Merge tag 'nios2-v3.20-rc1' of git://git.rocketboards.org/linux-socfpga-next

Pull arch/nios2 update from Ley Foon Tan:
 "Here is the nios2 update for 3.20:

   - add early printk support
   - add kgdb support
   - add compressed kernel support
   - bugfixes"

* tag 'nios2-v3.20-rc1' of git://git.rocketboards.org/linux-socfpga-next:
  nios2: add kgdb support
  MAINTAINERS: update arch/nios2 git tree
  nios2: default CONFIG_NIOS2_BOOT_LINK_OFFSET to 8MB
  nios2: Add support for compressed kernel
  nios2: add early printk support
  nios2: Port OOM changes to do_page_fault()
  nios2: Remove unused prepare_to_copy()

20 files changed, 1066 insertions, 10 deletions

diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
index 2361acf..4375554 100644
--- a/arch/nios2/Kconfig
+++ b/arch/nios2/Kconfig
@@ -8,6 +8,7 @@ config NIOS2
 	select GENERIC_IRQ_PROBE
 	select GENERIC_IRQ_SHOW
 	select HAVE_ARCH_TRACEHOOK
+	select HAVE_ARCH_KGDB
 	select IRQ_DOMAIN
 	select MODULES_USE_ELF_RELA
 	select OF
@@ -134,6 +135,14 @@ config NIOS2_PASS_CMDLINE
 	  will override "Default kernel command string".
 	  Say N if you are unsure.
 
+config NIOS2_BOOT_LINK_OFFSET
+	hex "Link address offset for booting"
+	default "0x00500000"
+	help
+	  This option allows you to set the link address offset of the zImage.
+	  This can be useful if you are on a board which has a small amount of
+	  memory.
+
 endmenu
 
 menu "Advanced setup"
diff --git a/arch/nios2/Kconfig.debug b/arch/nios2/Kconfig.debug
index 8d4e6ba..2fd08cb 100644
--- a/arch/nios2/Kconfig.debug
+++ b/arch/nios2/Kconfig.debug
@@ -14,4 +14,15 @@ config DEBUG_STACK_USAGE
 
 	  This option will slow down process creation somewhat.
 
+config EARLY_PRINTK
+	bool "Activate early kernel debugging"
+	default y
+	select SERIAL_CORE_CONSOLE
+	depends on SERIAL_ALTERA_JTAGUART_CONSOLE || SERIAL_ALTERA_UART_CONSOLE
+	help
+	  Enable early printk on console
+	  This is useful for kernel debugging when your machine crashes very
+	  early before the console code is initialized.
+	  You should normally say N here, unless you want to debug such a crash.
+
 endmenu
diff --git a/arch/nios2/boot/Makefile b/arch/nios2/boot/Makefile
index 59392dc..c899876 100644
--- a/arch/nios2/boot/Makefile
+++ b/arch/nios2/boot/Makefile
@@ -24,6 +24,13 @@ $(obj)/vmImage: $(obj)/vmlinux.gz
 	$(call if_changed,uimage)
 	@$(kecho) 'Kernel: $@ is ready'
 
+$(obj)/zImage: $(obj)/compressed/vmlinux FORCE
+	$(call if_changed,objcopy)
+	@$(kecho) 'Kernel: $@ is ready'
+
+$(obj)/compressed/vmlinux: $(obj)/vmlinux.gz FORCE
+	$(Q)$(MAKE) $(build)=$(obj)/compressed $@
+
 # Rule to build device tree blobs
 DTB_SRC := $(patsubst "%",%,$(CONFIG_NIOS2_DTB_SOURCE))
 
