From: Julien Grall <jgr...@amazon.com>
At the moment, enable_mmu() will return to an address in the 1:1 mapping
and each path is responsible to switch to the runtime mapping.
In a follow-up patch, the behavior to switch to the runtime mapping
will become more complex. So to avoid more code/comment duplication,
move the switch in enable_mmu().
Lastly, take the opportunity to replace load from literal pool with
mov_w.
Signed-off-by: Julien Grall <jgr...@amazon.com>
---
Changes in v3:
- Fix typo in the commit message
Changes in v2:
- Patch added
---
xen/arch/arm/arm32/head.S | 50 +++++++++++++++++++++++----------------
1 file changed, 30 insertions(+), 20 deletions(-)
diff --git a/xen/arch/arm/arm32/head.S b/xen/arch/arm/arm32/head.S
index ce680be91be1..40c1d7502007 100644
--- a/xen/arch/arm/arm32/head.S
+++ b/xen/arch/arm/arm32/head.S
@@ -167,19 +167,11 @@ past_zImage:
bl check_cpu_mode
bl cpu_init
bl create_page_tables
- bl enable_mmu
- /* We are still in the 1:1 mapping. Jump to the runtime Virtual
Address. */
- mov_w r0, primary_switched
- mov pc, r0
+ /* Address in the runtime mapping to jump to after the MMU is enabled
*/
+ mov_w lr, primary_switched
+ b enable_mmu
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_fixmap
#ifdef CONFIG_EARLY_PRINTK
/* Use a virtual address to access the UART. */
@@ -223,12 +215,10 @@ GLOBAL(init_secondary)
bl check_cpu_mode
bl cpu_init
bl create_page_tables
- bl enable_mmu
-
- /* We are still in the 1:1 mapping. Jump to the runtime Virtual
Address. */
- mov_w r0, secondary_switched
- mov pc, r0
+ /* 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
@@ -523,9 +513,12 @@ virtphys_clash:
ENDPROC(create_page_tables)
/*
- * 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:
+ * r9 : paddr(start)
+ * lr : Virtual address to return to
*
* Clobbers r0 - r3
*/
@@ -551,7 +544,24 @@ enable_mmu:
dsb /* Flush PTE writes and finish reads */
mcr CP32(r0, HSCTLR) /* now paging is enabled */
isb /* Now, flush the icache */
- mov pc, lr
+
+ /*
+ * The MMU is turned on and we are in the 1:1 mapping. Switch
+ * to the runtime mapping.
+ */
+ mov_w r0, 1f
+ mov pc, r0
+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
ENDPROC(enable_mmu)
/*
--
2.38.1
