From 309caa9cc6ff39d261264ec4ff10e29489afc8f8 Mon Sep 17 00:00:00 2001 From: Russell King <rmk+kernel@arm.linux.org.uk> Date: Mon, 21 Jun 2010 21:03:18 +0100 Subject: [PATCH] ARM: Prohibit ioremap() on kernel managed RAM ARMv6 and above have a restriction whereby aliasing virtual:physical mappings must not have differing memory type and sharability attributes. Strictly, this covers the memory type (strongly ordered, device, memory), cache attributes (uncached, write combine, write through, write back read alloc, write back write alloc) and the shared bit. However, using ioremap() and its variants on system RAM results in mappings which differ in these attributes from the main system RAM mapping. Other architectures which similar restrictions approch this problem in the same way - they do not permit ioremap on main system RAM. Make ARM behave in the same way, with a WARN_ON() such that users can be traced and an alternative approach found. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> --- arch/arm/mm/ioremap.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c index 28c8b950ef04..03f11935ed08 100644 --- a/arch/arm/mm/ioremap.c +++ b/arch/arm/mm/ioremap.c @@ -268,6 +268,12 @@ void __iomem * __arm_ioremap_pfn_caller(unsigned long pfn, if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SUPERSECTION_MASK)) return NULL; + /* + * Don't allow RAM to be mapped - this causes problems with ARMv6+ + */ + if (WARN_ON(pfn_valid(pfn))) + return NULL; + type = get_mem_type(mtype); if (!type) return NULL; -- 2.20.1