RISC-V: Build Infrastructure

This patch contains all the build infrastructure that actually enables
the RISC-V port.  This includes Makefiles, linker scripts, and Kconfig
files.  It also contains the only top-level change, which adds RISC-V to
the list of architectures that need a sed run to produce the ARCH
variable when building locally.

Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>

10 files changed, 581 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index d1119941261c..08ffcb172bec 100644
--- a/Makefile
+++ b/Makefile
@@ -225,7 +225,8 @@ SUBARCH := $(shell uname -m | sed -e s/i.86/x86/ -e s/x86_64/x86/ \
                                   -e s/arm.*/arm/ -e s/sa110/arm/ \
                                   -e s/s390x/s390/ -e s/parisc64/parisc/ \
                                   -e s/ppc.*/powerpc/ -e s/mips.*/mips/ \
-                                  -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ )
+                                  -e s/sh[234].*/sh/ -e s/aarch64.*/arm64/ \
+                                  -e s/riscv.*/riscv/)
 
 # Cross compiling and selecting different set of gcc/bin-utils
 # ---------------------------------------------------------------------------
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
new file mode 100644
index 000000000000..2c6adf12713a
--- /dev/null
+++ b/arch/riscv/Kconfig
@@ -0,0 +1,310 @@
+#
+# For a description of the syntax of this configuration file,
+# see Documentation/kbuild/kconfig-language.txt.
+#
+
+config RISCV
+        def_bool y
+        select OF
+        select OF_EARLY_FLATTREE
+        select OF_IRQ
+        select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
+        select ARCH_WANT_FRAME_POINTERS
+        select CLONE_BACKWARDS
+        select COMMON_CLK
+        select GENERIC_CLOCKEVENTS
+        select GENERIC_CPU_DEVICES
+        select GENERIC_IRQ_SHOW
+        select GENERIC_PCI_IOMAP
+        select GENERIC_STRNCPY_FROM_USER
+        select GENERIC_STRNLEN_USER
+        select GENERIC_SMP_IDLE_THREAD
+        select GENERIC_ATOMIC64 if !64BIT || !RISCV_ISA_A
+        select ARCH_WANT_OPTIONAL_GPIOLIB
+        select HAVE_MEMBLOCK
+        select HAVE_DMA_API_DEBUG
+        select HAVE_DMA_CONTIGUOUS
+        select HAVE_GENERIC_DMA_COHERENT
+        select IRQ_DOMAIN
+        select NO_BOOTMEM
+        select RISCV_ISA_A if SMP
+        select SPARSE_IRQ
+        select SYSCTL_EXCEPTION_TRACE
+        select HAVE_ARCH_TRACEHOOK
+        select MODULES_USE_ELF_RELA if MODULES
+        select THREAD_INFO_IN_TASK
+        select RISCV_IRQ_INTC
+        select RISCV_TIMER
+
+config MMU
+        def_bool y
+
+# even on 32-bit, physical (and DMA) addresses are > 32-bits
+config ARCH_PHYS_ADDR_T_64BIT
+        def_bool y
+
+config ARCH_DMA_ADDR_T_64BIT
+        def_bool y
+
+config PAGE_OFFSET
+        hex
+        default 0xC0000000 if 32BIT && MAXPHYSMEM_2GB
+        default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
+        default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
+
+config STACKTRACE_SUPPORT
+        def_bool y
+
+config RWSEM_GENERIC_SPINLOCK
+        def_bool y
+
+config GENERIC_BUG
+        def_bool y
+        depends on BUG
+        select GENERIC_BUG_RELATIVE_POINTERS if 64BIT
+
+config GENERIC_BUG_RELATIVE_POINTERS
+        bool
+
+config GENERIC_CALIBRATE_DELAY
+        def_bool y
+
+config GENERIC_CSUM
+        def_bool y
+
+config GENERIC_HWEIGHT
+        def_bool y
+
+config PGTABLE_LEVELS
+        int
+        default 3 if 64BIT
+        default 2
+
+config HAVE_KPROBES
+        def_bool n
+
+config DMA_NOOP_OPS
+        def_bool y
+
+menu "Platform type"
+
+choice
+        prompt "Base ISA"
+        default ARCH_RV64I
+        help
+          This selects the base ISA that this kernel will traget and must match
+          the target platform.
