fix(embed/core): fix stack protection on STM32U5

[no changelog]

core/embed/boardloader/startup_stm32u5.s

@@ -7,7 +7,7 @@
 reset_handler:
   // set the stack protection
   ldr r0, =_sstack
-  add r0, r0, #16        // padding
+  add r0, r0, #128      // safety margin for the exception frame
   msr MSPLIM, r0
 
   bl SystemInit

core/embed/bootloader/startup_stm32u5.s

@@ -7,7 +7,7 @@
 reset_handler:
   // set the stack protection
   ldr r0, =_sstack
-  add r0, r0, #16        // padding
+  add r0, r0, #128       // safety margin for the exception frame
   msr MSPLIM, r0
 
   // setup environment for subsequent stage of code

core/embed/bootloader_ci/startup_stm32u5.s

@@ -7,7 +7,7 @@
 reset_handler:
   // set the stack protection
   ldr r0, =_sstack
-  add r0, r0, #16        // padding
+  add r0, r0, #128       // safety margin for the exception frame
   msr MSPLIM, r0
 
   // setup environment for subsequent stage of code

core/embed/firmware/startup_stm32u5.S

@@ -7,7 +7,7 @@
 reset_handler:
   // set the stack protection
   ldr r0, =_sstack
-  add r0, r0, #16        // padding
+  add r0, r0, #128       // safety margin for the exception frame
   msr MSPLIM, r0
 
   // setup environment for subsequent stage of code

core/embed/prodtest/startup_stm32u5.s

@@ -7,7 +7,7 @@
 reset_handler:
   // set the stack protection
   ldr r0, =_sstack
-  add r0, r0, #16        // padding
+  add r0, r0, #128       // safety margin for the exception frame
   msr MSPLIM, r0
 
   // setup environment for subsequent stage of code

core/embed/reflash/startup_stm32u5.s

@@ -7,7 +7,7 @@
 reset_handler:
   // set the stack protection
   ldr r0, =_sstack
-  add r0, r0, #16        // padding
+  add r0, r0, #128       // safety margin for the exception frame
   msr MSPLIM, r0
 
   // setup environment for subsequent stage of code