From patchwork series 487104

https://patchwork.ozlabs.org//project/linuxppc-dev/list/?series=487104

Author: Fox Snowpatch

arch/arm/include/asm/pgtable.h

@@ -15,8 +15,8 @@
  * ZERO_PAGE is a global shared page that is always zero: used
  * for zero-mapped memory areas etc..
  */
-extern struct page *empty_zero_page;
-#define ZERO_PAGE(vaddr)	(empty_zero_page)
+extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
+#define ZERO_PAGE(vaddr)	(virt_to_page(empty_zero_page))
 #endif
 
 #include <asm-generic/pgtable-nopud.h>

arch/arm/mm/mmu.c

@@ -45,7 +45,7 @@ extern unsigned long __atags_pointer;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
 /*
@@ -1754,8 +1754,6 @@ static void __init early_fixmap_shutdown(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 #ifdef CONFIG_XIP_KERNEL
 	/* Store the kernel RW RAM region start/end in these variables */
 	kernel_sec_start = CONFIG_PHYS_OFFSET & SECTION_MASK;
@@ -1781,13 +1779,7 @@ void __init paging_init(const struct machine_desc *mdesc)
 
 	top_pmd = pmd_off_k(0xffff0000);
 
-	/* allocate the zero page. */
-	zero_page = early_alloc(PAGE_SIZE);
-
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	__flush_dcache_folio(NULL, page_folio(empty_zero_page));
 }
 
 void __init early_mm_init(const struct machine_desc *mdesc)

arch/arm/mm/nommu.c

@@ -31,7 +31,7 @@ unsigned long vectors_base;
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
  */
-struct page *empty_zero_page;
+unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
 EXPORT_SYMBOL(empty_zero_page);
 
 #ifdef CONFIG_ARM_MPU
@@ -156,18 +156,10 @@ void __init adjust_lowmem_bounds(void)
  */
 void __init paging_init(const struct machine_desc *mdesc)
 {
-	void *zero_page;
-
 	early_trap_init((void *)vectors_base);
 	mpu_setup();
 
-	/* allocate the zero page. */
-	zero_page = (void *)memblock_alloc_or_panic(PAGE_SIZE, PAGE_SIZE);
-
 	bootmem_init();
-
-	empty_zero_page = virt_to_page(zero_page);
-	flush_dcache_page(empty_zero_page);
 }
 
 /*