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authorRussell King <rmk+kernel@arm.linux.org.uk>2010-06-21 21:03:18 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2010-06-21 21:03:18 +0100
commit309caa9cc6ff39d261264ec4ff10e29489afc8f8 (patch)
tree7ade7d69461250a39fabcd8a79d885253c6fd299 /arch/arm/mm/ioremap.c
parent7e27d6e778cd87b6f2415515d7127eba53fe5d02 (diff)
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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>
Diffstat (limited to 'arch/arm/mm/ioremap.c')
-rw-r--r--arch/arm/mm/ioremap.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index 28c8b95..03f1193 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;
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