Commit 7c321eb2 authored by Lianbo Jiang's avatar Lianbo Jiang Committed by Borislav Petkov
Browse files

x86/kdump: Remove the backup region handling 



When the crashkernel kernel command line option is specified, the low
1M memory will always be reserved now. Therefore, it's not necessary to
create a backup region anymore and also no need to copy the contents of
the first 640k to it.

Remove all the code related to handling that backup region.

 [ bp: Massage commit message. ]

Signed-off-by: default avatarLianbo Jiang <lijiang@redhat.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: bhe@redhat.com
Cc: Dave Young <dyoung@redhat.com>
Cc: d.hatayama@fujitsu.com
Cc: dhowells@redhat.com
Cc: ebiederm@xmission.com
Cc: horms@verge.net.au
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jürgen Gross <jgross@suse.com>
Cc: kexec@lists.infradead.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: vgoyal@redhat.com
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20191108090027.11082-3-lijiang@redhat.com
parent 6f599d84

arch/x86/include/asm/kexec.h

+0 −10
Original line number Diff line number Diff line
@@ -66,10 +66,6 @@ struct kimage; 
# define KEXEC_ARCH KEXEC_ARCH_X86_64

#endif



/* Memory to backup during crash kdump */

#define KEXEC_BACKUP_SRC_START	(0UL)

#define KEXEC_BACKUP_SRC_END	(640 * 1024UL - 1)	/* 640K */



/*

 * This function is responsible for capturing register states if coming

 * via panic otherwise just fix up the ss and sp if coming via kernel
@@ -154,12 +150,6 @@ struct kimage_arch { 
	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;

	/* Details of backup region */

	unsigned long backup_src_start;

	unsigned long backup_src_sz;



	/* Physical address of backup segment */

	unsigned long backup_load_addr;



	/* Core ELF header buffer */

	void *elf_headers;

arch/x86/include/asm/purgatory.h

+0 −10
Original line number Diff line number Diff line
@@ -6,16 +6,6 @@ 
#include <linux/purgatory.h>



extern void purgatory(void);

/*

 * These forward declarations serve two purposes:

 *

 * 1) Make sparse happy when checking arch/purgatory

 * 2) Document that these are required to be global so the symbol

 *    lookup in kexec works

 */

extern unsigned long purgatory_backup_dest;

extern unsigned long purgatory_backup_src;

extern unsigned long purgatory_backup_sz;

#endif	/* __ASSEMBLY__ */



#endif /* _ASM_PURGATORY_H */

arch/x86/kernel/crash.c

+11 −76
Original line number Diff line number Diff line
@@ -188,8 +188,6 @@ void native_machine_crash_shutdown(struct pt_regs *regs) 


#ifdef CONFIG_KEXEC_FILE



static unsigned long crash_zero_bytes;



static int get_nr_ram_ranges_callback(struct resource *res, void *arg)

{

	unsigned int *nr_ranges = arg;
@@ -232,6 +230,11 @@ static int elf_header_exclude_ranges(struct crash_mem *cmem) 
{

	int ret = 0;



	/* Exclude the low 1M because it is always reserved */

	ret = crash_exclude_mem_range(cmem, 0, 1<<20);

	if (ret)

		return ret;



	/* Exclude crashkernel region */

	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);

	if (ret)
@@ -261,9 +264,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr, 
					unsigned long *sz)

{

	struct crash_mem *cmem;

	Elf64_Ehdr *ehdr;

	Elf64_Phdr *phdr;

	int ret, i;

	int ret;



	cmem = fill_up_crash_elf_data();

	if (!cmem)
@@ -282,22 +283,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr, 
	/* By default prepare 64bit headers */

	ret =  crash_prepare_elf64_headers(cmem,

				IS_ENABLED(CONFIG_X86_64), addr, sz);

	if (ret)

		goto out;



	/*

	 * If a range matches backup region, adjust offset to backup

	 * segment.

	 */

	ehdr = (Elf64_Ehdr *)*addr;

	phdr = (Elf64_Phdr *)(ehdr + 1);

	for (i = 0; i < ehdr->e_phnum; phdr++, i++)

		if (phdr->p_type == PT_LOAD &&

				phdr->p_paddr == image->arch.backup_src_start &&

				phdr->p_memsz == image->arch.backup_src_sz) {

			phdr->p_offset = image->arch.backup_load_addr;

			break;

		}

out:

	vfree(cmem);

	return ret;
@@ -336,19 +322,11 @@ static int memmap_exclude_ranges(struct kimage *image, struct crash_mem *cmem, 
				 unsigned long long mend)

{

	unsigned long start, end;

	int ret = 0;



	cmem->ranges[0].start = mstart;

	cmem->ranges[0].end = mend;

	cmem->nr_ranges = 1;



	/* Exclude Backup region */

	start = image->arch.backup_load_addr;

	end = start + image->arch.backup_src_sz - 1;

	ret = crash_exclude_mem_range(cmem, start, end);

	if (ret)

		return ret;



	/* Exclude elf header region */

	start = image->arch.elf_load_addr;

	end = start + image->arch.elf_headers_sz - 1;
@@ -371,11 +349,11 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params) 
	memset(&cmd, 0, sizeof(struct crash_memmap_data));

	cmd.params = params;



