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authorNicolas Pitre <nicolas.pitre@linaro.org>2016-07-28 20:38:07 +0200
committerRussell King <rmk+kernel@armlinux.org.uk>2016-08-09 23:57:40 +0200
commitb9a019899f61acca18df5fb5e38a8fcdfea86fcd (patch)
treeb82cffdfbc870cf30555cfe57459559d62a60eee /arch/arm/mm/mmu.c
parentLinux 4.8-rc1 (diff)
downloadlinux-b9a019899f61acca18df5fb5e38a8fcdfea86fcd.tar.xz
linux-b9a019899f61acca18df5fb5e38a8fcdfea86fcd.zip
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 <kernel@esmil.dk> Signed-off-by: Nicolas Pitre <nico@linaro.org> Tested-by: Emil Renner Berthing <kernel@esmil.dk> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mm/mmu.c')
-rw-r--r--arch/arm/mm/mmu.c18
1 files changed, 14 insertions, 4 deletions
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;
}
}