Setup VBAR_EL3 incrementally

This patch ensures that VBAR_EL3 points to the simple stack-less
'early_exceptions' when the C runtime stack is not correctly setup to
use the more complex 'runtime_exceptions'. It is initialised to
'runtime_exceptions' once this is done.

This patch also moves all exception vectors into a '.vectors' section
and modifies linker scripts to place all such sections together. This
will minimize space wastage from alignment restrictions.

Change-Id: I8c3e596ea3412c8bd582af9e8d622bb1cb2e049d

bl1/aarch64/early_exceptions.S

@@ -37,12 +37,12 @@
 	.globl	early_exceptions
 	.weak	display_boot_progress
 
-	.section	.text, "ax"; .align 11
+	.section	.vectors, "ax"; .align 11
 
 	/* -----------------------------------------------------
-	 * Very simple exception handlers used by BL1 and BL2.
-	 * Apart from one SMC exception all other traps loop
-	 * endlessly.
+	 * Very simple stackless exception handlers used by all
+	 * bootloader stages. BL31 uses them before stacks are
+	 * setup. BL1/BL2 use them throughout.
 	 * -----------------------------------------------------
 	 */
 	.align	7
@@ -164,6 +164,7 @@ SErrorA32:
 
 	.align	7
 
+	.section	.text, "ax"
 process_exception:
 	sub	sp, sp, #0x40
 	stp	x0, x1, [sp, #0x0]

bl1/bl1.ld.S

@@ -45,6 +45,7 @@ SECTIONS
         *bl1_entrypoint.o(.text)
         *(.text)
         *(.rodata*)
+        *(.vectors)
         __RO_END__ = .;
     } >ROM
 

bl2/bl2.ld.S

@@ -49,6 +49,7 @@ SECTIONS
         *bl2_entrypoint.o(.text)
         *(.text)
         *(.rodata*)
+        *(.vectors)
         __RO_END_UNALIGNED__ = .;
         /*
          * Memory page(s) mapped to this section will be marked as

bl31/aarch64/bl31_entrypoint.S

@@ -58,7 +58,7 @@ bl31_entrypoint: ; .type bl31_entrypoint, %function
 	 * Set the exception vector to something sane.
 	 * ---------------------------------------------
 	 */
-	adr	x1, runtime_exceptions
+	adr	x1, early_exceptions
 	msr	vbar_el3, x1
 
 	/* ---------------------------------------------------------------------
@@ -154,6 +154,14 @@ bl31_entrypoint: ; .type bl31_entrypoint, %function
 	mov	x0, x19
 	bl	platform_set_stack
 
+	/* ---------------------------------------------
+	 * Use the more complex exception vectors now
+	 * the stacks are setup.
+	 * ---------------------------------------------
+	 */
+	adr	x1, runtime_exceptions
+	msr	vbar_el3, x1
+
 	/* ---------------------------------------------
 	 * Use SP_EL0 to initialize BL31. It allows us
 	 * to jump to the next image without having to

bl31/aarch64/runtime_exceptions.S

@@ -37,8 +37,8 @@
 #include <asm_macros.S>
 
 
-	.section	.text, "ax"; .align 11
-	
+	.section	.vectors, "ax"; .align 11
+
 	.align	7
 runtime_exceptions:
 	/* -----------------------------------------------------

bl31/bl31.ld.S

@@ -50,6 +50,7 @@ SECTIONS
         *bl31_entrypoint.o(.text)
         *(.text)
         *(.rodata*)
+        *(.vectors)
         __RO_END_UNALIGNED__ = .;
         /*
          * Memory page(s) mapped to this section will be marked as read-only,

bl31/bl31.mk

@@ -62,7 +62,8 @@ BL31_OBJS		+=	bl31_arch_setup.o			\
 				spinlock.o				\
 				gic_v3_sysregs.o			\
 				bakery_lock.o				\
-				runtime_svc.o
+				runtime_svc.o				\
+				early_exceptions.o
 
 BL31_ENTRY_POINT	:=	bl31_entrypoint
 BL31_MAPFILE		:=	bl31.map

common/psci/psci_afflvl_on.c

@@ -353,7 +353,6 @@ static unsigned int psci_afflvl0_on_finish(unsigned long mpidr,
 	/*
 	 * Arch. management: Turn on mmu & restore architectural state
 	 */
-	write_vbar((unsigned long) runtime_exceptions);
 	enable_mmu();
 
 	/*

common/psci/psci_afflvl_suspend.c

@@ -115,7 +115,6 @@ static int psci_afflvl0_suspend(unsigned long mpidr,
 	psci_suspend_context[index].sec_sysregs.mair = read_mair();
 	psci_suspend_context[index].sec_sysregs.tcr = read_tcr();
 	psci_suspend_context[index].sec_sysregs.ttbr = read_ttbr0();
-	psci_suspend_context[index].sec_sysregs.vbar = read_vbar();
 	psci_suspend_context[index].sec_sysregs.pstate =
 		read_daif() & (DAIF_ABT_BIT | DAIF_DBG_BIT);
 
@@ -424,7 +423,6 @@ static unsigned int psci_afflvl0_suspend_finish(unsigned long mpidr,
 	 * Arch. management: Restore the stashed secure architectural
 	 * context in the right order.
 	 */
-	write_vbar(psci_suspend_context[index].sec_sysregs.vbar);
 	write_daif(read_daif() | psci_suspend_context[index].sec_sysregs.pstate);
 	write_mair(psci_suspend_context[index].sec_sysregs.mair);
 	write_tcr(psci_suspend_context[index].sec_sysregs.tcr);

common/psci/psci_entry.S

@@ -63,6 +63,17 @@ psci_aff_suspend_finish_entry:
 
 psci_aff_common_finish_entry:
 	adr	x22, psci_afflvl_power_on_finish
+
+	/* ---------------------------------------------
+	 * Exceptions should not occur at this point.
+	 * Set VBAR in order to handle and report any
+	 * that do occur
+	 * ---------------------------------------------
+	 */
+	adr	x0, early_exceptions
+	msr	vbar_el3, x0
+	isb
+
 	bl	read_mpidr
 	mov	x19, x0
 	bl	platform_set_coherent_stack
@@ -90,6 +101,16 @@ psci_aff_common_finish_entry:
 	mov	x0, x19
 	bl	platform_set_stack
 
+	/* ---------------------------------------------
+	 * Now that the execution stack has been set
+	 * up, enable full runtime exception handling.
+	 * Since we're just about to leave this EL with
+	 * ERET, we don't need an ISB here
+	 * ---------------------------------------------
+	 */
+	adr	x0, runtime_exceptions
+	msr	vbar_el3, x0
+
 	/* --------------------------------------------
 	 * Use the size of the general purpose register
 	 * context to restore the register state

include/aarch64/arch.h

@@ -326,7 +326,6 @@ typedef struct {
 	unsigned long mair;
 	unsigned long tcr;
 	unsigned long ttbr;
-	unsigned long vbar;
 	unsigned long pstate;
 } sysregs_context;