return -EFAULT;
|
|
}
|
|
/*
|
|
* gups are always data accesses, not instruction
|
|
* fetches, so execute=false here
|
|
*/
|
|
if (!arch_vma_access_permitted(vma, write, false, foreign))
|
|
return -EFAULT;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* __get_user_pages() - pin user pages in memory
|
|
* @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.
|
|
* @locked: whether we're still with the mmap_lock held
|
|
*
|
|
* Returns either number of pages pinned (which may be less than the
|
|
* number requested), or an error. Details about the return value:
|
|
*
|
|
* -- If nr_pages is 0, returns 0.
|
|
* -- If nr_pages is >0, but no pages were pinned, returns -errno.
|
|
* -- If nr_pages is >0, and some pages were pinned, returns the number of
|
|
* pages pinned. Again, this may be less than nr_pages.
|
|
* -- 0 return value is possible when the fault would need to be retried.
|
|
*
|
|
* The caller is responsible for releasing returned @pages, via put_page().
|
|
*
|
|
* @vmas are valid only as long as mmap_lock is held.
|
|
*
|
|
* Must be called with mmap_lock held. It may be released. See below.
|
|
*
|
|
* __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 @locked != NULL, *@locked will be set to 0 when mmap_lock is
|
|
* released by an up_read(). That can happen if @gup_flags does not
|
|
* have FOLL_NOWAIT.
|
|
*
|
|
* A caller using such a combination of @locked and @gup_flags
|
|
* must therefore hold the mmap_lock for reading only, and recognize
|
|
* when it's been released. Otherwise, it must be held for either
|
|
* reading or writing and will not be released.
|
|
*
|
|
* 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.
|
|
*/
|
|
static long __get_user_pages(struct mm_struct *mm,
|
|
unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked)
|
|
{
|
|
long ret = 0, i = 0;
|
|
struct vm_area_struct *vma = NULL;
|
|
struct follow_page_context ctx = { NULL };
|
|
|
|
if (!nr_pages)
|
|
return 0;
|
|
|
|
start = untagged_addr(start);
|
|
|
|
VM_BUG_ON(!!pages != !!(gup_flags & (FOLL_GET | FOLL_PIN)));
|
|
|
|
/*
|
|
* 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;
|
|
|
|
do {
|
|
struct page *page;
|
|
unsigned int foll_flags = gup_flags;
|
|
unsigned int page_increm;
|
|
|
|
/* first iteration or cross vma bound */
|
|
if (!vma || start >= vma->vm_end) {
|
|
vma = find_extend_vma(mm, start);
|
|
if (!vma && in_gate_area(mm, start)) {
|
|
ret = get_gate_page(mm, start & PAGE_MASK,
|
|
gup_flags, &vma,
|
|
pages ? &pages[i] : NULL);
|
|
if (ret)
|
|
goto out;
|
|
ctx.page_mask = 0;
|
|
goto next_page;
|
|
}
|
|
|
|
if (!vma) {
|
|
ret = -EFAULT;
|
|
goto out;
|
|
}
|
|
ret = check_vma_flags(vma, gup_flags);
|
|
if (ret)
|
|
goto out;
|
|
|
|
if (is_vm_hugetlb_page(vma)) {
|
|
i = follow_hugetlb_page(mm, vma, pages, vmas,
|
|
&start, &nr_pages, i,
|
|
gup_flags, locked);
|
|
if (locked && *locked == 0) {
|
|
/*
|
|
* We've got a VM_FAULT_RETRY
|
|
* and we've lost mmap_lock.
|
|
* We must stop here.
|
|
*/
|
|
BUG_ON(gup_flags & FOLL_NOWAIT);
|
|
BUG_ON(ret != 0);
|
|
goto out;
|
|
}
|
|
continue;
|
|
}
|
|
}
|
|
retry:
|
|
/*
|
|
* If we have a pending SIGKILL, don't keep faulting pages and
|
|
* potentially allocating memory.
|
|
*/
|
|
if (fatal_signal_pending(current)) {
|
|
ret = -EINTR;
|
|
goto out;
|
|
}
|
|
cond_resched();
|
|
|
|
page = follow_page_mask(vma, start, foll_flags, &ctx);
|
|
if (!page) {
|
|
ret = faultin_page(vma, start, &foll_flags, locked);
|
|
switch (ret) {
|
|
case 0:
|
|
goto retry;
|
|
case -EBUSY:
|
|
ret = 0;
|
|
fallthrough;
|
|
case -EFAULT:
|
|
case -ENOMEM:
|
|
case -EHWPOISON:
|
|
goto out;
|
|
case -ENOENT:
|
|
goto next_page;
|
|
}
|
|
BUG();
|
|
} else if (PTR_ERR(page) == -EEXIST) {
|
|
/*
|
|
* Proper page table entry exists, but no corresponding
|
|
* struct page.
|
|
*/
|
|
goto next_page;
|
|
} else if (IS_ERR(page)) {
|
|
ret = PTR_ERR(page);
|
|
goto out;
|
|
}
|
|
if (pages) {
|
|
pages[i] = page;
|
|
flush_anon_page(vma, page, start);
|
|
flush_dcache_page(page);
|
|
ctx.page_mask = 0;
|
|
}
|
|
next_page:
|
|
if (vmas) {
|
|
vmas[i] = vma;
|
|
ctx.page_mask = 0;
|
|
}
|
|
page_increm = 1 + (~(start >> PAGE_SHIFT) & ctx.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);
|
|
out:
|
|
if (ctx.pgmap)
|
|
put_dev_pagemap(ctx.pgmap);
|
|
return i ? i : ret;
|
|
}
|
|
|
|
static bool vma_permits_fault(struct vm_area_struct *vma,
|
|
unsigned int fault_flags)
|
|
{
|
|
bool write = !!(fault_flags & FAULT_FLAG_WRITE);
|
|
bool foreign = !!(fault_flags & FAULT_FLAG_REMOTE);
|
|
vm_flags_t vm_flags = write ? VM_WRITE : VM_READ;
|
|
|
|
if (!(vm_flags & vma->vm_flags))
|
|
return false;
|
|
|
|
/*
|
|
* The architecture might have a hardware protection
|
|
* mechanism other than read/write that can deny access.
|
|
*
|
|
* gup always represents data access, not instruction
|
|
* fetches, so execute=false here:
|
|
*/
|
|
if (!arch_vma_access_permitted(vma, write, false, foreign))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* fixup_user_fault() - manually resolve a user page fault
|
|
* @mm: mm_struct of target mm
|
|
* @address: user address
|
|
* @fault_flags:flags to pass down to handle_mm_fault()
|
|
* @unlocked: did we unlock the mmap_lock while retrying, maybe NULL if caller
|
|
* does not allow retry. If NULL, the caller must guarantee
|
|
* that fault_flags does not contain FAULT_FLAG_ALLOW_RETRY.
|
|
*
|
|
* 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
|
|
* get_user_pages() 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 function will not return with an unlocked mmap_lock. So it has not the
|
|
* same semantics wrt the @mm->mmap_lock as does filemap_fault().
