From c06c10f6f3f0e5eae0f7690a7f7c5161b80bd943 Mon Sep 17 00:00:00 2001
From: hujun5 <hujun5@xiaomi.com>
Date: Wed, 24 Jan 2024 13:36:59 +0800
Subject: [PATCH] armv6/7/8-m: use ISB instruction immediately after the MSR
 instruction

when changing the stack pointer, software must use an
ISB instruction immediately after the MSR instruction.
This ensures that instructions after the ISB instruction
execute using the new stack pointer.

https://developer.arm.com/documentation/101928/0101/The-Cortex-M85-Processor--Reference-Material/Programmer-s-model/Core-registers/CONTROL-register?lang=en

" When changing the stack pointer, software must use an ISB instruction immediately after the MSR instruction. This ensures that instructions after the ISB instruction execute using the new stack pointer."

Signed-off-by: hujun5 <hujun5@xiaomi.com>
---
 arch/arm/src/armv6-m/arm_exception.S    | 4 ++++
 arch/arm/src/armv6-m/arm_initialstate.c | 2 ++
 arch/arm/src/armv7-m/arm_exception.S    | 1 +
 arch/arm/src/armv7-m/arm_initialstate.c | 2 ++
 arch/arm/src/armv8-m/arm_exception.S    | 1 +
 arch/arm/src/armv8-m/arm_initialstate.c | 2 ++
 6 files changed, 12 insertions(+)

diff --git a/arch/arm/src/armv6-m/arm_exception.S b/arch/arm/src/armv6-m/arm_exception.S
index 6408d4d1f1..22dea51a5a 100644
--- a/arch/arm/src/armv6-m/arm_exception.S
+++ b/arch/arm/src/armv6-m/arm_exception.S
@@ -100,6 +100,7 @@ exception_common:
 	mrs		r1, msp					/* R1=The main stack pointer */
 	subs		r1, #SW_XCPT_SIZE			/* R1=Beginning of context array on the stack */
 	msr		msp, r1					/* Reserved stack space */
+	isb		sy
 	b		2f
 
 1:
@@ -160,6 +161,7 @@ exception_common:
 	mov		r2, r1					/* Reserve signal context */
 	subs		r2, r2, #XCPTCONTEXT_SIZE
 	msr		msp, r2					/* We are using the main stack pointer */
+	isb		sy
 3:
 #endif
 
@@ -197,10 +199,12 @@ exception_common:
 	lsls		r0, #(31 - EXC_RETURN_PROCESS_BITNO)	/* Move to bit 31 */
 	bmi		4f					/* Test bit 31 */
 	msr		msp, r1					/* R1=The main stack pointer */
+	isb		sy
 	b		5f
 
 4:
 	msr		psp, r1					/* R1=The process stack pointer */
+	isb		sy
 
 5:
 
diff --git a/arch/arm/src/armv6-m/arm_initialstate.c b/arch/arm/src/armv6-m/arm_initialstate.c
index 129cd99d1b..979e77e3bf 100644
--- a/arch/arm/src/armv6-m/arm_initialstate.c
+++ b/arch/arm/src/armv6-m/arm_initialstate.c
@@ -168,6 +168,7 @@ noinline_function void arm_initialize_stack(void)
 
       "mov %1, sp\n"
       "msr psp, %1\n"
+      "isb sy\n"
 
       /* Select PSP */
 
@@ -179,6 +180,7 @@ noinline_function void arm_initialize_stack(void)
       /* Initialize MSP */
 
       "msr msp, %0\n"
+      "isb sy\n"
       :
       : "r" (stack), "r" (tempa), "r" (tempb)
       : "memory");
diff --git a/arch/arm/src/armv7-m/arm_exception.S b/arch/arm/src/armv7-m/arm_exception.S
index 809f3aad3d..d2478aadd2 100644
--- a/arch/arm/src/armv7-m/arm_exception.S
+++ b/arch/arm/src/armv7-m/arm_exception.S
@@ -138,6 +138,7 @@ exception_common:
 	mrs		r1, msp					/* R1=The main stack pointer (MSP) */
 	sub		r2, r1, #SW_XCPT_SIZE			/* Reserved stack space */
 	msr		msp, r2
+	isb		sy
 
 2:
 	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
diff --git a/arch/arm/src/armv7-m/arm_initialstate.c b/arch/arm/src/armv7-m/arm_initialstate.c
index 20510c9e95..1d4250edc8 100644
--- a/arch/arm/src/armv7-m/arm_initialstate.c
+++ b/arch/arm/src/armv7-m/arm_initialstate.c
@@ -190,6 +190,7 @@ noinline_function void arm_initialize_stack(void)
 
       "mov %1, sp\n"
       "msr psp, %1\n"
+      "isb sy\n"
 
       /* Select PSP */
 
@@ -201,6 +202,7 @@ noinline_function void arm_initialize_stack(void)
       /* Initialize MSP */
 
       "msr msp, %0\n"
+      "isb sy\n"
       :
       : "r" (stack), "r" (temp)
       : "memory");
diff --git a/arch/arm/src/armv8-m/arm_exception.S b/arch/arm/src/armv8-m/arm_exception.S
index 01ac94eb65..cd9cc92bc7 100644
--- a/arch/arm/src/armv8-m/arm_exception.S
+++ b/arch/arm/src/armv8-m/arm_exception.S
@@ -137,6 +137,7 @@ exception_common:
 	mrs		r1, msp					/* R1=The main stack pointer (MSP) */
 	sub		r2, r1, #SW_XCPT_SIZE			/* Reserve the stack space */
 	msr		msp, r2
+	isb		sy
 2:
 	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
 	add		r2, #HW_XCPT_SIZE			/* R2=MSP/PSP before the interrupt was taken */
diff --git a/arch/arm/src/armv8-m/arm_initialstate.c b/arch/arm/src/armv8-m/arm_initialstate.c
index c88e35ae79..ccbf494fa0 100644
--- a/arch/arm/src/armv8-m/arm_initialstate.c
+++ b/arch/arm/src/armv8-m/arm_initialstate.c
@@ -204,6 +204,7 @@ noinline_function void arm_initialize_stack(void)
       "mrs %1, msplim\n"
       "msr psplim, %1\n"
 #endif
+      "isb sy\n"
 
       /* Select PSP */
 
@@ -219,6 +220,7 @@ noinline_function void arm_initialize_stack(void)
 #ifdef CONFIG_ARMV8M_STACKCHECK_HARDWARE
       "msr msplim, %2\n"
 #endif
+      "isb sy\n"
       :
 #ifdef CONFIG_ARMV8M_STACKCHECK_HARDWARE
       : "r" (stack), "r" (temp), "r" (stacklim)