Merge pull request #1286 from antonio-nino-diaz-arm/an/mmu-mismatch

Clarify comments in xlat tables lib and fixes related to the TLB

bl1/bl1.ld.S

 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -129,7 +129,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)

bl2/bl2.ld.S

 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -108,7 +108,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)

bl2/bl2_el3.ld.S

 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -139,7 +139,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unnecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)

bl2u/bl2u.ld.S

 /*
- * Copyright (c) 2015-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -95,7 +95,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)

bl31/aarch64/bl31_entrypoint.S

@@ -9,7 +9,7 @@
 #include <el3_common_macros.S>
 #include <pmf_asm_macros.S>
 #include <runtime_instr.h>
-#include <xlat_tables_defs.h>
+#include <xlat_mmu_helpers.h>
 
 	.globl	bl31_entrypoint
 	.globl	bl31_warm_entrypoint

bl31/bl31.ld.S

 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -217,7 +217,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
 #if ENABLE_SPM

bl32/sp_min/sp_min.ld.S

 /*
- * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -176,7 +176,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)

bl32/tsp/tsp.ld.S

 /*
- * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -94,7 +94,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)

include/lib/xlat_tables/xlat_mmu_helpers.h

 /*
- * Copyright (c) 2014-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,13 +7,51 @@
 #ifndef __XLAT_MMU_HELPERS_H__
 #define __XLAT_MMU_HELPERS_H__
 
+/*
+ * The following flags are passed to enable_mmu_xxx() to override the default
+ * values used to program system registers while enabling the MMU.
+ */
+
+/*
+ * When this flag is used, all data access to Normal memory from this EL and all
+ * Normal memory accesses to the translation tables of this EL are non-cacheable
+ * for all levels of data and unified cache until the caches are enabled by
+ * setting the bit SCTLR_ELx.C.
+ */
+#define DISABLE_DCACHE			(U(1) << 0)
+
+/*
+ * Mark the translation tables as non-cacheable for the MMU table walker, which
+ * is a different observer from the PE/CPU. If the flag is not specified, the
+ * tables are cacheable for the MMU table walker.
+ *
+ * Note that, as far as the PE/CPU observer is concerned, the attributes used
+ * are the ones specified in the translation tables themselves. The MAIR
+ * register specifies the cacheability through the field AttrIndx of the lower
+ * attributes of the translation tables. The shareability is specified in the SH
+ * field of the lower attributes.
+ *
+ * The MMU table walker uses the attributes specified in the fields ORGNn, IRGNn
+ * and SHn of the TCR register to access the translation tables.
+ *
+ * The attributes specified in the TCR register and the tables can be different
+ * as there are no checks to prevent that. Special care must be taken to ensure
+ * that there aren't mismatches. The behaviour in that case is described in the
+ * sections 'Mismatched memory attributes' in the ARMv8 ARM.
+ */
+#define XLAT_TABLE_NC			(U(1) << 1)
+
+#ifndef __ASSEMBLY__
+
 #ifdef AARCH32
 /* AArch32 specific translation table API */
-void enable_mmu_secure(uint32_t flags);
+void enable_mmu_secure(unsigned int flags);
 #else
 /* AArch64 specific translation table APIs */
 void enable_mmu_el1(unsigned int flags);
 void enable_mmu_el3(unsigned int flags);
 #endif /* AARCH32 */
 
+#endif /* __ASSEMBLY__ */
+
 #endif /* __XLAT_MMU_HELPERS_H__ */

include/lib/xlat_tables/xlat_tables_defs.h

 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,6 +9,7 @@
 
 #include <arch.h>
 #include <utils_def.h>
+#include <xlat_mmu_helpers.h>
 
 /* Miscellaneous MMU related constants */
 #define NUM_2MB_IN_GB		(U(1) << 9)
@@ -165,16 +166,4 @@
 #define XN_SHIFT			54
 #define UXN_SHIFT			XN_SHIFT
 
-/*
- * Flags to override default values used to program system registers while
- * enabling the MMU.
- */
-#define DISABLE_DCACHE			(U(1) << 0)
-
-/*
- * This flag marks the translation tables are Non-cacheable for MMU accesses.
- * If the flag is not specified, by default the tables are cacheable.
- */
-#define XLAT_TABLE_NC			(U(1) << 1)
-
 #endif /* __XLAT_TABLES_DEFS_H__ */

lib/psci/aarch32/psci_helpers.S

 /*
- * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -91,6 +91,28 @@ func psci_do_pwrup_cache_maintenance
 	stcopr	r0, SCTLR
 	isb
 
+#if PLAT_XLAT_TABLES_DYNAMIC
+	/* ---------------------------------------------
+	 * During warm boot the MMU is enabled with data
+	 * cache disabled, then the interconnect is set
+	 * up and finally the data cache is enabled.
+	 *
+	 * During this period, if another CPU modifies
+	 * the translation tables, the MMU table walker
+	 * may read the old entries. This is only a
+	 * problem for dynamic regions, the warm boot
+	 * code isn't affected because it is static.
+	 *
+	 * Invalidate all TLB entries loaded while the
+	 * CPU wasn't coherent with the rest of the
+	 * system.
+	 * ---------------------------------------------
+	 */
+	stcopr	r0, TLBIALL
+	dsb	ish
+	isb
+#endif
+
 	pop	{r12, pc}
 endfunc psci_do_pwrup_cache_maintenance
 

lib/psci/aarch64/psci_helpers.S

 /*
- * Copyright (c) 2014-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -115,6 +115,28 @@ func psci_do_pwrup_cache_maintenance
 	msr	sctlr_el3, x0
 	isb
 
+#if PLAT_XLAT_TABLES_DYNAMIC
+	/* ---------------------------------------------
+	 * During warm boot the MMU is enabled with data
+	 * cache disabled, then the interconnect is set
+	 * up and finally the data cache is enabled.
+	 *
+	 * During this period, if another CPU modifies
+	 * the translation tables, the MMU table walker
+	 * may read the old entries. This is only a
+	 * problem for dynamic regions, the warm boot
+	 * code isn't affected because it is static.
+	 *
+	 * Invalidate all TLB entries loaded while the
+	 * CPU wasn't coherent with the rest of the
+	 * system.
+	 * ---------------------------------------------
+	 */
+	tlbi	alle3
+	dsb	ish
+	isb
+#endif
+
 	ldp	x29, x30, [sp], #16
 	ret
 endfunc psci_do_pwrup_cache_maintenance

plat/mediatek/mt6795/bl31.ld.S

 /*
- * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -132,7 +132,8 @@ SECTIONS
     /*
      * The xlat_table section is for full, aligned page tables (4K).
      * Removing them from .bss avoids forcing 4K alignment on
-     * the .bss section and eliminates the unecessary zero init
+     * the .bss section. The tables are initialized to zero by the translation
+     * tables library.
      */
     xlat_table (NOLOAD) : {
         *(xlat_table)