Add comments about mismatched TCR_ELx and xlat tables

When the MMU is enabled and the translation tables are mapped, data
read/writes to the translation tables are made using the attributes
specified in the translation tables themselves. However, the MMU
performs table walks with the attributes specified in TCR_ELx. They are
completely independent, so special care has to be taken to make sure
that they are the same.

This has to be done manually because it is not practical to have a test
in the code. Such a test would need to know the virtual memory region
that contains the translation tables and check that for all of the
tables the attributes match the ones in TCR_ELx. As the tables may not
even be mapped at all, this isn't a test that can be made generic.

The flags used by enable_mmu_xxx() have been moved to the same header
where the functions are.

Also, some comments in the linker scripts related to the translation
tables have been fixed.

Change-Id: I1754768bffdae75f53561b1c4a5baf043b45a304
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

diff --git a/bl1/bl1.ld.S b/bl1/bl1.ld.S
index e4c454b31a94c82db45d877002456539e97f8d94..26c0ae4b34cbf4d41021cec46f9eaba098a9533b 100644 (file)
--- a/bl1/bl1.ld.S
+++ b/bl1/bl1.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)

diff --git a/bl2/bl2.ld.S b/bl2/bl2.ld.S
index 4fe78f9e913301d651b18bbbc82c046afaec34f4..69c22eb328a72452e1d2397aba72164bc5dae31c 100644 (file)
--- a/bl2/bl2.ld.S
+++ b/bl2/bl2.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)

diff --git a/bl2/bl2_el3.ld.S b/bl2/bl2_el3.ld.S
index 57709e352bba5e1c1905b9554a0be14c9f45fe95..3728643caee3884f49f5c8dcbc46be18116565e2 100644 (file)
--- a/bl2/bl2_el3.ld.S
+++ b/bl2/bl2_el3.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)

diff --git a/bl2u/bl2u.ld.S b/bl2u/bl2u.ld.S
index da587172e380fbe460df03150f39f9464c196e19..7b97758d9b008e24dffe7afc5f4c84e7075dea0e 100644 (file)
--- a/bl2u/bl2u.ld.S
+++ b/bl2u/bl2u.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)

diff --git a/bl31/aarch64/bl31_entrypoint.S b/bl31/aarch64/bl31_entrypoint.S
index 419927d8eb2d43b4121c4d4348478f0bd185acea..e7d94b509ca7ca29c428dbec0c33863450c72091 100644 (file)
--- a/bl31/aarch64/bl31_entrypoint.S
+++ b/bl31/aarch64/bl31_entrypoint.S
@@ -1,5 +1,5 @@
 /*
- * 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
  */
@@ -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

diff --git a/bl31/bl31.ld.S b/bl31/bl31.ld.S
index dd046c43197b199686decbe608e4f7eda58f393f..c6a4fe49930ba22b462d1aa7b1305d6ad36570fe 100644 (file)
--- a/bl31/bl31.ld.S
+++ b/bl31/bl31.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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

diff --git a/bl32/sp_min/sp_min.ld.S b/bl32/sp_min/sp_min.ld.S
index e798a0d38e3d2d03d80ce9acf8ff81e8d1825e4f..71de883975e3d91db70c205683b86222967436c9 100644 (file)
--- a/bl32/sp_min/sp_min.ld.S
+++ b/bl32/sp_min/sp_min.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)

diff --git a/bl32/tsp/tsp.ld.S b/bl32/tsp/tsp.ld.S
index d256b46c8699cc4c3dc745df4de47a011033311d..31c5a67e04b55f9540cbf70c5f8c76b5f726f61b 100644 (file)
--- a/bl32/tsp/tsp.ld.S
+++ b/bl32/tsp/tsp.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)

diff --git a/include/lib/xlat_tables/xlat_mmu_helpers.h b/include/lib/xlat_tables/xlat_mmu_helpers.h
index fd3efc3f16e05802c13e3bb205554e3b467b50ac..d83d7640fd0b66d8b9519d194daa45aeda3fd5b4 100644 (file)
--- a/include/lib/xlat_tables/xlat_mmu_helpers.h
+++ b/include/lib/xlat_tables/xlat_mmu_helpers.h
@@ -1,5 +1,5 @@
 /*
- * 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__ */

diff --git a/include/lib/xlat_tables/xlat_tables_defs.h b/include/lib/xlat_tables/xlat_tables_defs.h
index 3a7f2456b1df05d6be36e5b10ee8c5d908e9d632..1c84fe07e9bc52c4862d4eb46ca8d3d6e3a9d81f 100644 (file)
--- a/include/lib/xlat_tables/xlat_tables_defs.h
+++ b/include/lib/xlat_tables/xlat_tables_defs.h
@@ -1,5 +1,5 @@
 /*
- * 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__ */

diff --git a/plat/mediatek/mt6795/bl31.ld.S b/plat/mediatek/mt6795/bl31.ld.S
index eacb1b27f0d93992b84188c4ae5d0875f3ba435c..0fbd3f78549b952b0b0c405a550c5cc7f58d695d 100644 (file)
--- a/plat/mediatek/mt6795/bl31.ld.S
+++ b/plat/mediatek/mt6795/bl31.ld.S
@@ -1,5 +1,5 @@
 /*
- * 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)