[bootwrapper PATCH v2 12/13] Rework bootmethod initialization

[Mark Rutland <mark.rutland@arm.com>]

We currently initialize the bootmethod late, in assembly code. This
requires us to maintain the el3/no_el3 distintion late into the boot
process, and means we cannot produce any helpful diagnostic when booted
at an unexpected exception level.

Rework things so that we initialize the bootmethod early, with a warning
when things are wrong. The el3/no_el3 distinction is now irrelevant to
the bootmethod code, and can be removed in subsequent patches.

When a boot-wrapper configured for PSCI is entered at EL2, a warning is
looged to the serial console as:

| Boot-wrapper v0.2
| Entered at EL2
| Memory layout:
| [0000000080000000..0000000080001f90] => boot-wrapper
| [000000008000fff8..0000000080010000] => mbox
| [0000000080200000..00000000822af200] => kernel
| [0000000088000000..0000000088002857] => dtb
|
| WARNING: PSCI could not be initialized. Boot may fail

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
---
 arch/aarch32/include/asm/cpu.h  |  1 +
 arch/aarch32/include/asm/psci.h | 28 ++++++++++++++++++++++++++++
 arch/aarch32/psci.S             |  8 +-------
 arch/aarch32/utils.S            |  9 ---------
 arch/aarch64/include/asm/psci.h | 28 ++++++++++++++++++++++++++++
 arch/aarch64/psci.S             | 21 ++-------------------
 arch/aarch64/spin.S             |  3 +++
 arch/aarch64/utils.S            |  9 ---------
 common/init.c                   |  7 ++++++-
 common/psci.c                   | 22 +++++++++++++++++++---
 include/boot.h                  |  2 ++
 11 files changed, 90 insertions(+), 48 deletions(-)
 create mode 100644 arch/aarch32/include/asm/psci.h
 create mode 100644 arch/aarch64/include/asm/psci.h

diff --git a/arch/aarch32/include/asm/cpu.h b/arch/aarch32/include/asm/cpu.h
index c1bce9a..3426075 100644
--- a/arch/aarch32/include/asm/cpu.h
+++ b/arch/aarch32/include/asm/cpu.h
@@ -63,6 +63,7 @@ static inline unsigned long read_cpsr(void)
 #define SCR		"p15, 0, %0, c1, c1, 0"
 #define NSACR		"p15, 0, %0, c1, c1, 2"
 #define ICIALLU		"p15, 0, %0, c7, c5, 0"
+#define MVBAR		"p15, 0, %0, c12, c0, 1"
 
 #define ICC_SRE		"p15, 6, %0, c12, c12, 5"
 #define ICC_CTLR	"p15, 6, %0, c12, c12, 4"
diff --git a/arch/aarch32/include/asm/psci.h b/arch/aarch32/include/asm/psci.h
new file mode 100644
index 0000000..50c7c70
--- /dev/null
+++ b/arch/aarch32/include/asm/psci.h
@@ -0,0 +1,28 @@
+/*
+ * arch/aarch64/include/asm/psci.h
+ *
+ * Copyright (C) 2021 ARM Limited. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE.txt file.
+ */
+#ifndef __ASM_AARCH64_PSCI_H
+#define __ASM_AARCH64_PSCI_H
+
+#include <cpu.h>
+#include <stdbool.h>
+
+extern char psci_vectors[];
+
+static inline bool cpu_init_psci_arch(void)
+{
+	if (read_cpsr_mode() != PSR_MON)
+		return false;
+
+	mcr(MVBAR, (unsigned long)psci_vectors);
+	isb();
+
+	return true;
+}
+
+#endif
diff --git a/arch/aarch32/psci.S b/arch/aarch32/psci.S
index e0d2972..cdc36b0 100644
--- a/arch/aarch32/psci.S
+++ b/arch/aarch32/psci.S
@@ -15,7 +15,7 @@
 
 	.section .vectors
 	.align 6
-smc_vectors:
+ASM_DATA(psci_vectors)
 	b	err_exception			@ Reset
 	b	err_exception			@ Undef
 	b	handle_smc			@ SMC
@@ -39,11 +39,5 @@ handle_smc:
 	movs	pc, lr
 
 ASM_FUNC(start_el3)
-	ldr	r0, =smc_vectors
-	blx	setup_vector
-	/* pass through */
-
 ASM_FUNC(start_no_el3)
-	cpuid	r0, r1
-	blx	find_logical_id
 	b	psci_first_spin
diff --git a/arch/aarch32/utils.S b/arch/aarch32/utils.S
index 5809f48..58279aa 100644
--- a/arch/aarch32/utils.S
+++ b/arch/aarch32/utils.S
@@ -35,12 +35,3 @@ ASM_FUNC(find_logical_id)
 	bx	lr
 3:	mov	r0, #MPIDR_INVALID
 	bx	lr
-
-/*
- * Setup EL3 vectors.
- * r0: vector address
- */
-ASM_FUNC(setup_vector)
-	mcr	p15, 0, r0, c12, c0, 1	@ MVBAR
-	isb
-	bx	lr
diff --git a/arch/aarch64/include/asm/psci.h b/arch/aarch64/include/asm/psci.h
new file mode 100644
index 0000000..491e685
--- /dev/null
+++ b/arch/aarch64/include/asm/psci.h
@@ -0,0 +1,28 @@
+/*
+ * arch/aarch64/include/asm/psci.h
+ *
+ * Copyright (C) 2021 ARM Limited. All rights reserved.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE.txt file.
+ */
+#ifndef __ASM_AARCH64_PSCI_H
+#define __ASM_AARCH64_PSCI_H
+
+#include <cpu.h>
+#include <stdbool.h>
+
+extern char psci_vectors[];
+
+static inline bool cpu_init_psci_arch(void)
+{
+	if (mrs(CurrentEL) != CURRENTEL_EL3)
+		return false;
+
+	msr(VBAR_EL3, (unsigned long)psci_vectors);
+	isb();
+
+	return true;
+}
+
+#endif
diff --git a/arch/aarch64/psci.S b/arch/aarch64/psci.S
index 8bd224b..d6ca2eb 100644
--- a/arch/aarch64/psci.S
+++ b/arch/aarch64/psci.S
@@ -19,7 +19,7 @@
 	.section .vectors, "w"
 