|
|
*/
|
|
int fixup_user_fault(struct mm_struct *mm,
|
|
unsigned long address, unsigned int fault_flags,
|
|
bool *unlocked)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
vm_fault_t ret, major = 0;
|
|
|
|
address = untagged_addr(address);
|
|
|
|
if (unlocked)
|
|
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
|
|
|
|
retry:
|
|
vma = find_extend_vma(mm, address);
|
|
if (!vma || address < vma->vm_start)
|
|
return -EFAULT;
|
|
|
|
if (!vma_permits_fault(vma, fault_flags))
|
|
return -EFAULT;
|
|
|
|
if ((fault_flags & FAULT_FLAG_KILLABLE) &&
|
|
fatal_signal_pending(current))
|
|
return -EINTR;
|
|
|
|
ret = handle_mm_fault(vma, address, fault_flags, NULL);
|
|
major |= ret & VM_FAULT_MAJOR;
|
|
if (ret & VM_FAULT_ERROR) {
|
|
int err = vm_fault_to_errno(ret, 0);
|
|
|
|
if (err)
|
|
return err;
|
|
BUG();
|
|
}
|
|
|
|
if (ret & VM_FAULT_RETRY) {
|
|
mmap_read_lock(mm);
|
|
*unlocked = true;
|
|
fault_flags |= FAULT_FLAG_TRIED;
|
|
goto retry;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(fixup_user_fault);
|
|
|
|
/*
|
|
* Please note that this function, unlike __get_user_pages will not
|
|
* return 0 for nr_pages > 0 without FOLL_NOWAIT
|
|
*/
|
|
static __always_inline long __get_user_pages_locked(struct mm_struct *mm,
|
|
unsigned long start,
|
|
unsigned long nr_pages,
|
|
struct page **pages,
|
|
struct vm_area_struct **vmas,
|
|
int *locked,
|
|
unsigned int flags)
|
|
{
|
|
long ret, pages_done;
|
|
bool lock_dropped;
|
|
|
|
if (locked) {
|
|
/* if VM_FAULT_RETRY can be returned, vmas become invalid */
|
|
BUG_ON(vmas);
|
|
/* check caller initialized locked */
|
|
BUG_ON(*locked != 1);
|
|
}
|
|
|
|
if (flags & FOLL_PIN)
|
|
atomic_set(&mm->has_pinned, 1);
|
|
|
|
/*
|
|
* FOLL_PIN and FOLL_GET are mutually exclusive. Traditional behavior
|
|
* is to set FOLL_GET if the caller wants pages[] filled in (but has
|
|
* carelessly failed to specify FOLL_GET), so keep doing that, but only
|
|
* for FOLL_GET, not for the newer FOLL_PIN.
|
|
*
|
|
* FOLL_PIN always expects pages to be non-null, but no need to assert
|
|
* that here, as any failures will be obvious enough.
|
|
*/
|
|
if (pages && !(flags & FOLL_PIN))
|
|
flags |= FOLL_GET;
|
|
|
|
pages_done = 0;
|
|
lock_dropped = false;
|
|
for (;;) {
|
|
ret = __get_user_pages(mm, start, nr_pages, flags, pages,
|
|
vmas, locked);
|
|
if (!locked)
|
|
/* VM_FAULT_RETRY couldn't trigger, bypass */
|
|
return ret;
|
|
|
|
/* VM_FAULT_RETRY cannot return errors */
|
|
if (!*locked) {
|
|
BUG_ON(ret < 0);
|
|
BUG_ON(ret >= nr_pages);
|
|
}
|
|
|
|
if (ret > 0) {
|
|
nr_pages -= ret;
|
|
pages_done += ret;
|
|
if (!nr_pages)
|
|
break;
|
|
}
|
|
if (*locked) {
|
|
/*
|
|
* VM_FAULT_RETRY didn't trigger or it was a
|
|
* FOLL_NOWAIT.
|
|
*/
|
|
if (!pages_done)
|
|
pages_done = ret;
|
|
break;
|
|
}
|
|
/*
|
|
* VM_FAULT_RETRY triggered, so seek to the faulting offset.
|
|
* For the prefault case (!pages) we only update counts.
|
|
*/
|
|
if (likely(pages))
|
|
pages += ret;
|
|
start += ret << PAGE_SHIFT;
|
|
lock_dropped = true;
|
|
|
|
retry:
|
|
/*
|
|
* Repeat on the address that fired VM_FAULT_RETRY
|
|
* with both FAULT_FLAG_ALLOW_RETRY and
|
|
* FAULT_FLAG_TRIED. Note that GUP can be interrupted
|
|
* by fatal signals, so we need to check it before we
|
|
* start trying again otherwise it can loop forever.
|
|
*/
|
|
|
|
if (fatal_signal_pending(current)) {
|
|
if (!pages_done)
|
|
pages_done = -EINTR;
|
|
break;
|
|
}
|
|
|
|
ret = mmap_read_lock_killable(mm);
|
|
if (ret) {
|
|
BUG_ON(ret > 0);
|
|
if (!pages_done)
|
|
pages_done = ret;
|
|
break;
|
|
}
|
|
|
|
*locked = 1;
|
|
ret = __get_user_pages(mm, start, 1, flags | FOLL_TRIED,
|
|
pages, NULL, locked);
|
|
if (!*locked) {
|
|
/* Continue to retry until we succeeded */
|
|
BUG_ON(ret != 0);
|
|
goto retry;
|
|
}
|
|
if (ret != 1) {
|
|
BUG_ON(ret > 1);
|
|
if (!pages_done)
|
|
pages_done = ret;
|
|
break;
|
|
}
|
|
nr_pages--;
|
|
pages_done++;
|
|
if (!nr_pages)
|
|
break;
|
|
if (likely(pages))
|
|
pages++;
|
|
start += PAGE_SIZE;
|
|
}
|
|
if (lock_dropped && *locked) {
|
|
/*
|
|
* We must let the caller know we temporarily dropped the lock
|
|
* and so the critical section protected by it was lost.
|
|
*/
|
|
mmap_read_unlock(mm);
|
|
*locked = 0;
|
|
}
|
|
return pages_done;
|
|
}
|
|
|
|
/**
|
|
* populate_vma_page_range() - populate a range of pages in the vma.
|
|
* @vma: target vma
|
|
* @start: start address
|
|
* @end: end address
|
|
* @locked: whether the mmap_lock is still held
|
|
*
|
|
* This takes care of mlocking the pages too if VM_LOCKED is set.
|
|
*
|
|
* Return either number of pages pinned in the vma, or a negative error
|
|
* code on error.
|
|
*
|
|
* vma->vm_mm->mmap_lock must be held.
|
|
*
|
|
* If @locked is NULL, it may be held for read or write and will
|
|
* be unperturbed.
|
|
*
|
|
* If @locked is non-NULL, it must held for read only and may be
|
|
* released. If it's released, *@locked will be set to 0.
|
|
*/
|
|
long populate_vma_page_range(struct vm_area_struct *vma,
|
|
unsigned long start, unsigned long end, int *locked)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long nr_pages = (end - start) / PAGE_SIZE;
|
|
int gup_flags;
|
|
|
|
VM_BUG_ON(start & ~PAGE_MASK);
|
|
VM_BUG_ON(end & ~PAGE_MASK);
|
|
VM_BUG_ON_VMA(start < vma->vm_start, vma);
|
|
VM_BUG_ON_VMA(end > vma->vm_end, vma);
|
|
mmap_assert_locked(mm);
|
|
|
|
gup_flags = FOLL_TOUCH | FOLL_POPULATE | FOLL_MLOCK;
|
|
if (vma->vm_flags & VM_LOCKONFAULT)
|
|
gup_flags &= ~FOLL_POPULATE;
|
|
/*
|
|
* We want to touch writable mappings with a write fault in order
|
|
* to break COW, except for shared mappings because these don't COW
|
|
* and we would not want to dirty them for nothing.
|
|
*/
|
|
if ((vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
|
|
gup_flags |= FOLL_WRITE;
|
|
|
|
/*
|
|
* We want mlock to succeed for regions that have any permissions
|
|
* other than PROT_NONE.
|
|
*/
|
|
if (vma_is_accessible(vma))
|
|
gup_flags |= FOLL_FORCE;
|
|
|
|
/*
|
|
* We made sure addr is within a VMA, so the following will
|
|
* not result in a stack expansion that recurses back here.
|
|
*/
|
|
return __get_user_pages(mm, start, nr_pages, gup_flags,
|
|
NULL, NULL, locked);
|
|
}
|
|
|
|
/*
|
|
* __mm_populate - populate and/or mlock pages within a range of address space.
|
|
*
|
|
* This is used to implement mlock() and the MAP_POPULATE / MAP_LOCKED mmap
|
|
* flags. VMAs must be already marked with the desired vm_flags, and
|
|
* mmap_lock must not be held.
|
|
*/
|
|
int __mm_populate(unsigned long start, unsigned long len, int ignore_errors)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned long end, nstart, nend;
|
|
struct vm_area_struct *vma = NULL;
|
|
int locked = 0;
|
|
long ret = 0;
|
|
|
|
end = start + len;
|
|
|
|
for (nstart = start; nstart < end; nstart = nend) {
|
|
/*
|
|
* We want to fault in pages for [nstart; end) address range.
