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: Andrew Morton <akpm@osdl.org>
---
25-akpm/arch/i386/mm/highmem.c | 18 ++++++++++++++++++
25-akpm/include/asm-i386/highmem.h | 1 +
25-akpm/include/linux/highmem.h | 1 +
25-akpm/kernel/crash.c | 31 +++++++++++++++++++++++++++++++
4 files changed, 51 insertions(+)
diff -puN arch/i386/mm/highmem.c~crashdump-routines-for-copying-dump-pages arch/i386/mm/highmem.c
--- 25/arch/i386/mm/highmem.c~crashdump-routines-for-copying-dump-pages Tue Sep 21 14:36:45 2004
+++ 25-akpm/arch/i386/mm/highmem.c Tue Sep 21 14:36:45 2004
@@ -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/include/asm-i386/highmem.h~crashdump-routines-for-copying-dump-pages Tue Sep 21 14:36:45 2004
+++ 25-akpm/include/asm-i386/highmem.h Tue Sep 21 14:36:45 2004
@@ -61,6 +61,7 @@ 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/include/linux/highmem.h~crashdump-routines-for-copying-dump-pages Tue Sep 21 14:36:45 2004
+++ 25-akpm/include/linux/highmem.h Tue Sep 21 14:36:45 2004
@@ -30,6 +30,7 @@ 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.c~crashdump-routines-for-copying-dump-pages kernel/crash.c
--- 25/kernel/crash.c~crashdump-routines-for-copying-dump-pages Tue Sep 21 14:36:45 2004
+++ 25-akpm/kernel/crash.c Tue Sep 21 14:36:45 2004
@@ -11,6 +11,7 @@
#include <linux/proc_fs.h>
#include <asm/io.h>
#include <asm/uaccess.h>
+#include <asm/highmem.h>
/*
* Enable kexec reboot upon panic; for dumping
@@ -54,3 +55,33 @@ void __crash_machine_kexec(void)
printk(KERN_EMERG "kexec: No kernel image loaded!\n");
}
}
+
+/*
+ * 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;
+}
_