core: introduce crossfile arrays (xfa) v3

Makefile.include

@@ -416,6 +416,10 @@ TOOLCHAINS_SUPPORTED ?= gnu
 # Import all toolchain settings
 include $(RIOTMAKE)/toolchain/$(TOOLCHAIN).inc.mk
 
+# Append ldscript path after importing CPU and board makefiles to allow
+# overriding the core ldscripts
+LINKFLAGS += -L$(RIOTBASE)/core/ldscripts
+
 # Tell ccache to pass the original file to the compiler, instead of passing the
 # preprocessed code. Without this setting, the compilation will fail with
 # -Wimplicit-fallthrough warnings even when the fall through case is properly

boards/native/Makefile.include

@@ -59,6 +59,9 @@ else
   LINKFLAGS += -ldl
 endif
 
+# XFA (cross file array) support
+LINKFLAGS += -T$(RIOTBASE)/cpu/native/ldscripts/xfa.ld
+
 # clean up unused functions
 CFLAGS += -ffunction-sections -fdata-sections
 ifeq ($(OS),Darwin)

core/include/xfa.h

@@ -0,0 +1,186 @@
+/*
+ * Copyright (C) 2016 Kaspar Schleiser <kaspar@schleiser.de>
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     core_util
+ * @brief       Cross File Arrays
+ * @{
+ *
+ * This macro, in combination with an entry in the linker scripts, allows the
+ * definition of constant arrays to be spread over multiple C compilation
+ * units. These arrays are called "cross-file arrays" or short xfa.
+ *
+ * @experimental This API is considered experimental and will probably change
+ *               without notice!
+ *
+ * @file
+ * @author      Kaspar Schleiser <kaspar@schleiser.de>
+ */
+
+#ifndef XFA_H
+#define XFA_H
+
+/*
+ * Unfortunately, current gcc trips over accessing XFA's because of their
+ * zero-size start/end array that are used of symbol markers, with an "array
+ * index out of bounds" warning.  So until a solution for that is found, we
+ * need to disable array bounds checks for files using XFAs.
+ */
+#ifndef DOXYGEN
+_Pragma("GCC diagnostic ignored \"-Warray-bounds\"")
+#endif
+
+/**
+ * @brief helper macro for other XFA_* macros
+ *
+ * @internal
+ */
+#define _XFA(name, prio) __attribute__((used, section(".xfa." #name "." #prio)))
+
+/**
+ * @brief helper macro for other XFA_* macros
+ *
+ * @internal
+ */
+#define _XFA_CONST(name, \
+                   prio) __attribute__((used, \
+                                        section(".roxfa." #name "." #prio)))
+
+/**
+ * @brief Define a read-only cross-file array
+ *
+ * This macro defines the symbols necessary to use XFA_START() and XFA_END().
+ * It needs to be part of one single compilation unit.
+ *
+ * The pragmas prevent these errors:
+ *
+ *     error: ISO C forbids empty initializer braces
+ *     error: ISO C forbids zero-size array ‘xfatest_const_end’
+ *
+ * @param[in]   type    name of the cross-file array
+ * @param[in]   name    name of the cross-file array
+ */
+#define XFA_INIT_CONST(type, name) \
+    _Pragma("GCC diagnostic push") \
+    _Pragma("GCC diagnostic ignored \"-Wpedantic\"") \
+    _XFA_CONST(name, 0_) const volatile type name [0] = {}; \
+    _XFA_CONST(name, 9_) const volatile type name ## _end [0] = {}; \
+    _Pragma("GCC diagnostic pop") \
+    extern const unsigned __xfa_dummy
+
+/**
+ * @brief Define a writable cross-file array
+ *
+ * This macro defines the symbols necessary to use XFA_START() and XFA_END().
+ * It needs to be part of one single compilation unit.
+ *
+ * The pragmas prevent these errors:
+ *
+ *     error: ISO C forbids empty initializer braces
+ *     error: ISO C forbids zero-size array ‘xfatest_end’
+ *
+ * @param[in]   type    name of the cross-file array
+ * @param[in]   name    name of the cross-file array
+ */
+#define XFA_INIT(type, name) \
+    _Pragma("GCC diagnostic push") \
+    _Pragma("GCC diagnostic ignored \"-Wpedantic\"") \
+    _XFA(name, 0_) type name [0] = {}; \
+    _XFA(name, 9_) type name ## _end [0] = {}; \
+    _Pragma("GCC diagnostic pop") \
+    extern const unsigned __xfa_dummy
+
+/**
+ * @brief Declare an external read-only cross-file array
+ *
+ * This macro defines the symbols necessary to use XFA_START() and XFA_END().
+ * Think of this as XFA_INIT() but with "extern" keyword.
+ * It is supposed to be used in compilation units where the cross file array is
+ * being accessed, but not defined using XFA_INIT.
+ *
+ * @param[in]   type    name of the cross-file array
+ * @param[in]   name    name of the cross-file array
+ */
+#define XFA_USE_CONST(type, name) \
+    extern const type name []; \
+    extern const type name ## _end []
+
+/**
+ * @brief Declare an external writable cross-file array
+ *
+ * This macro defines the symbols necessary to use XFA_START() and XFA_END().
+ * Think of this as XFA_INIT() but with "extern" keyword.
+ * It is supposed to be used in compilation units where the cross file array is
+ * being accessed, but not defined using XFA_INIT.
+ *
+ * @param[in]   type    name of the cross-file array
+ * @param[in]   name    name of the cross-file array
+ */
+#define XFA_USE(type, name) \
+    extern type name []; \
+    extern type name ## _end []
+
+/**
+ * @brief Define variable in writable cross-file array
+ *
+ * Variables will end up sorted by prio.
+ *
+ * Add this to the type in a variable definition, e.g.:
+ *
+ *     XFA(driver_params, 0) driver_params_t _onboard = { .pin=42 };
+ *
+ * @param[in]   xfa_name    name of the xfa
+ * @param[in]   prio        priority within the xfa
+ */
+#define XFA(xfa_name, prio) _XFA(xfa_name, 5_ ## prio)
+
+/**
+ * @brief Define variable in read-only cross-file array
+ *
+ * Variables will end up sorted by prio.
+ *
+ * Add this to the type in a variable definition, e.g.:
+ *
+ *     XFA(driver_params, 0) driver_params_t _onboard = { .pin=42 };
+ *
+ * @param[in]   xfa_name    name of the xfa
+ * @param[in]   prio        priority within the xfa
+ */
+#define XFA_CONST(xfa_name, prio) _XFA_CONST(xfa_name, 5_ ## prio)
+
+/**
+ * @brief Add a pointer to cross-file array
+ *
+ * Pointers will end up sorted by prio.
+ *
+ * @param[in]   xfa_name    name of the xfa
+ * @param[in]   prio        priority within the xfa
+ * @param[in]   name        symbol name
+ * @param[in]   entry       pointer variable to add to xfa
+ */
+#define XFA_ADD_PTR(xfa_name, prio, name, entry) \
+    _XFA_CONST(xfa_name, 5_ ## prio) \
+    const typeof(entry) xfa_name ## _ ## prio ## _ ## name = entry
+
+/**
+ * @brief Calculate number of entries in cross-file array
+ */
+#define XFA_LEN(type, \
+                name) (((const char *)name ## _end - (const char *)name) / \
+                       sizeof(type))
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+/* making externc happy */
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* XFA_H */
+/** @} */

