armclang: ARM Compiler C library support

Support for ARM Compiler C library.

This commit add support for the ARM Compiler C libary in:
- Kconfig
- libc/armstdc

A new Kconfig symbol is added to allow a toolchain to specify if they
support linking with the minimal C library.
Also the CMake variable `TOOLCHAIN_HAS_NEWLIB` is exported to Kconfig
so that CONFIG_NEWLIB_LIBS can only be enabled if the toolchain has
newlib.

The armclang toolchain selects the CMake scatter file generator and
disables support for the LD linker template which is not supported by
armlink.

For the ARM Compiler C library, a corresponding lib/libc/armstc/ folder
with a minimal implementation to work with the ARM Compiler C library
is added.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

Kconfig.zephyr

@@ -25,6 +25,8 @@ source "$(BOARD_DIR)/Kconfig.defconfig"
 osource "$(KCONFIG_BINARY_DIR)/Kconfig.soc.defconfig"
 # This loads Zephyr base SoC root defconfigs
 osource "soc/$(ARCH)/*/Kconfig.defconfig"
+# This loads the toolchain defconfigs
+osource "$(TOOLCHAIN_KCONFIG_DIR)/Kconfig.defconfig"
 
 menu "Modules"
 

cmake/compiler/armclang/compiler_flags.cmake

@@ -4,3 +4,6 @@ include(${ZEPHYR_BASE}/cmake/compiler/clang/compiler_flags.cmake)
 # Required ASM flags when using armclang, this should be handled by CMake, but
 # fails because of: https://gitlab.kitware.com/cmake/cmake/-/issues/19963
 set_property(TARGET asm APPEND PROPERTY required "--target=${triple}")
+
+# Only the ARM Compiler C library is currently supported.
+set_compiler_property(PROPERTY nostdinc)

cmake/compiler/armclang/target.cmake

@@ -67,13 +67,11 @@ foreach(isystem_include_dir ${NOSTDINC})
   list(APPEND isystem_include_flags -isystem ${isystem_include_dir})
 endforeach()
 
-set(CMAKE_REQUIRED_FLAGS -nostartfiles -nostdlib ${isystem_include_flags})
+set(CMAKE_REQUIRED_FLAGS ${isystem_include_flags})
 string(REPLACE ";" " " CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}")
 
-# Load toolchain_cc-family macros
-
-macro(toolchain_cc_nostdinc)
-  if(NOT "${ARCH}" STREQUAL "posix")
-    zephyr_compile_options( -nostdinc)
-  endif()
-endmacro()
+if(CONFIG_ARMCLANG_STD_LIBC)
+  # Zephyr requires AEABI portability to ensure correct functioning of the C
+  # library, for example error numbers, errno.h.
+  list(APPEND TOOLCHAIN_C_FLAGS -D_AEABI_PORTABILITY_LEVEL=1)
+endif()

cmake/kconfig.cmake

@@ -103,6 +103,7 @@ set(COMMON_KCONFIG_ENV_SETTINGS
   BOARD_DIR=${BOARD_DIR}
   KCONFIG_BINARY_DIR=${KCONFIG_BINARY_DIR}
   TOOLCHAIN_KCONFIG_DIR=${TOOLCHAIN_KCONFIG_DIR}
+  TOOLCHAIN_HAS_NEWLIB=$<IF:$<BOOL:${TOOLCHAIN_HAS_NEWLIB}>,y,n>
   EDT_PICKLE=${EDT_PICKLE}
   # Export all Zephyr modules to Kconfig
   ${ZEPHYR_KCONFIG_MODULES_DIR}

cmake/toolchain/armclang/Kconfig

@@ -0,0 +1,23 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+config LD_LINKER_SCRIPT_SUPPORTED
+	bool
+	default n
+
+choice LINKER_SCRIPT
+	default CMAKE_LINKER_GENERATOR
+endchoice
+
+choice LIBC_IMPLEMENTATION
+	prompt "C Library Implementation"
+	default ARMCLANG_STD_LIBC
+
+config ARMCLANG_STD_LIBC
+	bool "ARM Compiler C library"
+	help
+	  Use the full Arm Compiler runtime libraries.
+	  A reduced Zephyr minimal libc will be used for library functionality
+	  not provided by ARM Compiler standard libraries.
+
+endchoice

cmake/toolchain/armclang/Kconfig.defconfig

@@ -0,0 +1,6 @@
+# Copyright (c) 2021 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+config SUPPORT_MINIMAL_LIBC
+	bool
+	default n

