mm: move tlb_flush_pending inline helpers to mm_inline.h

linux/mm_types.h should only define structure definitions, to make it
cheap to include elsewhere.  The atomic_t helper function definitions
are particularly large, so it's better to move the helpers using those
into the existing linux/mm_inline.h and only include that where needed.

As a follow-up, we may want to go through all the indirect includes in
mm_types.h and reduce them as much as possible.

Link: https://lkml.kernel.org/r/20211207125710.2503446-2-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Colin Cross <ccross@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 45 insertions, 84 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 4d5fb84eed5e..6a89f128c990 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -692,90 +692,6 @@ extern void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm);
 extern void tlb_gather_mmu_fullmm(struct mmu_gather *tlb, struct mm_struct *mm);
 extern void tlb_finish_mmu(struct mmu_gather *tlb);
 
-static inline void init_tlb_flush_pending(struct mm_struct *mm)
-{
-	atomic_set(&mm->tlb_flush_pending, 0);
-}
-
-static inline void inc_tlb_flush_pending(struct mm_struct *mm)
-{
-	atomic_inc(&mm->tlb_flush_pending);
-	/*
-	 * The only time this value is relevant is when there are indeed pages
-	 * to flush. And we'll only flush pages after changing them, which
-	 * requires the PTL.
-	 *
-	 * So the ordering here is:
-	 *
-	 *	atomic_inc(&mm->tlb_flush_pending);
-	 *	spin_lock(&ptl);
-	 *	...
-	 *	set_pte_at();
-	 *	spin_unlock(&ptl);
-	 *
-	 *				spin_lock(&ptl)
-	 *				mm_tlb_flush_pending();
-	 *				....
-	 *				spin_unlock(&ptl);
-	 *
-	 *	flush_tlb_range();
-	 *	atomic_dec(&mm->tlb_flush_pending);
-	 *
-	 * Where the increment if constrained by the PTL unlock, it thus
-	 * ensures that the increment is visible if the PTE modification is
-	 * visible. After all, if there is no PTE modification, nobody cares
-	 * about TLB flushes either.
-	 *
-	 * This very much relies on users (mm_tlb_flush_pending() and
-	 * mm_tlb_flush_nested()) only caring about _specific_ PTEs (and
-	 * therefore specific PTLs), because with SPLIT_PTE_PTLOCKS and RCpc
-	 * locks (PPC) the unlock of one doesn't order against the lock of
-	 * another PTL.
-	 *
-	 * The decrement is ordered by the flush_tlb_range(), such that
-	 * mm_tlb_flush_pending() will not return false unless all flushes have
-	 * completed.
-	 */
-}
-
-static inline void dec_tlb_flush_pending(struct mm_struct *mm)
-{
-	/*
-	 * See inc_tlb_flush_pending().
-	 *
-	 * This cannot be smp_mb__before_atomic() because smp_mb() simply does
-	 * not order against TLB invalidate completion, which is what we need.
-	 *
-	 * Therefore we must rely on tlb_flush_*() to guarantee order.
-	 */
-	atomic_dec(&mm->tlb_flush_pending);
-}
-
-static inline bool mm_tlb_flush_pending(struct mm_struct *mm)
-{
-	/*
-	 * Must be called after having acquired the PTL; orders against that
-	 * PTLs release and therefore ensures that if we observe the modified
-	 * PTE we must also observe the increment from inc_tlb_flush_pending().
-	 *
-	 * That is, it only guarantees to return true if there is a flush
-	 * pending for _this_ PTL.
-	 */
-	return atomic_read(&mm->tlb_flush_pending);
-}
-
-static inline bool mm_tlb_flush_nested(struct mm_struct *mm)
-{
-	/*
-	 * Similar to mm_tlb_flush_pending(), we must have acquired the PTL
-	 * for which there is a TLB flush pending in order to guarantee
-	 * we've seen both that PTE modification and the increment.
-	 *
-	 * (no requirement on actually still holding the PTL, that is irrelevant)
-	 */
-	return atomic_read(&mm->tlb_flush_pending) > 1;
-}
-
 struct vm_fault;
 
 /**
@@ -890,4 +806,49 @@ typedef struct {
 	unsigned long val;
 } swp_entry_t;
 
+/**
+ * enum fault_flag - Fault flag definitions.
+ * @FAULT_FLAG_WRITE: Fault was a write fault.
+ * @FAULT_FLAG_MKWRITE: Fault was mkwrite of existing PTE.
+ * @FAULT_FLAG_ALLOW_RETRY: Allow to retry the fault if blocked.
+ * @FAULT_FLAG_RETRY_NOWAIT: Don't drop mmap_lock and wait when retrying.
+ * @FAULT_FLAG_KILLABLE: The fault task is in SIGKILL killable region.
+ * @FAULT_FLAG_TRIED: The fault has been tried once.
+ * @FAULT_FLAG_USER: The fault originated in userspace.
+ * @FAULT_FLAG_REMOTE: The fault is not for current task/mm.
+ * @FAULT_FLAG_INSTRUCTION: The fault was during an instruction fetch.
+ * @FAULT_FLAG_INTERRUPTIBLE: The fault can be interrupted by non-fatal signals.
+ *
+ * About @FAULT_FLAG_ALLOW_RETRY and @FAULT_FLAG_TRIED: we can specify
+ * whether we would allow page faults to retry by specifying these two
+ * fault flags correctly.  Currently there can be three legal combinations:
+ *
+ * (a) ALLOW_RETRY and !TRIED:  this means the page fault allows retry, and
+ *                              this is the first try
+ *
+ * (b) ALLOW_RETRY and TRIED:   this means the page fault allows retry, and
+ *                              we've already tried at least once
+ *
+ * (c) !ALLOW_RETRY and !TRIED: this means the page fault does not allow retry
+ *
+ * The unlisted combination (!ALLOW_RETRY && TRIED) is illegal and should never
+ * be used.  Note that page faults can be allowed to retry for multiple times,
+ * in which case we'll have an initial fault with flags (a) then later on
+ * continuous faults with flags (b).  We should always try to detect pending
+ * signals before a retry to make sure the continuous page faults can still be
+ * interrupted if necessary.
+ */
+enum fault_flag {
+	FAULT_FLAG_WRITE =		1 << 0,
+	FAULT_FLAG_MKWRITE =		1 << 1,
+	FAULT_FLAG_ALLOW_RETRY =	1 << 2,
+	FAULT_FLAG_RETRY_NOWAIT = 	1 << 3,
+	FAULT_FLAG_KILLABLE =		1 << 4,
+	FAULT_FLAG_TRIED = 		1 << 5,
+	FAULT_FLAG_USER =		1 << 6,
+	FAULT_FLAG_REMOTE =		1 << 7,
+	FAULT_FLAG_INSTRUCTION =	1 << 8,
+	FAULT_FLAG_INTERRUPTIBLE =	1 << 9,
+};
+
 #endif /* _LINUX_MM_TYPES_H */