[PATCH] libgloss/aarch64: Add support for Armv8-R AArch64

[Alex Coplan]

Hello,

This patch adds support for Armv8-R AArch64. We update the AArch64 CPU
boot code to work on Armv8-R if __ARM_ARCH_PROFILE is set to 'R'.
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.

We also add a specs file for use with Armv8-R AArch64 models.

Testing:
 * Ran AArch64 GCC testsuite using --with-arch=armv8-r together with the
   new specs file and boot code in an Armv8-R AArch64 model.
 * Ran newlib testsuite, no regressions.

OK for master?

Thanks,
Alex

---

2020-09-18  Alex Coplan  <alex.coplan@arm.com>

libgloss/ChangeLog:

	* aarch64/Makefile.in: Install new specs file.
	* aarch64/cpu-init/Makefile.in: Also build boot code for Armv8-R.
	* aarch64/cpu-init/rdimon-aem-el3.S: Add support for Armv8-R.
	* aarch64/elf-aem-v8-r.specs: New.
-------------- next part --------------
diff --git a/libgloss/aarch64/Makefile.in b/libgloss/aarch64/Makefile.in
index 546557e3c..b8c2ca43c 100644
--- a/libgloss/aarch64/Makefile.in
+++ b/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
diff --git a/libgloss/aarch64/cpu-init/Makefile.in b/libgloss/aarch64/cpu-init/Makefile.in
index 08aa1760f..3ada50d64 100644
--- a/libgloss/aarch64/cpu-init/Makefile.in
+++ b/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 +79,15 @@ 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
+	# Force the ACLE macro __ARM_ARCH_PROFILE='R'. This should be defined by
+	# the compiler for compilers supporting -march=armv8-r on AArch64 but we
+	# want to be able to build this code with older compilers.
+	$(CC) $(CFLAGS_FOR_TARGET) $(CFLAGS) $(INCLUDES) -DARM_RDI_MONITOR -D__ARM_ARCH_PROFILE=82 -o $@ -c $<
+
 clean mostlyclean:
 	rm -f a.out core *.i *.o *-test *.srec *.dis *.x
 
diff --git a/libgloss/aarch64/cpu-init/rdimon-aem-el3.S b/libgloss/aarch64/cpu-init/rdimon-aem-el3.S
index e00f0b2c8..93dcdb353 100644
--- a/libgloss/aarch64/cpu-init/rdimon-aem-el3.S
+++ b/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
+#if __ARM_ARCH_PROFILE != 'R'
 	msr	vbar_el3, x0
+#endif
 	msr	vbar_el2, x0
 	msr	vbar_el1, x0
 	ret
@@ -110,6 +112,14 @@ vectors:
 	.text
 	.align 2
 _flat_map:
+#if __ARM_ARCH_PROFILE == 'R'
+	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
diff --git a/libgloss/aarch64/elf-aem-v8-r.specs b/libgloss/aarch64/elf-aem-v8-r.specs
new file mode 100644
index 000000000..4daeffd11
--- /dev/null
+++ b/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}