riscv32: added a generic linker script for the riscv32 platform

Added a linker script that shall be common to most riscv SOCs.
Linker script also accounts for execution in place in ROM, when
CONFIG_XIP is set.

Nonetheless, riscv32 SOCs (like pulpino) requiring a different
system layout can still define their own linker script.

Change-Id: I3ad670446d439772c29a8204e307ac79643dc650
Signed-off-by: Jean-Paul Etienne <fractalclone@gmail.com>

arch/riscv32/Makefile

@@ -14,3 +14,6 @@ soc-aflags ?= $(soc-cflags)
 KBUILD_CFLAGS += $(soc-cflags)
 KBUILD_CXXFLAGS += $(soc-cxxflags)
 KBUILD_AFLAGS += $(soc-aflags)
+
+soc_ld_include := -I$(srctree)/arch/$(ARCH)/soc/$(SOC_PATH)/
+EXTRA_LINKER_CMD_OPT += $(soc_ld_include)

arch/riscv32/core/prep_c.c

@@ -31,6 +31,9 @@
 void _PrepC(void)
 {
 	_bss_zero();
+#ifdef CONFIG_XIP
+	_data_copy();
+#endif
 	_Cstart();
 	CODE_UNREACHABLE;
 }

arch/riscv32/soc/riscv32-qemu/Kconfig.defconfig

@@ -20,19 +20,19 @@ config NUM_IRQS
 	int
 	default 32
 
-config VECTOR_BASE_ADDR
+config RISCV_ROM_BASE_ADDR
 	hex
 	default 0x00001000
 
-config VECTOR_SIZE
+config RISCV_ROM_SIZE
 	hex
-	default 0x1000
+	default 0x100000
 
-config RAM_BASE_ADDR
+config RISCV_RAM_BASE_ADDR
 	hex
 	default	0x80000000
 
-config RAM_SIZE_MB
+config RISCV_RAM_SIZE_MB
 	int
 	default 32
 

arch/riscv32/soc/riscv32-qemu/linker.ld

@@ -8,4 +8,4 @@
  * @brief Linker script for riscv32-qemu
  */
 
-#include <arch/riscv32/riscv32-qemu/linker.ld>
+#include <arch/riscv32/common/linker.ld>

arch/riscv32/soc/riscv32-qemu/soc.h

@@ -11,6 +11,8 @@
 #ifndef __RISCV32_QEMU_SOC_H_
 #define __RISCV32_QEMU_SOC_H_
 
+#include <misc/util.h>
+
 /* CSR Registers */
 #define RISCV_QEMU_MSTATUS               mstatus /* Machine Status Register */
 
@@ -56,18 +58,17 @@
 #define RISCV_MTIME_BASE             0x40000000
 #define RISCV_MTIMECMP_BASE          0x40000008
 
+/* lib-c hooks required RAM defined variables */
+#define RISCV_RAM_BASE             CONFIG_RISCV_RAM_BASE_ADDR
+#define RISCV_RAM_SIZE             MB(CONFIG_RISCV_RAM_SIZE_MB)
+
 #ifndef _ASMLANGUAGE
 #include <irq.h>
-#include <misc/util.h>
 
 #if defined(CONFIG_RISCV_SOC_INTERRUPT_INIT)
 void soc_interrupt_init(void);
 #endif
 
-/* lib-c hooks required RAM defined variables */
-#define RISCV_RAM_BASE             CONFIG_RAM_BASE_ADDR
-#define RISCV_RAM_SIZE             MB(CONFIG_RAM_SIZE_MB)
-
 #endif /* !_ASMLANGUAGE */
 
 #endif /* __RISCV32_QEMU_SOC_H_ */

boards/riscv32/qemu_riscv32/Makefile.board

@@ -2,7 +2,7 @@
 EMU_PLATFORM = qemu
 
 QEMU_CPU_TYPE_riscv32 = riscv32
-QEMU_FLAGS_riscv32 = -machine sifive -nographic -m $(CONFIG_RAM_SIZE_MB)
+QEMU_FLAGS_riscv32 = -machine sifive -nographic -m $(CONFIG_RISCV_RAM_SIZE_MB)
 QEMU_riscv32 = qemu-system-riscv32
 
 DEBUG_SCRIPT = qemu.sh

include/arch/riscv32/common/linker.ld

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 Jean-Paul Etienne <fractalclone@gmail.com>
+ * Copyright (c) 2016-2017 Jean-Paul Etienne <fractalclone@gmail.com>
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -8,93 +8,68 @@
  * @file
  * @brief Linker command/script file
  *
- * Linker script for the riscv32-qemu platform
+ * Generic Linker script for the riscv32 platform
  */
 
 #define _LINKER
 #define _ASMLANGUAGE
 
+#include <soc.h>
+
 #include <autoconf.h>
 #include <sections.h>
 
 #include <linker-defs.h>
 #include <linker-tool.h>
 
+#ifdef CONFIG_XIP
+#define ROMABLE_REGION              ROM
+#else
 #define ROMABLE_REGION              RAM
+#endif
 #define RAMABLE_REGION              RAM
 
 #define _VECTOR_SECTION_NAME        vector
 #define _EXCEPTION_SECTION_NAME     exceptions
 #define _RESET_SECTION_NAME         reset
 
