Commit c090cac1 authored by Zhen Lei's avatar Zhen Lei Committed by Zheng Zengkai
Browse files

arm64: kdump: Try not to use NO_BLOCK_MAPPINGS for memory under 4G 

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I545H8


CVE: NA

-------------------------------------------------------------------------

For the case crashkernel=X@offset and crashkernel=X,high, we've explicitly
used 'crashk_res' to mark the scope of the page-level mapping required, so
NO_BLOCK_MAPPINGS should not be required for other areas. Otherwise,
system performance will be affected. In fact, only the case crashkernel=X
requires page-level mapping for all low memory under 4G because it
attempts high memory after it fails to request low memory first, and we
cannot predict its final location.

Signed-off-by: default avatarZhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: default avatarKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent baac34dd

arch/arm64/include/asm/kexec.h

+2 −0
Original line number Diff line number Diff line
@@ -97,6 +97,8 @@ static inline void crash_prepare_suspend(void) {} 
static inline void crash_post_resume(void) {}

#endif



extern bool crash_low_mem_page_map;



#ifdef CONFIG_KEXEC_CORE

extern void __init reserve_crashkernel(void);

extern void __init reserve_crashkernel_high(void);

arch/arm64/mm/mmu.c

+1 −16
Original line number Diff line number Diff line
@@ -470,21 +470,6 @@ void __init mark_linear_text_alias_ro(void) 
			    PAGE_KERNEL_RO);

}



static bool crash_mem_map __initdata;



static int __init enable_crash_mem_map(char *arg)

{

	/*

	 * Proper parameter parsing is done by reserve_crashkernel(). We only

	 * need to know if the linear map has to avoid block mappings so that

	 * the crashkernel reservations can be unmapped later.

	 */

	crash_mem_map = true;



	return 0;

}

early_param("crashkernel", enable_crash_mem_map);



static void __init map_mem(pgd_t *pgdp)

{

	phys_addr_t kernel_start = __pa_symbol(_text);
@@ -515,7 +500,7 @@ static void __init map_mem(pgd_t *pgdp) 
	memblock_mark_nomap(kernel_start, kernel_end - kernel_start);



#ifdef CONFIG_KEXEC_CORE

	if (crash_mem_map)

	if (crash_low_mem_page_map)

		eflags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;



	if (crashk_res.end)

kernel/crash_core.c

+3 −0
Original line number Diff line number Diff line
@@ -321,6 +321,7 @@ int __init parse_crashkernel_low(char *cmdline, 
 */



#ifdef CONFIG_ARCH_WANT_RESERVE_CRASH_KERNEL

bool crash_low_mem_page_map __initdata;

static bool crash_high_mem_reserved __initdata;

static struct resource crashk_res_high;
@@ -393,6 +394,8 @@ void __init reserve_crashkernel_high(void) 
		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);

		if (ret || !crash_size)

			return;

	} else if (!crash_base) {

		crash_low_mem_page_map = true;

	}



	crash_size = PAGE_ALIGN(crash_size);