|
|
* Find first corresponding VMA.
|
|
*/
|
|
if (!locked) {
|
|
locked = 1;
|
|
mmap_read_lock(mm);
|
|
vma = find_vma(mm, nstart);
|
|
} else if (nstart >= vma->vm_end)
|
|
vma = vma->vm_next;
|
|
if (!vma || vma->vm_start >= end)
|
|
break;
|
|
/*
|
|
* Set [nstart; nend) to intersection of desired address
|
|
* range with the first VMA. Also, skip undesirable VMA types.
|
|
*/
|
|
nend = min(end, vma->vm_end);
|
|
if (vma->vm_flags & (VM_IO | VM_PFNMAP))
|
|
continue;
|
|
if (nstart < vma->vm_start)
|
|
nstart = vma->vm_start;
|
|
/*
|
|
* Now fault in a range of pages. populate_vma_page_range()
|
|
* double checks the vma flags, so that it won't mlock pages
|
|
* if the vma was already munlocked.
|
|
*/
|
|
ret = populate_vma_page_range(vma, nstart, nend, &locked);
|
|
if (ret < 0) {
|
|
if (ignore_errors) {
|
|
ret = 0;
|
|
continue; /* continue at next VMA */
|
|
}
|
|
break;
|
|
}
|
|
nend = nstart + ret * PAGE_SIZE;
|
|
ret = 0;
|
|
}
|
|
if (locked)
|
|
mmap_read_unlock(mm);
|
|
return ret; /* 0 or negative error code */
|
|
}
|
|
#else /* CONFIG_MMU */
|
|
static long __get_user_pages_locked(struct mm_struct *mm, unsigned long start,
|
|
unsigned long nr_pages, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked,
|
|
unsigned int foll_flags)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
unsigned long vm_flags;
|
|
int i;
|
|
|
|
/* calculate required read or write permissions.
|
|
* If FOLL_FORCE is set, we only require the "MAY" flags.
|
|
*/
|
|
vm_flags = (foll_flags & FOLL_WRITE) ?
|
|
(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
|
|
vm_flags &= (foll_flags & FOLL_FORCE) ?
|
|
(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
|
|
|
|
for (i = 0; i < nr_pages; i++) {
|
|
vma = find_vma(mm, start);
|
|
if (!vma)
|
|
goto finish_or_fault;
|
|
|
|
/* protect what we can, including chardevs */
|
|
if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
|
|
!(vm_flags & vma->vm_flags))
|
|
goto finish_or_fault;
|
|
|
|
if (pages) {
|
|
pages[i] = virt_to_page(start);
|
|
if (pages[i])
|
|
get_page(pages[i]);
|
|
}
|
|
if (vmas)
|
|
vmas[i] = vma;
|
|
start = (start + PAGE_SIZE) & PAGE_MASK;
|
|
}
|
|
|
|
return i;
|
|
|
|
finish_or_fault:
|
|
return i ? : -EFAULT;
|
|
}
|
|
#endif /* !CONFIG_MMU */
|
|
|
|
/**
|
|
* 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 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_lock (takes and releases the mmap_lock by itself).
|
|
*/
|
|
#ifdef CONFIG_ELF_CORE
|
|
struct page *get_dump_page(unsigned long addr)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct page *page;
|
|
int locked = 1;
|
|
int ret;
|
|
|
|
if (mmap_read_lock_killable(mm))
|
|
return NULL;
|
|
ret = __get_user_pages_locked(mm, addr, 1, &page, NULL, &locked,
|
|
FOLL_FORCE | FOLL_DUMP | FOLL_GET);
|
|
if (locked)
|
|
mmap_read_unlock(mm);
|
|
|
|
if (ret == 1 && is_page_poisoned(page))
|
|
return NULL;
|
|
|
|
return (ret == 1) ? page : NULL;
|
|
}
|
|
#endif /* CONFIG_ELF_CORE */
|
|
|
|
#ifdef CONFIG_CMA
|
|
static long check_and_migrate_cma_pages(struct mm_struct *mm,
|
|
unsigned long start,
|
|
unsigned long nr_pages,
|
|
struct page **pages,
|
|
struct vm_area_struct **vmas,
|
|
unsigned int gup_flags)
|
|
{
|
|
unsigned long i;
|
|
unsigned long step;
|
|
bool drain_allow = true;
|
|
bool migrate_allow = true;
|
|
LIST_HEAD(cma_page_list);
|
|
long ret = nr_pages;
|
|
struct migration_target_control mtc = {
|
|
.nid = NUMA_NO_NODE,
|
|
.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_NOWARN,
|
|
};
|
|
|
|
check_again:
|
|
for (i = 0; i < nr_pages;) {
|
|
|
|
struct page *head = compound_head(pages[i]);
|
|
|
|
/*
|
|
* gup may start from a tail page. Advance step by the left
|
|
* part.
|
|
*/
|
|
step = compound_nr(head) - (pages[i] - head);
|
|
/*
|
|
* If we get a page from the CMA zone, since we are going to
|
|
* be pinning these entries, we might as well move them out
|
|
* of the CMA zone if possible.
|
|
*/
|
|
if (is_migrate_cma_page(head)) {
|
|
if (PageHuge(head))
|
|
isolate_huge_page(head, &cma_page_list);
|
|
else {
|
|
if (!PageLRU(head) && drain_allow) {
|
|
lru_add_drain_all();
|
|
drain_allow = false;
|
|
}
|
|
|
|
if (!isolate_lru_page(head)) {
|
|
list_add_tail(&head->lru, &cma_page_list);
|
|
mod_node_page_state(page_pgdat(head),
|
|
NR_ISOLATED_ANON +
|
|
page_is_file_lru(head),
|
|
thp_nr_pages(head));
|
|
}
|
|
}
|
|
}
|
|
|
|
i += step;
|
|
}
|
|
|
|
if (!list_empty(&cma_page_list)) {
|
|
/*
|
|
* drop the above get_user_pages reference.
|
|
*/
|
|
if (gup_flags & FOLL_PIN)
|
|
unpin_user_pages(pages, nr_pages);
|
|
else
|
|
for (i = 0; i < nr_pages; i++)
|
|
put_page(pages[i]);
|
|
|
|
if (migrate_pages(&cma_page_list, alloc_migration_target, NULL,
|
|
(unsigned long)&mtc, MIGRATE_SYNC, MR_CONTIG_RANGE)) {
|
|
/*
|
|
* some of the pages failed migration. Do get_user_pages
|
|
* without migration.
|
|
*/
|
|
migrate_allow = false;
|
|
|
|
if (!list_empty(&cma_page_list))
|
|
putback_movable_pages(&cma_page_list);
|
|
}
|
|
/*
|
|
* We did migrate all the pages, Try to get the page references
|
|
* again migrating any new CMA pages which we failed to isolate
|
|
* earlier.
|
|
*/
|
|
ret = __get_user_pages_locked(mm, start, nr_pages,
|
|
pages, vmas, NULL,
|
|
gup_flags);
|
|
|
|
if ((ret > 0) && migrate_allow) {
|
|
nr_pages = ret;
|
|
drain_allow = true;
|
|
goto check_again;
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
#else
|
|
static long check_and_migrate_cma_pages(struct mm_struct *mm,
|
|
unsigned long start,
|
|
unsigned long nr_pages,
|
|
struct page **pages,
|
|
struct vm_area_struct **vmas,
|
|
unsigned int gup_flags)
|
|
{
|
|
return nr_pages;
|
|
}
|
|
#endif /* CONFIG_CMA */
|
|
|
|
/*
|
|
* __gup_longterm_locked() is a wrapper for __get_user_pages_locked which
|
|
* allows us to process the FOLL_LONGTERM flag.
|
|
*/
|
|
static long __gup_longterm_locked(struct mm_struct *mm,
|
|
unsigned long start,
|
|
unsigned long nr_pages,
|
|
struct page **pages,
|
|
struct vm_area_struct **vmas,
|
|
unsigned int gup_flags)
|
|
{
|
|
unsigned long flags = 0;
|
|
long rc;
|
|
|
|
if (gup_flags & FOLL_LONGTERM)
|
|
flags = memalloc_nocma_save();
|
|
|
|
rc = __get_user_pages_locked(mm, start, nr_pages, pages, vmas, NULL,
|
|
gup_flags);
|
|
|
|
if (gup_flags & FOLL_LONGTERM) {
|
|
if (rc > 0)
|
|
rc = check_and_migrate_cma_pages(mm, start, rc, pages,
|
|
vmas, gup_flags);
|
|
memalloc_nocma_restore(flags);
|
|
}
|
|
return rc;
|
|
}
|
|
|
|
static bool is_valid_gup_flags(unsigned int gup_flags)
|
|
{
|
|
/*
|
|
* FOLL_PIN must only be set internally by the pin_user_pages*() APIs,
|
|
* never directly by the caller, so enforce that with an assertion:
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
|
|
return false;
|
|
/*
|
|
* FOLL_PIN is a prerequisite to FOLL_LONGTERM. Another way of saying
|
|
* that is, FOLL_LONGTERM is a specific case, more restrictive case of
|
|
* FOLL_PIN.