diff --git a/arch/nios2/boot/compressed/Makefile b/arch/nios2/boot/compressed/Makefile
new file mode 100644
index 0000000..5b0fb34
--- /dev/null
+++ b/arch/nios2/boot/compressed/Makefile
@@ -0,0 +1,19 @@
+#
+# create a compressed vmlinux image from the original vmlinux
+#
+
+targets		:= vmlinux head.o misc.o piggy.o vmlinux.lds
+asflags-y	:=
+
+OBJECTS = $(obj)/head.o $(obj)/misc.o
+
+LDFLAGS_vmlinux := -T
+
+$(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS) $(obj)/piggy.o FORCE
+	$(call if_changed,ld)
+	@:
+
+LDFLAGS_piggy.o := -r --format binary --oformat elf32-littlenios2 -T
+
+$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/../vmlinux.gz FORCE
+	$(call if_changed,ld)
diff --git a/arch/nios2/boot/compressed/console.c b/arch/nios2/boot/compressed/console.c
new file mode 100644
index 0000000..2675e879
--- /dev/null
+++ b/arch/nios2/boot/compressed/console.c
@@ -0,0 +1,125 @@
+/*
+ *  Copyright (C) 2008-2010 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/>.
+ *
+ */
+
+#include <linux/io.h>
+
+#if (defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) && defined(JTAG_UART_BASE))\
+	|| (defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE) && defined(UART0_BASE))
+static void *my_ioremap(unsigned long physaddr)
+{
+	return (void *)(physaddr | CONFIG_NIOS2_IO_REGION_BASE);
+}
+#endif
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) && defined(JTAG_UART_BASE)
+
+#define ALTERA_JTAGUART_SIZE				8
+#define ALTERA_JTAGUART_DATA_REG			0
+#define ALTERA_JTAGUART_CONTROL_REG			4
+#define ALTERA_JTAGUART_CONTROL_AC_MSK			(0x00000400)
+#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK		(0xFFFF0000)
+static void *uartbase;
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
+static void jtag_putc(int ch)
+{
+	if (readl(uartbase + ALTERA_JTAGUART_CONTROL_REG) &
+		ALTERA_JTAGUART_CONTROL_WSPACE_MSK)
+		writeb(ch, uartbase + ALTERA_JTAGUART_DATA_REG);
+}
+#else
+static void jtag_putc(int ch)
+{
+	while ((readl(uartbase + ALTERA_JTAGUART_CONTROL_REG) &
+		ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0)
+		;
+	writeb(ch, uartbase + ALTERA_JTAGUART_DATA_REG);
+}
+#endif
+
+static int putchar(int ch)
+{
+	jtag_putc(ch);
+	return ch;
+}
+
+static void console_init(void)
+{
+	uartbase = my_ioremap((unsigned long) JTAG_UART_BASE);
+	writel(ALTERA_JTAGUART_CONTROL_AC_MSK,
+		uartbase + ALTERA_JTAGUART_CONTROL_REG);
+}
+
+#elif defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE) && defined(UART0_BASE)
+
+#define ALTERA_UART_SIZE		32
+#define ALTERA_UART_TXDATA_REG		4
+#define ALTERA_UART_STATUS_REG		8
+#define ALTERA_UART_DIVISOR_REG		16
+#define ALTERA_UART_STATUS_TRDY_MSK	(0x40)
+static unsigned uartbase;
+
+static void uart_putc(int ch)
+{
+	int i;
+
+	for (i = 0; (i < 0x10000); i++) {
+		if (readw(uartbase + ALTERA_UART_STATUS_REG) &
+			ALTERA_UART_STATUS_TRDY_MSK)
+			break;
+	}
+	writeb(ch, uartbase + ALTERA_UART_TXDATA_REG);
+}
+
+static int putchar(int ch)
+{
+	uart_putc(ch);
+	if (ch == '\n')
+		uart_putc('\r');
+	return ch;
+}
+
+static void console_init(void)
+{
+	unsigned int baud, baudclk;
+
+	uartbase = (unsigned long) my_ioremap((unsigned long) UART0_BASE);
+	baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
+	baudclk = UART0_FREQ / baud;
+	writew(baudclk, uartbase + ALTERA_UART_DIVISOR_REG);
+}
+
+#else
+
+static int putchar(int ch)
+{
+	return ch;
+}
+
+static void console_init(void)
+{
+}
+
+#endif
+
+static int puts(const char *s)
+{
+	while (*s)
+		putchar(*s++);
+	return 0;
+}
diff --git a/arch/nios2/boot/compressed/head.S b/arch/nios2/boot/compressed/head.S
new file mode 100644
index 0000000..15c6c48
--- /dev/null
+++ b/arch/nios2/boot/compressed/head.S