doc/CMakeLists.txt

@@ -142,6 +142,7 @@ add_custom_target(
   ARCH=*
   ARCH_DIR=arch
   SOC_DIR=soc
+  TOOLCHAIN_HAS_NEWLIB=y
   KCONFIG_BINARY_DIR=${KCONFIG_BINARY_DIR}
   KCONFIG_WARN_UNDEF=y
   KCONFIG_TURBO_MODE=${KCONFIG_TURBO_MODE}

lib/libc/CMakeLists.txt

@@ -4,6 +4,8 @@ if(CONFIG_NEWLIB_LIBC)
   add_subdirectory(newlib)
 elseif(CONFIG_ARCMWDT_LIBC)
   add_subdirectory(arcmwdt)
-else()
+elseif(CONFIG_MINIMAL_LIBC)
   add_subdirectory(minimal)
+elseif(CONFIG_ARMCLANG_STD_LIBC)
+  add_subdirectory(armstdc)
 endif()

lib/libc/Kconfig

@@ -11,6 +11,10 @@ config REQUIRES_FULL_LIBC
 	  Helper symbol to indicate some feature requires a C library implementation
 	  with more functionality than what MINIMAL_LIBC provides
 
+config SUPPORT_MINIMAL_LIBC
+	bool
+	default y
+
 choice LIBC_IMPLEMENTATION
 	prompt "C Library Implementation"
 	default EXTERNAL_LIBC if NATIVE_APPLICATION
@@ -21,6 +25,7 @@ config MINIMAL_LIBC
 	bool "Minimal C library"
 	depends on !NATIVE_APPLICATION
 	depends on !REQUIRES_FULL_LIBC
+	depends on SUPPORT_MINIMAL_LIBC
 	help
 	  Build with minimal C library.
 

lib/libc/armstdc/CMakeLists.txt

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_library()
+zephyr_library_sources(src/errno.c)
+zephyr_library_sources(src/string.c)
+zephyr_library_sources(src/libc-hooks.c)
+
+zephyr_system_include_directories(include)