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifdef CONFIG_MMU
|
|
static long __get_user_pages_remote(struct mm_struct *mm,
|
|
unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked)
|
|
{
|
|
/*
|
|
* Parts of FOLL_LONGTERM behavior are incompatible with
|
|
* FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
|
|
* vmas. However, this only comes up if locked is set, and there are
|
|
* callers that do request FOLL_LONGTERM, but do not set locked. So,
|
|
* allow what we can.
|
|
*/
|
|
if (gup_flags & FOLL_LONGTERM) {
|
|
if (WARN_ON_ONCE(locked))
|
|
return -EINVAL;
|
|
/*
|
|
* This will check the vmas (even if our vmas arg is NULL)
|
|
* and return -ENOTSUPP if DAX isn't allowed in this case:
|
|
*/
|
|
return __gup_longterm_locked(mm, start, nr_pages, pages,
|
|
vmas, gup_flags | FOLL_TOUCH |
|
|
FOLL_REMOTE);
|
|
}
|
|
|
|
return __get_user_pages_locked(mm, start, nr_pages, pages, vmas,
|
|
locked,
|
|
gup_flags | FOLL_TOUCH | FOLL_REMOTE);
|
|
}
|
|
|
|
/**
|
|
* get_user_pages_remote() - pin user pages in memory
|
|
* @mm: mm_struct of target mm
|
|
* @start: starting user address
|
|
* @nr_pages: number of pages from start to pin
|
|
* @gup_flags: flags modifying lookup 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.
|
|
* @locked: pointer to lock flag indicating whether lock is held and
|
|
* subsequently whether VM_FAULT_RETRY functionality can be
|
|
* utilised. Lock must initially be held.
|
|
*
|
|
* Returns either number of pages pinned (which may be less than the
|
|
* number requested), or an error. Details about the return value:
|
|
*
|
|
* -- If nr_pages is 0, returns 0.
|
|
* -- If nr_pages is >0, but no pages were pinned, returns -errno.
|
|
* -- If nr_pages is >0, and some pages were pinned, returns the number of
|
|
* pages pinned. Again, this may be less than nr_pages.
|
|
*
|
|
* The caller is responsible for releasing returned @pages, via put_page().
|
|
*
|
|
* @vmas are valid only as long as mmap_lock is held.
|
|
*
|
|
* Must be called with mmap_lock held for read or write.
|
|
*
|
|
* get_user_pages_remote 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_remote 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.
|
|
*
|
|
* get_user_pages_remote 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.
|
|
*
|
|
* get_user_pages_remote should be phased out in favor of
|
|
* get_user_pages_locked|unlocked or get_user_pages_fast. Nothing
|
|
* should use get_user_pages_remote because it cannot pass
|
|
* FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
|
|
*/
|
|
long get_user_pages_remote(struct mm_struct *mm,
|
|
unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked)
|
|
{
|
|
if (!is_valid_gup_flags(gup_flags))
|
|
return -EINVAL;
|
|
|
|
return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
|
|
pages, vmas, locked);
|
|
}
|
|
EXPORT_SYMBOL(get_user_pages_remote);
|
|
|
|
#else /* CONFIG_MMU */
|
|
long get_user_pages_remote(struct mm_struct *mm,
|
|
unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static long __get_user_pages_remote(struct mm_struct *mm,
|
|
unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* !CONFIG_MMU */
|
|
|
|
/**
|
|
* get_user_pages() - pin user pages in memory
|
|
* @start: starting user address
|
|
* @nr_pages: number of pages from start to pin
|
|
* @gup_flags: flags modifying lookup 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.
|
|
*
|
|
* This is the same as get_user_pages_remote(), just with a less-flexible
|
|
* calling convention where we assume that the mm being operated on belongs to
|
|
* the current task, and doesn't allow passing of a locked parameter. We also
|
|
* obviously don't pass FOLL_REMOTE in here.
|
|
*/
|
|
long get_user_pages(unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas)
|
|
{
|
|
if (!is_valid_gup_flags(gup_flags))
|
|
return -EINVAL;
|
|
|
|
return __gup_longterm_locked(current->mm, start, nr_pages,
|
|
pages, vmas, gup_flags | FOLL_TOUCH);
|
|
}
|
|
EXPORT_SYMBOL(get_user_pages);
|
|
|
|
/**
|
|
* get_user_pages_locked() - variant of get_user_pages()
|
|
*
|
|
* @start: starting user address
|
|
* @nr_pages: number of pages from start to pin
|
|
* @gup_flags: flags modifying lookup 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.
|
|
* @locked: pointer to lock flag indicating whether lock is held and
|
|
* subsequently whether VM_FAULT_RETRY functionality can be
|
|
* utilised. Lock must initially be held.
|
|
*
|
|
* It is suitable to replace the form:
|
|
*
|
|
* mmap_read_lock(mm);
|
|
* do_something()
|
|
* get_user_pages(mm, ..., pages, NULL);
|
|
* mmap_read_unlock(mm);
|
|
*
|
|
* to:
|
|
*
|
|
* int locked = 1;
|
|
* mmap_read_lock(mm);
|
|
* do_something()
|
|
* get_user_pages_locked(mm, ..., pages, &locked);
|
|
* if (locked)
|
|
* mmap_read_unlock(mm);
|
|
*
|
|
* We can leverage the VM_FAULT_RETRY functionality in the page fault
|
|
* paths better by using either get_user_pages_locked() or
|
|
* get_user_pages_unlocked().
|
|
*
|
|
*/
|
|
long get_user_pages_locked(unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
int *locked)
|
|
{
|
|
/*
|
|
* FIXME: Current FOLL_LONGTERM behavior is incompatible with
|
|
* FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
|
|
* vmas. As there are no users of this flag in this call we simply
|
|
* disallow this option for now.
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
|
|
return -EINVAL;
|
|
/*
|
|
* FOLL_PIN must only be set internally by the pin_user_pages*() APIs,
|
|
* never directly by the caller, so enforce that:
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_PIN))
|
|
return -EINVAL;
|
|
|
|
return __get_user_pages_locked(current->mm, start, nr_pages,
|
|
pages, NULL, locked,
|
|
gup_flags | FOLL_TOUCH);
|
|
}
|
|
EXPORT_SYMBOL(get_user_pages_locked);
|
|
|
|
/*
|
|
* get_user_pages_unlocked() is suitable to replace the form:
|
|
*
|
|
* mmap_read_lock(mm);
|
|
* get_user_pages(mm, ..., pages, NULL);
|
|
* mmap_read_unlock(mm);
|
|
*
|
|
* with:
|
|
*
|
|
* get_user_pages_unlocked(mm, ..., pages);
|
|
*
|
|
* It is functionally equivalent to get_user_pages_fast so
|
|
* get_user_pages_fast should be used instead if specific gup_flags
|
|
* (e.g. FOLL_FORCE) are not required.
|
|
*/
|
|
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
|
|
struct page **pages, unsigned int gup_flags)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
int locked = 1;
|
|
long ret;
|
|
|
|
/*
|
|
* FIXME: Current FOLL_LONGTERM behavior is incompatible with
|
|
* FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
|
|
* vmas. As there are no users of this flag in this call we simply
|
|
* disallow this option for now.