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2009 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * Based on arch/nios2/kernel/head.S
+ *
+ * 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.
+ *
+ */
+
+/*
+ *  This code can be loaded anywhere, eg FLASH ROM as reset vector,
+ *  as long as output does not overlap it.
+ */
+
+#include <linux/linkage.h>
+#include <asm/cache.h>
+
+	.text
+	.set noat
+ENTRY(_start)
+	wrctl	status, r0		/* disable interrupt */
+	/* invalidate all instruction cache */
+	movia	r1, NIOS2_ICACHE_SIZE
+	movui	r2, NIOS2_ICACHE_LINE_SIZE
+1:	initi	r1
+	sub	r1, r1, r2
+	bgt	r1, r0, 1b
+	/* invalidate all data cache */
+	movia	r1, NIOS2_DCACHE_SIZE
+	movui	r2, NIOS2_DCACHE_LINE_SIZE
+1:	initd	0(r1)
+	sub	r1, r1, r2
+	bgt	r1, r0, 1b
+
+	nextpc	r1			/* Find out where we are */
+chkadr:
+	movia	r2, chkadr
+	beq	r1, r2, finish_move	/* We are running in correct address,
+					   done */
+	/* move code, r1: src, r2: dest, r3: last dest */
+	addi	r1, r1, (_start - chkadr)	/* Source */
+	movia	r2, _start		/* Destination */
+	movia	r3, __bss_start		/* End of copy */
+1:	ldw	r8, 0(r1)		/* load a word from [r1] */
+	stw	r8, 0(r2)		/* stort a word to dest [r2] */
+	addi	r1, r1, 4		/* inc the src addr */
+	addi	r2, r2, 4		/* inc the dest addr */
+	blt	r2, r3, 1b
+	/* flush the data cache after moving */
+	movia	r1, NIOS2_DCACHE_SIZE
+	movui	r2, NIOS2_DCACHE_LINE_SIZE
+1:	flushd	0(r1)
+	sub	r1, r1, r2
+	bgt	r1, r0, 1b
+	movia	r1, finish_move
+	jmp	r1			/* jmp to linked address */
+
+finish_move:
+	/* zero out the .bss segment (uninitialized common data) */
+	movia	r2, __bss_start		/* presume nothing is between */
+	movia	r1, _end		/* the .bss and _end. */
+1: 	stb	r0, 0(r2)
+	addi	r2, r2, 1
+	bne	r1, r2, 1b
+	/*
+	 * set up the stack pointer, some where higher than _end.
+	 * The stack space must be greater than 32K for decompress.
+	 */
+	movia	sp, 0x10000
+	add	sp, sp, r1
+	/* save args passed from u-boot, maybe */
+	addi	sp, sp, -16
+	stw	r4, 0(sp)
+	stw	r5, 4(sp)
+	stw	r6, 8(sp)
+	stw	r7, 12(sp)
+	/* decompress the kernel */
+	call	decompress_kernel
+	/* pass saved args to kernel */
+	ldw	r4, 0(sp)
+	ldw	r5, 4(sp)
+	ldw	r6, 8(sp)
+	ldw	r7, 12(sp)
+
+	/* flush all data cache after decompressing */
+	movia	r1, NIOS2_DCACHE_SIZE
+	movui	r2, NIOS2_DCACHE_LINE_SIZE
+1:	flushd	0(r1)
+	sub	r1, r1, r2
+	bgt	r1, r0, 1b
+	/* flush all instruction cache */
+	movia	r1, NIOS2_ICACHE_SIZE
+	movui	r2, NIOS2_ICACHE_LINE_SIZE
+1:	flushi	r1
+	sub	r1, r1, r2
+	bgt	r1, r0, 1b
+	flushp
+	/* jump to start real kernel */
+	movia	r1, (CONFIG_NIOS2_MEM_BASE | CONFIG_NIOS2_KERNEL_REGION_BASE)
+	jmp	r1
+
+	.balign 512
+fake_headers_as_bzImage:
+	.short	0
+	.ascii	"HdrS"
+	.short	0x0202
+	.short	0
+	.short	0
+	.byte	0x00, 0x10
+	.short	0
+	.byte	0
+	.byte	1
+	.byte	0x00, 0x80
+	.long	0
+	.long	0
diff --git a/arch/nios2/boot/compressed/misc.c b/arch/nios2/boot/compressed/misc.c
new file mode 100644
index 0000000..8437782
--- /dev/null
+++ b/arch/nios2/boot/compressed/misc.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2009 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * This is a collection of several routines from gzip-1.0.3
+ * adapted for Linux.
+ *
+ * malloc by Hannu Savolainen 1993 and Matthias Urlichs 1994
+ *
+ * Adapted for SH by Stuart Menefy, Aug 1999
+ *
+ * Modified to use standard LinuxSH BIOS by Greg Banks 7Jul2000
+ *
+ * Based on arch/sh/boot/compressed/misc.c
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/>.
+ *
+ */
+
+#include <linux/string.h>
+
+/*
+ * gzip declarations
+ */
+#define OF(args)  args
+#define STATIC static
+
+#undef memset
+#undef memcpy
+#define memzero(s, n)		memset((s), 0, (n))
+
