[ARM] 4137/1: Add kexec support

Add kexec support to ARM.

Improvements like commandline handling could be made but this patch gives
basic functional support. It uses the next available syscall number, 347.

Once the syscall number is known, userspace support will be
finalised/submitted to kexec-tools, various patches already exist.

Originally based on a patch by Maxim Syrchin but updated and forward
ported by various people.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -738,6 +738,20 @@ config XIP_PHYS_ADDR
 	  be linked for and stored to.  This address is dependent on your
 	  own flash usage.
 
+config KEXEC
+	bool "Kexec system call (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	help
+	  kexec is a system call that implements the ability to shutdown your
+	  current kernel, and to start another kernel.  It is like a reboot
+	  but it is indepedent of the system firmware.   And like a reboot
+	  you can start any kernel with it, not just Linux.
+
+	  It is an ongoing process to be certain the hardware in a machine
+	  is properly shutdown, so do not be surprised if this code does not
+	  initially work for you.  It may help to enable device hotplugging
+	  support.
+
 endmenu
 
 if (ARCH_SA1100 || ARCH_INTEGRATOR || ARCH_OMAP || ARCH_IMX )

arch/arm/kernel/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_ARTHUR)		+= arthur.o
 obj-$(CONFIG_ISA_DMA)		+= dma-isa.o
 obj-$(CONFIG_PCI)		+= bios32.o isa.o
 obj-$(CONFIG_SMP)		+= smp.o
+obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o
 obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o
 
 obj-$(CONFIG_CRUNCH)		+= crunch.o crunch-bits.o

arch/arm/kernel/calls.S

@@ -356,6 +356,7 @@
 		CALL(sys_move_pages)
 /* 345 */	CALL(sys_getcpu)
 		CALL(sys_ni_syscall)		/* eventually epoll_pwait */
+		CALL(sys_kexec_load)
 #ifndef syscalls_counted
 .equ syscalls_padding, ((NR_syscalls + 3) & ~3) - NR_syscalls
 #define syscalls_counted

arch/arm/kernel/machine_kexec.c

@@ -0,0 +1,78 @@
+/*
+ * machine_kexec.c - handle transition of Linux booting another kernel
+ */
+
+#include <linux/mm.h>
+#include <linux/kexec.h>
+#include <linux/delay.h>
+#include <linux/reboot.h>
+#include <asm/pgtable.h>
+#include <asm/pgalloc.h>
+#include <asm/mmu_context.h>
+#include <asm/io.h>
+#include <asm/cacheflush.h>
+#include <asm/mach-types.h>
+
+const extern unsigned char relocate_new_kernel[];
+const extern unsigned int relocate_new_kernel_size;
+
+extern void setup_mm_for_reboot(char mode);
+
+extern unsigned long kexec_start_address;
+extern unsigned long kexec_indirection_page;
+extern unsigned long kexec_mach_type;
+
+/*
+ * Provide a dummy crash_notes definition while crash dump arrives to arm.
+ * This prevents breakage of crash_notes attribute in kernel/ksysfs.c.
+ */
+
+int machine_kexec_prepare(struct kimage *image)
+{
+	return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *image)
+{
+}
+
+void machine_shutdown(void)
+{
+}
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+void machine_kexec(struct kimage *image)
+{
+	unsigned long page_list;
+	unsigned long reboot_code_buffer_phys;
+	void *reboot_code_buffer;
+
+
+	page_list = image->head & PAGE_MASK;
+
+	/* we need both effective and real address here */
+	reboot_code_buffer_phys =
+	    page_to_pfn(image->control_code_page) << PAGE_SHIFT;
+	reboot_code_buffer = page_address(image->control_code_page);
+
+	/* Prepare parameters for reboot_code_buffer*/
+	kexec_start_address = image->start;
+	kexec_indirection_page = page_list;
+	kexec_mach_type = machine_arch_type;
+
+	/* copy our kernel relocation code to the control code page */
+	memcpy(reboot_code_buffer,
+	       relocate_new_kernel, relocate_new_kernel_size);
+
+
+	flush_icache_range((unsigned long) reboot_code_buffer,
+			   (unsigned long) reboot_code_buffer + KEXEC_CONTROL_CODE_SIZE);
+	printk(KERN_INFO "Bye!\n");
+
+	cpu_proc_fin();
+	setup_mm_for_reboot(0); /* mode is not used, so just pass 0*/
+	cpu_reset(reboot_code_buffer_phys);
+}

