From b9a019899f61acca18df5fb5e38a8fcdfea86fcd Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Thu, 28 Jul 2016 19:38:07 +0100 Subject: 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: Emil Renner Berthing Signed-off-by: Nicolas Pitre Tested-by: Emil Renner Berthing Signed-off-by: Russell King --- arch/arm/mm/mmu.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) (limited to 'arch/arm/mm') diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 62f4d01941f7..12774c8e770c 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -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; } } -- cgit