+typedef unsigned char  uch;
+typedef unsigned short ush;
+typedef unsigned long  ulg;
+#define WSIZE 0x8000		/* Window size must be at least 32k, */
+				/* and a power of two */
+
+static uch *inbuf;		/* input buffer */
+static uch window[WSIZE];	/* Sliding window buffer */
+
+static unsigned insize;	/* valid bytes in inbuf */
+static unsigned inptr;	/* index of next byte to be processed in inbuf */
+static unsigned outcnt;	/* bytes in output buffer */
+
+/* gzip flag byte */
+#define ASCII_FLAG	0x01 /* bit 0 set: file probably ASCII text */
+#define CONTINUATION	0x02 /* bit 1 set: continuation of multi-part gzip
+				file */
+#define EXTRA_FIELD	0x04 /* bit 2 set: extra field present */
+#define ORIG_NAME	0x08 /* bit 3 set: original file name present */
+#define COMMENT		0x10 /* bit 4 set: file comment present */
+#define ENCRYPTED	0x20 /* bit 5 set: file is encrypted */
+#define RESERVED	0xC0 /* bit 6,7:   reserved */
+
+#define get_byte()  (inptr < insize ? inbuf[inptr++] : fill_inbuf())
+
+#ifdef DEBUG
+#  define Assert(cond, msg) {if (!(cond)) error(msg); }
+#  define Trace(x) fprintf x
+#  define Tracev(x) {if (verbose) fprintf x ; }
+#  define Tracevv(x) {if (verbose > 1) fprintf x ; }
+#  define Tracec(c, x) {if (verbose && (c)) fprintf x ; }
+#  define Tracecv(c, x) {if (verbose > 1 && (c)) fprintf x ; }
+#else
+#  define Assert(cond, msg)
+#  define Trace(x)
+#  define Tracev(x)
+#  define Tracevv(x)
+#  define Tracec(c, x)
+#  define Tracecv(c, x)
+#endif
+static int  fill_inbuf(void);
+static void flush_window(void);
+static void error(char *m);
+
+extern char input_data[];
+extern int input_len;
+
+static long bytes_out;
+static uch *output_data;
+static unsigned long output_ptr;
+
+#include "console.c"
+
+static void error(char *m);
+
+int puts(const char *);
+
+extern int _end;
+static unsigned long free_mem_ptr;
+static unsigned long free_mem_end_ptr;
+
+#define HEAP_SIZE			0x10000
+
+#include "../../../../lib/inflate.c"
+
+void *memset(void *s, int c, size_t n)
+{
+	int i;
+	char *ss = (char *)s;
+
+	for (i = 0; i < n; i++)
+		ss[i] = c;
+	return s;
+}
+
+void *memcpy(void *__dest, __const void *__src, size_t __n)
+{
+	int i;
+	char *d = (char *)__dest, *s = (char *)__src;
+
+	for (i = 0; i < __n; i++)
+		d[i] = s[i];
+	return __dest;
+}
+
+/*
+ * Fill the input buffer. This is called only when the buffer is empty
+ * and at least one byte is really needed.
+ */
+static int fill_inbuf(void)
+{
+	if (insize != 0)
+		error("ran out of input data");
+
+	inbuf = input_data;
+	insize = input_len;
+	inptr = 1;
+	return inbuf[0];
+}
+
+/*
+ * Write the output window window[0..outcnt-1] and update crc and bytes_out.
+ * (Used for the decompressed data only.)
+ */
+static void flush_window(void)
+{
+	ulg c = crc;	/* temporary variable */
+	unsigned n;
+	uch *in, *out, ch;
+
+	in = window;
+	out = &output_data[output_ptr];
+	for (n = 0; n < outcnt; n++) {
+		ch = *out++ = *in++;
+		c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
+	}
+	crc = c;
+	bytes_out += (ulg)outcnt;
+	output_ptr += (ulg)outcnt;
+	outcnt = 0;
+}
+
+static void error(char *x)
+{
+	puts("\nERROR\n");
+	puts(x);
+	puts("\n\n -- System halted");
+
+	while (1)	/* Halt */
+		;
+}
+
+void decompress_kernel(void)
+{
+	output_data = (void *) (CONFIG_NIOS2_MEM_BASE |
+				CONFIG_NIOS2_KERNEL_REGION_BASE);
+	output_ptr = 0;
+	free_mem_ptr = (unsigned long)&_end;
+	free_mem_end_ptr = free_mem_ptr + HEAP_SIZE;
+
+	console_init();
+	makecrc();
+	puts("Uncompressing Linux... ");
+	gunzip();
+	puts("Ok, booting the kernel.\n");
+}
diff --git a/arch/nios2/boot/compressed/vmlinux.lds.S b/arch/nios2/boot/compressed/vmlinux.lds.S
new file mode 100644
index 0000000..e867b37