+
+config ARCH_RV32I
+        bool "RV32I"
+        select CPU_SUPPORTS_32BIT_KERNEL
+        select 32BIT
+        select GENERIC_ASHLDI3
+        select GENERIC_ASHRDI3
+        select GENERIC_LSHRDI3
+
+config ARCH_RV64I
+        bool "RV64I"
+        select CPU_SUPPORTS_64BIT_KERNEL
+        select 64BIT
+
+endchoice
+
+# We must be able to map all physical memory into the kernel, but the compiler
+# is still a bit more efficient when generating code if it's setup in a manner
+# such that it can only map 2GiB of memory.
+choice
+        prompt "Kernel Code Model"
+        default CMODEL_MEDLOW if 32BIT
+        default CMODEL_MEDANY if 64BIT
+
+        config CMODEL_MEDLOW
+                bool "medium low code model"
+        config CMODEL_MEDANY
+                bool "medium any code model"
+endchoice
+
+choice
+        prompt "Maximum Physical Memory"
+        default MAXPHYSMEM_2GB if 32BIT
+        default MAXPHYSMEM_2GB if 64BIT && CMODEL_MEDLOW
+        default MAXPHYSMEM_128GB if 64BIT && CMODEL_MEDANY
+
+        config MAXPHYSMEM_2GB
+                bool "2GiB"
+        config MAXPHYSMEM_128GB
+                depends on 64BIT && CMODEL_MEDANY
+                bool "128GiB"
+endchoice
+
+
+config SMP
+        bool "Symmetric Multi-Processing"
+        help
+          This enables support for systems with more than one CPU.  If
+          you say N here, the kernel will run on single and
+          multiprocessor machines, but will use only one CPU of a
+          multiprocessor machine. If you say Y here, the kernel will run
+          on many, but not all, single processor machines. On a single
+          processor machine, the kernel will run faster if you say N
+          here.
+
+          If you don't know what to do here, say N.
+
+config NR_CPUS
+        int "Maximum number of CPUs (2-32)"
+        range 2 32
+        depends on SMP
+        default "8"
+
+config CPU_SUPPORTS_32BIT_KERNEL
+        bool
+config CPU_SUPPORTS_64BIT_KERNEL
+        bool
+
+choice
+        prompt "CPU Tuning"
+        default TUNE_GENERIC
+
+config TUNE_GENERIC
+        bool "generic"
+
+endchoice
+
+config RISCV_ISA_C
+        bool "Emit compressed instructions when building Linux"
+        default y
+        help
+           Adds "C" to the ISA subsets that the toolchain is allowed to emit
+           when building Linux, which results in compressed instructions in the
+           Linux binary.
+
+           If you don't know what to do here, say Y.
+
+config RISCV_ISA_A
+        def_bool y
+
+endmenu
+
+menu "Kernel type"
+
+choice
+        prompt "Kernel code model"
+        default 64BIT
+
+config 32BIT
+        bool "32-bit kernel"
+        depends on CPU_SUPPORTS_32BIT_KERNEL
+        help
+          Select this option to build a 32-bit kernel.
+
+config 64BIT
+        bool "64-bit kernel"
+        depends on CPU_SUPPORTS_64BIT_KERNEL
+        help
+          Select this option to build a 64-bit kernel.
+
+endchoice
+
+source "mm/Kconfig"
+
+source "kernel/Kconfig.preempt"
+
+source "kernel/Kconfig.hz"
+
+endmenu
+
+menu "Bus support"
+
+config PCI
+        bool "PCI support"
+        select PCI_MSI
+        help
+          This feature enables support for PCI bus system. If you say Y
+          here, the kernel will include drivers and infrastructure code
+          to support PCI bus devices.
