On Wednesday 18 October 2006 16:31, you wrote:
> > It may also not work on machines with more than 512 megabytes as the
> > kexec generic code may fill the page list with adresses over the 512
> > megabytes limit (the mips boards I use only have 16mbytes and 32mbytes
> > ram).
>
> This is only an issue with 32-bit software anyway. On these you can solve
> the problem by manually setting up TLB mappings. You may want to take a
> look at kmap_coherent in arch/mips/mm/init.c for how to create such
> temporary mappings.
I think that defining KEXEC_SOURCE_MEMORY_LIMIT,
KEXEC_DESTINATION_MEMORY_LIMIT and KEXEC_CONTROL_MEMORY_LIMIT to
HIGHMEM_START in include/asm-mips/kexec.h should solve this issue without
involving doing some TLB mappings.
> + /*
> + * The generic kexec code builds a page list with physical
> + * addresses. they are directly accessible through KSEG0,
> + * hence the pys_to_virt() call.
> + */
>
> On a 64-bit system this could actually be either an XKPHY or CKSEG address,
> depending on PAGE_OFFSET.
I just reworked the comment on the attached patch.
> + /*
> + * we do not want to be bothered.
> + */
> + local_irq_disable();
> +
> + flush_icache_range(reboot_code_buffer,
> + reboot_code_buffer + KEXEC_CONTROL_CODE_SIZE);
> +
> + printk("Will call new kernel at %08x\n", image->start);
> + printk("Bye ...\n");
> + flush_cache_all();
> + ((void (*)(void))reboot_code_buffer)();
>
> On SMP systems cache flushes may invoke smp_call_function which will barf
> when called with interrupts disabled. So you may want to move the
> local_irq_disable further down to somewhere after the last flush.
local_irq_disable() is called after flush_cache_all() in the attached patch.
> Your code does not try to deal with SMP at all. The strategy used by
> Linux to get hold of processors 1 and up on bootup relies on the
> firmware. Generally firmware breaks because Linux tramples over it and
> even if it would survive that, it does not regain control over non-boot
> processors, so starting of those processors would fail.
I do not have access to a SMP mips machine, so I won't be able to deal with
this. How about temporarily making KEXEC depend on !SMP for now ?
> The solution I have in mind would be something like:
>
> * The trampoline that transfers control between the old and new kernel
> needs to be modified to keep all additional processors in some sort of
> spinlock.
Something like calling stop_this_cpu() on each cpu except the one we are
running on ? However we are may face the risk of leaving the infinite loop in
stop_this_cpu() as the code in relocate_kernel.S overwrites the code of the
function.
> * A kernel needs a way to know if it has been executed via kexec or a
> normal bootup. It uses this knowledge to release one non-boot
> processor after another during SMP initialization.
The code in relocate_kernel.S could setup some magic values in a0, a1, a2 or
a3 before jumping to the new kernel to indicate that the kernel has been
kexec'd.
> PS: If you have to send patches as attachments, then please as text/plain.
Sorry for this, attached patch is as text/plain.
--
Nicolas Schichan
diff -Nru linux-orig/arch/mips/Kconfig linux-work/arch/mips/Kconfig
--- linux-orig/arch/mips/Kconfig 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/arch/mips/Kconfig 2006-10-17 16:12:04.000000000 +0200
@@ -820,6 +820,23 @@
endchoice
+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.
+
+ The name comes from the similiarity to the exec system call.
+
+ 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. As of this writing the exact hardware interface is
+ strongly in flux, so no good recommendation can be made.
