[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>

5 files changed, 168 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 6783c2e5512d..a8298949d166 100644
--- a/arch/arm/Kconfig
+++ b/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 )
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index ab06a86e85d5..d5002889773e 100644
--- a/arch/arm/kernel/Makefile
+++ b/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
diff --git a/arch/arm/kernel/calls.S b/arch/arm/kernel/calls.S
index f7598cbc7ec5..ae89cdd82b16 100644
--- a/arch/arm/kernel/calls.S
+++ b/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
diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
new file mode 100644
index 000000000000..863c66454f2b
--- /dev/null
+++ b/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);
+}
diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..7baadae7cb27
--- /dev/null
+++ b/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
+
+