powerpc/mm: Enable compound page check for both THP and HugeTLB

THP config results in compound pages. Make sure the kernel enables
the PageCompound() check with CONFIG_HUGETLB_PAGE disabled and
CONFIG_TRANSPARENT_HUGEPAGE enabled.

This makes sure we correctly flush the icache with THP pages.
flush_dcache_icache_page only matter for platforms that don't support
COHERENT_ICACHE.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210203045812.234439-1-aneesh.kumar@linux.ibm.com

arch/powerpc/include/asm/hugetlb.h

@@ -17,8 +17,6 @@ extern bool hugetlb_disabled;
 
 void hugetlbpage_init_default(void);
 
-void flush_dcache_icache_hugepage(struct page *page);
-
 int slice_is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
 			   unsigned long len);
 

arch/powerpc/mm/hugetlbpage.c

@@ -663,24 +663,6 @@ static int __init hugetlbpage_init(void)
 
 arch_initcall(hugetlbpage_init);
 
-void flush_dcache_icache_hugepage(struct page *page)
-{
-	int i;
-	void *start;
-
-	BUG_ON(!PageCompound(page));
-
-	for (i = 0; i < compound_nr(page); i++) {
-		if (!PageHighMem(page)) {
-			__flush_dcache_icache(page_address(page+i));
-		} else {
-			start = kmap_atomic(page+i);
-			__flush_dcache_icache(start);
-			kunmap_atomic(start);
-		}
-	}
-}
-
 void __init gigantic_hugetlb_cma_reserve(void)
 {
 	unsigned long order = 0;

arch/powerpc/mm/mem.c

@@ -494,14 +494,30 @@ void flush_dcache_page(struct page *page)
 }
 EXPORT_SYMBOL(flush_dcache_page);
 
+static void flush_dcache_icache_hugepage(struct page *page)
+{
+	int i;
+	void *start;
+
+	BUG_ON(!PageCompound(page));
+
+	for (i = 0; i < compound_nr(page); i++) {
+		if (!PageHighMem(page)) {
+			__flush_dcache_icache(page_address(page+i));
+		} else {
+			start = kmap_atomic(page+i);
+			__flush_dcache_icache(start);
+			kunmap_atomic(start);
+		}
+	}
+}
+
 void flush_dcache_icache_page(struct page *page)
 {
-#ifdef CONFIG_HUGETLB_PAGE
-	if (PageCompound(page)) {
-		flush_dcache_icache_hugepage(page);
-		return;
-	}
-#endif
+
+	if (PageCompound(page))
+		return flush_dcache_icache_hugepage(page);
+
 #if defined(CONFIG_PPC_8xx) || defined(CONFIG_PPC64)
 	/* On 8xx there is no need to kmap since highmem is not supported */
 	__flush_dcache_icache(page_address(page));