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-rw-r--r--arch/arm/mm/mmu.c39
1 files changed, 35 insertions, 4 deletions
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 4426ee67ceca..02243eeccf50 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -21,6 +21,7 @@
#include <asm/cachetype.h>
#include <asm/setup.h>
#include <asm/sizes.h>
+#include <asm/smp_plat.h>
#include <asm/tlb.h>
#include <asm/highmem.h>
@@ -709,10 +710,6 @@ static void __init sanity_check_meminfo(void)
if (meminfo.nr_banks >= NR_BANKS) {
printk(KERN_CRIT "NR_BANKS too low, "
"ignoring high memory\n");
- } else if (cache_is_vipt_aliasing()) {
- printk(KERN_CRIT "HIGHMEM is not yet supported "
- "with VIPT aliasing cache, "
- "ignoring high memory\n");
} else {
memmove(bank + 1, bank,
(meminfo.nr_banks - i) * sizeof(*bank));
@@ -726,6 +723,8 @@ static void __init sanity_check_meminfo(void)
bank->size = VMALLOC_MIN - __va(bank->start);
}
#else
+ bank->highmem = highmem;
+
/*
* Check whether this memory bank would entirely overlap
* the vmalloc area.
@@ -754,6 +753,38 @@ static void __init sanity_check_meminfo(void)
#endif
j++;
}
+#ifdef CONFIG_HIGHMEM
+ if (highmem) {
+ const char *reason = NULL;
+
+ if (cache_is_vipt_aliasing()) {
+ /*
+ * Interactions between kmap and other mappings
+ * make highmem support with aliasing VIPT caches
+ * rather difficult.
+ */
+ reason = "with VIPT aliasing cache";
+#ifdef CONFIG_SMP
+ } else if (tlb_ops_need_broadcast()) {
+ /*
+ * kmap_high needs to occasionally flush TLB entries,
+ * however, if the TLB entries need to be broadcast
+ * we may deadlock:
+ * kmap_high(irqs off)->flush_all_zero_pkmaps->
+ * flush_tlb_kernel_range->smp_call_function_many
+ * (must not be called with irqs off)
+ */
+ reason = "without hardware TLB ops broadcasting";
+#endif
+ }
+ if (reason) {
+ printk(KERN_CRIT "HIGHMEM is not supported %s, ignoring high memory\n",
+ reason);
+ while (j > 0 && meminfo.bank[j - 1].highmem)
+ j--;
+ }
+ }
+#endif
meminfo.nr_banks = j;
}