[ARM] 4497/1: Only allow safe cache configurations on ARMv6 and later
Currently, Linux doesn't generate correct page tables for ARMv6 and
later cores if the cache policy is different from the default one (it
may lead to strongly ordered or shared device mappings). This patch
disallows cache policies other than writeback and the
CPU_[ID]CACHE_DISABLE options only affect the CP15 system control
register rather than the page tables.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 3b5e47d..e5d61ee 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -114,6 +114,10 @@
}
if (i == ARRAY_SIZE(cache_policies))
printk(KERN_ERR "ERROR: unknown or unsupported cache policy\n");
+ if (cpu_architecture() >= CPU_ARCH_ARMv6) {
+ printk(KERN_WARNING "Only cachepolicy=writeback supported on ARMv6 and later\n");
+ cachepolicy = CPOLICY_WRITEBACK;
+ }
flush_cache_all();
set_cr(cr_alignment);
}
@@ -252,13 +256,15 @@
int cpu_arch = cpu_architecture();
int i;
+ if (cpu_arch < CPU_ARCH_ARMv6) {
#if defined(CONFIG_CPU_DCACHE_DISABLE)
- if (cachepolicy > CPOLICY_BUFFERED)
- cachepolicy = CPOLICY_BUFFERED;
+ if (cachepolicy > CPOLICY_BUFFERED)
+ cachepolicy = CPOLICY_BUFFERED;
#elif defined(CONFIG_CPU_DCACHE_WRITETHROUGH)
- if (cachepolicy > CPOLICY_WRITETHROUGH)
- cachepolicy = CPOLICY_WRITETHROUGH;
+ if (cachepolicy > CPOLICY_WRITETHROUGH)
+ cachepolicy = CPOLICY_WRITETHROUGH;
#endif
+ }
if (cpu_arch < CPU_ARCH_ARMv5) {
if (cachepolicy >= CPOLICY_WRITEALLOC)
cachepolicy = CPOLICY_WRITEBACK;