linux-kernel - [PATCH 3.16 069/305] powerpc/mm/hash64: Factor out hash preload psize check

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Message-ID: <lsq.1471110171.718053646@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Michael Ellerman" <mpe@...erman.id.au>
Subject: [PATCH 3.16 069/305] powerpc/mm/hash64: Factor out hash preload
 psize check

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Ellerman <mpe@...erman.id.au>

commit 8bbc9b7b001eaab8abf7e9e24edf1bb285c8d825 upstream.

Currently we have a check in hash_preload() against the psize, which is
only included when CONFIG_PPC_MM_SLICES is enabled. We want to expand
this check in a subsequent patch, so factor it out to allow that. As a
bonus it removes the #ifdef in the C code.

Unfortunately we can't put this in the existing CONFIG_PPC_MM_SLICES
block because it would require a forward declaration.

Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/powerpc/mm/hash_utils_64.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -1196,6 +1196,22 @@ bail:
 }
 EXPORT_SYMBOL_GPL(hash_page);
 
+#ifdef CONFIG_PPC_MM_SLICES
+static bool should_hash_preload(struct mm_struct *mm, unsigned long ea)
+{
+	/* We only prefault standard pages for now */
+	if (unlikely(get_slice_psize(mm, ea) != mm->context.user_psize))
+		return false;
+
+	return true;
+}
+#else
+static bool should_hash_preload(struct mm_struct *mm, unsigned long ea)
+{
+	return true;
+}
+#endif
+
 void hash_preload(struct mm_struct *mm, unsigned long ea,
 		  unsigned long access, unsigned long trap)
 {
@@ -1208,11 +1224,8 @@ void hash_preload(struct mm_struct *mm,
 
 	BUG_ON(REGION_ID(ea) != USER_REGION_ID);
 
-#ifdef CONFIG_PPC_MM_SLICES
-	/* We only prefault standard pages for now */
-	if (unlikely(get_slice_psize(mm, ea) != mm->context.user_psize))
+	if (!should_hash_preload(mm, ea))
 		return;
-#endif
 
 	DBG_LOW("hash_preload(mm=%p, mm->pgdir=%p, ea=%016lx, access=%lx,"
 		" trap=%lx\n", mm, mm->pgd, ea, access, trap);