libc: riscv support

libc-gen, libc-setjmp, task startup

issue #4312

repos/libports/lib/import/import-libc.mk

@@ -18,6 +18,10 @@ ifeq ($(filter-out $(SPECS),arm_64),)
 	LIBC_ARCH_INC_DIR := include/spec/arm_64/libc
 endif # ARM64
 
+ifeq ($(filter-out $(SPECS),riscv),)
+	LIBC_ARCH_INC_DIR := include/spec/riscv/libc
+endif # RISC-V
+
 #
 # If we found no valid include path for the configured target platform,
 # we have to prevent the build system from building the target. This is

repos/libports/lib/mk/spec/riscv/libc-gen.mk

@@ -0,0 +1,23 @@
+include $(REP_DIR)/lib/mk/libc-gen.inc
+
+LIBC_GEN_RISCV_DIR = $(LIBC_DIR)/lib/libc/riscv/gen
+
+SRC_S += _ctx_start.S sigsetjmp.S
+SRC_C += flt_rounds.c fpgetmask.c fpsetmask.c infinity.c makecontext.c
+
+#
+# Fix missing include prefix for 'ucontext.h', should be 'sys/ucontext.h'
+#
+# The first path is in effect when using the regular build system. The second
+# path is in effect when building the libc from a source archive (where the
+# ucontext.h header is taken from the libc API archive).
+#
+CC_OPT_makecontext = -I$(call select_from_ports,libc)/include/libc/sys \
+                     $(addprefix -I,$(call select_from_repositories,/include/libc/sys))
+
+CC_OPT += -DSOFTFLOAT_FOR_GCC
+
+vpath fpgetmask.c $(LIBC_DIR)/lib/libc/softfloat
+vpath fpsetmask.c $(LIBC_DIR)/lib/libc/softfloat
+vpath %.c $(LIBC_GEN_RISCV_DIR)
+vpath %.S $(LIBC_GEN_RISCV_DIR)

repos/libports/lib/mk/spec/riscv/libc-setjmp.mk

@@ -0,0 +1,9 @@
+LIBC_GEN_RISCV_DIR = $(LIBC_DIR)/lib/libc/riscv/gen
+
+SRC_S  = _setjmp.S setjmp.S
+
+include $(REP_DIR)/lib/mk/libc-common.inc
+
+vpath %.S $(LIBC_GEN_RISCV_DIR)
+
+CC_CXX_WARN_STRICT =

repos/libports/lib/mk/spec/riscv/libc.mk

@@ -0,0 +1,8 @@
+include $(REP_DIR)/lib/mk/libc.mk
+
+SRC_CC += fenv-softfloat.cc
+
+INC_DIR += $(REP_DIR)/src/lib/libc/spec/riscv
+INC_DIR += $(LIBC_DIR)/include/spec/riscv
+
+CC_CXX_WARN_STRICT =

repos/libports/ports/libc.hash

@@ -1 +1 @@
-1153300b5549eec9d7d3b171b7263d59b587b1ec
+130633868713e5f3e0dac32775bfcb8a1731f6ad

repos/libports/ports/libc.port

@@ -221,6 +221,23 @@ DIR_CONTENT(include/spec/arm_64/libc/machine) := \
     $(addprefix $(D)/sys/arm64/include/, armreg.h)
 
 
+#
+# RISC-V-specific headers
+#
+DIRS += include/spec/riscv/libc
+DIR_CONTENT(include/spec/riscv/libc) := \
+    $(call common_include_libc_arch_content,riscv,riscv) \
+    $(D)/lib/msun/riscv/fenv.h \
+    $(addprefix $(D)/lib/libc/softfloat/, softfloat-for-gcc.h) \
+    $(addprefix $(D)/lib/libc/riscv/softfloat/, milieu.h riscv-gcc.h \
+                softfloat.h)
+
+DIRS += include/spec/riscv/libc/machine
+DIR_CONTENT(include/spec/riscv/libc/machine) := \
+    $(call common_include_libc_arch_machine_content,riscv) \
+    $(addprefix $(D)/sys/riscv/include/, riscvreg.h)
+
+
 #
 # Rules for generating files
 #

repos/libports/recipes/src/libc/content.mk

@@ -18,7 +18,7 @@ include/libc-plugin include/libc/sys/ucontext.h:
 lib/mk:
 	mkdir -p $@
 	cp $(addprefix $(REP_DIR)/$@/,libc.mk libc-* libm.inc) $@
-	for spec in x86_32 x86_64 arm arm_64; do \
+	for spec in x86_32 x86_64 arm arm_64 riscv; do \
 	  mkdir -p $@/spec/$$spec; \
 	  cp $(addprefix $(REP_DIR)/$@/spec/$$spec/,libc-* libc.mk libm.mk) $@/spec/$$spec/; done
 

repos/libports/src/lib/libc/fenv-softfloat.cc

@@ -0,0 +1,18 @@
+/*
+ * \brief  Soft float support
+ * \author Sebastian Sumpf
+ * \date   2021-06-29
+ */
+
+/*
+ * Copyright (C) 2021 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+extern "C"  {
+	int __softfloat_float_rounding_mode;
+	int __softfloat_float_exception_mask;
+	int __softfloat_float_exception_flags;
+}

repos/libports/src/lib/libc/patches/ieeefp_riscv.patch

@@ -0,0 +1,11 @@
+diff --git a/src/lib/libc/sys/riscv/include/ieeefp.h b/src/lib/libc/sys/riscv/include/ieeefp.h
+index ed7381d..44a1c00 100644
+--- src/lib/libc/sys/riscv/include/ieeefp.h
++++ src/lib/libc/sys/riscv/include/ieeefp.h
+@@ -4,5 +4,6 @@
+ #define	_MACHINE_IEEEFP_H_
+ 
+ /* TODO */
++typedef int fp_except;
+ 
+ #endif /* _MACHINE_IEEEFP_H_ */

repos/libports/src/lib/libc/spec/riscv/internal/call_func.h

@@ -0,0 +1,35 @@
+/*
+ * \brief  User-level task helpers (riscv)
+ * \author Sebastian Sumpf
+ * \date   2021-06-29
+ */
+
+/*
+ * Copyright (C) 2021 Genode Labs GmbH
+ *
+ * This file is part of the Genode OS framework, which is distributed
+ * under the terms of the GNU Affero General Public License version 3.
+ */
+
+#ifndef _INCLUDE__SPEC__RISCV__INTERNAL__CALL_FUNC_H_
+#define _INCLUDE__SPEC__RISCV__INTERNAL__CALL_FUNC_H_
+
+/* Libc includes */
+#include <setjmp.h>  /* _setjmp() as we don't care about signal state */
+
+
+/**
+ * Call function with a new stack
+ */
+[[noreturn]] inline void call_func(void *sp, void *func, void *arg)
+{
+	asm volatile ("mv a0, %2\n" /* set arg */
+	              "mv sp, %0\n" /* set stack */
+	              "mv fp, x0\n" /* clear frame pointer */
+	              "jalr %1\n"   /* call func */
+	              ""
+	              : : "r"(sp), "r"(func), "r"(arg) : "a0");
+	__builtin_unreachable();
+}
+
+#endif /* _INCLUDE__SPEC__RISCV__INTERNAL__CALL_FUNC_H_ */