crash_dump: export is_kdump_kernel to modules, consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn

The Xen PV drivers in a crashed HVM guest can not connect to the dom0
backend drivers because both frontend and backend drivers are still in
connected state.  To run the connection reset function only in case of a
crashdump, the is_kdump_kernel() function needs to be available for the PV
driver modules.

Consolidate elfcorehdr_addr, setup_elfcorehdr and saved_max_pfn into
kernel/crash_dump.c Also export elfcorehdr_addr to make is_kdump_kernel()
usable for modules.

Leave 'elfcorehdr' as early_param().  This changes powerpc from __setup()
to early_param().  It adds an address range check from x86 also on ia64
and powerpc.

[akpm@linux-foundation.org: additional #includes]
[akpm@linux-foundation.org: remove elfcorehdr_addr export]
[akpm@linux-foundation.org: fix for Tejun's mm/nobootmem.c changes]
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

16 files changed, 37 insertions, 135 deletions

diff --git a/arch/arm/kernel/crash_dump.c b/arch/arm/kernel/crash_dump.c
index cd3b853a8a6..90c50d4b43f 100644
--- a/arch/arm/kernel/crash_dump.c
+++ b/arch/arm/kernel/crash_dump.c
@@ -18,9 +18,6 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 
-/* stores the physical address of elf header of crash image */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-
 /**
  * copy_oldmem_page() - copy one page from old kernel memory
  * @pfn: page frame number to be copied
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index d1da9217427..c36c1a4250f 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -788,30 +788,6 @@ static void __init reserve_crashkernel(void)
 static inline void reserve_crashkernel(void) {}
 #endif /* CONFIG_KEXEC */
 
-/*
- * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
- * is_kdump_kernel() to determine if we are booting after a panic. Hence
- * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
- */
-
-#ifdef CONFIG_CRASH_DUMP
-/*
- * elfcorehdr= specifies the location of elf core header stored by the crashed
- * kernel. This option will be passed by kexec loader to the capture kernel.
- */
-static int __init setup_elfcorehdr(char *arg)
-{
-	char *end;
-
-	if (!arg)
-		return -EINVAL;
-
-	elfcorehdr_addr = memparse(arg, &end);
-	return end > arg ? 0 : -EINVAL;
-}
-early_param("elfcorehdr", setup_elfcorehdr);
-#endif /* CONFIG_CRASH_DUMP */
-
 static void __init squash_mem_tags(struct tag *tag)
 {
 	for (; tag->hdr.size; tag = tag_next(tag))
diff --git a/arch/ia64/kernel/crash_dump.c b/arch/ia64/kernel/crash_dump.c
index 23e91290e41..c8c9298666f 100644
--- a/arch/ia64/kernel/crash_dump.c
+++ b/arch/ia64/kernel/crash_dump.c
@@ -13,9 +13,6 @@
 #include <asm/page.h>
 #include <asm/uaccess.h>
 
-/* Stores the physical address of elf header of crash image. */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-
 /**
  * copy_oldmem_page - copy one page from "oldmem"
  * @pfn: page frame number to be copied
diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index a0f00192850..6fc03aff046 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -23,6 +23,7 @@
  */
 #include <linux/module.h>
 #include <linux/bootmem.h>
+#include <linux/crash_dump.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/types.h>
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 911cf974970..5e2c72498c5 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -479,25 +479,7 @@ static __init int setup_nomca(char *s)
 }
 early_param("nomca", setup_nomca);
 
-/*
- * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
- * is_kdump_kernel() to determine if we are booting after a panic. Hence
- * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
- */
 #ifdef CONFIG_CRASH_DUMP
-/* elfcorehdr= specifies the location of elf core header
- * stored by the crashed kernel.
- */
-static int __init parse_elfcorehdr(char *arg)
-{
-	if (!arg)
-		return -EINVAL;
-
-        elfcorehdr_addr = memparse(arg, &arg);
-	return 0;
-}
-early_param("elfcorehdr", parse_elfcorehdr);
-
 int __init reserve_elfcorehdr(u64 *start, u64 *end)
 {
 	u64 length;
diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 0a2af50243c..424afb6b8fb 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -28,9 +28,6 @@
 #define DBG(fmt...)
 #endif
 
-/* Stores the physical address of elf header of crash image. */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-
 #ifndef CONFIG_RELOCATABLE
 void __init reserve_kdump_trampoline(void)
 {
@@ -72,20 +69,6 @@ void __init setup_kdump_trampoline(void)
 }
 #endif /* CONFIG_RELOCATABLE */
 
-/*
- * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
- * is_kdump_kernel() to determine if we are booting after a panic. Hence
- * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
- */
-static int __init parse_elfcorehdr(char *p)
-{
-	if (p)
-		elfcorehdr_addr = memparse(p, &p);
-
-	return 1;
-}
-__setup("elfcorehdr=", parse_elfcorehdr);
-
 static int __init parse_savemaxmem(char *p)
 {
 	if (p)
diff --git a/arch/sh/kernel/crash_dump.c b/arch/sh/kernel/crash_dump.c
index 37c97d44457..569e7b171c0 100644
--- a/arch/sh/kernel/crash_dump.c
+++ b/arch/sh/kernel/crash_dump.c
@@ -9,28 +9,6 @@
 #include <linux/io.h>
 #include <asm/uaccess.h>
 