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
|
|
return -EINVAL;
|
|
|
|
mmap_read_lock(mm);
|
|
ret = __get_user_pages_locked(mm, start, nr_pages, pages, NULL,
|
|
&locked, gup_flags | FOLL_TOUCH);
|
|
if (locked)
|
|
mmap_read_unlock(mm);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(get_user_pages_unlocked);
|
|
|
|
/*
|
|
* Fast GUP
|
|
*
|
|
* get_user_pages_fast attempts to pin user pages by walking the page
|
|
* tables directly and avoids taking locks. Thus the walker needs to be
|
|
* protected from page table pages being freed from under it, and should
|
|
* block any THP splits.
|
|
*
|
|
* One way to achieve this is to have the walker disable interrupts, and
|
|
* rely on IPIs from the TLB flushing code blocking before the page table
|
|
* pages are freed. This is unsuitable for architectures that do not need
|
|
* to broadcast an IPI when invalidating TLBs.
|
|
*
|
|
* Another way to achieve this is to batch up page table containing pages
|
|
* belonging to more than one mm_user, then rcu_sched a callback to free those
|
|
* pages. Disabling interrupts will allow the fast_gup walker to both block
|
|
* the rcu_sched callback, and an IPI that we broadcast for splitting THPs
|
|
* (which is a relatively rare event). The code below adopts this strategy.
|
|
*
|
|
* Before activating this code, please be aware that the following assumptions
|
|
* are currently made:
|
|
*
|
|
* *) Either MMU_GATHER_RCU_TABLE_FREE is enabled, and tlb_remove_table() is used to
|
|
* free pages containing page tables or TLB flushing requires IPI broadcast.
|
|
*
|
|
* *) ptes can be read atomically by the architecture.
|
|
*
|
|
* *) access_ok is sufficient to validate userspace address ranges.
|
|
*
|
|
* The last two assumptions can be relaxed by the addition of helper functions.
|
|
*
|
|
* This code is based heavily on the PowerPC implementation by Nick Piggin.
|
|
*/
|
|
#ifdef CONFIG_HAVE_FAST_GUP
|
|
|
|
static void __maybe_unused undo_dev_pagemap(int *nr, int nr_start,
|
|
unsigned int flags,
|
|
struct page **pages)
|
|
{
|
|
while ((*nr) - nr_start) {
|
|
struct page *page = pages[--(*nr)];
|
|
|
|
ClearPageReferenced(page);
|
|
if (flags & FOLL_PIN)
|
|
unpin_user_page(page);
|
|
else
|
|
put_page(page);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_HAS_PTE_SPECIAL
|
|
static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
struct dev_pagemap *pgmap = NULL;
|
|
int nr_start = *nr, ret = 0;
|
|
pte_t *ptep, *ptem;
|
|
|
|
ptem = ptep = pte_offset_map(&pmd, addr);
|
|
do {
|
|
pte_t pte = ptep_get_lockless(ptep);
|
|
struct page *head, *page;
|
|
|
|
/*
|
|
* Similar to the PMD case below, NUMA hinting must take slow
|
|
* path using the pte_protnone check.
|
|
*/
|
|
if (pte_protnone(pte))
|
|
goto pte_unmap;
|
|
|
|
if (!pte_access_permitted(pte, flags & FOLL_WRITE))
|
|
goto pte_unmap;
|
|
|
|
if (pte_devmap(pte)) {
|
|
if (unlikely(flags & FOLL_LONGTERM))
|
|
goto pte_unmap;
|
|
|
|
pgmap = get_dev_pagemap(pte_pfn(pte), pgmap);
|
|
if (unlikely(!pgmap)) {
|
|
undo_dev_pagemap(nr, nr_start, flags, pages);
|
|
goto pte_unmap;
|
|
}
|
|
} else if (pte_special(pte))
|
|
goto pte_unmap;
|
|
|
|
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
|
|
page = pte_page(pte);
|
|
|
|
head = try_grab_compound_head(page, 1, flags);
|
|
if (!head)
|
|
goto pte_unmap;
|
|
|
|
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
|
|
put_compound_head(head, 1, flags);
|
|
goto pte_unmap;
|
|
}
|
|
|
|
VM_BUG_ON_PAGE(compound_head(page) != head, page);
|
|
|
|
/*
|
|
* We need to make the page accessible if and only if we are
|
|
* going to access its content (the FOLL_PIN case). Please
|
|
* see Documentation/core-api/pin_user_pages.rst for
|
|
* details.
|
|
*/
|
|
if (flags & FOLL_PIN) {
|
|
ret = arch_make_page_accessible(page);
|
|
if (ret) {
|
|
unpin_user_page(page);
|
|
goto pte_unmap;
|
|
}
|
|
}
|
|
SetPageReferenced(page);
|
|
pages[*nr] = page;
|
|
(*nr)++;
|
|
|
|
} while (ptep++, addr += PAGE_SIZE, addr != end);
|
|
|
|
ret = 1;
|
|
|
|
pte_unmap:
|
|
if (pgmap)
|
|
put_dev_pagemap(pgmap);
|
|
pte_unmap(ptem);
|
|
return ret;
|
|
}
|
|
#else
|
|
|
|
/*
|
|
* If we can't determine whether or not a pte is special, then fail immediately
|
|
* for ptes. Note, we can still pin HugeTLB and THP as these are guaranteed not
|
|
* to be special.
|
|
*
|
|
* For a futex to be placed on a THP tail page, get_futex_key requires a
|
|
* get_user_pages_fast_only implementation that can pin pages. Thus it's still
|
|
* useful to have gup_huge_pmd even if we can't operate on ptes.
