RISC-V Patches for 4.20-rc4

This week is a bit bigger than I expected.  That's my fault, as I missed
 a few patches while I was at Plumbers last week.  We have:
 
 * A fix to a quite embarassing issue where raw_copy_to_user() was
   implemented with asm_copy_from_user() (and vice versa).
 * Improvements to our makefile to allow flat binaries to be generated.
 * A build fix that predeclares "struct module" at the top of
   <asm/module.h>, which triggers warnings later in that header.
 * The addition of our own <uapi/asm/unistd> header, which is necessary
   to align our stat ABI on 32-bit systems.
 * A fix to avoid printing a warning when the S or U bits are set in
   print_isa().
 
 I already have one patch in the queue for next week.
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Merge tag 'riscv-for-linus-4.20-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux

Pull RISC-V fixes from Palmer Dabbelt:
 "This week is a bit bigger than I expected. That's my fault, as I
  missed a few patches while I was at Plumbers last week. We have:

   - A fix to a quite embarassing issue where raw_copy_to_user() was
     implemented with asm_copy_from_user() (and vice versa).

   - Improvements to our makefile to allow flat binaries to be
     generated.

   - A build fix that predeclares "struct module" at the top of
     <asm/module.h>, which triggers warnings later in that header.

   - The addition of our own <uapi/asm/unistd> header, which is
     necessary to align our stat ABI on 32-bit systems.

   - A fix to avoid printing a warning when the S or U bits are set in
     print_isa().

  I already have one patch in the queue for next week"

* tag 'riscv-for-linus-4.20-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/riscv-linux:
  RISC-V: recognize S/U mode bits in print_isa
  riscv: add asm/unistd.h UAPI header
  riscv: fix warning in arch/riscv/include/asm/module.h
  RISC-V: Build flat and compressed kernel images
  RISC-V: Fix raw_copy_{to,from}_user()

arch/riscv/Makefile

@@ -71,6 +71,10 @@ KBUILD_CFLAGS += $(call cc-option,-mstrict-align)
 # arch specific predefines for sparse
 CHECKFLAGS += -D__riscv -D__riscv_xlen=$(BITS)
 
+# Default target when executing plain make
+boot		:= arch/riscv/boot
+KBUILD_IMAGE	:= $(boot)/Image.gz
+
 head-y := arch/riscv/kernel/head.o
 
 core-y += arch/riscv/kernel/ arch/riscv/mm/
@@ -81,4 +85,13 @@ PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@
 
-all: vmlinux
+all: Image.gz
+
+Image: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+
+Image.%: Image
+	$(Q)$(MAKE) $(build)=$(boot) $(boot)/$@
+
+zinstall install:
+	$(Q)$(MAKE) $(build)=$(boot) $@

arch/riscv/boot/.gitignore

@@ -0,0 +1,2 @@
+Image
+Image.gz

arch/riscv/boot/Makefile

@@ -0,0 +1,33 @@
+#
+# arch/riscv/boot/Makefile
+#
+# This file is included by the global makefile so that you can add your own
+# architecture-specific flags and dependencies.
+#
+# 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.
+#
+# Copyright (C) 2018, Anup Patel.
+# Author: Anup Patel <anup@brainfault.org>
+#
+# Based on the ia64 and arm64 boot/Makefile.
+#
+
+OBJCOPYFLAGS_Image :=-O binary -R .note -R .note.gnu.build-id -R .comment -S
+
+targets := Image
+
+$(obj)/Image: vmlinux FORCE
+	$(call if_changed,objcopy)
+
+$(obj)/Image.gz: $(obj)/Image FORCE
+	$(call if_changed,gzip)
+
+install:
+	$(CONFIG_SHELL) $(srctree)/$(src)/install.sh $(KERNELRELEASE) \
+	$(obj)/Image System.map "$(INSTALL_PATH)"
+
+zinstall:
+	$(CONFIG_SHELL) $(srctree)/$(src)/install.sh $(KERNELRELEASE) \
+	$(obj)/Image.gz System.map "$(INSTALL_PATH)"

