commit 300c68da11fda3669d7b80b68dcd67b0b2082cbc
author Kevin Peng <kevin.peng@arm.com> Thu Aug 12 17:40:17 2021 +0800
committer Kevin Peng <kevin.peng@arm.com> Mon Sep 13 11:23:32 2021 +0800
tree a3e0cc35b8e7966b94631028d50f91c8c2f6a49e
parent e863e5ce570c9a76f633a765b22f1d608e24e75a

SPM: Use Main Stack for initialization

On reset, the Main Stack is used by default.
TF-M changes the stack to Processor Stack.

This patch remove the change to PSP in startup.s and:
- Rename the ARM_LIB_STACK to ER_INITIAL_PSP
- Rename the ARM_LIB_STACK_MSP to ARM_LIB_STACK
The renaming is to align the __main function of ARMClang where the
ARM_LIB_STACK is set to the current SP (MSP)

For Library Mode, the stacks are set to back to use PSP before entering
c code to avoid massive corresponding changes.

For FF-M implementations, this patch also:
- Seal the Main Stack before entering c code
- Manually free the Main Stack usage after initialization as the init
  function does not return

Change-Id: Ie1b6f2fca1f774c4812a89fa45bb039b16fe5af0
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
Co-authored-by: Summer Qin <summer.qin@arm.com>

secure_fw/spm/cmsis_func/main.c

diff --git a/secure_fw/spm/cmsis_func/main.c b/secure_fw/spm/cmsis_func/main.c
index c9ef011..4cbecd8 100644
--- a/secure_fw/spm/cmsis_func/main.c
+++ b/secure_fw/spm/cmsis_func/main.c
@@ -33,7 +33,7 @@
 #error Only TFM_LVL 1 is supported for library model!
 #endif
 
-REGION_DECLARE(Image$$, ARM_LIB_STACK_MSP,  $$ZI$$Base);
+REGION_DECLARE(Image$$, ARM_LIB_STACK,  $$ZI$$Base);
 
 static fih_int tfm_core_init(void)
 {
@@ -134,14 +134,33 @@
     FIH_RET(fih_int_encode(TFM_SUCCESS));
 }
 
+__attribute__((naked))
 int main(void)
 {
+    __ASM volatile(
+#if !defined(__ICCARM__)
+        ".syntax unified                               \n"
+#endif
+        "ldr     r0, =Image$$ARM_LIB_STACK$$ZI$$Limit  \n"
+        "msr     msp, r0                               \n"
+        "ldr     r0, =Image$$ER_INITIAL_PSP$$ZI$$Limit \n"
+        "msr     psp, r0                               \n"
+        "mrs     r0, control                           \n"
+        "movs    r1, #2                                \n"
+        "orrs    r0, r0, r1                            \n" /* Switch to PSP */
+        "msr     control, r0                           \n"
+        "bl      c_main                                \n"
+    );
+}
+
+int c_main(void)
+{
     enum spm_err_t spm_err = SPM_ERR_GENERIC_ERR;
     fih_int fih_rc = FIH_FAILURE;
 
     /* set Main Stack Pointer limit */
     tfm_arch_init_secure_msp((uint32_t)&REGION_NAME(Image$$,
-                                                    ARM_LIB_STACK_MSP,
+                                                    ARM_LIB_STACK,
                                                     $$ZI$$Base));
 
     /* Seal the PSP stacks viz ARM_LIB_STACK and TFM_SECURE_STACK */
@@ -167,9 +186,9 @@
 
     tfm_spm_partition_set_state(TFM_SP_CORE_ID, SPM_PARTITION_STATE_RUNNING);
 
-    REGION_DECLARE(Image$$, ARM_LIB_STACK, $$ZI$$Base)[];
+    REGION_DECLARE(Image$$, ER_INITIAL_PSP, $$ZI$$Base)[];
     uint32_t psp_stack_bottom =
-                      (uint32_t)REGION_NAME(Image$$, ARM_LIB_STACK, $$ZI$$Base);
+                      (uint32_t)REGION_NAME(Image$$, ER_INITIAL_PSP, $$ZI$$Base);
 
     tfm_arch_set_psplim(psp_stack_bottom);
 
@@ -206,4 +225,6 @@
 #endif
 
     jump_to_ns_code();
+
+    return 0;
 }