lib/libc/armstdc/include/errno.h

@@ -0,0 +1,141 @@
+/*
+ * Copyright (c) 1984-1999, 2012 Wind River Systems, Inc.
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * Copyright (c) 1982, 1986 Regents of the University of California.
+ * All rights reserved.  The Berkeley software License Agreement
+ * specifies the terms and conditions for redistribution.
+ *
+ *	@(#)errno.h	7.1 (Berkeley) 6/4/86
+ */
+
+/**
+ * @file
+ * @brief System error numbers
+ */
+
+#ifndef ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_ERRNO_H_
+#define ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_ERRNO_H_
+
+/**
+ * @brief System error numbers
+ *        Error codes returned by functions.
+ *        Includes a list of those defined by IEEE Std 1003.1-2017.
+ *
+ *        This file is supposed to be used together with ARMClang and
+ *        #define _AEABI_PORTABILITY_LEVEL 1
+ *        or
+ *        -D_AEABI_PORTABILITY_LEVEL=1
+ *
+ *        For details, please refer to the document:
+ *        'C Library ABI for the Arm® Architecture, 2021Q1'
+ *
+ * @defgroup system_errno Error numbers
+ * @ingroup c_std_lib
+ * @{
+ */
+
+#include <sys/errno_private.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define errno (*z_errno())
+
+#define EPERM 1         /**< Not owner */
+#define ENOENT 2        /**< No such file or directory */
+#define ESRCH 3         /**< No such context */
+#define EINTR 4         /**< Interrupted system call */
+#define EIO 5           /**< I/O error */
+#define ENXIO 6         /**< No such device or address */
+#define E2BIG 7         /**< Arg list too long */
+#define ENOEXEC 8       /**< Exec format error */
+#define EBADF 9         /**< Bad file number */
+#define ECHILD 10       /**< No children */
+#define EAGAIN 11       /**< No more contexts */
+#define ENOMEM 12       /**< Not enough core */
+#define EACCES 13       /**< Permission denied */
+#define EFAULT 14       /**< Bad address */
+#define ENOTBLK 15      /**< Block device required */
+#define EBUSY 16        /**< Mount device busy */
+#define EEXIST 17       /**< File exists */
+#define EXDEV 18        /**< Cross-device link */
+#define ENODEV 19       /**< No such device */
+#define ENOTDIR 20      /**< Not a directory */
+#define EISDIR 21       /**< Is a directory */
+#define EINVAL 22       /**< Invalid argument */
+#define ENFILE 23       /**< File table overflow */
+#define EMFILE 24       /**< Too many open files */
+#define ENOTTY 25       /**< Not a typewriter */
+#define ETXTBSY 26      /**< Text file busy */
+#define EFBIG 27        /**< File too large */
+#define ENOSPC 28       /**< No space left on device */
+#define ESPIPE 29       /**< Illegal seek */
+#define EROFS 30        /**< Read-only file system */
+#define EMLINK 31       /**< Too many links */
+#define EPIPE 32        /**< Broken pipe */
+/* Implemented in errno.c    Argument too large */
+/* Implemented in errno.c    Result too large */
+#define ENOMSG 35       /**< Unexpected message type */
+#define EDEADLK 45      /**< Resource deadlock avoided */
+#define ENOLCK 46       /**< No locks available */
+#define ENOSTR 60       /**< STREAMS device required */
+#define ENODATA 61      /**< Missing expected message data */
+#define ETIME 62        /**< STREAMS timeout occurred */
+#define ENOSR 63        /**< Insufficient memory */
+#define EPROTO 71       /**< Generic STREAMS error */
+#define EBADMSG 77      /**< Invalid STREAMS message */
+#define ENOSYS 88       /**< Function not implemented */
+#define ENOTEMPTY 90    /**< Directory not empty */
+#define ENAMETOOLONG 91 /**< File name too long */
+#define ELOOP 92        /**< Too many levels of symbolic links */
+#define EOPNOTSUPP 95   /**< Operation not supported on socket */
+#define EPFNOSUPPORT 96 /**< Protocol family not supported */
+#define ECONNRESET 104   /**< Connection reset by peer */
+#define ENOBUFS 105      /**< No buffer space available */
+#define EAFNOSUPPORT 106 /**< Addr family not supported */
+#define EPROTOTYPE 107   /**< Protocol wrong type for socket */
+#define ENOTSOCK 108     /**< Socket operation on non-socket */
+#define ENOPROTOOPT 109  /**< Protocol not available */
+#define ESHUTDOWN 110    /**< Can't send after socket shutdown */
+#define ECONNREFUSED 111 /**< Connection refused */
+#define EADDRINUSE 112   /**< Address already in use */
+#define ECONNABORTED 113 /**< Software caused connection abort */
+#define ENETUNREACH 114  /**< Network is unreachable */
+#define ENETDOWN 115     /**< Network is down */
+#define ETIMEDOUT 116    /**< Connection timed out */
+#define EHOSTDOWN 117    /**< Host is down */
+#define EHOSTUNREACH 118 /**< No route to host */
+#define EINPROGRESS 119  /**< Operation now in progress */
+#define EALREADY 120     /**< Operation already in progress */
+#define EDESTADDRREQ 121 /**< Destination address required */
+#define EMSGSIZE 122        /**< Message size */
+#define EPROTONOSUPPORT 123 /**< Protocol not supported */
+#define ESOCKTNOSUPPORT 124 /**< Socket type not supported */
+#define EADDRNOTAVAIL 125   /**< Can't assign requested address */
+#define ENETRESET 126       /**< Network dropped connection on reset */
+#define EISCONN 127         /**< Socket is already connected */
+#define ENOTCONN 128        /**< Socket is not connected */
+#define ETOOMANYREFS 129    /**< Too many references: can't splice */
+#define ENOTSUP 134         /**< Unsupported value */
+/* Implemented in errno.c   Illegal byte sequence */
+#define EOVERFLOW 139       /**< Value overflow */
+#define ECANCELED 140       /**< Operation canceled */
+
+#define EWOULDBLOCK EAGAIN /**< Operation would block */
+
+/**
+ * @}
+ */
+#include_next <errno.h>
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_ERRNO_H_ */

lib/libc/armstdc/include/fcntl.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2018 Linaro Limited
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_FCNTL_H_
+#define ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_FCNTL_H_
+
+#define O_CREAT    0x0200
+#define O_APPEND   0x0400
+#define O_EXCL     0x0800
+#define O_NONBLOCK 0x4000
+
+#define F_DUPFD 0
+#define F_GETFL 3
+#define F_SETFL 4
+
+int open(const char *name, int flags, ...);
+
+#endif /* ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_FCNTL_H_ */

lib/libc/armstdc/include/sys/timespec.h

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2019 Linaro Limited
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_TIMESPEC_H_
+#define ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_TIMESPEC_H_
+
+#include <sys/types.h>
+
+struct timespec {
+	time_t tv_sec;
+	long tv_nsec;
+};
+
+struct itimerspec {
+	struct timespec it_interval;  /* Timer interval */
+	struct timespec it_value;     /* Timer expiration */
+};
+
+#endif /* ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_TIMESPEC_H_ */