arch/riscv/boot/install.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+#
+# arch/riscv/boot/install.sh
+#
+# 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.
+#
+# Copyright (C) 1995 by Linus Torvalds
+#
+# Adapted from code in arch/i386/boot/Makefile by H. Peter Anvin
+# Adapted from code in arch/i386/boot/install.sh by Russell King
+#
+# "make install" script for the RISC-V Linux port
+#
+# Arguments:
+#   $1 - kernel version
+#   $2 - kernel image file
+#   $3 - kernel map file
+#   $4 - default install path (blank if root directory)
+#
+
+verify () {
+	if [ ! -f "$1" ]; then
+		echo ""                                                   1>&2
+		echo " *** Missing file: $1"                              1>&2
+		echo ' *** You need to run "make" before "make install".' 1>&2
+		echo ""                                                   1>&2
+		exit 1
+	fi
+}
+
+# Make sure the files actually exist
+verify "$2"
+verify "$3"
+
+# User may have a custom install script
+if [ -x ~/bin/${INSTALLKERNEL} ]; then exec ~/bin/${INSTALLKERNEL} "$@"; fi
+if [ -x /sbin/${INSTALLKERNEL} ]; then exec /sbin/${INSTALLKERNEL} "$@"; fi
+
+if [ "$(basename $2)" = "Image.gz" ]; then
+# Compressed install
+  echo "Installing compressed kernel"
+  base=vmlinuz
+else
+# Normal install
+  echo "Installing normal kernel"
+  base=vmlinux
+fi
+
+if [ -f $4/$base-$1 ]; then
+  mv $4/$base-$1 $4/$base-$1.old
+fi
+cat $2 > $4/$base-$1
+
+# Install system map file
+if [ -f $4/System.map-$1 ]; then
+  mv $4/System.map-$1 $4/System.map-$1.old
+fi
+cp $3 $4/System.map-$1

arch/riscv/include/asm/module.h

@@ -8,6 +8,7 @@
 
 #define MODULE_ARCH_VERMAGIC    "riscv"
 
+struct module;
 u64 module_emit_got_entry(struct module *mod, u64 val);
 u64 module_emit_plt_entry(struct module *mod, u64 val);
 

arch/riscv/include/asm/uaccess.h

@@ -400,13 +400,13 @@ extern unsigned long __must_check __asm_copy_from_user(void *to,
 static inline unsigned long
 raw_copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	return __asm_copy_to_user(to, from, n);
+	return __asm_copy_from_user(to, from, n);
 }
 
 static inline unsigned long
 raw_copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-	return __asm_copy_from_user(to, from, n);
+	return __asm_copy_to_user(to, from, n);
 }
 
 extern long strncpy_from_user(char *dest, const char __user *src, long count);

arch/riscv/include/asm/unistd.h

@@ -13,10 +13,9 @@
 
 /*
  * There is explicitly no include guard here because this file is expected to
- * be included multiple times.  See uapi/asm/syscalls.h for more info.
+ * be included multiple times.
  */
 
-#define __ARCH_WANT_NEW_STAT
 #define __ARCH_WANT_SYS_CLONE
+
 #include <uapi/asm/unistd.h>
-#include <uapi/asm/syscalls.h>

arch/riscv/include/uapi/asm/unistd.h

@@ -1,13 +1,25 @@
-/* SPDX-License-Identifier: GPL-2.0 */
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
 /*
- * Copyright (C) 2017-2018 SiFive
+ * Copyright (C) 2018 David Abdurachmanov <david.abdurachmanov@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-/*
- * There is explicitly no include guard here because this file is expected to
- * be included multiple times in order to define the syscall macros via
- * __SYSCALL.
- */
+#ifdef __LP64__
+#define __ARCH_WANT_NEW_STAT
+#endif /* __LP64__ */
+
+#include <asm-generic/unistd.h>
 
 /*
  * Allows the instruction cache to be flushed from userspace.  Despite RISC-V

arch/riscv/kernel/cpu.c

@@ -64,7 +64,7 @@ int riscv_of_processor_hartid(struct device_node *node)
 
 static void print_isa(struct seq_file *f, const char *orig_isa)
 {
-	static const char *ext = "mafdc";
+	static const char *ext = "mafdcsu";
 	const char *isa = orig_isa;
 	const char *e;
 
@@ -88,11 +88,14 @@ static void print_isa(struct seq_file *f, const char *orig_isa)
 	/*
 	 * Check the rest of the ISA string for valid extensions, printing those
 	 * we find.  RISC-V ISA strings define an order, so we only print the
-	 * extension bits when they're in order.
+	 * extension bits when they're in order. Hide the supervisor (S)
+	 * extension from userspace as it's not accessible from there.
 	 */
 	for (e = ext; *e != '\0'; ++e) {
 		if (isa[0] == e[0]) {
-			seq_write(f, isa, 1);
+			if (isa[0] != 's')
+				seq_write(f, isa, 1);
+
 			isa++;
 		}
 	}

arch/riscv/kernel/head.S

@@ -44,6 +44,16 @@ ENTRY(_start)
 	amoadd.w a3, a2, (a3)
 	bnez a3, .Lsecondary_start
 
+	/* Clear BSS for flat non-ELF images */
+	la a3, __bss_start
+	la a4, __bss_stop
+	ble a4, a3, clear_bss_done
+clear_bss:
+	REG_S zero, (a3)
+	add a3, a3, RISCV_SZPTR
+	blt a3, a4, clear_bss
+clear_bss_done:
+
 	/* Save hart ID and DTB physical address */
 	mv s0, a0
 	mv s1, a1

arch/riscv/kernel/vmlinux.lds.S

@@ -74,7 +74,7 @@ SECTIONS
 		*(.sbss*)
 	}
 
-	BSS_SECTION(0, 0, 0)
+	BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0)
 
 	EXCEPTION_TABLE(0x10)
 	NOTES