1 files changed, 43 insertions, 5 deletions

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 4722582b17b8..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>
 
@@ -687,13 +688,19 @@ __early_param("vmalloc=", early_vmalloc);
 
 static void __init sanity_check_meminfo(void)
 {
-	int i, j;
+	int i, j, highmem = 0;
 
 	for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
 		struct membank *bank = &meminfo.bank[j];
 		*bank = meminfo.bank[i];
 
 #ifdef CONFIG_HIGHMEM
+		if (__va(bank->start) > VMALLOC_MIN ||
+		    __va(bank->start) < (void *)PAGE_OFFSET)
+			highmem = 1;
+
+		bank->highmem = highmem;
+
 		/*
 		 * Split those memory banks which are partially overlapping
 		 * the vmalloc area greatly simplifying things later.
@@ -703,10 +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));
@@ -714,11 +717,14 @@ static void __init sanity_check_meminfo(void)
 				i++;
 				bank[1].size -= VMALLOC_MIN - __va(bank->start);
 				bank[1].start = __pa(VMALLOC_MIN - 1) + 1;
+				bank[1].highmem = highmem = 1;
 				j++;
 			}
 			bank->size = VMALLOC_MIN - __va(bank->start);
 		}
 #else
+		bank->highmem = highmem;
+
 		/*
 		 * Check whether this memory bank would entirely overlap
 		 * the vmalloc area.
@@ -747,6 +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;
 }