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From 3e7cfbe39a2a053d2a6b0d928cc172ed9d1c6da8 Mon Sep 17 00:00:00 2001
From: Jaxson Han <jaxson.han@arm.com>
Date: Tue, 25 May 2021 07:25:00 +0100
Subject: [PATCH] aarch64: Rename labels and prepare for lower EL booting
Prepare for booting from lower EL. Rename *_el3 relavant labels with
*_el_max and *_no_el3 with *_keep_el. Since the original _no_el3 means
"We neither do init sequence at this highest EL nor drop to lower EL
when entering to kernel", we rename it with _keep_el to make it more
clear for lower EL initialisation.
Upstream-Status: Pending
Signed-off-by: Jaxson Han <jaxson.han@arm.com>
---
arch/aarch64/boot.S | 28 ++++++++++++++++++++--------
arch/aarch64/psci.S | 9 +++++----
arch/aarch64/spin.S | 4 ++--
3 files changed, 27 insertions(+), 14 deletions(-)
diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S
index 27ba449..84e1646 100644
--- a/arch/aarch64/boot.S
+++ b/arch/aarch64/boot.S
@@ -21,18 +21,30 @@ ASM_FUNC(_start)
/*
* EL3 initialisation
+ * Boot sequence
+ * If CurrentEL == EL3, then goto EL3 initialisation and drop to
+ * lower EL before entering the kernel.
+ * Else, no initialisation and keep the current EL before
+ * entering the kernel.
*/
mrs x0, CurrentEL
cmp x0, #CURRENTEL_EL3
- b.eq 1f
+ b.eq el3_init
+ /*
+ * We stay in the current EL for entering the kernel
+ */
mov w0, #1
- ldr x1, =flag_no_el3
+ ldr x1, =flag_keep_el
str w0, [x1]
- b start_no_el3
+ b start_keep_el
-1: mov x0, #0x30 // RES1
+ /*
+ * EL3 initialisation
+ */
+el3_init:
+ mov x0, #0x30 // RES1
orr x0, x0, #(1 << 0) // Non-secure EL1
orr x0, x0, #(1 << 8) // HVC enable
@@ -124,7 +136,7 @@ ASM_FUNC(_start)
bl gic_secure_init
- b start_el3
+ b start_el_max
err_invalid_id:
b .
@@ -151,7 +163,7 @@ ASM_FUNC(jump_kernel)
bl find_logical_id
bl setup_stack // Reset stack pointer
- ldr w0, flag_no_el3
+ ldr w0, flag_keep_el
cmp w0, #0 // Prepare Z flag
mov x0, x20
@@ -160,7 +172,7 @@ ASM_FUNC(jump_kernel)
mov x3, x23
b.eq 1f
- br x19 // No EL3
+ br x19 // Keep current EL
1: mov x4, #SPSR_KERNEL
@@ -178,5 +190,5 @@ ASM_FUNC(jump_kernel)
.data
.align 3
-flag_no_el3:
+flag_keep_el:
.long 0
diff --git a/arch/aarch64/psci.S b/arch/aarch64/psci.S
index 8bd224b..7b8919a 100644
--- a/arch/aarch64/psci.S
+++ b/arch/aarch64/psci.S
@@ -79,7 +79,7 @@ smc_exit:
ldp x18, x19, [sp], #16
eret
-ASM_FUNC(start_el3)
+ASM_FUNC(start_el_max)
ldr x0, =vector
bl setup_vector
@@ -89,10 +89,11 @@ ASM_FUNC(start_el3)
b psci_first_spin
/*
- * This PSCI implementation requires EL3. Without EL3 we'll only boot the
- * primary cpu, all others will be trapped in an infinite loop.
+ * This PSCI implementation requires the highest EL(EL3 or Armv8-R EL2).
+ * Without the highest EL, we'll only boot the primary cpu, all othersr
+ * will be trapped in an infinite loop.
*/
-ASM_FUNC(start_no_el3)
+ASM_FUNC(start_keep_el)
cpuid x0, x1
bl find_logical_id
cbz x0, psci_first_spin
diff --git a/arch/aarch64/spin.S b/arch/aarch64/spin.S
index 1ea1c0b..bfb1d47 100644
--- a/arch/aarch64/spin.S
+++ b/arch/aarch64/spin.S
@@ -12,8 +12,8 @@
.text
-ASM_FUNC(start_el3)
-ASM_FUNC(start_no_el3)
+ASM_FUNC(start_el_max)
+ASM_FUNC(start_keep_el)
cpuid x0, x1
bl find_logical_id
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