+
source "arch/mips/ddb5xxx/Kconfig"
source "arch/mips/gt64120/ev64120/Kconfig"
source "arch/mips/jazz/Kconfig"
diff -Nru linux-orig/arch/mips/kernel/machine_kexec.c linux-work/arch/mips/kernel/machine_kexec.c
--- linux-orig/arch/mips/kernel/machine_kexec.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-work/arch/mips/kernel/machine_kexec.c 2006-10-18 20:54:16.000000000 +0200
@@ -0,0 +1,79 @@
+/*
+ * machine_kexec.c for kexec
+ * Created by <nschichan@xxxxxxxxxxxx> on Thu Oct 12 15:15:06 2006
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <linux/kexec.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+const extern unsigned char relocate_new_kernel[];
+const extern unsigned int relocate_new_kernel_size;
+
+extern unsigned long kexec_start_address;
+extern unsigned long kexec_indirection_page;
+
+int
+machine_kexec_prepare(struct kimage *kimage)
+{
+ return 0;
+}
+
+void
+machine_kexec_cleanup(struct kimage *kimage)
+{
+}
+
+void
+machine_shutdown(void)
+{
+}
+
+void
+machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+void
+machine_kexec(struct kimage *image)
+{
+ unsigned long reboot_code_buffer;
+ unsigned long entry;
+ unsigned long *ptr;
+
+ reboot_code_buffer =
+ (unsigned long)page_address(image->control_code_page);
+
+ kexec_start_address = image->start;
+ kexec_indirection_page =
+ (unsigned long)phys_to_virt(image->head & PAGE_MASK);
+
+ memcpy((void*)reboot_code_buffer, relocate_new_kernel,
+ relocate_new_kernel_size);
+
+ /*
+ * The generic kexec code builds a page list with physical
+ * addresses. they are directly accessible through KSEG0 (or
+ * XKSEG0 or XPHYS if on 64bit system), hence the
+ * pys_to_virt() call.
+ */
+ for (ptr = &image->head; (entry = *ptr) && !(entry &IND_DONE);
+ ptr = (entry & IND_INDIRECTION) ?
+ phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
+ if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
+ *ptr & IND_DESTINATION)
+ *ptr = (unsigned long)phys_to_virt(*ptr);
+ }
+
+ printk("Will call new kernel at %08lx\n", image->start);
+ printk("Bye ...\n");
+ flush_cache_all();
+ local_irq_disable();
+ ((void (*)(void))reboot_code_buffer)();
+}
diff -Nru linux-orig/arch/mips/kernel/Makefile linux-work/arch/mips/kernel/Makefile
--- linux-orig/arch/mips/kernel/Makefile 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/arch/mips/kernel/Makefile 2006-10-17 15:55:11.000000000 +0200
@@ -66,6 +66,8 @@
obj-$(CONFIG_I8253) += i8253.o
+obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
+
CFLAGS_cpu-bugs64.o = $(shell if $(CC) $(CFLAGS) -Wa,-mdaddi -c -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi)
EXTRA_AFLAGS := $(CFLAGS)
diff -Nru linux-orig/arch/mips/kernel/relocate_kernel.S linux-work/arch/mips/kernel/relocate_kernel.S
--- linux-orig/arch/mips/kernel/relocate_kernel.S 1970-01-01 01:00:00.000000000 +0100
+++ linux-work/arch/mips/kernel/relocate_kernel.S 2006-10-17 20:01:06.000000000 +0200
@@ -0,0 +1,80 @@
+/*
+ * relocate_kernel.S for kexec
+ * Created by <nschichan@xxxxxxxxxxxx> on Thu Oct 12 17:49:57 2006
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/regdef.h>
+#include <asm/page.h>
+#include <asm/mipsregs.h>
+#include <asm/stackframe.h>
