powerpc: Remove find_current_mm_pte()

Last usage of find_current_mm_pte() was removed by
commit 15759cb0 ("powerpc/perf/callchain: Use
__get_user_pages_fast in read_user_stack_slow")

Remove it.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/ec79f462a3bfa8365b7df505e574d5d85246bc68.1646818177.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/pte-walk.h

@@ -60,29 +60,4 @@ static inline phys_addr_t ppc_find_vmap_phys(unsigned long addr)
 	return pa;
 }
 
-/*
- * This is what we should always use. Any other lockless page table lookup needs
- * careful audit against THP split.
- */
-static inline pte_t *find_current_mm_pte(pgd_t *pgdir, unsigned long ea,
-					 bool *is_thp, unsigned *hshift)
-{
-	pte_t *pte;
-
-	VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__);
-	VM_WARN(pgdir != current->mm->pgd,
-		"%s lock less page table lookup called on wrong mm\n", __func__);
-	pte = __find_linux_pte(pgdir, ea, is_thp, hshift);
-
-#if defined(CONFIG_DEBUG_VM) &&						\
-	!(defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE))
-	/*
-	 * We should not find huge page if these configs are not enabled.
-	 */
-	if (hshift)
-		WARN_ON(*hshift);
-#endif
-	return pte;
-}
-
 #endif /* _ASM_POWERPC_PTE_WALK_H */

arch/powerpc/mm/book3s64/pgtable.c

@@ -100,14 +100,14 @@ static void do_serialize(void *arg)
 }
 
 /*
- * Serialize against find_current_mm_pte which does lock-less
+ * Serialize against __find_linux_pte() which does lock-less
  * lookup in page tables with local interrupts disabled. For huge pages
  * it casts pmd_t to pte_t. Since format of pte_t is different from
  * pmd_t we want to prevent transit from pmd pointing to page table
  * to pmd pointing to huge page (and back) while interrupts are disabled.
  * We clear pmd to possibly replace it with page table pointer in
  * different code paths. So make sure we wait for the parallel
- * find_current_mm_pte to finish.
+ * __find_linux_pte() to finish.
  */
 void serialize_against_pte_lookup(struct mm_struct *mm)
 {