riscv: mremap speedup - enable HAVE_MOVE_PUD and HAVE_MOVE_PMD

HAVE_MOVE_PUD enables remapping pages at the PUD level if both the source
and destination addresses are PUD-aligned.
HAVE_MOVE_PMD does similar speedup on the PMD level.

With HAVE_MOVE_PUD enabled, there is about a 143x improvement on qemu
With HAVE_MOVE_PMD enabled, there is about a 5x improvement on qemu
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/Kconfig

@@ -82,6 +82,8 @@ config RISCV
 	select HAVE_KPROBES
 	select HAVE_KPROBES_ON_FTRACE
 	select HAVE_KRETPROBES
+	select HAVE_MOVE_PMD
+	select HAVE_MOVE_PUD
 	select HAVE_PCI
 	select HAVE_PERF_EVENTS
 	select HAVE_PERF_REGS

arch/riscv/include/asm/pgtable.h

@@ -241,6 +241,11 @@ static inline pte_t pmd_pte(pmd_t pmd)
 	return __pte(pmd_val(pmd));
 }
 
+static inline pte_t pud_pte(pud_t pud)
+{
+	return __pte(pud_val(pud));
+}
+
 /* Yields the page frame number (PFN) of a page table entry */
 static inline unsigned long pte_pfn(pte_t pte)
 {
@@ -570,6 +575,12 @@ static inline void set_pmd_at(struct mm_struct *mm, unsigned long addr,
 	return set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd));
 }
 
+static inline void set_pud_at(struct mm_struct *mm, unsigned long addr,
+				pud_t *pudp, pud_t pud)
+{
+	return set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud));
+}
+
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static inline int pmd_trans_huge(pmd_t pmd)
 {