arch/arm/kernel/relocate_kernel.S

@@ -0,0 +1,74 @@
+/*
+ * relocate_kernel.S - put the kernel image in place to boot
+ */
+
+#include <asm/kexec.h>
+
+	.globl relocate_new_kernel
+relocate_new_kernel:
+
+	ldr	r0,kexec_indirection_page
+	ldr	r1,kexec_start_address
+
+
+0:	/* top, read another word for the indirection page */
+	ldr	r3, [r0],#4
+
+	/* Is it a destination page. Put destination address to r4 */
+	tst	r3,#1,0
+	beq	1f
+	bic	r4,r3,#1
+	b	0b
+1:
+	/* Is it an indirection page */
+	tst	r3,#2,0
+	beq	1f
+	bic	r0,r3,#2
+	b	0b
+1:
+
+	/* are we done ? */
+	tst	r3,#4,0
+	beq	1f
+	b	2f
+
+1:
+	/* is it source ? */
+	tst	r3,#8,0
+	beq	0b
+	bic r3,r3,#8
+	mov r6,#1024
+9:
+	ldr r5,[r3],#4
+	str r5,[r4],#4
+	subs r6,r6,#1
+	bne 9b
+	b 0b
+
+2:
+	/* Jump to relocated kernel */
+	mov lr,r1
+	mov r0,#0
+	ldr r1,kexec_mach_type
+	mov r2,#0
+	mov pc,lr
+
+	.globl kexec_start_address
+kexec_start_address:
+	.long	0x0
+
+	.globl kexec_indirection_page
+kexec_indirection_page:
+	.long	0x0
+
+	.globl kexec_mach_type
+kexec_mach_type:
+	.long	0x0
+
+relocate_new_kernel_end:
+
+	.globl relocate_new_kernel_size
+relocate_new_kernel_size:
+	.long relocate_new_kernel_end - relocate_new_kernel
+
+

include/asm-arm/kexec.h

@@ -0,0 +1,30 @@
+#ifndef _ARM_KEXEC_H
+#define _ARM_KEXEC_H
+
+#ifdef CONFIG_KEXEC
+
+/* Maximum physical address we can use pages from */
+#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
+/* Maximum address we can reach in physical address mode */
+#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
+/* Maximum address we can use for the control code buffer */
+#define KEXEC_CONTROL_MEMORY_LIMIT TASK_SIZE
+
+#define KEXEC_CONTROL_CODE_SIZE	4096
+
+#define KEXEC_ARCH KEXEC_ARCH_ARM
+
+#ifndef __ASSEMBLY__
+
+#define MAX_NOTE_BYTES 1024
+
+struct kimage;
+/* Provide a dummy definition to avoid build failures. */
+static inline void crash_setup_regs(struct pt_regs *newregs,
+                                        struct pt_regs *oldregs) { }
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_KEXEC */
+
+#endif /* _ARM_KEXEC_H */

include/asm-arm/unistd.h

@@ -372,6 +372,7 @@
 #define __NR_move_pages			(__NR_SYSCALL_BASE+344)
 #define __NR_getcpu			(__NR_SYSCALL_BASE+345)
 					/* 346 for epoll_pwait */
+#define __NR_sys_kexec_load		(__NR_SYSCALL_BASE+347)
 
 /*
  * The following SWIs are ARM private.

include/linux/kexec.h

@@ -125,6 +125,7 @@ extern struct kimage *kexec_crash_image;
 #define KEXEC_ARCH_PPC     (20 << 16)
 #define KEXEC_ARCH_PPC64   (21 << 16)
 #define KEXEC_ARCH_IA_64   (50 << 16)
+#define KEXEC_ARCH_ARM     (40 << 16)
 #define KEXEC_ARCH_S390    (22 << 16)
 #define KEXEC_ARCH_SH      (42 << 16)
 #define KEXEC_ARCH_MIPS_LE (10 << 16)