[RESEND v7 04/29] powerpc: mm: add PMD swap-exclusive helpers

[Usama Arif <usama.arif@linux.dev>]

A later patch keeps a PMD-mapped anonymous THP mapped by a PMD across the
swap round-trip, so PG_anon_exclusive now has to survive in a swap PMD and
not just in a swap PTE.

book3s64 builds a swap PMD by running the PTE encoding over pmd_pte(), so
the PMD helpers use the same _PAGE_SWP_EXCLUSIVE bit. It is also the only
powerpc variant that selects ARCH_HAS_PMD_SOFTLEAVES, via PPC_THP.

Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Usama Arif <usama.arif@linux.dev>
---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
index dff8790a047db..28943ef3c1c80 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -699,6 +699,23 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
 	return __pte_raw(pte_raw(pte) & cpu_to_be64(~_PAGE_SWP_EXCLUSIVE));
 }
 
+#ifdef CONFIG_ARCH_HAS_PMD_SOFTLEAVES
+static inline pmd_t pmd_swp_mkexclusive(pmd_t pmd)
+{
+	return __pmd_raw(pmd_raw(pmd) | cpu_to_be64(_PAGE_SWP_EXCLUSIVE));
+}
+
+static inline bool pmd_swp_exclusive(pmd_t pmd)
+{
+	return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_SWP_EXCLUSIVE));
+}
+
+static inline pmd_t pmd_swp_clear_exclusive(pmd_t pmd)
+{
+	return __pmd_raw(pmd_raw(pmd) & cpu_to_be64(~_PAGE_SWP_EXCLUSIVE));
+}
+#endif
+
 static inline bool check_pte_access(unsigned long access, unsigned long ptev)
 {
 	/*
-- 
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