sh: kdump support.

This adds support for kexec based crash dumps.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/Kconfig

@@ -551,6 +551,20 @@ config KEXEC
 	  support.  As of this writing the exact hardware interface is
 	  strongly in flux, so no good recommendation can be made.
 
+config CRASH_DUMP
+	bool "kernel crash dumps (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	help
+	  Generate crash dump after being started by kexec.
+	  This should be normally only set in special crash dump kernels
+	  which are loaded in the main kernel with kexec-tools into
+	  a specially reserved region and then later executed after
+	  a crash by kdump/kexec. The crash dump kernel must be compiled
+	  to a memory address not used by the main kernel using
+	  MEMORY_START.
+
+	  For more details see Documentation/kdump/kdump.txt
+
 config SMP
 	bool "Symmetric multi-processing support"
 	---help---

arch/sh/kernel/Makefile

@@ -20,5 +20,6 @@ obj-$(CONFIG_SH_CPU_FREQ)	+= cpufreq.o
 obj-$(CONFIG_MODULES)		+= module.o
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_PM)		+= pm.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o

arch/sh/kernel/crash_dump.c

@@ -0,0 +1,46 @@
+/*
+ *	crash_dump.c - Memory preserving reboot related code.
+ *
+ *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
+ *	Copyright (C) IBM Corporation, 2004. All rights reserved
+ */
+
+#include <linux/errno.h>
+#include <linux/crash_dump.h>
+#include <linux/io.h>
+#include <asm/uaccess.h>
+
+/**
+ * copy_oldmem_page - copy one page from "oldmem"
+ * @pfn: page frame number to be copied
+ * @buf: target memory address for the copy; this can be in kernel address
+ *	space or user address space (see @userbuf)
+ * @csize: number of bytes to copy
+ * @offset: offset in bytes into the page (based on pfn) to begin the copy
+ * @userbuf: if set, @buf is in user address space, use copy_to_user(),
+ *	otherwise @buf is in kernel address space, use memcpy().
+ *
+ * Copy a page from "oldmem". For this page, there is no pte mapped
+ * in the current kernel. We stitch up a pte, similar to kmap_atomic.
+ */
+ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
+                               size_t csize, unsigned long offset, int userbuf)
+{
+	void  *vaddr;
+
+	if (!csize)
+		return 0;
+
+	vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
+
+	if (userbuf) {
+		if (copy_to_user(buf, (vaddr + offset), csize)) {
+			iounmap(vaddr);
+			return -EFAULT;
+		}
+	} else
+	memcpy(buf, (vaddr + offset), csize);
+
+	iounmap(vaddr);
+	return csize;
+}

arch/sh/kernel/machine_kexec.c

@@ -59,13 +59,13 @@ static void kexec_info(struct kimage *image)
 	        printk("  segment[%d]: 0x%08x - 0x%08x (0x%08x)\n",
 		       i,
 		       (unsigned int)image->segment[i].mem,
-		       (unsigned int)image->segment[i].mem + image->segment[i].memsz,
+		       (unsigned int)image->segment[i].mem +
+				     image->segment[i].memsz,
 		       (unsigned int)image->segment[i].memsz);
 	}
 	printk("  start     : 0x%08x\n\n", (unsigned int)image->start);
 }
 
-
 /*
  * Do not allocate memory (or fail in any way) in machine_kexec().
  * We are past the point of no return, committed to rebooting now.
@@ -104,3 +104,24 @@ NORET_TYPE void machine_kexec(struct kimage *image)
 	(*rnk)(page_list, reboot_code_buffer, image->start, vbr_reg);
 }
 