cpu/atmega_common/ldscripts/xfa.ld

@@ -0,0 +1,16 @@
+SECTIONS
+{
+    .data :
+    {
+        /* Special case for AVR (Harvard architecture) where .rodata is merged
+         * into .data by the toolchain default ldscripts. */
+        KEEP (*(SORT(.roxfa.*)))
+        KEEP (*(SORT(.xfa.*)))
+    }
+    __data_start = ADDR(.data);
+    __data_load_start = LOADADDR(.data);
+    __data_end = (__data_start + SIZEOF(.data));
+    __data_load_end = (__data_load_start + SIZEOF(.data));
+}
+
+INSERT AFTER .text;

cpu/cortexm_common/ldscripts/cortexm_base.ld

@@ -55,6 +55,7 @@ SECTIONS
         *(.text .text.* .gnu.linkonce.t.*)
         *(.glue_7t) *(.glue_7)
         *(.rodata .rodata* .gnu.linkonce.r.*)
+        KEEP (*(SORT(.roxfa.*)))
         *(.ARM.extab* .gnu.linkonce.armextab.*)
 
         /* Support C constructors, and C destructors in both user code
@@ -167,6 +168,7 @@ SECTIONS
         _srelocate = .;
         *(.ramfunc .ramfunc.*);
         *(.data .data.*);
+        KEEP (*(SORT(.xfa.*)))
         KEEP (*(.openocd .openocd.*))
         . = ALIGN(4);
         _erelocate = .;

cpu/esp32/ld/esp32.common.ld

@@ -158,6 +158,7 @@ SECTIONS
     _data_start = ABSOLUTE(.);
     *(.data)
     *(.data.*)
+    KEEP (*(SORT(.xfa.*)))
     *(.gnu.linkonce.d.*)
     *(.data1)
     *(.sdata)
@@ -243,6 +244,7 @@ SECTIONS
     _rodata_start = ABSOLUTE(.);
     *(.rodata)
     *(.rodata.*)
+    KEEP (*(SORT(.roxfa.*)))
     *(.irom1.text) /* catch stray ICACHE_RODATA_ATTR */
     *(.gnu.linkonce.r.*)
     *(.rodata1)

cpu/esp8266/Makefile.include

@@ -61,9 +61,10 @@ endif
 
 ARCHIVES += -lgcc -lwpa -lcore -lnet80211 -lphy -lpp -lstdc++
 
-LINKFLAGS += -T$(RIOTCPU)/$(CPU)/ld/esp8266.rom.ld
-LINKFLAGS += -T$(RIOTCPU)/$(CPU)/ld/esp8266.riot-os.ld
-LINKFLAGS += -T$(RIOTCPU)/$(CPU)/ld/esp8266.peripherals.ld
+LINKFLAGS += -L$(RIOTCPU)/$(CPU)/ld
+LINKFLAGS += -Tesp8266.rom.ld
+LINKFLAGS += -Tesp8266.riot-os.ld
+LINKFLAGS += -Tesp8266.peripherals.ld
 
