---

yaml
---
r: 166746
b: refs/heads/master
c: e616c59
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 9a0f6b4646a0acaf7f06fd2e02f10f303fe85d8f
+refs/heads/master: e616c591405c168f6dc3dfd1221e105adfe49b8d

trunk/arch/arm/include/asm/smp_plat.h

@@ -0,0 +1,16 @@
+/*
+ * ARM specific SMP header, this contains our implementation
+ * details.
+ */
+#ifndef __ASMARM_SMP_PLAT_H
+#define __ASMARM_SMP_PLAT_H
+
+#include <asm/cputype.h>
+
+/* all SMP configurations have the extended CPUID registers */
+static inline int tlb_ops_need_broadcast(void)
+{
+	return ((read_cpuid_ext(CPUID_EXT_MMFR3) >> 12) & 0xf) < 2;
+}
+
+#endif

trunk/arch/arm/kernel/smp.c

@@ -36,6 +36,7 @@
 #include <asm/tlbflush.h>
 #include <asm/ptrace.h>
 #include <asm/localtimer.h>
+#include <asm/smp_plat.h>
 
 /*
  * as from 2.5, kernels no longer have an init_tasks structure
@@ -586,12 +587,6 @@ struct tlb_args {
 	unsigned long ta_end;
 };
 
-/* all SMP configurations have the extended CPUID registers */
-static inline int tlb_ops_need_broadcast(void)
-{
-	return ((read_cpuid_ext(CPUID_EXT_MMFR3) >> 12) & 0xf) < 2;
-}
-
 static inline void ipi_flush_tlb_all(void *ignored)
 {
 	local_flush_tlb_all();

trunk/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));
@@ -756,6 +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;
 }