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Commit b9a01989 authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Russell King
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ARM: 8590/1: sanity_check_meminfo(): avoid overflow on vmalloc_limit 



To limit the amount of mapped low memory, we determine a physical address
boundary based on the start of the vmalloc area using __pa().
Strictly speaking, the vmalloc area location is arbitrary and does not
necessarily corresponds to a valid physical address. For example, if

	PAGE_OFFSET = 0x80000000
	PHYS_OFFSET = 0x90000000
	vmalloc_min = 0xf0000000

then __pa(vmalloc_min) overflows and returns a wrapped 0 when phys_addr_t
is a 32-bit type. Then the code that follows determines that the entire
physical memory is above that boundary and no low memory gets mapped at
all:

|[...]
|Machine model: Freescale i.MX51 NA04 Board
|Ignoring RAM at 0x90000000-0xb0000000 (!CONFIG_HIGHMEM)
|Consider using a HIGHMEM enabled kernel.

To avoid this problem let's make vmalloc_limit a 64-bit value all the
time and determine that boundary explicitly without using __pa().

Reported-by: default avatarEmil Renner Berthing <kernel@esmil.dk>
Signed-off-by: default avatarNicolas Pitre <nico@linaro.org>
Tested-by: default avatarEmil Renner Berthing <kernel@esmil.dk>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 29b4817d

arch/arm/mm/mmu.c

+14 −4
Original line number Diff line number Diff line
@@ -1155,10 +1155,19 @@ void __init sanity_check_meminfo(void) 
{

	phys_addr_t memblock_limit = 0;

	int highmem = 0;

	phys_addr_t vmalloc_limit = __pa(vmalloc_min - 1) + 1;

	u64 vmalloc_limit;

	struct memblock_region *reg;

	bool should_use_highmem = false;



	/*

	 * Let's use our own (unoptimized) equivalent of __pa() that is

	 * not affected by wrap-arounds when sizeof(phys_addr_t) == 4.

	 * The result is used as the upper bound on physical memory address

	 * and may itself be outside the valid range for which phys_addr_t

	 * and therefore __pa() is defined.

	 */

	vmalloc_limit = (u64)(uintptr_t)vmalloc_min - PAGE_OFFSET + PHYS_OFFSET;



	for_each_memblock(memory, reg) {

		phys_addr_t block_start = reg->base;

		phys_addr_t block_end = reg->base + reg->size;
@@ -1183,10 +1192,11 @@ void __init sanity_check_meminfo(void) 
			if (reg->size > size_limit) {

				phys_addr_t overlap_size = reg->size - size_limit;



				pr_notice("Truncating RAM at %pa-%pa to -%pa",

					  &block_start, &block_end, &vmalloc_limit);

				memblock_remove(vmalloc_limit, overlap_size);

				pr_notice("Truncating RAM at %pa-%pa",

					  &block_start, &block_end);

				block_end = vmalloc_limit;

				pr_cont(" to -%pa", &block_end);

				memblock_remove(vmalloc_limit, overlap_size);

				should_use_highmem = true;

			}

		}