[PATCH v2 5/6] armv8: Simplify switch_el macro

Andre Przywara andre.przywara at arm.com
Fri Feb 11 12:29:38 CET 2022

The switch_el macro is a neat contraption to handle cases where we need
different code depending on the current exception level, but its
implementation was longer than needed.

Simplify it by doing just one comparison, then using the different
condition codes to branch to the desired target. PState.CurrentEL just
holds two bits, and since we don't care about EL0, we can use >, =, < to
select EL3, EL2 and EL1, respectively.

Signed-off-by: Andre Przywara <andre.przywara at arm.com>
 arch/arm/include/asm/macro.h | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/macro.h b/arch/arm/include/asm/macro.h
index ec0171e0e6..acd519020d 100644
--- a/arch/arm/include/asm/macro.h
+++ b/arch/arm/include/asm/macro.h
@@ -69,12 +69,10 @@ lr	.req	x30
 .macro	switch_el, xreg, el3_label, el2_label, el1_label
 	mrs	\xreg, CurrentEL
-	cmp	\xreg, 0xc
-	b.eq	\el3_label
-	cmp	\xreg, 0x8
+	cmp	\xreg, #0x8
+	b.gt	\el3_label
 	b.eq	\el2_label
-	cmp	\xreg, 0x4
-	b.eq	\el1_label
+	b.lt	\el1_label

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