Commit ced1bf52 authored by Hari Bathini's avatar Hari Bathini Committed by Michael Ellerman
Browse files

powerpc/fadump: merge adjacent memory ranges to reduce PT_LOAD segements 



With dynamic memory allocation support for crash memory ranges array,
there is no hard limit on the no. of crash memory ranges kernel could
export, but program headers count could overflow in the /proc/vmcore
ELF file while exporting each memory range as PT_LOAD segment. Reduce
the likelihood of a such scenario, by folding adjacent crash memory
ranges which minimizes the total number of PT_LOAD segments.

Signed-off-by: default avatarHari Bathini <hbathini@linux.ibm.com>
Reviewed-by: default avatarMahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 1bd6a1c4

arch/powerpc/kernel/fadump.c

+36 −9
Original line number Diff line number Diff line
@@ -908,9 +908,25 @@ static int allocate_crash_memory_ranges(void) 
static inline int fadump_add_crash_memory(unsigned long long base,

					  unsigned long long end)

{

	u64  start, size;

	bool is_adjacent = false;



	if (base == end)

		return 0;



	/*

	 * Fold adjacent memory ranges to bring down the memory ranges/

	 * PT_LOAD segments count.

	 */

	if (crash_mem_ranges) {

		start = crash_memory_ranges[crash_mem_ranges - 1].base;

		size = crash_memory_ranges[crash_mem_ranges - 1].size;



		if ((start + size) == base)

			is_adjacent = true;

	}

	if (!is_adjacent) {

		/* resize the array on reaching the limit */

		if (crash_mem_ranges == max_crash_mem_ranges) {

			int ret;
@@ -919,11 +935,14 @@ static inline int fadump_add_crash_memory(unsigned long long base, 
				return ret;

		}



	pr_debug("crash_memory_range[%d] [%#016llx-%#016llx], %#llx bytes\n",

		crash_mem_ranges, base, end - 1, (end - base));

	crash_memory_ranges[crash_mem_ranges].base = base;

	crash_memory_ranges[crash_mem_ranges].size = end - base;

		start = base;

		crash_memory_ranges[crash_mem_ranges].base = start;

		crash_mem_ranges++;

	}



	crash_memory_ranges[crash_mem_ranges - 1].size = (end - start);

	pr_debug("crash_memory_range[%d] [%#016llx-%#016llx], %#llx bytes\n",

		(crash_mem_ranges - 1), start, end - 1, (end - start));

	return 0;

}
@@ -999,6 +1018,14 @@ static int fadump_setup_crash_memory_ranges(void) 


	pr_debug("Setup crash memory ranges.\n");

	crash_mem_ranges = 0;



	/* allocate memory for crash memory ranges for the first time */

	if (!max_crash_mem_ranges) {

		ret = allocate_crash_memory_ranges();

		if (ret)

			return ret;

	}



	/*

	 * add the first memory chunk (RMA_START through boot_memory_size) as

	 * a separate memory chunk. The reason is, at the time crash firmware

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