librecmc-gitorious/target/linux/generic/patches-3.3/331-mips-kexec-enhanche-the-support.patch

From 03cd81fbca6b91317ec1a7b3b3c09fb8d08f83a6 Mon Sep 17 00:00:00 2001
From: Wu Zhangjin <wuzhangjin@gmail.com>
Date: Tue, 11 Jan 2011 18:42:08 +0000
Subject: MIPS: Kexec: Enhance the support

Changes:
  o Print more information in machine_kexec() for debugging
    E.g. with this information, the kexec_start_address has been found
    it was wrong with 64bit kernel / o32 kexec-tools. Which must be
    fixed later.
  o Link relocate_kernel.S to a section for future extension
    This allows more functions can be added for the kexec relocation
    part even written in C. to add code into that section, you just need
    to mark your function or data with __kexec or
    __attribute__((__section__(".__kexec.relocate")))

TODO:

1. Make 64bit kernel / o32|n32|64 kexec-tools works

Fix the user-space kexec-tools, seems the tool only work for 32bit
machine. So, we need to add 64bit support for it. The address of the
entry point(kexec_start_address) is wrong and make the "kexec -e" fail.
the real entry point must be read from the new kernel image by the
user-space kexec-tools, otherwise, it will not work.  The above 64bit
support tested is 64bit kernel with o32 user-space kexec-tools. The root
cause may be the different definition of virt_to_phys() and
phys_to_virt() in the kexec-tools and kernel space for 64bit system /
o32 kernel.

Ref: http://www.linux-mips.org/archives/linux-mips/2009-08/msg00149.html

2. Pass the arguments from kexec-tools to the new kernel image

Please refer to: "MIPS: Loongson: Kexec: Pass parameters to new kernel"

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
--- a/arch/mips/include/asm/kexec.h
+++ b/arch/mips/include/asm/kexec.h
@@ -36,6 +36,16 @@ static inline void crash_setup_regs(stru
 }
 
 #ifdef CONFIG_KEXEC
+
+#define __kexec __attribute__((__section__(".__kexec.relocate")))
+
+/* The linker tells us where the relocate_new_kernel part is. */
+extern const unsigned char __start___kexec_relocate;
+extern const unsigned char __end___kexec_relocate;
+
+extern unsigned long kexec_start_address;
+extern unsigned long kexec_indirection_page;
+
 struct kimage;
 extern unsigned long kexec_args[4];
 extern int (*_machine_kexec_prepare)(struct kimage *);
--- a/arch/mips/kernel/machine_kexec.c
+++ b/arch/mips/kernel/machine_kexec.c
@@ -14,10 +14,6 @@
 #include <asm/page.h>
 
 extern const unsigned char relocate_new_kernel[];
-extern const size_t relocate_new_kernel_size;
-
-extern unsigned long kexec_start_address;
-extern unsigned long kexec_indirection_page;
 
 int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 void (*_machine_kexec_shutdown)(void) = NULL;
@@ -61,21 +57,34 @@ typedef void (*noretfun_t)(void) __attri
 void
 machine_kexec(struct kimage *image)
 {
+	unsigned long kexec_relocate_size;
 	unsigned long reboot_code_buffer;
 	unsigned long entry;
 	unsigned long *ptr;
 
+	kexec_relocate_size = (unsigned long)(&__end___kexec_relocate) -
+		(unsigned long)(&__start___kexec_relocate);
+	pr_info("kexec_relocate_size = %lu\n", kexec_relocate_size);
+
 	reboot_code_buffer =
 	  (unsigned long)page_address(image->control_code_page);
+	pr_info("reboot_code_buffer = %p\n", (void *)reboot_code_buffer);
 
 	kexec_start_address =
 	  (unsigned long) phys_to_virt(image->start);
+	pr_info("kexec_start_address(entry point of new kernel) = %p\n",
+			(void *)kexec_start_address);
 
 	kexec_indirection_page =
 		(unsigned long) phys_to_virt(image->head & PAGE_MASK);
+	pr_info("kexec_indirection_page = %p\n",
+			(void *)kexec_indirection_page);
 
-	memcpy((void*)reboot_code_buffer, relocate_new_kernel,
-	       relocate_new_kernel_size);
+	memcpy((void *)reboot_code_buffer, &__start___kexec_relocate,
+	       kexec_relocate_size);
+
+	pr_info("Copy kexec_relocate section from %p to reboot_code_buffer: %p\n",
+			&__start___kexec_relocate, (void *)reboot_code_buffer);
 
 	/*
 	 * The generic kexec code builds a page list with physical
@@ -96,8 +105,8 @@ machine_kexec(struct kimage *image)
 	 */
 	local_irq_disable();
 
-	printk("Will call new kernel at %08lx\n", image->start);
-	printk("Bye ...\n");
+	pr_info("Will call new kernel at %p\n", (void *)kexec_start_address);
+	pr_info("Bye ...\n");
 	__flush_cache_all();
 #ifdef CONFIG_SMP
 	/* All secondary cpus now may jump to kexec_wait cycle */
@@ -108,4 +117,3 @@ machine_kexec(struct kimage *image)
 #endif
 	((noretfun_t) reboot_code_buffer)();
 }
-
--- a/arch/mips/kernel/relocate_kernel.S
+++ b/arch/mips/kernel/relocate_kernel.S
@@ -14,6 +14,8 @@
 #include <asm/stackframe.h>
 #include <asm/addrspace.h>
 
+	.section	.kexec.relocate, "ax"
+
 LEAF(relocate_new_kernel)
 	PTR_L a0,	arg0
 	PTR_L a1,	arg1
@@ -155,9 +157,3 @@ EXPORT(kexec_start_address)
 EXPORT(kexec_indirection_page)
 	PTR		0
 	.size		kexec_indirection_page, PTRSIZE
-
-relocate_new_kernel_end:
-
-EXPORT(relocate_new_kernel_size)
-	PTR		relocate_new_kernel_end - relocate_new_kernel
-	.size		relocate_new_kernel_size, PTRSIZE
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -50,6 +50,10 @@ SECTIONS
 		*(.text.*)
 		*(.fixup)
 		*(.gnu.warning)
+		__start___kexec_relocate = .;
+		KEEP(*(.kexec.relocate))
+		KEEP(*(.__kexec.relocate))
+		__end___kexec_relocate = .;
 	} :text = 0
 	_etext = .;	/* End of text section */