-/* Stores the physical address of elf header of crash image. */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-
-/*
- * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
- * is_kdump_kernel() to determine if we are booting after a panic. Hence
- * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
- *
- * elfcorehdr= specifies the location of elf core header
- * stored by the crashed kernel.
- */
-static int __init parse_elfcorehdr(char *arg)
-{
-	if (!arg)
-		return -EINVAL;
-
-	elfcorehdr_addr = memparse(arg, &arg);
-
-	return 0;
-}
-early_param("elfcorehdr", parse_elfcorehdr);
-
 /**
  * copy_oldmem_page - copy one page from "oldmem"
  * @pfn: page frame number to be copied
diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index d5cd13945d5..642f75a68cd 100644
--- a/arch/x86/kernel/crash_dump_32.c
+++ b/arch/x86/kernel/crash_dump_32.c
@@ -14,9 +14,6 @@
 
 static void *kdump_buf_page;
 
-/* Stores the physical address of elf header of crash image. */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-
 static inline bool is_crashed_pfn_valid(unsigned long pfn)
 {
 #ifndef CONFIG_X86_PAE
diff --git a/arch/x86/kernel/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index 994828899e0..afa64adb75e 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -10,9 +10,6 @@
 #include <linux/uaccess.h>
 #include <linux/io.h>
 
-/* Stores the physical address of elf header of crash image. */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-
 /**
  * copy_oldmem_page - copy one page from "oldmem"
  * @pfn: page frame number to be copied
diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index cdf5bfd9d4d..3e2ef842531 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <linux/init.h>
+#include <linux/crash_dump.h>
 #include <linux/bootmem.h>
 #include <linux/pfn.h>
 #include <linux/suspend.h>
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 32bd87cbf98..5a0484a95ad 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -619,28 +619,6 @@ void __init reserve_standard_io_resources(void)
 
 }
 
-/*
- * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
- * is_kdump_kernel() to determine if we are booting after a panic. Hence
- * ifdef it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
- */
-
-#ifdef CONFIG_CRASH_DUMP
-/* elfcorehdr= specifies the location of elf core header
- * stored by the crashed kernel. This option will be passed
- * by kexec loader to the capture kernel.
- */
-static int __init setup_elfcorehdr(char *arg)
-{
-	char *end;
-	if (!arg)
-		return -EINVAL;
-	elfcorehdr_addr = memparse(arg, &end);
-	return end > arg ? 0 : -EINVAL;
-}
-early_param("elfcorehdr", setup_elfcorehdr);
-#endif
-
 static __init void reserve_ibft_region(void)
 {
 	unsigned long addr, size = 0;
diff --git a/include/linux/bootmem.h b/include/linux/bootmem.h
index 499dfe982a0..b8613e806aa 100644
--- a/include/linux/bootmem.h
+++ b/include/linux/bootmem.h
@@ -19,10 +19,6 @@ extern unsigned long min_low_pfn;
  */
 extern unsigned long max_pfn;
 
-#ifdef CONFIG_CRASH_DUMP
-extern unsigned long saved_max_pfn;
-#endif
-
 #ifndef CONFIG_NO_BOOTMEM
 /*
  * node_bootmem_map is a map pointer - the bits represent all physical 
diff --git a/kernel/Makefile b/kernel/Makefile
index 353d3fe8ba3..85cbfb31e73 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -107,6 +107,7 @@ obj-$(CONFIG_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
+obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
 
 ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
new file mode 100644
index 00000000000..5f85690285d
--- /dev/null
+++ b/kernel/crash_dump.c
@@ -0,0 +1,34 @@
+#include <linux/kernel.h>
+#include <linux/crash_dump.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+
+/*
+ * 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;
+
+/*
+ * stores the physical address of elf header of crash image
+ *
+ * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
+ * is_kdump_kernel() to determine if we are booting after a panic. Hence put
+ * it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
+ */
+unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
+
+/*
+ * elfcorehdr= specifies the location of elf core header stored by the crashed
+ * kernel. This option will be passed by kexec loader to the capture kernel.
+ */
+static int __init setup_elfcorehdr(char *arg)
+{
+	char *end;
+	if (!arg)
+		return -EINVAL;
+	elfcorehdr_addr = memparse(arg, &end);
+	return end > arg ? 0 : -EINVAL;
+}
+early_param("elfcorehdr", setup_elfcorehdr);
diff --git a/mm/bootmem.c b/mm/bootmem.c
index 07aeb89e396..01d5a4b3dd0 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -34,14 +34,6 @@ unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;
 
-#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
-
 bootmem_data_t bootmem_node_data[MAX_NUMNODES] __initdata;
 
 static struct list_head bdata_list __initdata = LIST_HEAD_INIT(bdata_list);
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index e2bdb07079c..e99f6cd1da1 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -32,14 +32,6 @@ unsigned long max_low_pfn;
 unsigned long min_low_pfn;
 unsigned long max_pfn;
 
-#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
-
 static void * __init __alloc_memory_core_early(int nid, u64 size, u64 align,
 					u64 goal, u64 limit)
 {