+#include <asm/addrspace.h>
+
+ .globl relocate_new_kernel
+relocate_new_kernel:
+
+ PTR_L s0, kexec_indirection_page
+ PTR_L s1, kexec_start_address
+
+process_entry:
+ PTR_L s2, (s0)
+ PTR_ADD s0, s0, SZREG
+
+ /* destination page */
+ and s3, s2, 0x1
+ beq s3, zero, 1f
+ and s4, s2, ~0x1 /* store destination addr in s4 */
+ move a0, s4
+ b process_entry
+
+1:
+ /* indirection page, update s0 */
+ and s3, s2, 0x2
+ beq s3, zero, 1f
+ and s0, s2, ~0x2
+ b process_entry
+
+1:
+ /* done page */
+ and s3, s2, 0x4
+ beq s3, zero, 1f
+ b done
+1:
+ /* source page */
+ and s3, s2, 0x8
+ beq s3, zero, process_entry
+ and s2, s2, ~0x8
+ li s6, (1 << PAGE_SHIFT) / SZREG
+
+copy_word:
+ /* copy page word by word */
+ REG_L s5, (s2)
+ REG_S s5, (s4)
+ INT_ADD s4, s4, SZREG
+ INT_ADD s2, s2, SZREG
+ INT_SUB s6, s6, 1
+ beq s6, zero, process_entry
+ b copy_word
+ b process_entry
+
+done:
+ /* jump to kexec_start_address */
+ j s1
+
+ .globl kexec_start_address
+kexec_start_address:
+ .long 0x0
+
+ .globl kexec_indirection_page
+kexec_indirection_page:
+ .long 0x0
+
+relocate_new_kernel_end:
+
+ .globl relocate_new_kernel_size
+relocate_new_kernel_size:
+ .long relocate_new_kernel_end - relocate_new_kernel
diff -Nru linux-orig/arch/mips/kernel/scall32-o32.S linux-work/arch/mips/kernel/scall32-o32.S
--- linux-orig/arch/mips/kernel/scall32-o32.S 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/arch/mips/kernel/scall32-o32.S 2006-10-17 16:23:21.000000000 +0200
@@ -662,6 +662,7 @@
sys sys_tee 4
sys sys_vmsplice 4
sys sys_move_pages 6
+ sys sys_kexec_load 1
.endm
/* We pre-compute the number of _instruction_ bytes needed to
diff -Nru linux-orig/arch/mips/kernel/scall64-64.S linux-work/arch/mips/kernel/scall64-64.S
--- linux-orig/arch/mips/kernel/scall64-64.S 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/arch/mips/kernel/scall64-64.S 2006-10-17 15:57:15.000000000 +0200
@@ -466,3 +466,4 @@
PTR sys_tee /* 5265 */
PTR sys_vmsplice
PTR sys_move_pages
+ PTR sys_kexec_load
diff -Nru linux-orig/arch/mips/kernel/scall64-n32.S linux-work/arch/mips/kernel/scall64-n32.S
--- linux-orig/arch/mips/kernel/scall64-n32.S 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/arch/mips/kernel/scall64-n32.S 2006-10-17 15:58:59.000000000 +0200
@@ -392,3 +392,4 @@
PTR sys_tee
PTR sys_vmsplice /* 6271 */
PTR sys_move_pages
+ PTR sys_kexec_load
diff -Nru linux-orig/arch/mips/kernel/scall64-o32.S linux-work/arch/mips/kernel/scall64-o32.S
--- linux-orig/arch/mips/kernel/scall64-o32.S 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/arch/mips/kernel/scall64-o32.S 2006-10-17 15:59:23.000000000 +0200
@@ -514,4 +514,5 @@
PTR sys_tee
PTR sys_vmsplice
PTR compat_sys_move_pages
+ PTR sys_kexec_load
.size sys_call_table,.-sys_call_table
diff -Nru linux-orig/include/asm-mips/kexec.h linux-work/include/asm-mips/kexec.h
--- linux-orig/include/asm-mips/kexec.h 1970-01-01 01:00:00.000000000 +0100
+++ linux-work/include/asm-mips/kexec.h 2006-10-18 22:39:22.000000000 +0200
@@ -0,0 +1,32 @@
+/*
+ * kexec.h for kexec
+ * Created by <nschichan@xxxxxxxxxxxx> on Thu Oct 12 14:59:34 2006
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2. See the file COPYING for more details.