--- /dev/null
+++ b/arch/nios2/boot/compressed/vmlinux.lds.S
@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2009 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/>.
+ *
+ */
+
+#include <asm-generic/vmlinux.lds.h>
+
+OUTPUT_FORMAT("elf32-littlenios2", "elf32-littlenios2", "elf32-littlenios2")
+
+OUTPUT_ARCH(nios)
+ENTRY(_start)	/* Defined in head.S */
+
+SECTIONS
+{
+	. = (CONFIG_NIOS2_MEM_BASE + CONFIG_NIOS2_BOOT_LINK_OFFSET) |	\
+		CONFIG_NIOS2_KERNEL_REGION_BASE;
+
+	_text = .;
+	.text : { *(.text) } = 0
+	.rodata : { *(.rodata) *(.rodata.*) }
+	_etext = .;
+
+	. = ALIGN(32 / 8);
+	.data : { *(.data) }
+	. = ALIGN(32 / 8);
+	_got = .;
+	.got : {
+		*(.got.plt)
+		*(.igot.plt)
+		*(.got)
+		*(.igot)
+	}
+	_egot = .;
+	_edata =  .;
+
+	. = ALIGN(32 / 8);
+	__bss_start = .;
+	.bss : { *(.bss) *(.sbss) }
+	. = ALIGN(32 / 8);
+	_ebss = .;
+	end = . ;
+	_end = . ;
+
+	got_len = (_egot - _got);
+}
diff --git a/arch/nios2/boot/compressed/vmlinux.scr b/arch/nios2/boot/compressed/vmlinux.scr
new file mode 100644
index 0000000..28c42f1
--- /dev/null
+++ b/arch/nios2/boot/compressed/vmlinux.scr
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2009 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/>.
+ *
+ */
+
+SECTIONS
+{
+	.data : {
+		input_len = .;
+		LONG(input_data_end - input_data) input_data = .;
+		*(.data)
+		. = ALIGN(4);
+		input_data_end = .;
+	}
+}
diff --git a/arch/nios2/configs/3c120_defconfig b/arch/nios2/configs/3c120_defconfig
index 87541f0..9451940 100644
--- a/arch/nios2/configs/3c120_defconfig
+++ b/arch/nios2/configs/3c120_defconfig
@@ -22,6 +22,7 @@ CONFIG_NIOS2_DCACHE_SIZE=0x8000
 CONFIG_NIOS2_ICACHE_SIZE=0x8000
 # CONFIG_NIOS2_CMDLINE_IGNORE_DTB is not set
 CONFIG_NIOS2_PASS_CMDLINE=y
+CONFIG_NIOS2_BOOT_LINK_OFFSET=0x00800000
 CONFIG_NET=y
 CONFIG_PACKET=y
 CONFIG_UNIX=y
diff --git a/arch/nios2/include/asm/kgdb.h b/arch/nios2/include/asm/kgdb.h
new file mode 100644
index 0000000..8fd5e3b
--- /dev/null
+++ b/arch/nios2/include/asm/kgdb.h
@@ -0,0 +1,93 @@
+/*
+ * Copyright (C) 2015 Altera Corporation
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ *
+ * Based on the code posted by Kazuyasu on the Altera Forum at:
+ * http://www.alteraforum.com/forum/showpost.php?p=77003&postcount=20
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/>.
+ *
+ */
+
+#ifndef _ASM_NIOS2_KGDB_H
+#define _ASM_NIOS2_KGDB_H
+
+#define CACHE_FLUSH_IS_SAFE	1
+#define BUFMAX			2048
+
+enum regnames {
+	GDB_R0 = 0,
+	GDB_AT,
+	GDB_R2,
+	GDB_R3,
+	GDB_R4,
+	GDB_R5,
+	GDB_R6,
+	GDB_R7,
+	GDB_R8,
+	GDB_R9,
+	GDB_R10,
+	GDB_R11,
+	GDB_R12,
+	GDB_R13,
+	GDB_R14,
+	GDB_R15,
+	GDB_R16,
+	GDB_R17,
+	GDB_R18,
+	GDB_R19,
+	GDB_R20,
+	GDB_R21,
+	GDB_R22,
+	GDB_R23,
+	GDB_ET,
+	GDB_BT,
+	GDB_GP,
+	GDB_SP,
+	GDB_FP,
+	GDB_EA,
+	GDB_BA,
+	GDB_RA,
+	GDB_PC,
+	GDB_STATUS,
+	GDB_ESTATUS,
+	GDB_BSTATUS,
+	GDB_IENABLE,
+	GDB_IPENDING,
+	GDB_CPUID,
+	GDB_CTL6,
+	GDB_EXCEPTION,
+	GDB_PTEADDR,
+	GDB_TLBACC,
+	GDB_TLBMISC,
+	GDB_ECCINJ,
+	GDB_BADADDR,
+	GDB_CONFIG,
+	GDB_MPUBASE,
+	GDB_MPUACC,
+	/* do not change the last entry or anything below! */
+	GDB_NUMREGBYTES		/* number of registers */
+};
+
+#define GDB_SIZEOF_REG		sizeof(u32)
+#define DBG_MAX_REG_NUM	(49)
+#define NUMREGBYTES		(DBG_MAX_REG_NUM * sizeof(GDB_SIZEOF_REG))
+
+#define BREAK_INSTR_SIZE	4
+static inline void arch_kgdb_breakpoint(void)
+{
+	__asm__ __volatile__("trap 30\n");
+}
+
+#endif /* _ASM_NIOS2_KGDB_H */
diff --git a/arch/nios2/include/asm/processor.h b/arch/nios2/include/asm/processor.h
index 3bd3494..c2ba45c 100644
--- a/arch/nios2/include/asm/processor.h
+++ b/arch/nios2/include/asm/processor.h
@@ -85,9 +85,6 @@ static inline void exit_thread(void)
 