|
|
*/
|
|
static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_ARCH_HAS_PTE_SPECIAL */
|
|
|
|
#if defined(CONFIG_ARCH_HAS_PTE_DEVMAP) && defined(CONFIG_TRANSPARENT_HUGEPAGE)
|
|
static int __gup_device_huge(unsigned long pfn, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
int nr_start = *nr;
|
|
struct dev_pagemap *pgmap = NULL;
|
|
|
|
do {
|
|
struct page *page = pfn_to_page(pfn);
|
|
|
|
pgmap = get_dev_pagemap(pfn, pgmap);
|
|
if (unlikely(!pgmap)) {
|
|
undo_dev_pagemap(nr, nr_start, flags, pages);
|
|
return 0;
|
|
}
|
|
SetPageReferenced(page);
|
|
pages[*nr] = page;
|
|
if (unlikely(!try_grab_page(page, flags))) {
|
|
undo_dev_pagemap(nr, nr_start, flags, pages);
|
|
return 0;
|
|
}
|
|
(*nr)++;
|
|
pfn++;
|
|
} while (addr += PAGE_SIZE, addr != end);
|
|
|
|
if (pgmap)
|
|
put_dev_pagemap(pgmap);
|
|
return 1;
|
|
}
|
|
|
|
static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
unsigned long fault_pfn;
|
|
int nr_start = *nr;
|
|
|
|
fault_pfn = pmd_pfn(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
|
|
if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr))
|
|
return 0;
|
|
|
|
if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
|
|
undo_dev_pagemap(nr, nr_start, flags, pages);
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static int __gup_device_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
unsigned long fault_pfn;
|
|
int nr_start = *nr;
|
|
|
|
fault_pfn = pud_pfn(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
|
|
if (!__gup_device_huge(fault_pfn, addr, end, flags, pages, nr))
|
|
return 0;
|
|
|
|
if (unlikely(pud_val(orig) != pud_val(*pudp))) {
|
|
undo_dev_pagemap(nr, nr_start, flags, pages);
|
|
return 0;
|
|
}
|
|
return 1;
|
|
}
|
|
#else
|
|
static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
BUILD_BUG();
|
|
return 0;
|
|
}
|
|
|
|
static int __gup_device_huge_pud(pud_t pud, pud_t *pudp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
BUILD_BUG();
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
static int record_subpages(struct page *page, unsigned long addr,
|
|
unsigned long end, struct page **pages)
|
|
{
|
|
int nr;
|
|
|
|
for (nr = 0; addr != end; addr += PAGE_SIZE)
|
|
pages[nr++] = page++;
|
|
|
|
return nr;
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_HAS_HUGEPD
|
|
static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
|
|
unsigned long sz)
|
|
{
|
|
unsigned long __boundary = (addr + sz) & ~(sz-1);
|
|
return (__boundary - 1 < end - 1) ? __boundary : end;
|
|
}
|
|
|
|
static int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
unsigned long pte_end;
|
|
struct page *head, *page;
|
|
pte_t pte;
|
|
int refs;
|
|
|
|
pte_end = (addr + sz) & ~(sz-1);
|
|
if (pte_end < end)
|
|
end = pte_end;
|
|
|
|
pte = huge_ptep_get(ptep);
|
|
|
|
if (!pte_access_permitted(pte, flags & FOLL_WRITE))
|
|
return 0;
|
|
|
|
/* hugepages are never "special" */
|
|
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
|
|
|
|
head = pte_page(pte);
|
|
page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
|
|
refs = record_subpages(page, addr, end, pages + *nr);
|
|
|
|
head = try_grab_compound_head(head, refs, flags);
|
|
if (!head)
|
|
return 0;
|
|
|
|
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
|
|
put_compound_head(head, refs, flags);
|
|
return 0;
|
|
}
|
|
|
|
*nr += refs;
|
|
SetPageReferenced(head);
|
|
return 1;
|
|
}
|
|
|
|
static int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
|
|
unsigned int pdshift, unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
pte_t *ptep;
|
|
unsigned long sz = 1UL << hugepd_shift(hugepd);
|
|
unsigned long next;
|
|
|
|
ptep = hugepte_offset(hugepd, addr, pdshift);
|
|
do {
|
|
next = hugepte_addr_end(addr, end, sz);
|
|
if (!gup_hugepte(ptep, sz, addr, end, flags, pages, nr))
|
|
return 0;
|
|
} while (ptep++, addr = next, addr != end);
|
|
|
|
return 1;
|
|
}
|
|
#else
|
|
static inline int gup_huge_pd(hugepd_t hugepd, unsigned long addr,
|
|
unsigned int pdshift, unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_ARCH_HAS_HUGEPD */
|
|
|
|
static int gup_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
struct page *head, *page;
|
|
int refs;
|
|
|
|
if (!pmd_access_permitted(orig, flags & FOLL_WRITE))
|
|
return 0;
|
|
|
|
if (pmd_devmap(orig)) {
|
|
if (unlikely(flags & FOLL_LONGTERM))
|
|
return 0;
|
|
return __gup_device_huge_pmd(orig, pmdp, addr, end, flags,
|
|
pages, nr);
|
|
}
|
|
|
|
page = pmd_page(orig) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
|
|
refs = record_subpages(page, addr, end, pages + *nr);
|
|
|
|
head = try_grab_compound_head(pmd_page(orig), refs, flags);
|
|
if (!head)
|
|
return 0;
|
|
|
|
if (unlikely(pmd_val(orig) != pmd_val(*pmdp))) {
|
|
put_compound_head(head, refs, flags);
|
|
return 0;
|
|
}
|
|
|
|
*nr += refs;
|
|
SetPageReferenced(head);
|
|
return 1;
|
|
}
|
|
|
|
static int gup_huge_pud(pud_t orig, pud_t *pudp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
struct page *head, *page;
|
|
int refs;
|
|
|
|
if (!pud_access_permitted(orig, flags & FOLL_WRITE))
|
|
return 0;
|
|
|
|
if (pud_devmap(orig)) {
|
|
if (unlikely(flags & FOLL_LONGTERM))
|
|
return 0;
|
|
return __gup_device_huge_pud(orig, pudp, addr, end, flags,
|
|
pages, nr);
|
|
}
|
|
|
|
page = pud_page(orig) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
|
|
refs = record_subpages(page, addr, end, pages + *nr);
|
|
|
|
head = try_grab_compound_head(pud_page(orig), refs, flags);
|
|
if (!head)
|
|
return 0;
|
|
|
|
if (unlikely(pud_val(orig) != pud_val(*pudp))) {
|
|
put_compound_head(head, refs, flags);
|
|
return 0;
|
|
}
|
|
|
|
*nr += refs;
|
|
SetPageReferenced(head);
|
|
return 1;
|
|
}
|
|
|
|
static int gup_huge_pgd(pgd_t orig, pgd_t *pgdp, unsigned long addr,
|
|
unsigned long end, unsigned int flags,
|
|
struct page **pages, int *nr)
|
|
{
|
|
int refs;
|
|
struct page *head, *page;
|
|
|
|
if (!pgd_access_permitted(orig, flags & FOLL_WRITE))
|
|
return 0;
|
|
|
|
BUILD_BUG_ON(pgd_devmap(orig));
|
|
|
|
page = pgd_page(orig) + ((addr & ~PGDIR_MASK) >> PAGE_SHIFT);
|
|
refs = record_subpages(page, addr, end, pages + *nr);
|
|
|
|
head = try_grab_compound_head(pgd_page(orig), refs, flags);
|
|
if (!head)
|
|
return 0;
|
|
|
|
if (unlikely(pgd_val(orig) != pgd_val(*pgdp))) {
|
|
put_compound_head(head, refs, flags);
|
|
return 0;
|
|
}
|
|
|
|
*nr += refs;
|
|
SetPageReferenced(head);
|
|
return 1;
|
|
}
|
|
|
|
static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
unsigned long next;
|
|
pmd_t *pmdp;
|
|
|
|
pmdp = pmd_offset_lockless(pudp, pud, addr);
|
|
do {
|
|
pmd_t pmd = READ_ONCE(*pmdp);
|
|
|
|
next = pmd_addr_end(addr, end);
|
|
if (!pmd_present(pmd))
|
|
return 0;
|
|
|
|
if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) ||
|
|
pmd_devmap(pmd))) {
|
|
/*
|
|
* NUMA hinting faults need to be handled in the GUP
|
|
* slowpath for accounting purposes and so that they
|
|
* can be serialised against THP migration.