-#define RAM_LENGTH                  (CONFIG_RAM_SIZE_MB * 1024 * 1024)
-
-ENTRY(__reset)
-
 MEMORY
-    {
+{
-    VECTOR (rx)  : ORIGIN = CONFIG_VECTOR_BASE_ADDR, LENGTH = CONFIG_VECTOR_SIZE
+    ROM (rx)  : ORIGIN = CONFIG_RISCV_ROM_BASE_ADDR, LENGTH = CONFIG_RISCV_ROM_SIZE
-    RAM    (rwx) : ORIGIN = CONFIG_RAM_BASE_ADDR, LENGTH = RAM_LENGTH
+    RAM (rwx) : ORIGIN = CONFIG_RISCV_RAM_BASE_ADDR, LENGTH = RISCV_RAM_SIZE
 }
 
 SECTIONS
     {
 
-    GROUP_START(VECTOR)
+    GROUP_START(ROM)
+    _image_rom_start = .;
 
     SECTION_PROLOGUE(_VECTOR_SECTION_NAME,,)
     {
 		. = ALIGN(4);
 		KEEP(*(.vectors.*))
-    } GROUP_LINK_IN(VECTOR)
+    } GROUP_LINK_IN(ROM)
 
-    GROUP_END(VECTOR)
+    GROUP_END(ROM)
 
-    GROUP_START(RAM)
+    GROUP_START(ROMABLE_REGION)
 
     SECTION_PROLOGUE(_RESET_SECTION_NAME,,)
     {
 		KEEP(*(.reset.*))
-    } GROUP_LINK_IN(RAM)
+    } GROUP_LINK_IN(ROMABLE_REGION)
 
     SECTION_PROLOGUE(_EXCEPTION_SECTION_NAME,,)
     {
 		 KEEP(*(".exception.entry.*"))
 		 *(".exception.other.*")
-    } GROUP_LINK_IN(RAM)
+    } GROUP_LINK_IN(ROMABLE_REGION)
 
     SECTION_PROLOGUE(_TEXT_SECTION_NAME,,)
 	{
 		. = ALIGN(4);
 
-		_image_text_start = .;
-		*(.text)
-		*(".text.*")
-		*(.gnu.linkonce.t.*)
-	} GROUP_LINK_IN(RAM)
-
-    _image_text_end = .;
-
-    GROUP_END(RAM)
-
-    GROUP_START(RAMABLE_REGION)
-
-#include <linker/common-rom.ld>
-
-    SECTION_PROLOGUE(_RODATA_SECTION_NAME,,)
-	{
-		 . = ALIGN(4);
-		 *(.rodata)
-		 *(".rodata.*")
-		 *(.gnu.linkonce.r.*)
-	} GROUP_LINK_IN(RAMABLE_REGION)
-
-#include <linker/common-ram.ld>
-
-    SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
-	{
-
-		 . = ALIGN(4);
 		 KEEP(*(.isr_irq*))
 
 		 /* sections for IRQ0-9 */
@@ -106,13 +81,48 @@ SECTIONS
 		 /* sections for IRQ100-999 */
 		 KEEP(*(SORT(.gnu.linkonce.isr_irq[0-9][0-9][0-9])))
 
+		_image_text_start = .;
+		*(.text)
+		*(".text.*")
+		*(.gnu.linkonce.t.*)
+	} GROUP_LINK_IN(ROMABLE_REGION)
+
+    _image_text_end = .;
+
+#include <linker/common-rom.ld>
+
+    SECTION_PROLOGUE(_RODATA_SECTION_NAME,,)
+	{
+		 . = ALIGN(4);
+		 *(.rodata)
+		 *(".rodata.*")
+		 *(.gnu.linkonce.r.*)
+	} GROUP_LINK_IN(ROMABLE_REGION)
+
+    _image_rom_end = .;
+    __data_rom_start = .;
+
+    GROUP_END(ROMABLE_REGION)
+
+    GROUP_START(RAMABLE_REGION)
+
+    SECTION_DATA_PROLOGUE(_DATA_SECTION_NAME,,)
+	{
+		 . = ALIGN(4);
+		 _image_ram_start = .;
+		 __data_ram_start = .;
+
 		 *(.data)
 		 *(".data.*")
 
 		 *(.sdata .sdata.* .gnu.linkonce.s.*)
 		 *(.sdata2 .sdata2.* .gnu.linkonce.s2.*)
 
-	}  GROUP_LINK_IN(RAMABLE_REGION)
+	}  GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
+
+#include <linker/common-ram.ld>
+
+    __data_ram_end = .;
 
     SECTION_DATA_PROLOGUE(_BSS_SECTION_NAME,(NOLOAD),)
 	{
@@ -132,7 +142,7 @@ SECTIONS
 		  * section ends on a 4 byte boundary. This wastes a maximum of 3 bytes.
 		  */
 		  __bss_end = ALIGN(4);
-	}  GROUP_LINK_IN(RAMABLE_REGION)
+	}  GROUP_DATA_LINK_IN(RAMABLE_REGION, RAMABLE_REGION)
 
     SECTION_PROLOGUE(_NOINIT_SECTION_NAME,(NOLOAD),)
 	{
@@ -144,6 +154,7 @@ SECTIONS
 		 *(".noinit.*")
 	} GROUP_LINK_IN(RAMABLE_REGION)
 
+     _image_ram_end = .;
      _end = .; /* end of image */
 
      GROUP_END(RAMABLE_REGION)