+
+          If you don't know what to do here, say Y.
+
+config PCI_DOMAINS
+        def_bool PCI
+
+config PCI_DOMAINS_GENERIC
+        def_bool PCI
+
+source "drivers/pci/Kconfig"
+
+endmenu
+
+source "init/Kconfig"
+
+source "kernel/Kconfig.freezer"
+
+menu "Executable file formats"
+
+source "fs/Kconfig.binfmt"
+
+endmenu
+
+menu "Power management options"
+
+source kernel/power/Kconfig
+
+endmenu
+
+source "net/Kconfig"
+
+source "drivers/Kconfig"
+
+source "fs/Kconfig"
+
+menu "Kernel hacking"
+
+config CMDLINE_BOOL
+        bool "Built-in kernel command line"
+        help
+          For most platforms, it is firmware or second stage bootloader
+          that by default specifies the kernel command line options.
+          However, it might be necessary or advantageous to either override
+          the default kernel command line or add a few extra options to it.
+          For such cases, this option allows hardcoding command line options
+          directly into the kernel.
+
+          For that, choose 'Y' here and fill in the extra boot parameters
+          in CONFIG_CMDLINE.
+
+          The built-in options will be concatenated to the default command
+          line if CMDLINE_OVERRIDE is set to 'N'. Otherwise, the default
+          command line will be ignored and replaced by the built-in string.
+
+config CMDLINE
+        string "Built-in kernel command string"
+        depends on CMDLINE_BOOL
+        default ""
+        help
+          Supply command-line options at build time by entering them here.
+
+config CMDLINE_OVERRIDE
+        bool "Built-in command line overrides bootloader arguments"
+        depends on CMDLINE_BOOL
+        help
+          Set this option to 'Y' to have the kernel ignore the bootloader
+          or firmware command line.  Instead, the built-in command line
+          will be used exclusively.
+
+          If you don't know what to do here, say N.
+
+config EARLY_PRINTK
+        def_bool y
+
+source "lib/Kconfig.debug"
+
+config CMDLINE_BOOL
+        bool
+endmenu
+
+source "security/Kconfig"
+
+source "crypto/Kconfig"
+
+source "lib/Kconfig"
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
new file mode 100644
index 000000000000..6719dd30ec5b
--- /dev/null
+++ b/arch/riscv/Makefile
@@ -0,0 +1,72 @@
+# This file is included by the global makefile so that you can add your own
+# architecture-specific flags and dependencies. Remember to do have actions
+# for "archclean" and "archdep" for cleaning up and making dependencies for
+# this architecture
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+
+LDFLAGS         :=
+OBJCOPYFLAGS    := -O binary
+LDFLAGS_vmlinux :=
+KBUILD_AFLAGS_MODULE += -fPIC
+KBUILD_CFLAGS_MODULE += -fPIC
+
+KBUILD_DEFCONFIG = defconfig
+
+export BITS
+ifeq ($(CONFIG_ARCH_RV64I),y)
+        BITS := 64
+        UTS_MACHINE := riscv64
+
+        KBUILD_CFLAGS += -mabi=lp64
+        KBUILD_AFLAGS += -mabi=lp64
+        KBUILD_MARCH = rv64im
+        LDFLAGS += -melf64lriscv
+else
+        BITS := 32
+        UTS_MACHINE := riscv32
+
+        KBUILD_CFLAGS += -mabi=ilp32
+        KBUILD_AFLAGS += -mabi=ilp32
+        KBUILD_MARCH = rv32im
+        LDFLAGS += -melf32lriscv
+endif
+
+KBUILD_CFLAGS += -Wall
+
+ifeq ($(CONFIG_RISCV_ISA_A),y)
+        KBUILD_ARCH_A = a
+endif
+ifeq ($(CONFIG_RISCV_ISA_C),y)
+        KBUILD_ARCH_C = c
+endif
+
+KBUILD_AFLAGS += -march=$(KBUILD_MARCH)$(KBUILD_ARCH_A)fd$(KBUILD_ARCH_C)
+
+KBUILD_CFLAGS += -march=$(KBUILD_MARCH)$(KBUILD_ARCH_A)$(KBUILD_ARCH_C)
+KBUILD_CFLAGS += -mno-save-restore
+KBUILD_CFLAGS += -DCONFIG_PAGE_OFFSET=$(CONFIG_PAGE_OFFSET)
+
+ifeq ($(CONFIG_CMODEL_MEDLOW),y)
+        KBUILD_CFLAGS += -mcmodel=medlow
+endif
+ifeq ($(CONFIG_CMODEL_MEDANY),y)
+        KBUILD_CFLAGS += -mcmodel=medany
+endif
+
+# GCC versions that support the "-mstrict-align" option default to allowing
+# unaligned accesses.  While unaligned accesses are explicitly allowed in the
+# RISC-V ISA, they're emulated by machine mode traps on all extant
+# architectures.  It's faster to have GCC emit only aligned accesses.