|
|
*/
|
|
if (pmd_protnone(pmd))
|
|
return 0;
|
|
|
|
if (!gup_huge_pmd(pmd, pmdp, addr, next, flags,
|
|
pages, nr))
|
|
return 0;
|
|
|
|
} else if (unlikely(is_hugepd(__hugepd(pmd_val(pmd))))) {
|
|
/*
|
|
* architecture have different format for hugetlbfs
|
|
* pmd format and THP pmd format
|
|
*/
|
|
if (!gup_huge_pd(__hugepd(pmd_val(pmd)), addr,
|
|
PMD_SHIFT, next, flags, pages, nr))
|
|
return 0;
|
|
} else if (!gup_pte_range(pmd, addr, next, flags, pages, nr))
|
|
return 0;
|
|
} while (pmdp++, addr = next, addr != end);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int gup_pud_range(p4d_t *p4dp, p4d_t p4d, unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
unsigned long next;
|
|
pud_t *pudp;
|
|
|
|
pudp = pud_offset_lockless(p4dp, p4d, addr);
|
|
do {
|
|
pud_t pud = READ_ONCE(*pudp);
|
|
|
|
next = pud_addr_end(addr, end);
|
|
if (unlikely(!pud_present(pud)))
|
|
return 0;
|
|
if (unlikely(pud_huge(pud))) {
|
|
if (!gup_huge_pud(pud, pudp, addr, next, flags,
|
|
pages, nr))
|
|
return 0;
|
|
} else if (unlikely(is_hugepd(__hugepd(pud_val(pud))))) {
|
|
if (!gup_huge_pd(__hugepd(pud_val(pud)), addr,
|
|
PUD_SHIFT, next, flags, pages, nr))
|
|
return 0;
|
|
} else if (!gup_pmd_range(pudp, pud, addr, next, flags, pages, nr))
|
|
return 0;
|
|
} while (pudp++, addr = next, addr != end);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static int gup_p4d_range(pgd_t *pgdp, pgd_t pgd, unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
unsigned long next;
|
|
p4d_t *p4dp;
|
|
|
|
p4dp = p4d_offset_lockless(pgdp, pgd, addr);
|
|
do {
|
|
p4d_t p4d = READ_ONCE(*p4dp);
|
|
|
|
next = p4d_addr_end(addr, end);
|
|
if (p4d_none(p4d))
|
|
return 0;
|
|
BUILD_BUG_ON(p4d_huge(p4d));
|
|
if (unlikely(is_hugepd(__hugepd(p4d_val(p4d))))) {
|
|
if (!gup_huge_pd(__hugepd(p4d_val(p4d)), addr,
|
|
P4D_SHIFT, next, flags, pages, nr))
|
|
return 0;
|
|
} else if (!gup_pud_range(p4dp, p4d, addr, next, flags, pages, nr))
|
|
return 0;
|
|
} while (p4dp++, addr = next, addr != end);
|
|
|
|
return 1;
|
|
}
|
|
|
|
static void gup_pgd_range(unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
unsigned long next;
|
|
pgd_t *pgdp;
|
|
|
|
pgdp = pgd_offset(current->mm, addr);
|
|
do {
|
|
pgd_t pgd = READ_ONCE(*pgdp);
|
|
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none(pgd))
|
|
return;
|
|
if (unlikely(pgd_huge(pgd))) {
|
|
if (!gup_huge_pgd(pgd, pgdp, addr, next, flags,
|
|
pages, nr))
|
|
return;
|
|
} else if (unlikely(is_hugepd(__hugepd(pgd_val(pgd))))) {
|
|
if (!gup_huge_pd(__hugepd(pgd_val(pgd)), addr,
|
|
PGDIR_SHIFT, next, flags, pages, nr))
|
|
return;
|
|
} else if (!gup_p4d_range(pgdp, pgd, addr, next, flags, pages, nr))
|
|
return;
|
|
} while (pgdp++, addr = next, addr != end);
|
|
}
|
|
#else
|
|
static inline void gup_pgd_range(unsigned long addr, unsigned long end,
|
|
unsigned int flags, struct page **pages, int *nr)
|
|
{
|
|
}
|
|
#endif /* CONFIG_HAVE_FAST_GUP */
|
|
|
|
#ifndef gup_fast_permitted
|
|
/*
|
|
* Check if it's allowed to use get_user_pages_fast_only() for the range, or
|
|
* we need to fall back to the slow version:
|
|
*/
|
|
static bool gup_fast_permitted(unsigned long start, unsigned long end)
|
|
{
|
|
return true;
|
|
}
|
|
#endif
|
|
|
|
static int __gup_longterm_unlocked(unsigned long start, int nr_pages,
|
|
unsigned int gup_flags, struct page **pages)
|
|
{
|
|
int ret;
|
|
|
|
/*
|
|
* FIXME: FOLL_LONGTERM does not work with
|
|
* get_user_pages_unlocked() (see comments in that function)
|
|
*/
|
|
if (gup_flags & FOLL_LONGTERM) {
|
|
mmap_read_lock(current->mm);
|
|
ret = __gup_longterm_locked(current->mm,
|
|
start, nr_pages,
|
|
pages, NULL, gup_flags);
|
|
mmap_read_unlock(current->mm);
|
|
} else {
|
|
ret = get_user_pages_unlocked(start, nr_pages,
|
|
pages, gup_flags);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
static unsigned long lockless_pages_from_mm(unsigned long start,
|
|
unsigned long end,
|
|
unsigned int gup_flags,
|
|
struct page **pages)
|
|
{
|
|
unsigned long flags;
|
|
int nr_pinned = 0;
|
|
unsigned seq;
|
|
|
|
if (!IS_ENABLED(CONFIG_HAVE_FAST_GUP) ||
|
|
!gup_fast_permitted(start, end))
|
|
return 0;
|
|
|
|
if (gup_flags & FOLL_PIN) {
|
|
seq = raw_read_seqcount(¤t->mm->write_protect_seq);
|
|
if (seq & 1)
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Disable interrupts. The nested form is used, in order to allow full,
|
|
* general purpose use of this routine.
|
|
*
|
|
* With interrupts disabled, we block page table pages from being freed
|
|
* from under us. See struct mmu_table_batch comments in
|
|
* include/asm-generic/tlb.h for more details.
|
|
*
|
|
* We do not adopt an rcu_read_lock() here as we also want to block IPIs
|
|
* that come from THPs splitting.
|
|
*/
|
|
local_irq_save(flags);
|
|
gup_pgd_range(start, end, gup_flags, pages, &nr_pinned);
|
|
local_irq_restore(flags);
|
|
|
|
/*
|
|
* When pinning pages for DMA there could be a concurrent write protect
|
|
* from fork() via copy_page_range(), in this case always fail fast GUP.
|
|
*/
|
|
if (gup_flags & FOLL_PIN) {
|
|
if (read_seqcount_retry(¤t->mm->write_protect_seq, seq)) {
|
|
unpin_user_pages(pages, nr_pinned);
|
|
return 0;
|
|
}
|
|
}
|
|
return nr_pinned;
|
|
}
|
|
|
|
static int internal_get_user_pages_fast(unsigned long start,
|
|
unsigned long nr_pages,
|
|
unsigned int gup_flags,
|
|
struct page **pages)
|
|
{
|
|
unsigned long len, end;
|
|
unsigned long nr_pinned;
|
|
int ret;
|
|
|
|
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
|
|
FOLL_FORCE | FOLL_PIN | FOLL_GET |
|
|
FOLL_FAST_ONLY)))
|
|
return -EINVAL;
|
|
|
|
if (gup_flags & FOLL_PIN)
|
|
atomic_set(¤t->mm->has_pinned, 1);
|
|
|
|
if (!(gup_flags & FOLL_FAST_ONLY))
|
|
might_lock_read(¤t->mm->mmap_lock);
|
|
|
|
start = untagged_addr(start) & PAGE_MASK;
|
|
len = nr_pages << PAGE_SHIFT;
|
|
if (check_add_overflow(start, len, &end))
|
|
return 0;
|
|
if (unlikely(!access_ok((void __user *)start, len)))
|
|
return -EFAULT;
|
|
|
|
nr_pinned = lockless_pages_from_mm(start, end, gup_flags, pages);
|
|
if (nr_pinned == nr_pages || gup_flags & FOLL_FAST_ONLY)
|
|
return nr_pinned;
|
|
|
|
/* Slow path: try to get the remaining pages with get_user_pages */
|
|
start += nr_pinned << PAGE_SHIFT;
|
|
pages += nr_pinned;
|
|
ret = __gup_longterm_unlocked(start, nr_pages - nr_pinned, gup_flags,
|
|
pages);
|
|
if (ret < 0) {
|
|
/*
|
|
* The caller has to unpin the pages we already pinned so
|
|
* returning -errno is not an option
|
|
*/
|
|
if (nr_pinned)
|
|
return nr_pinned;
|
|
return ret;
|
|
}
|
|
return ret + nr_pinned;
|
|
}
|
|
|
|
/**
|
|
* get_user_pages_fast_only() - pin user pages in memory
|
|
* @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.
|
|
*
|
|
* Like get_user_pages_fast() except it's IRQ-safe in that it won't fall back to
|
|
* the regular GUP.
|
|
* Note a difference with get_user_pages_fast: this always returns the
|
|
* number of pages pinned, 0 if no pages were pinned.
|
|
*
|
|
* If the architecture does not support this function, simply return with no
|
|
* pages pinned.
|
|
*
|
|
* Careful, careful! COW breaking can go either way, so a non-write
|
|
* access can get ambiguous page results. If you call this function without
|
|
* 'write' set, you'd better be sure that you're ok with that ambiguity.
|
|
*/
|
|
int get_user_pages_fast_only(unsigned long start, int nr_pages,
|
|
unsigned int gup_flags, struct page **pages)
|
|
{
|
|
int nr_pinned;
|
|
/*
|
|
* Internally (within mm/gup.c), gup fast variants must set FOLL_GET,
|
|
* because gup fast is always a "pin with a +1 page refcount" request.
