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Re: [PATCH] xen/arm64: head.S: Fix wrong enable_boot_cpu_mm() code movement
- To: Henry Wang <Henry.Wang@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Ayan Kumar Halder <ayankuma@xxxxxxx>
- Date: Thu, 21 Sep 2023 15:00:45 +0100
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Wei Chen <wei.chen@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Julien Grall <jgrall@xxxxxxxxxx>
- Delivery-date: Thu, 21 Sep 2023 14:01:04 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 16/09/2023 05:06, Henry Wang wrote:
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Some addressed comments on enable_boot_cpu_mm() were reintroduced
back during the code movement from arm64/head.S to arm64/mmu/head.S.
We should drop the unreachable code, move the 'mov lr, x5' closer to
'b remove_identity_mapping' so it is clearer that it will return,
and update the in-code comment accordingly.
Fixes: 6734327d76be ("xen/arm64: Split and move MMU-specific head.S to
mmu/head.S")
Reported-by: Julien Grall <jgrall@xxxxxxxxxx>
Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx>
Reviewed-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
---
xen/arch/arm/arm64/mmu/head.S | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
diff --git a/xen/arch/arm/arm64/mmu/head.S b/xen/arch/arm/arm64/mmu/head.S
index a5271e3880..88075ef083 100644
--- a/xen/arch/arm/arm64/mmu/head.S
+++ b/xen/arch/arm/arm64/mmu/head.S
@@ -329,7 +329,6 @@ ENTRY(enable_boot_cpu_mm)
load_paddr x0, boot_pgtable
bl enable_mmu
- mov lr, x5
/*
* The MMU is turned on and we are in the 1:1 mapping. Switch
@@ -338,19 +337,15 @@ ENTRY(enable_boot_cpu_mm)
ldr x0, =1f
br x0
1:
+ mov lr, x5
/*
* 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. Function will return to primary_switched.
+ * afterwards. Function will return to the virtual address requested
+ * by the caller.
*/
b remove_identity_mapping
-
- /*
- * Below is supposed to be unreachable code, as "ret" in
- * remove_identity_mapping will use the return address in LR in
advance.
- */
- b fail
ENDPROC(enable_boot_cpu_mm)
/*
--
2.25.1
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