xtensa: simplify coherent_kvaddr logic

Functions coherent_kvaddr, clear_page_alias and copy_page_alias use
physical address 0 as a special value that means 'this page is in the
KSEG mapping and its existing virtual address has the same color as the
virtual address of its future mapping, so don't map it to the
TLBTEMP_BASE area'.

Simplify this logic and drop special handling of low memory pages/pages
with coherent mapping and always use TLBTEMP_BASE area.

Signed-off-by: Max Filippov <[e-mail]>

arch/xtensa/mm/cache.c

···
 static inline void *coherent_kvaddr(struct page *page, unsigned long base,
 				    unsigned long vaddr, unsigned long *paddr)
 {
-	if (PageHighMem(page) || !DCACHE_ALIAS_EQ(page_to_phys(page), vaddr)) {
-		*paddr = page_to_phys(page);
-		return (void *)(base + (vaddr & DCACHE_ALIAS_MASK));
-	} else {
-		*paddr = 0;
-		return page_to_virt(page);
-	}
+	*paddr = page_to_phys(page);
+	return (void *)(base + (vaddr & DCACHE_ALIAS_MASK));
 }
 
 void clear_user_highpage(struct page *page, unsigned long vaddr)

arch/xtensa/mm/misc.S

···
 
 	abi_entry_default
 
-	/* Skip setting up a temporary DTLB if not aliased low page. */
-
 	movi	a5, PAGE_OFFSET
-	movi	a6, 0
-	beqz	a3, 1f
-
-	/* Setup a temporary DTLB for the addr. */
-
 	addi	a6, a3, (PAGE_KERNEL | _PAGE_HW_WRITE)
 	mov	a4, a2
 	wdtlb	a6, a2
 	dsync
 
-1:	movi	a3, 0
+	movi	a3, 0
 	__loopi	a2, a7, PAGE_SIZE, 32
 	s32i	a3, a2, 0
 	s32i	a3, a2, 4
···
 	s32i	a3, a2, 28
 	__endla	a2, a7, 32
 
-	bnez	a6, 1f
-	abi_ret_default
+	/* We need to invalidate the temporary dtlb entry. */
 
-	/* We need to invalidate the temporary idtlb entry, if any. */
-
-1:	idtlb	a4
+	idtlb	a4
 	dsync
 
 	abi_ret_default
···
 
 	abi_entry_default
 
-	/* Skip setting up a temporary DTLB for destination if not aliased. */
-
-	movi	a6, 0
-	movi	a7, 0
-	beqz	a4, 1f
-
 	/* Setup a temporary DTLB for destination. */
 
 	addi	a6, a4, (PAGE_KERNEL | _PAGE_HW_WRITE)
 	wdtlb	a6, a2
 	dsync
-
-	/* Skip setting up a temporary DTLB for source if not aliased. */
-
-1:	beqz	a5, 1f
 
 	/* Setup a temporary DTLB for source. */
 
···
 
 	/* We need to invalidate any temporary mapping! */
 
-	bnez	a6, 1f
-	bnez	a7, 2f
-	abi_ret_default
-
-1:	addi	a2, a2, -PAGE_SIZE
+	addi	a2, a2, -PAGE_SIZE
 	idtlb	a2
 	dsync
-	bnez	a7, 2f
-	abi_ret_default
 
-2:	addi	a3, a3, -PAGE_SIZE+1
+	addi	a3, a3, -PAGE_SIZE+1
 	idtlb	a3
 	dsync