libgloss: aarch64: Add support for Armv8-R AArch64

This patch adds support for Armv8-R AArch64.

Armv8-R AArch64 has no EL3, so we don't set vbar_el3, and adjust the
code to set up the MPU for Armv8-R.  So build a different flavour of the
startup code to support that.

We also add a specs file that uses this alternative startup code which
can be used with Armv8-R AArch64 models.

libgloss/aarch64/Makefile.in

@@ -85,7 +85,8 @@ RDIMON_BSP	= librdimon${${MULTILIBNAME}}.a
 RDIMON_OBJS	= $(patsubst %,rdimon-%,$(OBJS))
 RDIMON_SCRIPTS	= rdimon${${MULTILIBNAME}}.specs \
 		  aem-ve${${MULTILIBNAME}}.specs \
-		  aem-validation${${MULTILIBNAME}}.specs
+		  aem-validation${${MULTILIBNAME}}.specs \
+		  aem-v8-r${${MULTILIBNAME}}.specs
 RDIMON_INSTALL	= install-rdimon
 
 CFLAGS		= -g

libgloss/aarch64/cpu-init/Makefile.in

@@ -62,7 +62,7 @@ AR = @AR@
 LD = @LD@
 RANLIB = @RANLIB@
 
-CPU_INIT_OBJS = rdimon-aem-el3.o
+CPU_INIT_OBJS = rdimon-aem-el3.o rdimon-aem-v8-r.o
 CPU_INIT_INSTALL = install-cpu-init
 
 CFLAGS		= -g
@@ -79,10 +79,12 @@ all: ${CPU_INIT_OBJS}
 .PHONY: test
 test:
 
-# Static pattern rule for assembling cpu init files to object files.
-${CPU_INIT_OBJS}: %.o: %.S
+rdimon-aem-el3.o : rdimon-aem-el3.S
 	$(CC) $(CFLAGS_FOR_TARGET) $(CFLAGS) $(INCLUDES) -DARM_RDI_MONITOR -o $@ -c $<
 
+rdimon-aem-v8-r.o : rdimon-aem-el3.S
+	$(CC) $(CFLAGS_FOR_TARGET) $(CFLAGS) $(INCLUDES) -DARM_RDI_MONITOR -DBUILD_FOR_R_PROFILE -o $@ -c $<
+
 clean mostlyclean:
 	rm -f a.out core *.i *.o *-test *.srec *.dis *.x
 

libgloss/aarch64/cpu-init/rdimon-aem-el3.S

@@ -43,7 +43,9 @@ _init_vectors:
         /* Installs a table of exception vectors to catch and handle all
            exceptions by terminating the process with a diagnostic.  */
 	adr	x0, vectors
+#ifndef BUILD_FOR_R_PROFILE
 	msr	vbar_el3, x0
+#endif
 	msr	vbar_el2, x0
 	msr	vbar_el1, x0
 	ret
@@ -110,6 +112,14 @@ vectors:
 	.text
 	.align 2
 _flat_map:
+#ifdef BUILD_FOR_R_PROFILE
+	mrs	x0, sctlr_el2
+	orr	x0, x0, #1         // SCTLR_EL2.M (enable MPU)
+	orr	x0, x0, #(1 << 17) // SCTLR_EL2.BR (background regions)
+	msr	sctlr_el2, x0
+	isb
+	ret
+#else
 	/* Page table setup (identity mapping).  */
 	adrp	x0, ttb
 	add	x0, x0, :lo12:ttb
@@ -173,6 +183,7 @@ _flat_map:
        isb
 .Lnosve:
 	ret
+#endif
 
 	.data
 	.align	12

libgloss/aarch64/elf-aem-v8-r.specs

@@ -0,0 +1,20 @@
+# elf-aem-v8-r.specs
+#
+# Spec file for AArch64 baremetal newlib, libgloss on Armv8-R with version 2 of
+# AngelAPI semi-hosting.
+
+%rename link old_link
+
+*link:
+-Ttext-segment 0x10000 %(old_link)
+
+%rename lib libc
+
+*libgloss:
+-lrdimon
+
+*lib:
+cpu-init/rdimon-aem-v8-r.o%s --start-group %(libc) %(libgloss) --end-group
+
+*startfile:
+crti%O%s crtbegin%O%s %{!pg:rdimon-crt0%O%s} %{pg:rdimon-crt0%O%s}