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authorDave Hansen <dave.hansen@linux.intel.com>2016-02-12 13:01:54 -0800
committerIngo Molnar <mingo@kernel.org>2016-02-16 10:04:09 +0100
commit1e9877902dc7e11d2be038371c6fbf2dfcd469d7 (patch)
tree715a45eca4c79168f0351421a7584c95212331f8 /mm/gup.c
parent1fe3f29e4a908461be16a9388e73837157cc7942 (diff)
downloadlinux-1e9877902dc7e11d2be038371c6fbf2dfcd469d7.tar.bz2
mm/gup: Introduce get_user_pages_remote()
For protection keys, we need to understand whether protections should be enforced in software or not. In general, we enforce protections when working on our own task, but not when on others. We call these "current" and "remote" operations. This patch introduces a new get_user_pages() variant: get_user_pages_remote() Which is a replacement for when get_user_pages() is called on non-current tsk/mm. We also introduce a new gup flag: FOLL_REMOTE which can be used for the "__" gup variants to get this new behavior. The uprobes is_trap_at_addr() location holds mmap_sem and calls get_user_pages(current->mm) on an instruction address. This makes it a pretty unique gup caller. Being an instruction access and also really originating from the kernel (vs. the app), I opted to consider this a 'remote' access where protection keys will not be enforced. Without protection keys, this patch should not change any behavior. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c27
1 files changed, 22 insertions, 5 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 7bf19ffa2199..36ca850936c9 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -870,7 +870,7 @@ long get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm,
EXPORT_SYMBOL(get_user_pages_unlocked);
/*
- * get_user_pages() - pin user pages in memory
+ * get_user_pages_remote() - pin user pages in memory
* @tsk: the task_struct to use for page fault accounting, or
* NULL if faults are not to be recorded.
* @mm: mm_struct of target mm
@@ -924,12 +924,29 @@ EXPORT_SYMBOL(get_user_pages_unlocked);
* should use get_user_pages because it cannot pass
* FAULT_FLAG_ALLOW_RETRY to handle_mm_fault.
*/
-long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long start, unsigned long nr_pages, int write,
- int force, struct page **pages, struct vm_area_struct **vmas)
+long get_user_pages_remote(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long start, unsigned long nr_pages,
+ int write, int force, struct page **pages,
+ struct vm_area_struct **vmas)
{
return __get_user_pages_locked(tsk, mm, start, nr_pages, write, force,
- pages, vmas, NULL, false, FOLL_TOUCH);
+ pages, vmas, NULL, false,
+ FOLL_TOUCH | FOLL_REMOTE);
+}
+EXPORT_SYMBOL(get_user_pages_remote);
+
+/*
+ * This is the same as get_user_pages_remote() for the time
+ * being.
+ */
+long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long start, unsigned long nr_pages,
+ int write, int force, struct page **pages,
+ struct vm_area_struct **vmas)
+{
+ return __get_user_pages_locked(tsk, mm, start, nr_pages,
+ write, force, pages, vmas, NULL, false,
+ FOLL_TOUCH);
}
EXPORT_SYMBOL(get_user_pages);