[XEN v1 2/4] xen/arm32: head.S: Introduce enable_{boot,secondary}_cpu_mm()

[Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>]

This is based on:-
"[PATCH v6 01/13] xen/arm64: head.S: Introduce enable_{boot,secondary}_cpu_mm()"
https://www.mail-archive.com/xen-devel@xxxxxxxxxxxxxxxxxxxx/msg151918.html

This is being done for Arm32 as MPU support will be added for Arm32 as well.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
---
 xen/arch/arm/arm32/head.S | 90 +++++++++++++++++++++++++++++----------
 1 file changed, 67 insertions(+), 23 deletions(-)

diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index 057c44a5a2..c0c425eac6 100644
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -201,13 +201,10 @@ past_zImage:
 
         bl    check_cpu_mode
         bl    cpu_init
-        bl    create_page_tables
+        ldr   lr, =primary_switched
+        b     enable_boot_cpu_mm
 
-        /* Address in the runtime mapping to jump to after the MMU is enabled 
*/
-        mov_w lr, primary_switched
-        b     enable_mmu
 primary_switched:
-        bl    setup_fixmap
 #ifdef CONFIG_EARLY_PRINTK
         /* Use a virtual address to access the UART. */
         mov_w r11, EARLY_UART_VIRTUAL_ADDRESS
@@ -249,27 +246,11 @@ GLOBAL(init_secondary)
 #endif
         bl    check_cpu_mode
         bl    cpu_init
-        bl    create_page_tables
 
-        /* Address in the runtime mapping to jump to after the MMU is enabled 
*/
         mov_w lr, secondary_switched
-        b     enable_mmu
-secondary_switched:
-        /*
-         * Non-boot CPUs need to move on to the proper pagetables, which were
-         * setup in prepare_secondary_mm.
-         *
-         * XXX: This is not compliant with the Arm Arm.
-         */
-        mov_w r4, init_ttbr          /* VA of HTTBR value stashed by CPU 0 */
-        ldrd  r4, r5, [r4]           /* Actual value */
-        dsb
-        mcrr  CP64(r4, r5, HTTBR)
-        dsb
-        isb
-        flush_xen_tlb_local r0
-        pt_enforce_wxn r0
+        b     enable_secondary_cpu_mm
 
+secondary_switched:
 #ifdef CONFIG_EARLY_PRINTK
         /* Use a virtual address to access the UART. */
         mov_w r11, EARLY_UART_VIRTUAL_ADDRESS
@@ -692,6 +673,69 @@ ready_to_switch:
         mov   pc, lr
 ENDPROC(switch_to_runtime_mapping)
 
+/*
+ * Enable mm (turn on the data cache and the MMU) for secondary CPUs.
+ * The function will return to the virtual address provided in LR (e.g. the
+ * runtime mapping).
+ *
+ * Inputs:
+ *   lr : Virtual address to return to.
+ *
+ * Clobbers r0 - r6
+ */
+enable_secondary_cpu_mm:
+        mov   r6, lr
+        bl    create_page_tables
+
+        mov_w lr, secondary_cpu_mmu_on
+        b     enable_mmu
+secondary_cpu_mmu_on:
+        /*
+         * Non-boot CPUs need to move on to the proper pagetables, which were
+         * setup in prepare_secondary_mm.
+         *
+         * XXX: This is not compliant with the Arm Arm.
+         */
+        mov_w r4, init_ttbr          /* VA of HTTBR value stashed by CPU 0 */
+        ldrd  r4, r5, [r4]           /* Actual value */
+        dsb
+        mcrr  CP64(r4, r5, HTTBR)
+        dsb
+        isb
+        flush_xen_tlb_local r0
+        pt_enforce_wxn r0
+        mov   lr, r6
+
+        /* Return to the virtual address requested by the caller. */
+        mov   pc, lr
+ENDPROC(enable_secondary_cpu_mm)
+
+/*
+ * Enable mm (turn on the data cache and the MMU) for the boot CPU.
+ * The function will return to the virtual address provided in LR (e.g. the
+ * runtime mapping).
+ *
+ * Inputs:
+ *   lr : Virtual address to return to.
+ *
+ * Clobbers r0 - r6
+ */
+enable_boot_cpu_mm:
+        mov   r6, lr
+        bl    create_page_tables
+
+        /* Address in the runtime mapping to jump to after the MMU is enabled 
*/
+        mov_w lr, boot_cpu_mmu_on
+        b     enable_mmu
+boot_cpu_mmu_on:
+        bl    setup_fixmap
+
+        mov   lr, r6
+
+        /* Return to the virtual address requested by the caller. */
+        mov   pc, lr
+ENDPROC(enable_boot_cpu_mm)
+
 /*
  * Remove the 1:1 map from the page-tables. It is not easy to keep track
  * where the 1:1 map was mapped, so we will look for the top-level entry
-- 
2.25.1