 extern unsigned long get_wchan(struct task_struct *p);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 #define task_pt_regs(p) \
 	((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
 
diff --git a/arch/nios2/include/asm/prom.h b/arch/nios2/include/asm/prom.h
new file mode 100644
index 0000000..75fffb4
--- /dev/null
+++ b/arch/nios2/include/asm/prom.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright Altera Corporation (C) <2015>. All rights reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/>.
+ */
+
+#ifndef __ASM_NIOS2_PROM_H__
+#define __ASM_NIOS2_PROM_H__
+
+extern unsigned long __init of_early_console(void);
+
+#endif
diff --git a/arch/nios2/kernel/Makefile b/arch/nios2/kernel/Makefile
index 8ae7682..1aae257 100644
--- a/arch/nios2/kernel/Makefile
+++ b/arch/nios2/kernel/Makefile
@@ -20,5 +20,7 @@ obj-y	+= syscall_table.o
 obj-y	+= time.o
 obj-y	+= traps.o
 
+obj-$(CONFIG_EARLY_PRINTK)		+= early_printk.o
+obj-$(CONFIG_KGDB)			+= kgdb.o
 obj-$(CONFIG_MODULES)			+= module.o
 obj-$(CONFIG_NIOS2_ALIGNMENT_TRAP)	+= misaligned.o
diff --git a/arch/nios2/kernel/early_printk.c b/arch/nios2/kernel/early_printk.c
new file mode 100644
index 0000000..c08e4c1
--- /dev/null
+++ b/arch/nios2/kernel/early_printk.c
@@ -0,0 +1,118 @@
+/*
+ * Early printk for Nios2.
+ *
+ * Copyright (C) 2015, Altera Corporation
+ * Copyright (C) 2010, Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2009, Wind River Systems Inc
+ *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
+ *
+ * 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.
+ */
+
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+
+#include <asm/prom.h>
+
+static unsigned long base_addr;
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE)
+
+#define ALTERA_JTAGUART_DATA_REG		0
+#define ALTERA_JTAGUART_CONTROL_REG		4
+#define ALTERA_JTAGUART_CONTROL_WSPACE_MSK	0xFFFF0000
+#define ALTERA_JTAGUART_CONTROL_AC_MSK		0x00000400
+
+#define JUART_GET_CR() \
+	__builtin_ldwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG))
+#define JUART_SET_CR(v) \
+	__builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_CONTROL_REG), v)
+#define JUART_SET_TX(v) \
+	__builtin_stwio((void *)(base_addr + ALTERA_JTAGUART_DATA_REG), v)
+
+static void early_console_write(struct console *con, const char *s, unsigned n)
+{
+	unsigned long status;
+
+	while (n-- && *s) {
+		while (((status = JUART_GET_CR())
+				& ALTERA_JTAGUART_CONTROL_WSPACE_MSK) == 0) {
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
+			if ((status & ALTERA_JTAGUART_CONTROL_AC_MSK) == 0)
+				return;	/* no connection activity */
+#endif
+		}
+		JUART_SET_TX(*s);
+		s++;
+	}
+}
+
+#elif defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
+
+#define ALTERA_UART_TXDATA_REG		4
+#define ALTERA_UART_STATUS_REG		8
+#define ALTERA_UART_STATUS_TRDY		0x0040
+
+#define UART_GET_SR() \
+	__builtin_ldwio((void *)(base_addr + ALTERA_UART_STATUS_REG))
+#define UART_SET_TX(v) \
+	__builtin_stwio((void *)(base_addr + ALTERA_UART_TXDATA_REG), v)
+
+static void early_console_putc(char c)
+{
+	while (!(UART_GET_SR() & ALTERA_UART_STATUS_TRDY))
+		;
+
+	UART_SET_TX(c);
+}
+
+static void early_console_write(struct console *con, const char *s, unsigned n)
+{
+	while (n-- && *s) {
+		early_console_putc(*s);
+		if (*s == '\n')
+			early_console_putc('\r');
+		s++;
+	}
+}
+
+#else
+# error Neither SERIAL_ALTERA_JTAGUART_CONSOLE nor SERIAL_ALTERA_UART_CONSOLE \
+selected
+#endif
+
+static struct console early_console_prom = {
+	.name	= "early",
+	.write	= early_console_write,
+	.flags	= CON_PRINTBUFFER | CON_BOOT,
+	.index	= -1
+};
+
+void __init setup_early_printk(void)
+{
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE) ||	\
+	defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)
+	base_addr = of_early_console();
+#else
+	base_addr = 0;
+#endif
+
+	if (!base_addr)
+		return;
+
+#if defined(CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE_BYPASS)
+	/* Clear activity bit so BYPASS doesn't stall if we've used JTAG for
+	 * downloading the kernel. This might cause early data to be lost even
+	 * if the JTAG terminal is running.
+	 */
+	JUART_SET_CR(JUART_GET_CR() | ALTERA_JTAGUART_CONTROL_AC_MSK);
+#endif
+
+	early_console = &early_console_prom;
+	register_console(early_console);
+	pr_info("early_console initialized at 0x%08lx\n", base_addr);
+}
diff --git a/arch/nios2/kernel/entry.S b/arch/nios2/kernel/entry.S
index 0bdfd13..7729bd3 100644
--- a/arch/nios2/kernel/entry.S
+++ b/arch/nios2/kernel/entry.S
@@ -121,7 +121,11 @@ trap_table:
 	.word	instruction_trap	/* 27 */
 	.word	instruction_trap	/* 28 */
 	.word	instruction_trap	/* 29 */
-	.word	instruction_trap	/* 30 */
+#ifdef CONFIG_KGDB
+	.word	handle_kgdb_breakpoint	/* 30 KGDB breakpoint */
+#else
+	.word	instruction_trap		/* 30 */
+#endif
 	.word	handle_breakpoint	/* 31 */
 
