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Commit 8d5f894a authored by AKASHI Takahiro's avatar AKASHI Takahiro Committed by Linus Torvalds
Browse files

x86: kexec_file: lift CRASH_MAX_RANGES limit on crash_mem buffer 

While CRASH_MAX_RANGES (== 16) seems to be good enough, fixed-number
array is not a good idea in general.

In this patch, size of crash_mem buffer is calculated as before and the
buffer is now dynamically allocated.  This change also allows removing
crash_elf_data structure.

Link: http://lkml.kernel.org/r/20180306102303.9063-6-takahiro.akashi@linaro.org


Signed-off-by: default avatarAKASHI Takahiro <takahiro.akashi@linaro.org>
Acked-by: default avatarDave Young <dyoung@redhat.com>
Tested-by: default avatarDave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c72c7e67

arch/x86/kernel/crash.c

+31 −51
Original line number Diff line number Diff line
@@ -41,32 +41,14 @@ 
/* Alignment required for elf header segment */

#define ELF_CORE_HEADER_ALIGN   4096



/* This primarily represents number of split ranges due to exclusion */

#define CRASH_MAX_RANGES	16



struct crash_mem_range {

	u64 start, end;

};



struct crash_mem {

	unsigned int nr_ranges;

	struct crash_mem_range ranges[CRASH_MAX_RANGES];

};



/* Misc data about ram ranges needed to prepare elf headers */

struct crash_elf_data {

	struct kimage *image;

	/*

	 * Total number of ram ranges we have after various adjustments for

	 * crash reserved region, etc.

	 */

	unsigned int max_nr_ranges;



	/* Pointer to elf header */

	void *ehdr;

	/* Pointer to next phdr */

	void *bufp;

	struct crash_mem mem;

	unsigned int nr_ranges;

	struct crash_mem_range ranges[0];

};



/* Used while preparing memory map entries for second kernel */
@@ -218,26 +200,31 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg) 
	return 0;

}





/* Gather all the required information to prepare elf headers for ram regions */

static void fill_up_crash_elf_data(struct crash_elf_data *ced,

				   struct kimage *image)

static struct crash_mem *fill_up_crash_elf_data(void)

{

	unsigned int nr_ranges = 0;



	ced->image = image;

	struct crash_mem *cmem;



	walk_system_ram_res(0, -1, &nr_ranges,

				get_nr_ram_ranges_callback);

	if (!nr_ranges)

		return NULL;



	ced->max_nr_ranges = nr_ranges;

	/*

	 * Exclusion of crash region and/or crashk_low_res may cause

	 * another range split. So add extra two slots here.

	 */

	nr_ranges += 2;

	cmem = vzalloc(sizeof(struct crash_mem) +

			sizeof(struct crash_mem_range) * nr_ranges);

	if (!cmem)

		return NULL;



	/* Exclusion of crash region could split memory ranges */

	ced->max_nr_ranges++;

	cmem->max_nr_ranges = nr_ranges;

	cmem->nr_ranges = 0;



	/* If crashk_low_res is not 0, another range split possible */

	if (crashk_low_res.end)

		ced->max_nr_ranges++;

	return cmem;

}



static int exclude_mem_range(struct crash_mem *mem,
@@ -294,10 +281,8 @@ static int exclude_mem_range(struct crash_mem *mem, 
		return 0;



	/* Split happened */

	if (i == CRASH_MAX_RANGES - 1) {

		pr_err("Too many crash ranges after split\n");

	if (i == mem->max_nr_ranges - 1)

		return -ENOMEM;

	}



	/* Location where new range should go */

	j = i + 1;
@@ -315,11 +300,10 @@ static int exclude_mem_range(struct crash_mem *mem, 


/*

 * Look for any unwanted ranges between mstart, mend and remove them. This

 * might lead to split and split ranges are put in ced->mem.ranges[] array

 * might lead to split and split ranges are put in cmem->ranges[] array

 */

static int elf_header_exclude_ranges(struct crash_elf_data *ced)

static int elf_header_exclude_ranges(struct crash_mem *cmem)

{

	struct crash_mem *cmem = &ced->mem;

	int ret = 0;



	/* Exclude crashkernel region */
@@ -338,8 +322,7 @@ static int elf_header_exclude_ranges(struct crash_elf_data *ced) 


static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)

{

	struct crash_elf_data *ced = arg;

	struct crash_mem *cmem = &ced->mem;

	struct crash_mem *cmem = arg;



	cmem->ranges[cmem->nr_ranges].start = res->start;

	cmem->ranges[cmem->nr_ranges].end = res->end;
@@ -348,7 +331,7 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg) 
	return 0;

}



static int prepare_elf64_headers(struct crash_elf_data *ced, bool kernel_map,

static int prepare_elf64_headers(struct crash_mem *cmem, bool kernel_map,

		void **addr, unsigned long *sz)

{

	Elf64_Ehdr *ehdr;
@@ -357,12 +340,11 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, bool kernel_map, 
	unsigned char *buf, *bufp;

	unsigned int cpu, i;

	unsigned long long notes_addr;

	struct crash_mem *cmem = &ced->mem;

	unsigned long mstart, mend;



	/* extra phdr for vmcoreinfo elf note */

	nr_phdr = nr_cpus + 1;

	nr_phdr += ced->max_nr_ranges;

	nr_phdr += cmem->nr_ranges;



	/*

	 * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
@@ -456,29 +438,27 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, bool kernel_map, 
static int prepare_elf_headers(struct kimage *image, void **addr,

					unsigned long *sz)

{

	struct crash_elf_data *ced;

	struct crash_mem *cmem;

	Elf64_Ehdr *ehdr;

	Elf64_Phdr *phdr;

	int ret, i;



	ced = kzalloc(sizeof(*ced), GFP_KERNEL);

	if (!ced)

	cmem = fill_up_crash_elf_data();

	if (!cmem)

		return -ENOMEM;



	fill_up_crash_elf_data(ced, image);



	ret = walk_system_ram_res(0, -1, ced,

	ret = walk_system_ram_res(0, -1, cmem,

				prepare_elf64_ram_headers_callback);

	if (ret)

		goto out;



	/* Exclude unwanted mem ranges */

	ret = elf_header_exclude_ranges(ced);

	ret = elf_header_exclude_ranges(cmem);

	if (ret)

		goto out;



	/* By default prepare 64bit headers */

	ret =  prepare_elf64_headers(ced, IS_ENABLED(CONFIG_X86_64), addr, sz);

	ret =  prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);

	if (ret)

		goto out;
@@ -496,7 +476,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr, 
			break;

		}

out:

	kfree(ced);

	vfree(cmem);

	return ret;

}