archives/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-03-13 23:46:14 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

arm: make initialization of zero page independent of the memory map

Browse source 
Unlike most architectures, arm keeps a struct page pointer to the
empty_zero_page and to initialize it requires conversion of a virtual
address to page which makes it necessary to have memory map initialized
before creating the empty_zero_page.

Make empty_zero_page a stataic array in BSS to decouple it's
initialization from the initialization of the memory map.

This also aligns arm with vast majorty of architectures.

Link: https://lkml.kernel.org/r/20260111082105.290734-5-rppt@kernel.org
Signed-off-by: Klara Modin <klarasmodin@gmail.com>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Klara Modin 2026-01-11 10:20:38 +02:00 • committed by Andrew Morton
parent 30a66f8a8c
commit 18b7cc70de
3 changed files with 4 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

4
arch/arm/include/asm/pgtable.h
View file

@ -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>

10
arch/arm/mm/mmu.c
View file

@ -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)

10
arch/arm/mm/nommu.c
View file

@ -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);
}
/*