A branch in the success case can be avoided by inverting the branch
condition. At the same time, remove a pointless comment as Xen can only
run at EL2.
Lastly, document the behavior and the main registers usage within the
function.
Signed-off-by: Julien Grall <julien.gr...@arm.com>
Reviewed-by: Stefano Stabellini <sstabell...@kernel.org>
---
Changes in v2:
- Add Stefano's reviewed-by
---
xen/arch/arm/arm64/head.S | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/xen/arch/arm/arm64/head.S b/xen/arch/arm/arm64/head.S
index df797a1573..fbcc792ade 100644
--- a/xen/arch/arm/arm64/head.S
+++ b/xen/arch/arm/arm64/head.S
@@ -350,6 +350,13 @@ secondary_switched:
b launch
ENDPROC(init_secondary)
+/*
+ * Check if the CPU has been booted in Hypervisor mode.
+ * This function will never return when the CPU is booted in another mode
+ * than Hypervisor mode.
+ *
+ * Clobbers x0 - x5
+ */
check_cpu_mode:
PRINT("- Current EL ")
mrs x5, CurrentEL
@@ -359,15 +366,13 @@ check_cpu_mode:
/* Are we in EL2 */
cmp x5, #PSR_MODE_EL2t
ccmp x5, #PSR_MODE_EL2h, #0x4, ne
- b.eq el2 /* Yes */
-
+ b.ne 1f /* No */
+ ret
+1:
/* OK, we're boned. */
PRINT("- Xen must be entered in NS EL2 mode -\r\n")
PRINT("- Please update the bootloader -\r\n")
b fail
-
-el2: PRINT("- Xen starting at EL2 -\r\n")
- ret
ENDPROC(check_cpu_mode)
zero_bss:
--
2.11.0
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