+/* crashkernel=size@addr specifies the location to reserve for
+ * a crash kernel.  By reserving this memory we guarantee
+ * that linux never sets it up as a DMA target.
+ * Useful for holding code to do something appropriate
+ * after a kernel panic.
+ */
+static int __init parse_crashkernel(char *arg)
+{
+	unsigned long size, base;
+	size = memparse(arg, &arg);
+	if (*arg == '@') {
+		base = memparse(arg+1, &arg);
+		/* FIXME: Do I want a sanity check
+		 * to validate the memory range?
+		 */
+		crashk_res.start = base;
+		crashk_res.end   = base + size - 1;
+	}
+	return 0;
+}
+early_param("crashkernel", parse_crashkernel);

arch/sh/kernel/setup.c

@@ -20,6 +20,7 @@
 #include <linux/pfn.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/kexec.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <asm/sections.h>
@@ -287,6 +288,11 @@ void __init setup_bootmem_allocator(unsigned long start_pfn)
 		}
 	}
 #endif
+#ifdef CONFIG_KEXEC
+	if (crashk_res.start != crashk_res.end)
+		reserve_bootmem(crashk_res.start,
+			crashk_res.end - crashk_res.start + 1);
+#endif
 }
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES

include/asm-sh/kexec.h

@@ -1,5 +1,8 @@
-#ifndef _SH_KEXEC_H
-#define _SH_KEXEC_H
+#ifndef __ASM_SH_KEXEC_H
+#define __ASM_SH_KEXEC_H
+
+#include <asm/ptrace.h>
+#include <asm/string.h>
 
 /*
  * KEXEC_SOURCE_MEMORY_LIMIT maximum page get_free_page can return.
@@ -25,8 +28,37 @@
 
 #define MAX_NOTE_BYTES 1024
 
-/* Provide a dummy definition to avoid build failures. */
 static inline void crash_setup_regs(struct pt_regs *newregs,
-					struct pt_regs *oldregs) { }
+				    struct pt_regs *oldregs)
+{
+	if (oldregs)
+		memcpy(newregs, oldregs, sizeof(*newregs));
+	else {
+		__asm__ __volatile__ ("mov r0, %0" : "=r" (newregs->regs[0]));
+		__asm__ __volatile__ ("mov r1, %0" : "=r" (newregs->regs[1]));
+		__asm__ __volatile__ ("mov r2, %0" : "=r" (newregs->regs[2]));
+		__asm__ __volatile__ ("mov r3, %0" : "=r" (newregs->regs[3]));
+		__asm__ __volatile__ ("mov r4, %0" : "=r" (newregs->regs[4]));
+		__asm__ __volatile__ ("mov r5, %0" : "=r" (newregs->regs[5]));
+		__asm__ __volatile__ ("mov r6, %0" : "=r" (newregs->regs[6]));
+		__asm__ __volatile__ ("mov r7, %0" : "=r" (newregs->regs[7]));
+		__asm__ __volatile__ ("mov r8, %0" : "=r" (newregs->regs[8]));
+		__asm__ __volatile__ ("mov r9, %0" : "=r" (newregs->regs[9]));
+		__asm__ __volatile__ ("mov r10, %0" : "=r" (newregs->regs[10]));
+		__asm__ __volatile__ ("mov r11, %0" : "=r" (newregs->regs[11]));
+		__asm__ __volatile__ ("mov r12, %0" : "=r" (newregs->regs[12]));
+		__asm__ __volatile__ ("mov r13, %0" : "=r" (newregs->regs[13]));
+		__asm__ __volatile__ ("mov r14, %0" : "=r" (newregs->regs[14]));
+		__asm__ __volatile__ ("mov r15, %0" : "=r" (newregs->regs[15]));
 
-#endif /* _SH_KEXEC_H */
+		__asm__ __volatile__ ("sts pr, %0" : "=r" (newregs->pr));
+		__asm__ __volatile__ ("sts macl, %0" : "=r" (newregs->macl));
+		__asm__ __volatile__ ("sts mach, %0" : "=r" (newregs->mach));
+
+		__asm__ __volatile__ ("stc gbr, %0" : "=r" (newregs->gbr));
+		__asm__ __volatile__ ("stc sr, %0" : "=r" (newregs->sr));
+
+		newregs->pc = (unsigned long)current_text_addr();
+	}
+}
+#endif /* __ASM_SH_KEXEC_H */