 LINKFLAGS += -Wl,-wrap=pp_attach
 LINKFLAGS += -Wl,-wrap=pm_attach

cpu/esp8266/ld/esp8266.riot-os.ld

@@ -105,6 +105,7 @@ SECTIONS
     *(.sdata2.*)
     *(.gnu.linkonce.s2.*)
     *(.jcr)
+    KEEP (*(SORT(.xfa.*)))
     _data_end = ABSOLUTE(.);
   } >dram0_0_seg :dram0_0_phdr
 
@@ -139,6 +140,7 @@ SECTIONS
     KEEP (*(EXCLUDE_FILE (*crtend.o) .dtors))
     KEEP (*(SORT(.dtors.*)))
     KEEP (*(.dtors))
+    KEEP (*(SORT(.roxfa.*)))
     /*  C++ exception handlers table:  */
     __XT_EXCEPTION_DESCS__ = ABSOLUTE(.);
     *(.xt_except_desc)

cpu/lpc23xx/ldscripts/lpc23xx.ld

@@ -65,6 +65,7 @@ SECTIONS
         KEEP (*(EXCLUDE_FILE (*crtend.o) .dtors))
         KEEP (*(SORT(.dtors.*)))
         KEEP (*crtend.o(.dtors))
+        KEEP (*(SORT(.roxfa.*)))
 
         . = ALIGN(4);
         _efixed = .;            /* End of text section */
@@ -163,6 +164,7 @@ SECTIONS
         *(.ramfunc .ramfunc.*);
         *(.data .data.*);
         KEEP (*(.openocd .openocd.*))
+        KEEP (*(SORT(.xfa.*)))
         . = ALIGN(4);
         _erelocate = .;
     } > ram AT> rom

cpu/mips_pic32_common/Makefile.include

@@ -6,7 +6,6 @@ include $(RIOTCPU)/mips32r2_common/Makefile.include
 CFLAGS += -D_SYS__PTHREADTYPES_H_
 
 CFLAGS += -DCPU_FAM_$(call uppercase_and_underscore,$(CPU_FAM))
-
+LINKFLAGS += -L$(RIOTCPU)/mips_pic32_common/ldscripts
 INCLUDES += -I$(RIOTCPU)/mips_pic32_common/include
-
 DIRS += $(RIOTCPU)/$(CPU)/$(CPU_MODEL)

cpu/mips_pic32_common/ldscripts/xfa.ld

@@ -0,0 +1,21 @@
+SECTIONS
+{
+    .data :
+    {
+        KEEP (*(SORT(.xfa.*)))
+    }
+    _fdata = ADDR(.data);
+    _edata = (_fdata + SIZEOF(.data));
+}
+
+INSERT BEFORE .sbss;
+
+SECTIONS
+{
+    .rodata :
+    {
+        KEEP (*(SORT(.roxfa.*)))
+    }
+}
+
+INSERT AFTER .dtors;

cpu/msp430_common/ldscripts/xfa.ld

@@ -0,0 +1,24 @@
+SECTIONS
+{
+    .rodata :
+    {
+        KEEP (*(SORT(.roxfa.*)))
+    } > ROM
+}
+
+INSERT AFTER .rodata;
+
+SECTIONS
+{
+    .data :
+    {
+        KEEP (*(SORT(.xfa.*)))
+    } > RAM AT> ROM
+
+    . = ALIGN(2);
+    _edata = .;
+    PROVIDE (edata = .);
+    PROVIDE (__dataend = .);
+}
+
+INSERT AFTER .data;

cpu/native/ldscripts/xfa.ld

@@ -0,0 +1,19 @@
+SECTIONS
+{
+    .data :
+    {
+        KEEP (*(SORT(.xfa.*)))
+    }
+}
+
+INSERT AFTER .text;
+
+SECTIONS
+{
+    .rodata :
+    {
+        KEEP (*(SORT(.roxfa.*)))
+    }
+}
+
+INSERT AFTER .text;

cpu/riscv_common/ldscripts/riscv_base.ld

@@ -61,6 +61,7 @@ SECTIONS
     *(.rdata)
     *(.rodata .rodata.*)
     *(.gnu.linkonce.r.*)
+    KEEP (*(SORT(.roxfa.*)))
   } >flash AT>flash :flash
 
   . = ALIGN(4);
@@ -182,6 +183,7 @@ SECTIONS
     *(.srodata.cst4)
     *(.srodata.cst2)
     *(.srodata .srodata.*)
+    KEEP (*(SORT(.xfa.*)))
   } >ram AT>flash :ram_init
 
   . = ALIGN(4);