ChangeLog 2007/8/25
1. The reboot command LINUX_REBOOT_CMD_KJUMP is splited into to two
reboot command to reflect the different function.
2. Document is added for added kernel parameters.
3. /sys/kernel/kexec_jump_buf_pfn is made writable, it is used for
memory image restoring.
4. Console restoring after jumping back is implemented.
ChangeLog 2007/7/15
1. The kexec jump implementation is put into the kexec/kdump framework
instead of software suspend framework. The device and CPU state
save/restore code of software suspend is called when needed.
2. The same code path is used for both kexec a new kernel and jump
back to original kernel.
---
This patch implements the functionality of jumping from the kexeced
kernel back to the original kernel.
Two new reboot command named LINUX_REBOOT_CMD_KJUMP_TO and
LINUX_REBOOT_CMD_KJUMP_BACK are defined to trigger the jumping to
(executing) the new kernel and jumping back to the original kernel.
To support jumping back from kexeced kernel, before executing the new
kernel, the devices are put into quiescent state (to be fully
implemented), and the state of devices and CPU is saved. After jumping
back from kexeced kernel, the state of devices and CPU are restored
accordingly. The devices/CPU state save/restore code of software
suspend is called to implement corresponding function.
Signed-off-by: Huang Ying <[email protected]>
---
Documentation/kernel-parameters.txt | 8 +++
arch/i386/Kconfig | 7 ++
arch/i386/kernel/Makefile | 1
arch/i386/kernel/kexec_jump.S | 74 ++++++++++++++++++++++++++++
arch/i386/kernel/machine_kexec.c | 59 +++++++++++++++++++++++
include/asm-i386/kexec.h | 4 +
include/linux/kexec.h | 16 ++++++
include/linux/reboot.h | 2
kernel/kexec.c | 92 ++++++++++++++++++++++++++++++++++++
kernel/ksysfs.c | 21 ++++++++
kernel/power/Kconfig | 2
kernel/sys.c | 16 ++++++
12 files changed, 301 insertions(+), 1 deletion(-)
Index: linux-2.6.23-rc3/arch/i386/kernel/machine_kexec.c
===================================================================
--- linux-2.6.23-rc3.orig/arch/i386/kernel/machine_kexec.c 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/arch/i386/kernel/machine_kexec.c 2007-08-25 21:57:00.000000000 +0800
@@ -10,6 +10,7 @@
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/init.h>
+#include <linux/highmem.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
@@ -169,3 +170,61 @@
return 0;
}
early_param("crashkernel", parse_crashkernel);
+
+#ifdef CONFIG_KEXEC_JUMP
+int machine_kexec_jump(void)
+{
+ asmlinkage int (*real_jump)(void *buf);
+ unsigned long jump_buf_pfn;
+ void *jump_buf;
+
+ if (!(kexec_jump_flags & KEXEC_JUMP_FLAG_IS_KEXECED_KERNEL) &&
+ !kexec_crash_image)
+ return -EINVAL;
+ jump_buf_pfn = kexec_get_jump_buf_pfn(0);
+ if (!jump_buf_pfn)
+ return -EINVAL;
+ jump_buf = kmap_atomic_pfn(jump_buf_pfn, KM_PTE0);
+ memcpy(jump_buf + PAGE_SIZE/2, machine_kexec_real_jump, PAGE_SIZE/2);
+ real_jump = jump_buf + PAGE_SIZE/2;
+
+ if (!real_jump(jump_buf))
+ machine_kexec(kexec_crash_image);
+ kunmap_atomic(jump_buf, KM_PTE0);
+ return 0;
+}
+
+static unsigned long kexec_backup_addr = ~0UL;
+
+/* kexec_backup= specifies the location of backuped 0~640k memory of
+ * crashed kernel.
