[PATCH RFC v2 07/20] mm/pgtable: define (pgd|p4d|pud)_offset_lockless() for folded page tables

[Yeoreum Yun <yeoreum.yun@arm.com>]

From: "David Hildenbrand (Arm)" <david@kernel.org>

The default helpers fallback to pud_offset(), passing a pointer to the
stack value.

Let's provide variants that do exactly what (pgd|p4d|pud)_offset() do,
but ignore the passed pgd_t/p4d_t/pud_t, consequently not working on a
pointer to the stack value like the default handlers would.

Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
 include/asm-generic/pgtable-nop4d.h | 7 +++++++
 include/asm-generic/pgtable-nopmd.h | 7 +++++++
 include/asm-generic/pgtable-nopud.h | 7 +++++++
 3 files changed, 21 insertions(+)

diff --git a/include/asm-generic/pgtable-nop4d.h b/include/asm-generic/pgtable-nop4d.h
index c6a5a43899b5..019c3f074b77 100644
--- a/include/asm-generic/pgtable-nop4d.h
+++ b/include/asm-generic/pgtable-nop4d.h
@@ -39,6 +39,13 @@ static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address)
 	return (p4d_t *)pgd;
 }
 
+static inline p4d_t *p4d_offset_lockless(pgd_t *pgdp, pgd_t pgd,
+		unsigned long address)
+{
+	return (p4d_t *)pgdp;
+}
+#define p4d_offset_lockless p4d_offset_lockless
+
 #define p4d_val(x)				(pgd_val((x).pgd))
 #define __p4d(x)				((p4d_t) { __pgd(x) })
 
diff --git a/include/asm-generic/pgtable-nopmd.h b/include/asm-generic/pgtable-nopmd.h
index dbd38b4c3a05..ae2eff44889a 100644
--- a/include/asm-generic/pgtable-nopmd.h
+++ b/include/asm-generic/pgtable-nopmd.h
@@ -50,6 +50,13 @@ static inline pmd_t * pmd_offset(pud_t * pud, unsigned long address)
 }
 #define pmd_offset pmd_offset
 
+static inline pmd_t *pmd_offset_lockless(pud_t *pudp, pud_t pud,
+		unsigned long address)
+{
+	return (pmd_t *)pudp;
+}
+#define pmd_offset_lockless pmd_offset_lockless
+
 #define pmd_val(x)				(pud_val((x).pud))
 #define __pmd(x)				((pmd_t) { __pud(x) } )
 
diff --git a/include/asm-generic/pgtable-nopud.h b/include/asm-generic/pgtable-nopud.h
index 6c9bca78047c..5a2b0a81ae19 100644
--- a/include/asm-generic/pgtable-nopud.h
+++ b/include/asm-generic/pgtable-nopud.h
@@ -47,6 +47,13 @@ static inline pud_t *pud_offset(p4d_t *p4d, unsigned long address)
 }
 #define pud_offset pud_offset
 
+static inline pud_t *pud_offset_lockless(p4d_t *p4dp, p4d_t p4d,
+		unsigned long address)
+{
+	return (pud_t *)p4dp;
+}
+#define pud_offset_lockless pud_offset_lockless
+
 #define pud_val(x)				(p4d_val((x).p4d))
 #define __pud(x)				((pud_t) { __p4d(x) })
 

-- 
2.43.0