 	.align 11
-vector:
+ASM_DATA(psci_vectors)
 	// current EL, SP_EL0
 	ventry	err_exception	// synchronous
 	ventry	err_exception	// IRQ
@@ -80,22 +80,5 @@ smc_exit:
 	eret
 
 ASM_FUNC(start_el3)
-	ldr	x0, =vector
-	bl	setup_vector
-
-	/* only boot the primary cpu (entry 0 in the table) */
-	cpuid	x0, x1
-	bl	find_logical_id
-	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.
- */
 ASM_FUNC(start_no_el3)
-	cpuid	x0, x1
-	bl	find_logical_id
-	cbz	x0, psci_first_spin
-spin_dead:
-	wfe
-	b	spin_dead
+	b	psci_first_spin
diff --git a/arch/aarch64/spin.S b/arch/aarch64/spin.S
index 1ea1c0b..764c532 100644
--- a/arch/aarch64/spin.S
+++ b/arch/aarch64/spin.S
@@ -12,6 +12,9 @@
 
 	.text
 
+ASM_FUNC(cpu_init_bootmethod)
+	ret
+
 ASM_FUNC(start_el3)
 ASM_FUNC(start_no_el3)
 	cpuid	x0, x1
diff --git a/arch/aarch64/utils.S b/arch/aarch64/utils.S
index 85c7f8a..32393cc 100644
--- a/arch/aarch64/utils.S
+++ b/arch/aarch64/utils.S
@@ -32,12 +32,3 @@ ASM_FUNC(find_logical_id)
 	ret
 3:	mov	x0, #MPIDR_INVALID
 	ret
-
-/*
- * Setup EL3 vectors
- * x0: vector address
- */
-ASM_FUNC(setup_vector)
-	msr	VBAR_EL3, x0
-	isb
-	ret
diff --git a/common/init.c b/common/init.c
index fc74b9e..3c05ac3 100644
--- a/common/init.c
+++ b/common/init.c
@@ -6,6 +6,7 @@
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE.txt file.
  */
+#include <boot.h>
 #include <cpu.h>
 #include <platform.h>
 
@@ -44,7 +45,9 @@ void announce_arch(void);
 
 void cpu_init_bootwrapper(void)
 {
-	if (this_cpu_logical_id() == 0) {
+	unsigned int cpu = this_cpu_logical_id();
+
+	if (cpu == 0) {
 		init_uart();
 		announce_bootwrapper();
 		announce_arch();
@@ -52,4 +55,6 @@ void cpu_init_bootwrapper(void)
 		print_string("\r\n");
 		init_platform();
 	}
+
+	cpu_init_bootmethod(cpu);
 }
diff --git a/common/psci.c b/common/psci.c
index a0e8700..8af6870 100644
--- a/common/psci.c
+++ b/common/psci.c
@@ -12,8 +12,11 @@
 #include <bakery_lock.h>
 #include <boot.h>
 #include <cpu.h>
+#include <platform.h>
 #include <psci.h>
 
+#include <asm/psci.h>
+
 #ifndef CPU_IDS
 #error "No MPIDRs provided"
 #endif
@@ -78,12 +81,25 @@ long psci_call(unsigned long fid, unsigned long arg1, unsigned long arg2)
 	}
 }
 
-void __noreturn psci_first_spin(unsigned int cpu)
+void __noreturn psci_first_spin(void)
 {
-	if (cpu == MPIDR_INVALID)
-		while (1);
+	unsigned int cpu = this_cpu_logical_id();
 
 	first_spin(cpu, branch_table + cpu, PSCI_ADDR_INVALID);
 
 	unreachable();
 }
+
+void cpu_init_bootmethod(unsigned int cpu)
+{
+	if (cpu_init_psci_arch())
+		return;
+
+	if (cpu == 0) {
+		print_string("WARNING: PSCI could not be initialized. Boot may fail\r\n\r\n");
+		return;
+	}
+
+	while (1)
+		wfe();
+}
diff --git a/include/boot.h b/include/boot.h
index d75e013..10968f8 100644
--- a/include/boot.h
+++ b/include/boot.h
@@ -16,4 +16,6 @@ void __noreturn spin(unsigned long *mbox, unsigned long invalid, int is_entry);
 void __noreturn first_spin(unsigned int cpu, unsigned long *mbox,
 			   unsigned long invalid_addr);
 
+void cpu_init_bootmethod(unsigned int cpu);
+
 #endif
-- 
2.30.2


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