+ */
+static int __init parse_kexec_backup(char *arg)
+{
+ if (!arg)
+ return -EINVAL;
+
+ kexec_backup_addr = memparse(arg, &arg);
+ return 0;
+}
+early_param("kexec_backup", parse_kexec_backup);
+
+void kexec_restore_backup(void)
+{
+ void *vaddr;
+ void *vaddr_backup;
+ unsigned long paddr;
+
+ if (kexec_backup_addr == ~0UL)
+ return;
+
+ for (paddr = 0; paddr < 640 * 1024; paddr += PAGE_SIZE) {
+ vaddr = kmap_atomic_pfn(paddr >> PAGE_SHIFT, KM_PTE0);
+ vaddr_backup = kmap_atomic_pfn((paddr+kexec_backup_addr) >> PAGE_SHIFT,
+ KM_PTE1);
+ memcpy(vaddr, vaddr_backup, PAGE_SIZE);
+ kunmap_atomic(vaddr, KM_PTE0);
+ kunmap_atomic(vaddr_backup, KM_PTE1);
+ }
+}
+#endif /* CONFIG_KEXEC_JUMP */
Index: linux-2.6.23-rc3/include/asm-i386/kexec.h
===================================================================
--- linux-2.6.23-rc3.orig/include/asm-i386/kexec.h 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/include/asm-i386/kexec.h 2007-08-25 21:57:00.000000000 +0800
@@ -94,6 +94,10 @@
unsigned long start_address,
unsigned int has_pae) ATTRIB_NORET;
+#ifdef CONFIG_KEXEC_JUMP
+extern asmlinkage int machine_kexec_real_jump(void *buf);
+#endif
+
#endif /* __ASSEMBLY__ */
#endif /* _I386_KEXEC_H */
Index: linux-2.6.23-rc3/include/linux/kexec.h
===================================================================
--- linux-2.6.23-rc3.orig/include/linux/kexec.h 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/include/linux/kexec.h 2007-08-25 21:57:00.000000000 +0800
@@ -1,6 +1,11 @@
#ifndef LINUX_KEXEC_H
#define LINUX_KEXEC_H
+#ifdef CONFIG_KEXEC_JUMP
+#define KEXEC_JUMP_FLAG_IS_KEXECED_KERNEL 0x1
+#endif /* CONFIG_KEXEC_JUMP */
+
+#ifndef __ASSEMBLY__
#ifdef CONFIG_KEXEC
#include <linux/types.h>
#include <linux/list.h>
@@ -161,4 +166,15 @@
static inline void crash_kexec(struct pt_regs *regs) { }
static inline int kexec_should_crash(struct task_struct *p) { return 0; }
#endif /* CONFIG_KEXEC */
+
+#ifdef CONFIG_KEXEC_JUMP
+extern int kexec_jump_flags;
+extern int machine_kexec_jump(void);
+extern int kexec_jump(void);
+extern unsigned long kexec_get_jump_buf_pfn(int alloc);
+extern void kexec_set_jump_buf_pfn(unsigned long pfn);
+extern void kexec_restore_backup(void);
+#endif /* CONFIG_KEXEC_JUMP */
+#endif /* !__ASSEMBLY__ */
+
#endif /* LINUX_KEXEC_H */
Index: linux-2.6.23-rc3/kernel/kexec.c
===================================================================
--- linux-2.6.23-rc3.orig/kernel/kexec.c 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/kernel/kexec.c 2007-08-25 21:57:00.000000000 +0800
@@ -21,6 +21,10 @@
#include <linux/hardirq.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
+#include <linux/suspend.h>
+#include <linux/pm.h>
+#include <linux/cpu.h>
+#include <linux/console.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1134,3 +1138,91 @@
return 0;
}
module_init(crash_notes_memory_init)
+
+#ifdef CONFIG_KEXEC_JUMP
+int kexec_jump_flags;
+
+static unsigned long kexec_jump_buf_pfn;
+
+static int __init parse_kexec_jump_buf_pfn(char *arg)
+{
+ unsigned long pfn;
+
+ if (!arg)
+ return -EINVAL;
+ pfn = memparse(arg, &arg);
+ kexec_set_jump_buf_pfn(pfn);
+ return 0;
+}
+early_param("kexec_jump_buf_pfn", parse_kexec_jump_buf_pfn);
+
+unsigned long kexec_get_jump_buf_pfn(int alloc)
+{
+ struct page *jump_buf_page;
+
+ if (!kexec_jump_buf_pfn && alloc) {
+ jump_buf_page = alloc_page(GFP_KERNEL);
+ kexec_jump_buf_pfn = page_to_pfn(jump_buf_page);
+ }
+ return kexec_jump_buf_pfn;
+}
+
+void kexec_set_jump_buf_pfn(unsigned long pfn)
+{
+ kexec_jump_buf_pfn = pfn;
+ kexec_jump_flags |= KEXEC_JUMP_FLAG_IS_KEXECED_KERNEL;
+}
+
+int kexec_jump(void)
+{
+ int error;
+ int is_kexeced;
+
+ is_kexeced = kexec_jump_flags & KEXEC_JUMP_FLAG_IS_KEXECED_KERNEL;
+ if (!is_kexeced && !kexec_crash_image)
+ return -EINVAL;
+
+ pm_prepare_console();
+ suspend_console();
+ error = device_suspend(PMSG_FREEZE);
+ if (error)
+ goto Resume_console;
+ error = disable_nonboot_cpus();
+ if (error)
+ goto Resume_devices;
+ local_irq_disable();
+ /* At this point, device_suspend() has been called, but *not*
+ * device_power_down(). We *must* device_power_down() now.
