At the moment, on MMU system, enable_mm() will return to an address in
the 1:1 mapping, then each path is responsible to switch to virtual runtime
mapping. Then remove_identity_mapping() is called to remove all 1:1 mapping.
Since remove_identity_mapping() is not necessary on MPU system, and we also
avoid creating empty function for MPU system, trying to keep only one codeflow
in arm64/head.S, we move path switch and remove_identity_mapping() in
enable_mm() on MMU system.
Signed-off-by: Penny Zheng <penny.zh...@arm.com>
Signed-off-by: Wei Chen <wei.c...@arm.com>
---
xen/arch/arm/arm64/head.S | 28 +++++++++++++---------------
xen/arch/arm/arm64/head_mmu.S | 33 ++++++++++++++++++++++++++++++---
2 files changed, 43 insertions(+), 18 deletions(-)
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index a92883319d..6358305f03 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -258,20 +258,15 @@ real_start_efi:
* and memory regions for MPU systems.
*/
bl prepare_early_mappings
+ /*
+ * Address in the runtime mapping to jump to after the
+ * MMU/MPU is enabled
+ */
+ ldr lr, =primary_switched
/* Turn on MMU or MPU */
- bl enable_mm
+ b enable_mm
- /* We are still in the 1:1 mapping. Jump to the runtime Virtual
Address. */
- ldr x0, =primary_switched
- br x0
primary_switched:
- /*
- * The 1:1 map may clash with other parts of the Xen virtual memory
- * layout. As it is not used anymore, remove it completely to
- * avoid having to worry about replacing existing mapping
- * afterwards.
- */
- bl remove_identity_mapping
bl setup_early_uart
#ifdef CONFIG_EARLY_PRINTK
/* Use a virtual address to access the UART. */
@@ -317,11 +312,14 @@ GLOBAL(init_secondary)
bl check_cpu_mode
bl cpu_init
bl prepare_early_mappings
- bl enable_mm
- /* We are still in the 1:1 mapping. Jump to the runtime Virtual
Address. */
- ldr x0, =secondary_switched
- br x0
+ /*
+ * Address in the runtime mapping to jump to after the
+ * MMU/MPU is enabled
+ */
+ ldr lr, =secondary_switched
+ b enable_mm
+
secondary_switched:
/*
* Non-boot CPUs need to move on to the proper pagetables, which were
diff --git a/xen/arch/arm/arm64/head_mmu.S b/xen/arch/arm/arm64/head_mmu.S
index a19b7c873d..c9e83bbe2d 100644
--- a/xen/arch/arm/arm64/head_mmu.S
+++ b/xen/arch/arm/arm64/head_mmu.S
@@ -211,9 +211,11 @@ virtphys_clash:
ENDPROC(prepare_early_mappings)
/*
- * Turn on the Data Cache and the MMU. The function will return on the 1:1
- * mapping. In other word, the caller is responsible to switch to the runtime
- * mapping.
+ * Turn on the Data Cache and the MMU. The function will return
+ * to the virtual address provided in LR (e.g. the runtime mapping).
+ *
+ * Inputs:
+ * lr(x30): Virtual address to return to
*
* Clobbers x0 - x3
*/
@@ -238,6 +240,31 @@ ENTRY(enable_mm)
dsb sy /* Flush PTE writes and finish reads */
msr SCTLR_EL2, x0 /* now paging is enabled */
isb /* Now, flush the icache */
+
+ /*
+ * The MMU is turned on and we are in the 1:1 mapping. Switch
+ * to the runtime mapping.
+ */
+ ldr x0, =1f
+ br x0
+1:
+ /*
+ * The 1:1 map may clash with other parts of the Xen virtual memory
+ * layout. As it is not used anymore, remove it completely to
+ * avoid having to worry about replacing existing mapping
+ * afterwards.
+ *
+ * On return this will jump to the virtual address requested by
+ * the caller
+ */
+ b remove_identity_mapping
+
+ /*
+ * Here might not be reached, as "ret" in remove_identity_mapping
+ * will use the return address in LR in advance. But keep ret here
+ * might be more safe if "ret" in remove_identity_mapping is removed
+ * in future.
+ */
ret
ENDPROC(enable_mm)
--
2.25.1