	/* Add first 640K segment */

	ei.addr = image->arch.backup_src_start;

	ei.size = image->arch.backup_src_sz;

	ei.type = E820_TYPE_RAM;

	add_e820_entry(params, &ei);

	/* Add the low 1M */

	cmd.type = E820_TYPE_RAM;

	flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;

	walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, (1<<20)-1, &cmd,

			memmap_entry_callback);



	/* Add ACPI tables */

	cmd.type = E820_TYPE_ACPI;
@@ -424,55 +402,12 @@ out: 
	return ret;

}



static int determine_backup_region(struct resource *res, void *arg)

{

	struct kimage *image = arg;



	image->arch.backup_src_start = res->start;

	image->arch.backup_src_sz = resource_size(res);



	/* Expecting only one range for backup region */

	return 1;

}



int crash_load_segments(struct kimage *image)

{

	int ret;

	struct kexec_buf kbuf = { .image = image, .buf_min = 0,

				  .buf_max = ULONG_MAX, .top_down = false };



	/*

	 * Determine and load a segment for backup area. First 640K RAM

	 * region is backup source

	 */



	ret = walk_system_ram_res(KEXEC_BACKUP_SRC_START, KEXEC_BACKUP_SRC_END,

				image, determine_backup_region);



	/* Zero or postive return values are ok */

	if (ret < 0)

		return ret;



	/* Add backup segment. */

	if (image->arch.backup_src_sz) {

		kbuf.buffer = &crash_zero_bytes;

		kbuf.bufsz = sizeof(crash_zero_bytes);

		kbuf.memsz = image->arch.backup_src_sz;

		kbuf.buf_align = PAGE_SIZE;

		/*

		 * Ideally there is no source for backup segment. This is

		 * copied in purgatory after crash. Just add a zero filled

		 * segment for now to make sure checksum logic works fine.

		 */

		ret = kexec_add_buffer(&kbuf);

		if (ret)

			return ret;

		image->arch.backup_load_addr = kbuf.mem;

		pr_debug("Loaded backup region at 0x%lx backup_start=0x%lx memsz=0x%lx\n",

			 image->arch.backup_load_addr,

			 image->arch.backup_src_start, kbuf.memsz);

	}



	/* Prepare elf headers and add a segment */

	ret = prepare_elf_headers(image, &kbuf.buffer, &kbuf.bufsz);

	if (ret)

arch/x86/kernel/machine_kexec_64.c

+0 −47
Original line number Diff line number Diff line
@@ -298,48 +298,6 @@ static void load_segments(void) 
		);

}



#ifdef CONFIG_KEXEC_FILE

/* Update purgatory as needed after various image segments have been prepared */

static int arch_update_purgatory(struct kimage *image)

{

	int ret = 0;



	if (!image->file_mode)

		return 0;



	/* Setup copying of backup region */

	if (image->type == KEXEC_TYPE_CRASH) {

		ret = kexec_purgatory_get_set_symbol(image,

				"purgatory_backup_dest",

				&image->arch.backup_load_addr,

				sizeof(image->arch.backup_load_addr), 0);

		if (ret)

			return ret;



		ret = kexec_purgatory_get_set_symbol(image,

				"purgatory_backup_src",

				&image->arch.backup_src_start,

				sizeof(image->arch.backup_src_start), 0);

		if (ret)

			return ret;



		ret = kexec_purgatory_get_set_symbol(image,

				"purgatory_backup_sz",

				&image->arch.backup_src_sz,

				sizeof(image->arch.backup_src_sz), 0);

		if (ret)

			return ret;

	}



	return ret;

}

#else /* !CONFIG_KEXEC_FILE */

static inline int arch_update_purgatory(struct kimage *image)

{

	return 0;

}

#endif /* CONFIG_KEXEC_FILE */



int machine_kexec_prepare(struct kimage *image)

{

	unsigned long start_pgtable;
@@ -353,11 +311,6 @@ int machine_kexec_prepare(struct kimage *image) 
	if (result)

		return result;



	/* update purgatory as needed */

	result = arch_update_purgatory(image);

	if (result)

		return result;



	return 0;

}

arch/x86/purgatory/purgatory.c

+0 −19
Original line number Diff line number Diff line
@@ -14,28 +14,10 @@ 


#include "../boot/string.h"



unsigned long purgatory_backup_dest __section(.kexec-purgatory);

unsigned long purgatory_backup_src __section(.kexec-purgatory);

unsigned long purgatory_backup_sz __section(.kexec-purgatory);



u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(.kexec-purgatory);



struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(.kexec-purgatory);



/*

 * On x86, second kernel requries first 640K of memory to boot. Copy

 * first 640K to a backup region in reserved memory range so that second

 * kernel can use first 640K.

 */

static int copy_backup_region(void)

{

	if (purgatory_backup_dest) {

		memcpy((void *)purgatory_backup_dest,

		       (void *)purgatory_backup_src, purgatory_backup_sz);

	}

	return 0;

}



static int verify_sha256_digest(void)

{

	struct kexec_sha_region *ptr, *end;
@@ -66,7 +48,6 @@ void purgatory(void) 
		for (;;)

			;

	}

	copy_backup_region();

}



/*

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