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Commit 76d71ebd authored by Petr Tesarik's avatar Petr Tesarik Committed by Tony Luck
Browse files

[IA64] Merge overlapping reserved regions at boot 



While working on the upcoming SLES11 SP2, I ran into an issue with booting the
panic kernel on a kernel crash. In the first iteration I found out that the
initial register backing store gets overwritten with zeroes, causing a kernel
crash shortly afterwards.

Further investigation revealed that rsvd_region[] contains overlapping
entries: find_memmap_space() returns a pointer which lies between KERNEL_START
and _end. This is correct with the EFI memmap as patched by the kexec
purgatory code. That code removes vmlinux LOAD segments from the usable map,
but there is a pretty large hole between the gate section and the per-cpu
section.

This happens because reserve_memory() blindly marks [KERNEL_START, __end]
as reserved, even though there is a free block in the middle in the kexec
case because it noticed a large gap between sections and modified the
efi_memory_map to account for this.

Signed-off-by: default avatarPetr Tesarik <ptesarik@suse.cz>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 5611cc45

arch/ia64/kernel/setup.c

+19 −0
Original line number Original line Diff line number Diff line
@@ -220,6 +220,23 @@ sort_regions (struct rsvd_region *rsvd_region, int max) 
	}

	}

}

}





/* merge overlaps */

static int __init

merge_regions (struct rsvd_region *rsvd_region, int max)

{

	int i;

	for (i = 1; i < max; ++i) {

		if (rsvd_region[i].start >= rsvd_region[i-1].end)

			continue;

		if (rsvd_region[i].end > rsvd_region[i-1].end)

			rsvd_region[i-1].end = rsvd_region[i].end;

		--max;

		memmove(&rsvd_region[i], &rsvd_region[i+1],

			(max - i) * sizeof(struct rsvd_region));

	}

	return max;

}



/*

/*

 * Request address space for all standard resources

 * Request address space for all standard resources

 */

 */
@@ -270,6 +287,7 @@ static void __init setup_crashkernel(unsigned long total, int *n) 
	if (ret == 0 && size > 0) {

	if (ret == 0 && size > 0) {

		if (!base) {

		if (!base) {

			sort_regions(rsvd_region, *n);

			sort_regions(rsvd_region, *n);

			*n = merge_regions(rsvd_region, *n);

			base = kdump_find_rsvd_region(size,

			base = kdump_find_rsvd_region(size,

					rsvd_region, *n);

					rsvd_region, *n);

		}

		}
@@ -373,6 +391,7 @@ reserve_memory (void) 
	BUG_ON(IA64_MAX_RSVD_REGIONS + 1 < n);

	BUG_ON(IA64_MAX_RSVD_REGIONS + 1 < n);





	sort_regions(rsvd_region, num_rsvd_regions);

	sort_regions(rsvd_region, num_rsvd_regions);

	num_rsvd_regions = merge_regions(rsvd_region, num_rsvd_regions);

}

}