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authorVivek Goyal <vgoyal@in.ibm.com>2005-06-25 14:58:18 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-25 16:24:52 -0700
commit92aa63a5a1bf2e7b0c79e6716d24b76dbbdcf951 (patch)
tree1f4d49c8e9bf02e834e6af8c1f7d4484d9f76c6e
parentd58831e4163699de204dea199be2e903bf5d6eff (diff)
[PATCH] kdump: Retrieve saved max pfn
This patch retrieves the max_pfn being used by previous kernel and stores it in a safe location (saved_max_pfn) before it is overwritten due to user defined memory map. This pfn is used to make sure that user does not try to read the physical memory beyond saved_max_pfn. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/setup.c12
-rw-r--r--include/linux/bootmem.h4
-rw-r--r--mm/bootmem.c8
3 files changed, 24 insertions, 0 deletions
diff --git a/arch/i386/kernel/setup.c b/arch/i386/kernel/setup.c
index d88ebdfa6cc..8d58a053e12 100644
--- a/arch/i386/kernel/setup.c
+++ b/arch/i386/kernel/setup.c
@@ -59,6 +59,9 @@
#include "setup_arch_pre.h"
#include <bios_ebda.h>
+/* Forward Declaration. */
+void __init find_max_pfn(void);
+
/* This value is set up by the early boot code to point to the value
immediately after the boot time page tables. It contains a *physical*
address, and must not be in the .bss segment! */
@@ -736,6 +739,15 @@ static void __init parse_cmdline_early (char ** cmdline_p)
if (to != command_line)
to--;
if (!memcmp(from+7, "exactmap", 8)) {
+#ifdef CONFIG_CRASH_DUMP
+ /* If we are doing a crash dump, we
+ * still need to know the real mem
+ * size before original memory map is
+ * reset.
+ */
+ find_max_pfn();
+ saved_max_pfn = max_pfn;
+#endif
from += 8+7;
e820.nr_map = 0;
userdef = 1;
diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index 500f451ce0c..82bd8842d11 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -22,6 +22,10 @@ extern unsigned long min_low_pfn;
*/
extern unsigned long max_pfn;
+#ifdef CONFIG_CRASH_DUMP
+extern unsigned long saved_max_pfn;
+#endif
+
/*
* node_bootmem_map is a map pointer - the bits represent all physical
* memory pages (including holes) on the node.
diff --git a/mm/bootmem.c b/mm/bootmem.c
index f82f7aebbee..45275f1f894 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -33,6 +33,14 @@ EXPORT_SYMBOL(max_pfn); /* This is exported so
* dma_get_required_mask(), which uses
* it, can be an inline function */
+#ifdef CONFIG_CRASH_DUMP
+/*
+ * If we have booted due to a crash, max_pfn will be a very low value. We need
+ * to know the amount of memory that the previous kernel used.
+ */
+unsigned long saved_max_pfn;
+#endif
+
/* return the number of _pages_ that will be allocated for the boot bitmap */
unsigned long __init bootmem_bootmap_pages (unsigned long pages)
{