DynamIQ: Enable MMU without using stack
Having an active stack while enabling MMU has shown coherency problems.
This patch builds on top of translation library changes that introduces
MMU-enabling without using stacks.
Previously, with HW_ASSISTED_COHERENCY, data caches were disabled while
enabling MMU only because of active stack. Now that we can enable MMU
without using stack, we can enable both MMU and data caches at the same
time.
NOTE: Since this feature depends on using translation table library v2,
disallow using translation table library v1 with HW_ASSISTED_COHERENCY.
Fixes ARM-software/tf-issues#566
Change-Id: Ie55aba0c23ee9c5109eb3454cb8fa45d74f8bbb2
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/bl31/aarch64/bl31_entrypoint.S b/bl31/aarch64/bl31_entrypoint.S
index 0d1077c..58e8afb 100644
--- a/bl31/aarch64/bl31_entrypoint.S
+++ b/bl31/aarch64/bl31_entrypoint.S
@@ -170,15 +170,12 @@
* enter coherency (as CPUs already are); and there's no reason to have
* caches disabled either.
*/
- mov x0, #DISABLE_DCACHE
- bl bl31_plat_enable_mmu
-
#if HW_ASSISTED_COHERENCY || WARMBOOT_ENABLE_DCACHE_EARLY
- mrs x0, sctlr_el3
- orr x0, x0, #SCTLR_C_BIT
- msr sctlr_el3, x0
- isb
+ mov x0, xzr
+#else
+ mov x0, #DISABLE_DCACHE
#endif
+ bl bl31_plat_enable_mmu
bl psci_warmboot_entrypoint
diff --git a/bl32/sp_min/aarch32/entrypoint.S b/bl32/sp_min/aarch32/entrypoint.S
index 87ef3f3..d6853cc 100644
--- a/bl32/sp_min/aarch32/entrypoint.S
+++ b/bl32/sp_min/aarch32/entrypoint.S
@@ -298,20 +298,17 @@
* enter coherency (as CPUs already are); and there's no reason to have
* caches disabled either.
*/
+#if HW_ASSISTED_COHERENCY || WARMBOOT_ENABLE_DCACHE_EARLY
+ mov r0, #0
+#else
mov r0, #DISABLE_DCACHE
+#endif
bl bl32_plat_enable_mmu
#if SP_MIN_WITH_SECURE_FIQ
route_fiq_to_sp_min r0
#endif
-#if HW_ASSISTED_COHERENCY || WARMBOOT_ENABLE_DCACHE_EARLY
- ldcopr r0, SCTLR
- orr r0, r0, #SCTLR_C_BIT
- stcopr r0, SCTLR
- isb
-#endif
-
bl sp_min_warm_boot
bl smc_get_next_ctx
/* r0 points to `smc_ctx_t` */
diff --git a/docs/porting-guide.rst b/docs/porting-guide.rst
index a737cf4..5462cc1 100644
--- a/docs/porting-guide.rst
+++ b/docs/porting-guide.rst
@@ -1997,6 +1997,25 @@
(that was copied during ``bl31_early_platform_setup()``) if the image exists. It
should return NULL otherwise.
+Function : bl31_plat_enable_mmu [optional]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+ Argument : uint32_t
+ Return : void
+
+This function enables the MMU. The boot code calls this function with MMU and
+caches disabled. This function should program necessary registers to enable
+translation, and upon return, the MMU on the calling PE must be enabled.
+
+The function must honor flags passed in the first argument. These flags are
+defined by the translation library, and can be found in the file
+``include/lib/xlat_tables/xlat_mmu_helpers.h``.
+
+On DynamIQ systems, this function must not use stack while enabling MMU, which
+is how the function in xlat table library version 2 is implementated.
+
Function : plat\_get\_syscnt\_freq2() [mandatory]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index a40615d..68a74ed 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -454,6 +454,10 @@
management operations. This option defaults to 0 and if it is enabled,
then it implies ``WARMBOOT_ENABLE_DCACHE_EARLY`` is also enabled.
+ Note that, when ``HW_ASSISTED_COHERENCY`` is enabled, version 2 of
+ translation library (xlat tables v2) must be used; version 1 of translation
+ library is not supported.
+
- ``JUNO_AARCH32_EL3_RUNTIME``: This build flag enables you to execute EL3
runtime software in AArch32 mode, which is required to run AArch32 on Juno.
By default this flag is set to '0'. Enabling this flag builds BL1 and BL2 in
diff --git a/lib/xlat_tables/xlat_tables_private.h b/lib/xlat_tables/xlat_tables_private.h
index 50d6bd5..810c48e 100644
--- a/lib/xlat_tables/xlat_tables_private.h
+++ b/lib/xlat_tables/xlat_tables_private.h
@@ -11,6 +11,10 @@
#include <platform_def.h>
#include <xlat_tables_arch.h>
+#if HW_ASSISTED_COHERENCY
+#error xlat tables v2 must be used with HW_ASSISTED_COHERENCY
+#endif
+
/*
* If the platform hasn't defined a physical and a virtual address space size
* default to ADDR_SPACE_SIZE.
diff --git a/plat/common/aarch64/plat_common.c b/plat/common/aarch64/plat_common.c
index 409ae55..5f2972c 100644
--- a/plat/common/aarch64/plat_common.c
+++ b/plat/common/aarch64/plat_common.c
@@ -18,8 +18,6 @@
* provide typical implementations that may be re-used by multiple
* platforms but may also be overridden by a platform if required.
*/
-#pragma weak bl31_plat_enable_mmu
-#pragma weak bl32_plat_enable_mmu
#pragma weak bl31_plat_runtime_setup
#if !ERROR_DEPRECATED
#pragma weak plat_get_syscnt_freq2
@@ -33,16 +31,6 @@
#pragma weak plat_ea_handler
-void bl31_plat_enable_mmu(uint32_t flags)
-{
- enable_mmu_el3(flags);
-}
-
-void bl32_plat_enable_mmu(uint32_t flags)
-{
- enable_mmu_el1(flags);
-}
-
void bl31_plat_runtime_setup(void)
{
#if MULTI_CONSOLE_API
diff --git a/plat/common/aarch64/platform_helpers.S b/plat/common/aarch64/platform_helpers.S
index 033a12f..a413f5f 100644
--- a/plat/common/aarch64/platform_helpers.S
+++ b/plat/common/aarch64/platform_helpers.S
@@ -17,6 +17,8 @@
.weak plat_disable_acp
.weak bl1_plat_prepare_exit
.weak plat_panic_handler
+ .weak bl31_plat_enable_mmu
+ .weak bl32_plat_enable_mmu
#if !ENABLE_PLAT_COMPAT
.globl platform_get_core_pos
@@ -164,3 +166,23 @@
wfi
b plat_panic_handler
endfunc plat_panic_handler
+
+ /* -----------------------------------------------------
+ * void bl31_plat_enable_mmu(uint32_t flags);
+ *
+ * Enable MMU in BL31.
+ * -----------------------------------------------------
+ */
+func bl31_plat_enable_mmu
+ b enable_mmu_direct_el3
+endfunc bl31_plat_enable_mmu
+
+ /* -----------------------------------------------------
+ * void bl32_plat_enable_mmu(uint32_t flags);
+ *
+ * Enable MMU in BL32.
+ * -----------------------------------------------------
+ */
+func bl32_plat_enable_mmu
+ b enable_mmu_direct_el1
+endfunc bl32_plat_enable_mmu