Commit e5f15b45 authored by Yinghai Lu's avatar Yinghai Lu Committed by H. Peter Anvin
Browse files

x86: Cleanup highmap after brk is concluded 



Now cleanup_highmap actually is in two steps: one is early in head64.c
and only clears above _end; a second one is in init_memory_mapping() and
tries to clean from _brk_end to _end.
It should check if those boundaries are PMD_SIZE aligned but currently
does not.
Also init_memory_mapping() is called several times for numa or memory
hotplug, so we really should not handle initial kernel mappings there.

This patch moves cleanup_highmap() down after _brk_end is settled so
we can do everything in one step.
Also we honor max_pfn_mapped in the implementation of cleanup_highmap.

Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
LKML-Reference: <alpine.DEB.2.00.1103171739050.3382@kaball-desktop>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 4981d01e

arch/x86/kernel/head64.c

+0 −3
Original line number Diff line number Diff line
@@ -77,9 +77,6 @@ void __init x86_64_start_kernel(char * real_mode_data) 
	/* Make NULL pointers segfault */

	zap_identity_mappings();



	/* Cleanup the over mapped high alias */

	cleanup_highmap();



	max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;



	for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {

arch/x86/kernel/setup.c

+3 −22
Original line number Diff line number Diff line
@@ -294,30 +294,11 @@ static void __init init_gbpages(void) 
	else

		direct_gbpages = 0;

}



static void __init cleanup_highmap_brk_end(void)

{

	pud_t *pud;

	pmd_t *pmd;



	mmu_cr4_features = read_cr4();



	/*

	 * _brk_end cannot change anymore, but it and _end may be

	 * located on different 2M pages. cleanup_highmap(), however,

	 * can only consider _end when it runs, so destroy any

	 * mappings beyond _brk_end here.

	 */

	pud = pud_offset(pgd_offset_k(_brk_end), _brk_end);

	pmd = pmd_offset(pud, _brk_end - 1);

	while (++pmd <= pmd_offset(pud, (unsigned long)_end - 1))

		pmd_clear(pmd);

}

#else

static inline void init_gbpages(void)

{

}

static inline void cleanup_highmap_brk_end(void)

static void __init cleanup_highmap(void)

{

}

#endif
@@ -330,8 +311,6 @@ static void __init reserve_brk(void) 
	/* Mark brk area as locked down and no longer taking any

	   new allocations */

	_brk_start = 0;



	cleanup_highmap_brk_end();

}



#ifdef CONFIG_BLK_DEV_INITRD
@@ -950,6 +929,8 @@ void __init setup_arch(char **cmdline_p) 
	 */

	reserve_brk();



	cleanup_highmap();



	memblock.current_limit = get_max_mapped();

	memblock_x86_fill();

arch/x86/mm/init_64.c

+6 −5
Original line number Diff line number Diff line
@@ -51,6 +51,7 @@ 
#include <asm/numa.h>

#include <asm/cacheflush.h>

#include <asm/init.h>

#include <asm/setup.h>



static int __init parse_direct_gbpages_off(char *arg)

{
@@ -293,18 +294,18 @@ void __init init_extra_mapping_uc(unsigned long phys, unsigned long size) 
 * to the compile time generated pmds. This results in invalid pmds up

 * to the point where we hit the physaddr 0 mapping.

 *

 * We limit the mappings to the region from _text to _end.  _end is

 * rounded up to the 2MB boundary. This catches the invalid pmds as

 * We limit the mappings to the region from _text to _brk_end.  _brk_end

 * is rounded up to the 2MB boundary. This catches the invalid pmds as

 * well, as they are located before _text:

 */

void __init cleanup_highmap(void)

{

	unsigned long vaddr = __START_KERNEL_map;

	unsigned long end = roundup((unsigned long)_end, PMD_SIZE) - 1;

	unsigned long vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT);

	unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;

	pmd_t *pmd = level2_kernel_pgt;

	pmd_t *last_pmd = pmd + PTRS_PER_PMD;



	for (; pmd < last_pmd; pmd++, vaddr += PMD_SIZE) {

	for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) {

		if (pmd_none(*pmd))

			continue;

		if (vaddr < (unsigned long) _text || vaddr > end)

CRA Git | Maintained and supported by SUSTech CRA and CCSE