|
|
*
|
|
* FOLL_FAST_ONLY is required in order to match the API description of
|
|
* this routine: no fall back to regular ("slow") GUP.
|
|
*/
|
|
gup_flags |= FOLL_GET | FOLL_FAST_ONLY;
|
|
|
|
nr_pinned = internal_get_user_pages_fast(start, nr_pages, gup_flags,
|
|
pages);
|
|
|
|
/*
|
|
* As specified in the API description above, this routine is not
|
|
* allowed to return negative values. However, the common core
|
|
* routine internal_get_user_pages_fast() *can* return -errno.
|
|
* Therefore, correct for that here:
|
|
*/
|
|
if (nr_pinned < 0)
|
|
nr_pinned = 0;
|
|
|
|
return nr_pinned;
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_user_pages_fast_only);
|
|
|
|
/**
|
|
* get_user_pages_fast() - pin user pages in memory
|
|
* @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.
|
|
*
|
|
* Attempt to pin user pages in memory without taking mm->mmap_lock.
|
|
* If not successful, it will fall back to taking the lock and
|
|
* calling get_user_pages().
|
|
*
|
|
* 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.
|
|
*/
|
|
int get_user_pages_fast(unsigned long start, int nr_pages,
|
|
unsigned int gup_flags, struct page **pages)
|
|
{
|
|
if (!is_valid_gup_flags(gup_flags))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* The caller may or may not have explicitly set FOLL_GET; either way is
|
|
* OK. However, internally (within mm/gup.c), gup fast variants must set
|
|
* FOLL_GET, because gup fast is always a "pin with a +1 page refcount"
|
|
* request.
|
|
*/
|
|
gup_flags |= FOLL_GET;
|
|
return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_user_pages_fast);
|
|
|
|
/**
|
|
* pin_user_pages_fast() - pin user pages in memory without taking locks
|
|
*
|
|
* @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.
|
|
*
|
|
* Nearly the same as get_user_pages_fast(), except that FOLL_PIN is set. See
|
|
* get_user_pages_fast() for documentation on the function arguments, because
|
|
* the arguments here are identical.
|
|
*
|
|
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
|
|
* see Documentation/core-api/pin_user_pages.rst for further details.
|
|
*/
|
|
int pin_user_pages_fast(unsigned long start, int nr_pages,
|
|
unsigned int gup_flags, struct page **pages)
|
|
{
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
|
|
return -EINVAL;
|
|
|
|
gup_flags |= FOLL_PIN;
|
|
return internal_get_user_pages_fast(start, nr_pages, gup_flags, pages);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pin_user_pages_fast);
|
|
|
|
/*
|
|
* This is the FOLL_PIN equivalent of get_user_pages_fast_only(). Behavior
|
|
* is the same, except that this one sets FOLL_PIN instead of FOLL_GET.
|
|
*
|
|
* The API rules are the same, too: no negative values may be returned.
|
|
*/
|
|
int pin_user_pages_fast_only(unsigned long start, int nr_pages,
|
|
unsigned int gup_flags, struct page **pages)
|
|
{
|
|
int nr_pinned;
|
|
|
|
/*
|
|
* FOLL_GET and FOLL_PIN are mutually exclusive. Note that the API
|
|
* rules require returning 0, rather than -errno:
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
|
|
return 0;
|
|
/*
|
|
* FOLL_FAST_ONLY is required in order to match the API description of
|
|
* this routine: no fall back to regular ("slow") GUP.
|
|
*/
|
|
gup_flags |= (FOLL_PIN | FOLL_FAST_ONLY);
|
|
nr_pinned = internal_get_user_pages_fast(start, nr_pages, gup_flags,
|
|
pages);
|
|
/*
|
|
* This routine is not allowed to return negative values. However,
|
|
* internal_get_user_pages_fast() *can* return -errno. Therefore,
|
|
* correct for that here:
|
|
*/
|
|
if (nr_pinned < 0)
|
|
nr_pinned = 0;
|
|
|
|
return nr_pinned;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pin_user_pages_fast_only);
|
|
|
|
/**
|
|
* pin_user_pages_remote() - pin pages of a remote process
|
|
*
|
|
* @mm: mm_struct of target mm
|
|
* @start: starting user address
|
|
* @nr_pages: number of pages from start to pin
|
|
* @gup_flags: flags modifying lookup 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.
|
|
* @locked: pointer to lock flag indicating whether lock is held and
|
|
* subsequently whether VM_FAULT_RETRY functionality can be
|
|
* utilised. Lock must initially be held.
|
|
*
|
|
* Nearly the same as get_user_pages_remote(), except that FOLL_PIN is set. See
|
|
* get_user_pages_remote() for documentation on the function arguments, because
|
|
* the arguments here are identical.
|
|
*
|
|
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
|
|
* see Documentation/core-api/pin_user_pages.rst for details.
|
|
*/
|
|
long pin_user_pages_remote(struct mm_struct *mm,
|
|
unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas, int *locked)
|
|
{
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
|
|
return -EINVAL;
|
|
|
|
gup_flags |= FOLL_PIN;
|
|
return __get_user_pages_remote(mm, start, nr_pages, gup_flags,
|
|
pages, vmas, locked);
|
|
}
|
|
EXPORT_SYMBOL(pin_user_pages_remote);
|
|
|
|
/**
|
|
* pin_user_pages() - pin user pages in memory for use by other devices
|
|
*
|
|
* @start: starting user address
|
|
* @nr_pages: number of pages from start to pin
|
|
* @gup_flags: flags modifying lookup 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.
|
|
*
|
|
* Nearly the same as get_user_pages(), except that FOLL_TOUCH is not set, and
|
|
* FOLL_PIN is set.
|
|
*
|
|
* FOLL_PIN means that the pages must be released via unpin_user_page(). Please
|
|
* see Documentation/core-api/pin_user_pages.rst for details.
|
|
*/
|
|
long pin_user_pages(unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
struct vm_area_struct **vmas)
|
|
{
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
|
|
return -EINVAL;
|
|
|
|
gup_flags |= FOLL_PIN;
|
|
return __gup_longterm_locked(current->mm, start, nr_pages,
|
|
pages, vmas, gup_flags);
|
|
}
|
|
EXPORT_SYMBOL(pin_user_pages);
|
|
|
|
/*
|
|
* pin_user_pages_unlocked() is the FOLL_PIN variant of
|
|
* get_user_pages_unlocked(). Behavior is the same, except that this one sets
|
|
* FOLL_PIN and rejects FOLL_GET.
|
|
*/
|
|
long pin_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
|
|
struct page **pages, unsigned int gup_flags)
|
|
{
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
|
|
return -EINVAL;
|
|
|
|
gup_flags |= FOLL_PIN;
|
|
return get_user_pages_unlocked(start, nr_pages, pages, gup_flags);
|
|
}
|
|
EXPORT_SYMBOL(pin_user_pages_unlocked);
|
|
|
|
/*
|
|
* pin_user_pages_locked() is the FOLL_PIN variant of get_user_pages_locked().
|
|
* Behavior is the same, except that this one sets FOLL_PIN and rejects
|
|
* FOLL_GET.
|
|
*/
|
|
long pin_user_pages_locked(unsigned long start, unsigned long nr_pages,
|
|
unsigned int gup_flags, struct page **pages,
|
|
int *locked)
|
|
{
|
|
/*
|
|
* FIXME: Current FOLL_LONGTERM behavior is incompatible with
|
|
* FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
|
|
* vmas. As there are no users of this flag in this call we simply
|
|
* disallow this option for now.
|
|
*/
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_LONGTERM))
|
|
return -EINVAL;
|
|
|
|
/* FOLL_GET and FOLL_PIN are mutually exclusive. */
|
|
if (WARN_ON_ONCE(gup_flags & FOLL_GET))
|
|
return -EINVAL;
|
|
|
|
gup_flags |= FOLL_PIN;
|
|
return __get_user_pages_locked(current->mm, start, nr_pages,
|
|
pages, NULL, locked,
|
|
gup_flags | FOLL_TOUCH);
|
|
}
|
|
EXPORT_SYMBOL(pin_user_pages_locked);
|