lib/libc/armstdc/include/sys/types.h

@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/*
+ * This defines the required types for the ARMClang compiler when comiling with
+ * _AEABI_PORTABILITY_LEVEL = 1
+ *
+ * The types defined are according to:
+ * C Library ABI for the Arm® Architecture, 2021Q1
+ *
+ */
+#ifndef ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_TYPES_H_
+#define ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_TYPES_H_
+
+#if !defined(__ssize_t_defined)
+#define __ssize_t_defined
+
+/* parasoft suppress item MISRAC2012-RULE_20_4-a item MISRAC2012-RULE_20_4-b
+ * "Trick compiler to make sure the type of ssize_t won't be
+ * unsigned long. View details in commit b889120"
+ */
+#define unsigned signed
+typedef __SIZE_TYPE__ ssize_t;
+#undef unsigned
+#endif
+
+#if !defined(__off_t_defined)
+#define __off_t_defined
+typedef int off_t;
+#endif
+
+#if !defined(__time_t_defined)
+#define __time_t_defined
+typedef unsigned int time_t;
+#endif
+
+#if !defined(__clock_t_defined)
+#define __clock_t_defined
+typedef unsigned int clock_t;
+#endif
+
+#endif /* ZEPHYR_LIB_LIBC_ARMSTDC_INCLUDE_SYS_TYPES_H_ */

lib/libc/armstdc/src/errno.c

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @brief System error numbers
+ *        Error codes returned by functions.
+ *        Includes a list of those defined by IEEE Std 1003.1-2017.
+ *
+ *        This file is supposed to be used together with ARMClang and
+ *        #define _AEABI_PORTABILITY_LEVEL 1
+ *        or
+ *        -D_AEABI_PORTABILITY_LEVEL=1
+ *
+ *        For details, please refer to the document:
+ *        'C Library ABI for the Arm® Architecture, 2021Q1'
+ *
+ * @defgroup system_errno Error numbers
+ * @ingroup c_std_lib
+ * @{
+ */
+
+const int __aeabi_EDOM = 33;    /**< Argument too large */
+const int __aeabi_ERANGE = 34;  /**< Result too large */
+const int __aeabi_EILSEQ = 138; /**< Illegal byte sequence */

lib/libc/armstdc/src/libc-hooks.c

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <kernel.h>
+#include <stdio.h>
+
+static int _stdout_hook_default(int c)
+{
+	(void)(c);  /* Prevent warning about unused argument */
+
+	return EOF;
+}
+
+static int (*_stdout_hook)(int) = _stdout_hook_default;
+
+void __stdout_hook_install(int (*hook)(int))
+{
+	_stdout_hook = hook;
+}
+
+volatile int *__aeabi_errno_addr(void)
+{
+	return &_current->errno_var;
+}

lib/libc/armstdc/src/string.c

@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 2014 Wind River Systems, Inc.
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <string.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+/**
+ *
+ * @brief Get fixed-size string length
+ *
+ *        This function is not available in ARM C Standard library.
+ *
+ * @return number of bytes in fixed-size string <s>
+ */
+
+size_t strnlen(const char *s, size_t maxlen)
+{
+	size_t n = 0;
+
+	while (*s != '\0' && n < maxlen) {
+		s++;
+		n++;
+	}
+
+	return n;
+}

scripts/ci/check_compliance.py

@@ -328,6 +328,7 @@ osource "{ZEPHYR_BASE}/soc/$(ARCH)/*/Kconfig"\n')
         os.environ["ARCH"] = "*"
         os.environ["KCONFIG_BINARY_DIR"] = tempfile.gettempdir()
         os.environ['DEVICETREE_CONF'] = "dummy"
+        os.environ['TOOLCHAIN_HAS_NEWLIB'] = "y"
 
         # Older name for DEVICETREE_CONF, for compatibility with older Zephyr
         # versions that don't have the renaming
@@ -522,6 +523,9 @@ def get_defined_syms(kconf):
 UNDEF_KCONFIG_WHITELIST = {
     "ALSO_MISSING",
     "APP_LINK_WITH_",
+    "ARMCLANG_STD_LIBC",  # The ARMCLANG_STD_LIBC is defined in the toolchain
+                          # Kconfig which is sourced based on Zephyr toolchain
+			  # variant and therefore not visible to compliance.
     "CDC_ACM_PORT_NAME_",
     "CLOCK_STM32_SYSCLK_SRC_",
     "CMU",