+ * Otherwise, drivers for some devices (e.g. interrupt controllers)
+ * become desynchronized with the actual state of the hardware
+ * at resume time, and evil weirdness ensues.
+ */
+ error = device_power_down(PMSG_FREEZE);
+ if (error)
+ goto Enable_irqs;
+
+ if (is_kexeced)
+ kexec_restore_backup();
+ save_processor_state();
+ error = machine_kexec_jump();
+ restore_processor_state();
+
+ /* NOTE: device_power_up() is just a resume() for devices
+ * that suspended with irqs off ... no overall powerup.
+ */
+ device_power_up();
+ Enable_irqs:
+ local_irq_enable();
+ enable_nonboot_cpus();
+ Resume_devices:
+ device_resume();
+ if (!is_kexeced && !error) {
+ kimage_free(kexec_crash_image);
+ kexec_crash_image = NULL;
+ }
+ Resume_console:
+ resume_console();
+ pm_restore_console();
+ return error;
+}
+#endif /* CONFIG_KEXEC_JUMP */
Index: linux-2.6.23-rc3/kernel/ksysfs.c
===================================================================
--- linux-2.6.23-rc3.orig/kernel/ksysfs.c 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/kernel/ksysfs.c 2007-08-25 21:57:00.000000000 +0800
@@ -60,6 +60,24 @@
return sprintf(page, "%d\n", !!kexec_crash_image);
}
KERNEL_ATTR_RO(kexec_crash_loaded);
+
+#ifdef CONFIG_KEXEC_JUMP
+static ssize_t kexec_jump_buf_pfn_show(struct kset *kset, char *page)
+{
+ return sprintf(page, "0x%lx\n", kexec_get_jump_buf_pfn(1));
+}
+static ssize_t kexec_jump_buf_pfn_store(struct kset *kset, const char *page,
+ size_t count)
+{
+ unsigned long pfn;
+
+ pfn = simple_strtoul(page, NULL, 0);
+ kexec_set_jump_buf_pfn(pfn);
+ return count;
+}
+
+KERNEL_ATTR_RW(kexec_jump_buf_pfn);
+#endif /* CONFIG_KEXEC_JUMP */
#endif /* CONFIG_KEXEC */
/*
@@ -95,6 +113,9 @@
#ifdef CONFIG_KEXEC
&kexec_loaded_attr.attr,
&kexec_crash_loaded_attr.attr,
+#ifdef CONFIG_KEXEC_JUMP
+ &kexec_jump_buf_pfn_attr.attr,
+#endif
#endif
NULL
};
Index: linux-2.6.23-rc3/arch/i386/kernel/kexec_jump.S
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.23-rc3/arch/i386/kernel/kexec_jump.S 2007-08-25 21:57:00.000000000 +0800
@@ -0,0 +1,74 @@
+/*
+ * kexec_jump.S - Jump between original kernel and kexeced kernel
+ * Copyright (C) 2007 Huang Ying <[email protected]>
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <linux/linkage.h>
+#include <linux/kexec.h>
+#include <asm/page.h>
+#include <asm/kexec.h>
+
+/*
+ * Must be relocatable PIC code callable as a C function
+ */
+#define HALF_PAGE_ALIGNED (1 << (PAGE_SHIFT-1))
+
+#define EBX 0x0
+#define ESI 0x4
+#define EDI 0x8
+#define EBP 0xc
+#define ESP 0x10
+#define CR0 0x14
+#define CR3 0x18
+#define CR4 0x1c
+#define FLAG 0x20
+#define RET 0x24
+
+ .text
+ .align HALF_PAGE_ALIGNED
+ .globl machine_kexec_real_jump
+machine_kexec_real_jump:
+ movl 4(%esp), %edx
+ movl kexec_jump_flags, %ecx
+ andl $KEXEC_JUMP_FLAG_IS_KEXECED_KERNEL, %ecx
+ jnz 1f
+ movl %ebx, EBX(%edx)
+ movl %esi, ESI(%edx)
+ movl %edi, EDI(%edx)
+ movl %ebp, EBP(%edx)
+ movl %esp, ESP(%edx)
+ movl %cr0, %eax
+ movl %eax, CR0(%edx)
+ movl %cr3, %eax
+ movl %eax, CR3(%edx)
+ movl %cr4, %eax
+ movl %eax, CR4(%edx)
+ pushf
+ popl %eax
+ movl %eax, FLAG(%edx)
+ movl (%esp), %eax
+ movl %eax, RET(%edx)
+ mov $0, %eax
+ ret
+1:
+ movl EBX(%edx), %ebx
+ movl ESI(%edx), %esi
+ movl EDI(%edx), %edi
+ movl EBP(%edx), %ebp
+ movl FLAG(%edx), %eax
+ pushl %eax
+ popf
+ movl ESP(%edx), %esp
+ movl CR4(%edx), %eax
+ movl %eax, %cr4
+ movl CR3(%edx), %eax
+ movl %eax, %cr3
+ movl CR0(%edx), %eax
+ movl %eax, %cr0
+ movl RET(%edx), %eax
+ movl %eax, (%esp)
+ mov $1, %eax
+ ret
Index: linux-2.6.23-rc3/kernel/sys.c
