From: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/crash.c has been renamed kernel/crash_dump.c to clarify it's purpose.

From: Hariprasad Nellitheertha <hari@in.ibm.com>

This patch provides the interfaces necessary to read the dump contents,
treating it as a high memory device.

Signed off by Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 25-ppc-akpm/arch/i386/mm/highmem.c     |   18 ++++++++++++++++++
 25-ppc-akpm/include/asm-i386/highmem.h |    1 +
 25-ppc-akpm/include/linux/highmem.h    |    1 +
 25-ppc-akpm/kernel/crash_dump.c        |   33 +++++++++++++++++++++++++++++++++
 4 files changed, 53 insertions(+)

diff -puN arch/i386/mm/highmem.c~crashdump-routines-for-copying-dump-pages arch/i386/mm/highmem.c
--- 25-ppc/arch/i386/mm/highmem.c~crashdump-routines-for-copying-dump-pages	2005-01-28 23:00:26.747236016 -0800
+++ 25-ppc-akpm/arch/i386/mm/highmem.c	2005-01-28 23:01:06.272227304 -0800
@@ -74,6 +74,24 @@ void kunmap_atomic(void *kvaddr, enum km
 	preempt_check_resched();
 }
 
+/* This is the same as kmap_atomic() but can map memory that doesn't
+ * have a struct page associated with it.
+ */
+void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
+{
+	enum fixed_addresses idx;
+	unsigned long vaddr;
+
+	inc_preempt_count();
+
+	idx = type + KM_TYPE_NR*smp_processor_id();
+	vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
+	set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
+	__flush_tlb_one(vaddr);
+
+	return (void*) vaddr;
+}
+
 struct page *kmap_atomic_to_page(void *ptr)
 {
 	unsigned long idx, vaddr = (unsigned long)ptr;
diff -puN include/asm-i386/highmem.h~crashdump-routines-for-copying-dump-pages include/asm-i386/highmem.h
--- 25-ppc/include/asm-i386/highmem.h~crashdump-routines-for-copying-dump-pages	2005-01-28 23:00:26.748235864 -0800
+++ 25-ppc-akpm/include/asm-i386/highmem.h	2005-01-28 23:01:28.081911728 -0800
@@ -72,6 +72,7 @@ void *kmap(struct page *page);
 void kunmap(struct page *page);
 void *kmap_atomic(struct page *page, enum km_type type);
 void kunmap_atomic(void *kvaddr, enum km_type type);
+void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
 struct page *kmap_atomic_to_page(void *ptr);
 
 #define flush_cache_kmaps()	do { } while (0)
diff -puN include/linux/highmem.h~crashdump-routines-for-copying-dump-pages include/linux/highmem.h
--- 25-ppc/include/linux/highmem.h~crashdump-routines-for-copying-dump-pages	2005-01-28 23:00:26.750235560 -0800
+++ 25-ppc-akpm/include/linux/highmem.h	2005-01-28 23:01:51.314379856 -0800
@@ -28,6 +28,7 @@ static inline void *kmap(struct page *pa
 
 #define kmap_atomic(page, idx)		page_address(page)
 #define kunmap_atomic(addr, idx)	do { } while (0)
+#define kmap_atomic_pfn(pfn, idx)	page_address(pfn_to_page(pfn))
 #define kmap_atomic_to_page(ptr)	virt_to_page(ptr)
 
 #endif /* CONFIG_HIGHMEM */
diff -puN kernel/crash_dump.c~crashdump-routines-for-copying-dump-pages kernel/crash_dump.c
--- 25-ppc/kernel/crash_dump.c~crashdump-routines-for-copying-dump-pages	2005-01-28 23:00:26.751235408 -0800
+++ 25-ppc-akpm/kernel/crash_dump.c	2005-01-28 23:00:26.757234496 -0800
@@ -8,6 +8,39 @@
 #include <linux/smp_lock.h>
 #include <linux/errno.h>
 #include <linux/proc_fs.h>
+#include <linux/bootmem.h>
+#include <linux/highmem.h>
+#include <linux/crash_dump.h>
+
 #include <asm/io.h>
 #include <asm/uaccess.h>
 
+/*
+ * 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, int userbuf)
+{
+	void *page, *vaddr;
+
+	if (!csize)
+		return 0;
+
+	page = kmalloc(PAGE_SIZE, GFP_KERNEL);
+
+	vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
+	copy_page(page, vaddr);
+	kunmap_atomic(vaddr, KM_PTE0);
+
+	if (userbuf) {
+		if (copy_to_user(buf, page, csize)) {
+			kfree(page);
+			return -EFAULT;
+		}
+	} else
+		memcpy(buf, page, csize);
+	kfree(page);
+
+	return 0;
+}
_