 .text
@@ -445,6 +449,12 @@ handle_diverror:
 	call	handle_diverror_c
 	br	ret_from_exception
 
+#ifdef CONFIG_KGDB
+handle_kgdb_breakpoint:
+	call	kgdb_breakpoint_c
+	br	ret_from_exception
+#endif
+
 /*
  * Beware - when entering resume, prev (the current task) is
  * in r4, next (the new task) is in r5, don't change these
diff --git a/arch/nios2/kernel/kgdb.c b/arch/nios2/kernel/kgdb.c
new file mode 100644
index 0000000..1178591
--- /dev/null
+++ b/arch/nios2/kernel/kgdb.c
@@ -0,0 +1,171 @@
+/*
+ * Nios2 KGDB support
+ *
+ * Copyright (C) 2015 Altera Corporation
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ *
+ * Based on the code posted by Kazuyasu on the Altera Forum at:
+ * http://www.alteraforum.com/forum/showpost.php?p=77003&postcount=20
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/>.
+ *
+ */
+#include <linux/ptrace.h>
+#include <linux/kgdb.h>
+#include <linux/kdebug.h>
+#include <linux/io.h>
+
+static int wait_for_remote_debugger;
+
+struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
+{
+	{ "zero", GDB_SIZEOF_REG, -1 },
+	{ "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, r1) },
+	{ "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, r2) },
+	{ "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, r3) },
+	{ "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, r4) },
+	{ "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, r5) },
+	{ "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, r6) },
+	{ "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, r7) },
+	{ "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, r8) },
+	{ "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, r9) },
+	{ "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, r10) },
+	{ "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, r11) },
+	{ "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, r12) },
+	{ "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, r13) },
+	{ "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, r14) },
+	{ "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, r15) },
+	{ "r16", GDB_SIZEOF_REG, -1 },
+	{ "r17", GDB_SIZEOF_REG, -1 },
+	{ "r18", GDB_SIZEOF_REG, -1 },
+	{ "r19", GDB_SIZEOF_REG, -1 },
+	{ "r20", GDB_SIZEOF_REG, -1 },
+	{ "r21", GDB_SIZEOF_REG, -1 },
+	{ "r22", GDB_SIZEOF_REG, -1 },
+	{ "r23", GDB_SIZEOF_REG, -1 },
+	{ "et", GDB_SIZEOF_REG, -1 },
+	{ "bt", GDB_SIZEOF_REG, -1 },
+	{ "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, gp) },
+	{ "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, sp) },
+	{ "fp", GDB_SIZEOF_REG, offsetof(struct pt_regs, fp) },
+	{ "ea", GDB_SIZEOF_REG, -1 },
+	{ "ba", GDB_SIZEOF_REG, -1 },
+	{ "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, ra) },
+	{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, ea) },
+	{ "status", GDB_SIZEOF_REG, -1 },
+	{ "estatus", GDB_SIZEOF_REG, offsetof(struct pt_regs, estatus) },
+	{ "bstatus", GDB_SIZEOF_REG, -1 },
+	{ "ienable", GDB_SIZEOF_REG, -1 },
+	{ "ipending", GDB_SIZEOF_REG, -1},
+	{ "cpuid", GDB_SIZEOF_REG, -1 },
+	{ "ctl6", GDB_SIZEOF_REG, -1 },
+	{ "exception", GDB_SIZEOF_REG, -1 },
+	{ "pteaddr", GDB_SIZEOF_REG, -1 },
+	{ "tlbacc", GDB_SIZEOF_REG, -1 },
+	{ "tlbmisc", GDB_SIZEOF_REG, -1 },
+	{ "eccinj", GDB_SIZEOF_REG, -1 },
+	{ "badaddr", GDB_SIZEOF_REG, -1 },
+	{ "config", GDB_SIZEOF_REG, -1 },
+	{ "mpubase", GDB_SIZEOF_REG, -1 },
+	{ "mpuacc", GDB_SIZEOF_REG, -1 },
+};
+
+char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return NULL;
+
+	if (dbg_reg_def[regno].offset != -1)
+		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
+		       dbg_reg_def[regno].size);
+	else
+		memset(mem, 0, dbg_reg_def[regno].size);
+
+	return dbg_reg_def[regno].name;
+}
+
+int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
+{
+	if (regno >= DBG_MAX_REG_NUM || regno < 0)
+		return -EINVAL;
+
+	if (dbg_reg_def[regno].offset != -1)
+		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
+		       dbg_reg_def[regno].size);
+
+	return 0;
+}
+
+void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
+{
+	memset((char *)gdb_regs, 0, NUMREGBYTES);
+	gdb_regs[GDB_SP] = p->thread.kregs->sp;
+	gdb_regs[GDB_PC] = p->thread.kregs->ea;
+}
+
+void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
+{
+	regs->ea = pc;
+}
+
+int kgdb_arch_handle_exception(int vector, int signo, int err_code,
+				char *remcom_in_buffer, char *remcom_out_buffer,
+				struct pt_regs *regs)
+{
+	char *ptr;
+	unsigned long addr;
+
+	switch (remcom_in_buffer[0]) {
+	case 's':
+	case 'c':
+		/* handle the optional parameters */
+		ptr = &remcom_in_buffer[1];
+		if (kgdb_hex2long(&ptr, &addr))
+			regs->ea = addr;
+
+		return 0;
+	}
+
+	return -1; /* this means that we do not want to exit from the handler */
+}
+
+asmlinkage void kgdb_breakpoint_c(struct pt_regs *regs)
+{
+	/*
+	 * The breakpoint entry code has moved the PC on by 4 bytes, so we must
+	 * move it back.  This could be done on the host but we do it here
+	 */
+	if (!wait_for_remote_debugger)
+		regs->ea -= 4;
+	else	/* pass the first trap 30 code */
+		wait_for_remote_debugger = 0;
+
+	kgdb_handle_exception(30, SIGTRAP, 0, regs);
+}
+
+int kgdb_arch_init(void)
+{
+	wait_for_remote_debugger = 1;
+	return 0;
+}
+
+void kgdb_arch_exit(void)
+{
+	/* Nothing to do */
+}
+
+struct kgdb_arch arch_kgdb_ops = {
+	/* Breakpoint instruction: trap 30 */
+	.gdb_bpt_instr = { 0xba, 0x6f, 0x3b, 0x00 },
+};
diff --git a/arch/nios2/kernel/prom.c b/arch/nios2/kernel/prom.c
index 0522d33..718dd19 100644
--- a/arch/nios2/kernel/prom.c
+++ b/arch/nios2/kernel/prom.c
@@ -1,7 +1,7 @@
 /*
  * Device tree support
  *
- * Copyright (C) 2013 Altera Corporation
+ * Copyright (C) 2013, 2015 Altera Corporation
  * Copyright (C) 2010 Thomas Chou <thomas@wytron.com.tw>
  *
  * Based on MIPS support for CONFIG_OF device tree support
@@ -30,6 +30,7 @@
 #include <linux/of_fdt.h>
 #include <linux/io.h>
 