===================================================================
--- linux-2.6.23-rc3.orig/kernel/sys.c 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/kernel/sys.c 2007-08-25 21:57:00.000000000 +0800
@@ -424,6 +424,22 @@
unlock_kernel();
return -EINVAL;
+#ifdef CONFIG_KEXEC_JUMP
+ case LINUX_REBOOT_CMD_KJUMP_BACK:
+ if (!(kexec_jump_flags & KEXEC_JUMP_FLAG_IS_KEXECED_KERNEL)) {
+ unlock_kernel();
+ return -EINVAL;
+ }
+ /* fall through */
+ case LINUX_REBOOT_CMD_KJUMP_TO:
+ {
+ int ret;
+ ret = kexec_jump();
+ unlock_kernel();
+ return ret;
+ }
+#endif
+
#ifdef CONFIG_HIBERNATION
case LINUX_REBOOT_CMD_SW_SUSPEND:
{
Index: linux-2.6.23-rc3/include/linux/reboot.h
===================================================================
--- linux-2.6.23-rc3.orig/include/linux/reboot.h 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/include/linux/reboot.h 2007-08-25 21:57:00.000000000 +0800
@@ -33,6 +33,8 @@
#define LINUX_REBOOT_CMD_RESTART2 0xA1B2C3D4
#define LINUX_REBOOT_CMD_SW_SUSPEND 0xD000FCE2
#define LINUX_REBOOT_CMD_KEXEC 0x45584543
+#define LINUX_REBOOT_CMD_KJUMP_TO 0x3928A5FD
+#define LINUX_REBOOT_CMD_KJUMP_BACK 0x4A39B60E
#ifdef __KERNEL__
Index: linux-2.6.23-rc3/arch/i386/Kconfig
===================================================================
--- linux-2.6.23-rc3.orig/arch/i386/Kconfig 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/arch/i386/Kconfig 2007-08-25 21:57:00.000000000 +0800
@@ -828,6 +828,13 @@
PHYSICAL_START.
For more details see Documentation/kdump/kdump.txt
+config KEXEC_JUMP
+ bool "kexec jump (EXPERIMENTAL)"
+ depends on EXPERIMENTAL
+ depends on PM && X86_32 && KEXEC
+ ---help---
+ Jump back from kexeced kernel to orignal kernel.
+
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
default "0x1000000" if X86_NUMAQ
Index: linux-2.6.23-rc3/arch/i386/kernel/Makefile
===================================================================
--- linux-2.6.23-rc3.orig/arch/i386/kernel/Makefile 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/arch/i386/kernel/Makefile 2007-08-25 21:57:00.000000000 +0800
@@ -30,6 +30,7 @@
obj-$(CONFIG_X86_REBOOTFIXUPS) += reboot_fixups.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
+obj-$(CONFIG_KEXEC_JUMP) += kexec_jump.o
obj-$(CONFIG_X86_NUMAQ) += numaq.o
obj-$(CONFIG_X86_SUMMIT_NUMA) += summit.o
obj-$(CONFIG_KPROBES) += kprobes.o
Index: linux-2.6.23-rc3/Documentation/kernel-parameters.txt
===================================================================
--- linux-2.6.23-rc3.orig/Documentation/kernel-parameters.txt 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/Documentation/kernel-parameters.txt 2007-08-25 21:57:00.000000000 +0800
@@ -899,6 +899,14 @@
keepinitrd [HW,ARM]
+ kexec_backup [X86-32]
+ Specifies physical address of backup area for 0~640k
+ memory area of original kernel.
+
+ kexec_jump_buf_pfn [X86-32]
+ Specifies page frame number of jump buffer page used
+ to jump between original kernel and kexeced kernel.
+
kstack=N [X86-32,X86-64] Print N words from the kernel stack
in oops dumps.
Index: linux-2.6.23-rc3/kernel/power/Kconfig
===================================================================
--- linux-2.6.23-rc3.orig/kernel/power/Kconfig 2007-08-25 21:56:54.000000000 +0800
+++ linux-2.6.23-rc3/kernel/power/Kconfig 2007-08-25 21:57:00.000000000 +0800
@@ -70,7 +70,7 @@
config PM_SLEEP
bool
- depends on SUSPEND || HIBERNATION
+ depends on SUSPEND || HIBERNATION || KEXEC_JUMP
default y
config SUSPEND_UP_POSSIBLE
-
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