spinlock_t *ptl;
pte_t *ptep, pte;
+ /* 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);
start = untagged_addr(start);
- VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
+ 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
BUG_ON(*locked != 1);
}
- if (pages)
+ /*
+ * 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;
* should use get_user_pages because it cannot pass
* FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
*/
+#ifdef CONFIG_MMU
long get_user_pages_remote(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 *locked)
{
+ /*
+ * 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 -EINVAL;
+
/*
* Parts of FOLL_LONGTERM behavior are incompatible with
* FAULT_FLAG_ALLOW_RETRY because of the FS DAX check requirement on
}
EXPORT_SYMBOL(get_user_pages_remote);
+#else /* CONFIG_MMU */
+long get_user_pages_remote(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 *locked)
+{
+ return 0;
+}
+#endif /* !CONFIG_MMU */
+
/*
* This is the same as get_user_pages_remote(), just with a
* less-flexible calling convention where we assume that the task
unsigned int gup_flags, struct page **pages,
struct vm_area_struct **vmas)
{
+ /*
+ * 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 -EINVAL;
+
return __gup_longterm_locked(current, current->mm, start, nr_pages,
pages, vmas, gup_flags | FOLL_TOUCH);
}
return ret;
}
-/**
- * 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_sem.
- * 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)
+static int internal_get_user_pages_fast(unsigned long start, int nr_pages,
+ unsigned int gup_flags,
+ struct page **pages)
{
unsigned long addr, len, end;
int nr = 0, ret = 0;
if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM |
- FOLL_FORCE)))
+ FOLL_FORCE | FOLL_PIN)))
return -EINVAL;
start = untagged_addr(start) & PAGE_MASK;
return ret;
}
+
+/**
+ * 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_sem.
+ * 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)
+{
+ /*
+ * 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 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
+ *
+ * For now, this is a placeholder function, until various call sites are
+ * converted to use the correct get_user_pages*() or pin_user_pages*() API. So,
+ * this is identical to get_user_pages_fast().
+ *
+ * This is intended for Case 1 (DIO) in Documentation/vm/pin_user_pages.rst. It
+ * is NOT intended for Case 2 (RDMA: long-term pins).
+ */
+int pin_user_pages_fast(unsigned long start, int nr_pages,
+ unsigned int gup_flags, struct page **pages)
+{
+ /*
+ * This is a placeholder, until the pin functionality is activated.
+ * Until then, just behave like the corresponding get_user_pages*()
+ * routine.
+ */
+ return get_user_pages_fast(start, nr_pages, gup_flags, pages);
+}
+EXPORT_SYMBOL_GPL(pin_user_pages_fast);
+
+/**
+ * pin_user_pages_remote() - pin pages of a remote process (task != current)
+ *
+ * For now, this is a placeholder function, until various call sites are
+ * converted to use the correct get_user_pages*() or pin_user_pages*() API. So,
+ * this is identical to get_user_pages_remote().
+ *
+ * This is intended for Case 1 (DIO) in Documentation/vm/pin_user_pages.rst. It
+ * is NOT intended for Case 2 (RDMA: long-term pins).
+ */
+long pin_user_pages_remote(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 *locked)
+{
+ /*
+ * This is a placeholder, until the pin functionality is activated.
+ * Until then, just behave like the corresponding get_user_pages*()
+ * routine.
+ */
+ return get_user_pages_remote(tsk, 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
+ *
+ * For now, this is a placeholder function, until various call sites are
+ * converted to use the correct get_user_pages*() or pin_user_pages*() API. So,
+ * this is identical to get_user_pages().
+ *
+ * This is intended for Case 1 (DIO) in Documentation/vm/pin_user_pages.rst. It
+ * is NOT intended for Case 2 (RDMA: long-term pins).
+ */
+long pin_user_pages(unsigned long start, unsigned long nr_pages,
+ unsigned int gup_flags, struct page **pages,
+ struct vm_area_struct **vmas)
+{
+ /*
+ * This is a placeholder, until the pin functionality is activated.
+ * Until then, just behave like the corresponding get_user_pages*()
+ * routine.
+ */
+ return get_user_pages(start, nr_pages, gup_flags, pages, vmas);
+}
+EXPORT_SYMBOL(pin_user_pages);
projects / linux-2.6-microblaze.git / blobdiff