+KBUILD_CFLAGS += $(call cc-option,-mstrict-align)
+
+head-y := arch/riscv/kernel/head.o
+
+core-y += arch/riscv/kernel/ arch/riscv/mm/
+
+libs-y += arch/riscv/lib/
+
+all: vmlinux
diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
new file mode 100644
index 000000000000..e69de29bb2d1
--- /dev/null
+++ b/arch/riscv/configs/defconfig
diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
new file mode 100644
index 000000000000..18158be62a2b
--- /dev/null
+++ b/arch/riscv/include/asm/Kbuild
@@ -0,0 +1,61 @@
+generic-y += bugs.h
+generic-y += cacheflush.h
+generic-y += checksum.h
+generic-y += clkdev.h
+generic-y += cputime.h
+generic-y += device.h
+generic-y += div64.h
+generic-y += dma.h
+generic-y += dma-contiguous.h
+generic-y += emergency-restart.h
+generic-y += errno.h
+generic-y += exec.h
+generic-y += fb.h
+generic-y += fcntl.h
+generic-y += ftrace.h
+generic-y += futex.h
+generic-y += hardirq.h
+generic-y += hash.h
+generic-y += hw_irq.h
+generic-y += ioctl.h
+generic-y += ioctls.h
+generic-y += ipcbuf.h
+generic-y += irq_regs.h
+generic-y += irq_work.h
+generic-y += kdebug.h
+generic-y += kmap_types.h
+generic-y += kvm_para.h
+generic-y += local.h
+generic-y += mm-arch-hooks.h
+generic-y += mman.h
+generic-y += module.h
+generic-y += msgbuf.h
+generic-y += mutex.h
+generic-y += param.h
+generic-y += percpu.h
+generic-y += poll.h
+generic-y += posix_types.h
+generic-y += preempt.h
+generic-y += resource.h
+generic-y += scatterlist.h
+generic-y += sections.h
+generic-y += sembuf.h
+generic-y += setup.h
+generic-y += shmbuf.h
+generic-y += shmparam.h
+generic-y += signal.h
+generic-y += socket.h
+generic-y += sockios.h
+generic-y += stat.h
+generic-y += statfs.h
+generic-y += swab.h
+generic-y += termbits.h
+generic-y += termios.h
+generic-y += topology.h
+generic-y += trace_clock.h
+generic-y += types.h
+generic-y += unaligned.h
+generic-y += user.h
+generic-y += vga.h
+generic-y += vmlinux.lds.h
+generic-y += xor.h
diff --git a/arch/riscv/kernel/.gitignore b/arch/riscv/kernel/.gitignore
new file mode 100644
index 000000000000..b51634f6a7cd
--- /dev/null
+++ b/arch/riscv/kernel/.gitignore
@@ -0,0 +1 @@
+/vmlinux.lds
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
new file mode 100644
index 000000000000..ab8baf7bd142
--- /dev/null
+++ b/arch/riscv/kernel/Makefile
@@ -0,0 +1,33 @@
+#
+# Makefile for the RISC-V Linux kernel
+#
+
+extra-y += head.o
+extra-y += vmlinux.lds
+
+obj-y   += cpu.o
+obj-y   += cpufeature.o
+obj-y   += entry.o
+obj-y   += irq.o
+obj-y   += process.o
+obj-y   += ptrace.o
+obj-y   += reset.o
+obj-y   += setup.o
+obj-y   += signal.o
+obj-y   += syscall_table.o
+obj-y   += sys_riscv.o
+obj-y   += time.o
+obj-y   += traps.o
+obj-y   += riscv_ksyms.o
+obj-y   += stacktrace.o
+obj-y   += vdso.o
+obj-y   += cacheinfo.o