+ */
+
+#ifndef _MIPS_KEXEC
+# define _MIPS_KEXEC
+
+/* Maximum physical address we can use pages from */
+#define KEXEC_SOURCE_MEMORY_LIMIT (HIGHMEM_START)
+/* Maximum address we can reach in physical address mode */
+#define KEXEC_DESTINATION_MEMORY_LIMIT (HIGHMEM_START)
+ /* Maximum address we can use for the control code buffer */
+#define KEXEC_CONTROL_MEMORY_LIMIT (HIGHMEM_START)
+
+#define KEXEC_CONTROL_CODE_SIZE 4096
+
+/* The native architecture */
+#define KEXEC_ARCH KEXEC_ARCH_MIPS
+
+#define MAX_NOTE_BYTES 1024
+
+static inline void crash_setup_regs(struct pt_regs *newregs,
+ struct pt_regs *oldregs)
+{
+ /* Dummy implementation for now */
+}
+
+#endif /* !_MIPS_KEXEC */
diff -Nru linux-orig/include/asm-mips/unistd.h linux-work/include/asm-mips/unistd.h
--- linux-orig/include/asm-mips/unistd.h 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/include/asm-mips/unistd.h 2006-10-17 16:07:57.000000000 +0200
@@ -329,16 +329,17 @@
#define __NR_tee (__NR_Linux + 306)
#define __NR_vmsplice (__NR_Linux + 307)
#define __NR_move_pages (__NR_Linux + 308)
+#define __NR_kexec_load (__NR_Linux + 309)
/*
* Offset of the last Linux o32 flavoured syscall
*/
-#define __NR_Linux_syscalls 308
+#define __NR_Linux_syscalls 309
#endif /* _MIPS_SIM == _MIPS_SIM_ABI32 */
#define __NR_O32_Linux 4000
-#define __NR_O32_Linux_syscalls 308
+#define __NR_O32_Linux_syscalls 309
#if _MIPS_SIM == _MIPS_SIM_ABI64
@@ -614,16 +615,17 @@
#define __NR_tee (__NR_Linux + 265)
#define __NR_vmsplice (__NR_Linux + 266)
#define __NR_move_pages (__NR_Linux + 267)
+#define __NR_kexec_load (__NR_Linux + 268)
/*
* Offset of the last Linux 64-bit flavoured syscall
*/
-#define __NR_Linux_syscalls 267
+#define __NR_Linux_syscalls 268
#endif /* _MIPS_SIM == _MIPS_SIM_ABI64 */
#define __NR_64_Linux 5000
-#define __NR_64_Linux_syscalls 267
+#define __NR_64_Linux_syscalls 268
#if _MIPS_SIM == _MIPS_SIM_NABI32
@@ -903,16 +905,16 @@
#define __NR_tee (__NR_Linux + 269)
#define __NR_vmsplice (__NR_Linux + 270)
#define __NR_move_pages (__NR_Linux + 271)
-
+#define __NR_kexec_load (__Nr_Linux + 272)
/*
* Offset of the last N32 flavoured syscall
*/
-#define __NR_Linux_syscalls 271
+#define __NR_Linux_syscalls 272
#endif /* _MIPS_SIM == _MIPS_SIM_NABI32 */
#define __NR_N32_Linux 6000
-#define __NR_N32_Linux_syscalls 271
+#define __NR_N32_Linux_syscalls 272
#ifdef __KERNEL__
diff -Nru linux-orig/include/linux/kexec.h linux-work/include/linux/kexec.h
--- linux-orig/include/linux/kexec.h 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/include/linux/kexec.h 2006-10-17 16:21:49.000000000 +0200
@@ -122,6 +122,8 @@
#define KEXEC_ARCH_IA_64 (50 << 16)
#define KEXEC_ARCH_S390 (22 << 16)
#define KEXEC_ARCH_SH (42 << 16)
+#define KEXEC_ARCH_MIPS_LE (10 << 16)
+#define KEXEC_ARCH_MIPS ( 8 << 16)
#define KEXEC_FLAGS (KEXEC_ON_CRASH) /* List of defined/legal kexec flags */
diff -Nru linux-orig/Makefile linux-work/Makefile
--- linux-orig/Makefile 2006-10-14 05:34:03.000000000 +0200
+++ linux-work/Makefile 2006-10-17 16:09:02.000000000 +0200
@@ -149,10 +149,11 @@
# then ARCH is assigned, getting whatever value it gets normally, and
# SUBARCH is subsequently ignored.
-SUBARCH := $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
- -e s/arm.*/arm/ -e s/sa110/arm/ \
- -e s/s390x/s390/ -e s/parisc64/parisc/ \
- -e s/ppc.*/powerpc/ -e s/mips.*/mips/ )
+SUBARCH := mips
+# $(shell uname -m | sed -e s/i.86/i386/ -e s/sun4u/sparc64/ \
+# -e s/arm.*/arm/ -e s/sa110/arm/ \
+# -e s/s390x/s390/ -e s/parisc64/parisc/ \
+# -e s/ppc.*/powerpc/ -e s/mips.*/mips/ )
# Cross compiling and selecting different set of gcc/bin-utils
# ---------------------------------------------------------------------------