+#include <asm/prom.h>
 #include <asm/sections.h>
 
 void __init early_init_dt_add_memory_arch(u64 base, u64 size)
@@ -63,3 +64,52 @@ void __init early_init_devtree(void *params)
 
 	early_init_dt_scan(params);
 }
+
+#ifdef CONFIG_EARLY_PRINTK
+static int __init early_init_dt_scan_serial(unsigned long node,
+			const char *uname, int depth, void *data)
+{
+	u64 *addr64 = (u64 *) data;
+	const char *p;
+
+	/* only consider serial nodes */
+	if (strncmp(uname, "serial", 6) != 0)
+		return 0;
+
+	p = of_get_flat_dt_prop(node, "compatible", NULL);
+	if (!p)
+		return 0;
+
+	/*
+	 * We found an altera_jtaguart but it wasn't configured for console, so
+	 * skip it.
+	 */
+#ifndef CONFIG_SERIAL_ALTERA_JTAGUART_CONSOLE
+	if (strncmp(p, "altr,juart", 10) == 0)
+		return 0;
+#endif
+
+	/*
+	 * Same for altera_uart.
+	 */
+#ifndef CONFIG_SERIAL_ALTERA_UART_CONSOLE
+	if (strncmp(p, "altr,uart", 9) == 0)
+		return 0;
+#endif
+
+	*addr64 = fdt_translate_address((const void *)initial_boot_params,
+		node);
+
+	return *addr64 == OF_BAD_ADDR ? 0 : 1;
+}
+
+unsigned long __init of_early_console(void)
+{
+	u64 base = 0;
+
+	if (of_scan_flat_dt(early_init_dt_scan_serial, &base))
+		return (u32)ioremap(base, 32);
+	else
+		return 0;
+}
+#endif /* CONFIG_EARLY_PRINTK */
diff --git a/arch/nios2/kernel/setup.c b/arch/nios2/kernel/setup.c
index cb3121f..b101a43 100644
--- a/arch/nios2/kernel/setup.c
+++ b/arch/nios2/kernel/setup.c
@@ -139,6 +139,10 @@ void __init setup_arch(char **cmdline_p)
 
 	console_verbose();
 
+#ifdef CONFIG_EARLY_PRINTK
+	setup_early_printk();
+#endif
+
 	memory_start = PAGE_ALIGN((unsigned long)__pa(_end));
 	memory_end = (unsigned long) CONFIG_NIOS2_MEM_BASE + memory_size;
 
diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c
index d194c04..0d231ad 100644
--- a/arch/nios2/mm/fault.c
+++ b/arch/nios2/mm/fault.c
@@ -47,7 +47,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
 	struct mm_struct *mm = tsk->mm;
 	int code = SEGV_MAPERR;
 	int fault;
-	unsigned int flags = 0;
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	cause >>= 2;
 
@@ -86,6 +86,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
 	if (!down_read_trylock(&mm->mmap_sem)) {
 		if (!user_mode(regs) && !search_exception_tables(regs->ea))
 			goto bad_area_nosemaphore;
+retry:
 		down_read(&mm->mmap_sem);
 	}
 
@@ -132,6 +133,10 @@ survive:
 	 * the fault.
 	 */
 	fault = handle_mm_fault(mm, vma, address, flags);
+
+	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+		return;
+
 	if (unlikely(fault & VM_FAULT_ERROR)) {
 		if (fault & VM_FAULT_OOM)
 			goto out_of_memory;
@@ -141,10 +146,32 @@ survive:
 			goto do_sigbus;
 		BUG();
 	}
-	if (fault & VM_FAULT_MAJOR)
-		tsk->maj_flt++;
-	else
-		tsk->min_flt++;
+
+	/*
+	 * Major/minor page fault accounting is only done on the
+	 * initial attempt. If we go through a retry, it is extremely
+	 * likely that the page will be found in page cache at that point.
+	 */
+	if (flags & FAULT_FLAG_ALLOW_RETRY) {
+		if (fault & VM_FAULT_MAJOR)
+			current->maj_flt++;
+		else
+			current->min_flt++;
+		if (fault & VM_FAULT_RETRY) {
+			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+			 * of starvation. */
+			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			flags |= FAULT_FLAG_TRIED;
+
+			/*
+			 * No need to up_read(&mm->mmap_sem) as we would
+			 * have already released it in __lock_page_or_retry
+			 * in mm/filemap.c.
+			 */
+
+			goto retry;
+		}
+	}
 
 	up_read(&mm->mmap_sem);
 	return;