+obj-y   += vdso/
+
+CFLAGS_setup.o := -mcmodel=medany
+
+obj-$(CONFIG_SMP)               += smpboot.o
+obj-$(CONFIG_SMP)               += smp.o
+obj-$(CONFIG_MODULES)           += module.o
+
+clean:
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
new file mode 100644
index 000000000000..ece84991609c
--- /dev/null
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -0,0 +1,92 @@
+/*
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2017 SiFive
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ */
+
+#define LOAD_OFFSET PAGE_OFFSET
+#include <asm/vmlinux.lds.h>
+#include <asm/page.h>
+#include <asm/cache.h>
+#include <asm/thread_info.h>
+
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+
+jiffies = jiffies_64;
+
+SECTIONS
+{
+        /* Beginning of code and text segment */
+        . = LOAD_OFFSET;
+        _start = .;
+        __init_begin = .;
+        HEAD_TEXT_SECTION
+        INIT_TEXT_SECTION(PAGE_SIZE)
+        INIT_DATA_SECTION(16)
+        /* we have to discard exit text and such at runtime, not link time */
+        .exit.text :
+        {
+                EXIT_TEXT
+        }
+        .exit.data :
+        {
+                EXIT_DATA
+        }
+        PERCPU_SECTION(L1_CACHE_BYTES)
+        __init_end = .;
+
+        .text : {
+                _text = .;
+                _stext = .;
+                TEXT_TEXT
+                SCHED_TEXT
+                CPUIDLE_TEXT
+                LOCK_TEXT
+                KPROBES_TEXT
+                ENTRY_TEXT
+                IRQENTRY_TEXT
+                *(.fixup)
+                _etext = .;
+        }
+
+        /* Start of data section */
+        _sdata = .;
+        RO_DATA_SECTION(L1_CACHE_BYTES)
+        .srodata : {
+                *(.srodata*)
+        }
+
+        RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
+        .sdata : {
+                __global_pointer$ = . + 0x800;
+                *(.sdata*)
+                /* End of data section */
+                _edata = .;
+                *(.sbss*)
+        }
+
+        BSS_SECTION(0, 0, 0)
+
+        EXCEPTION_TABLE(0x10)
+        NOTES
+
+        .rel.dyn : {
+                *(.rel.dyn*)
+        }
+
+        _end = .;
+
+        STABS_DEBUG
+        DWARF_DEBUG
+
+        DISCARDS
+}
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
new file mode 100644
index 000000000000..596c2ca40d63
--- /dev/null
+++ b/arch/riscv/lib/Makefile
@@ -0,0 +1,6 @@
+lib-y   += delay.o
+lib-y   += memcpy.o
+lib-y   += memset.o
+lib-y   += uaccess.o
+
+lib-$(CONFIG_32BIT) += udivdi3.o
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
new file mode 100644
index 000000000000..81f7d9ce6d88
--- /dev/null
+++ b/arch/riscv/mm/Makefile
@@ -0,0 +1,4 @@
+obj-y += init.o
+obj-y += fault.o
+obj-y += extable.o
+obj-y += ioremap.o