kdump: make elfcorehdr_addr independent of CONFIG_PROC_VMCORE

o elfcorehdr_addr is used by not only the code under CONFIG_PROC_VMCORE
  but also by the code which is not inside CONFIG_PROC_VMCORE.  For
  example, is_kdump_kernel() is used by powerpc code to determine if
  kernel is booting after a panic then use previous kernel's TCE table.
  So even if CONFIG_PROC_VMCORE is not set in second kernel, one should be
  able to correctly determine that we are booting after a panic and setup
  calgary iommu accordingly.

o So remove the assumption that elfcorehdr_addr is under
  CONFIG_PROC_VMCORE.

o Move definition of elfcorehdr_addr to arch dependent crash files.
  (Unfortunately crash dump does not have an arch independent file
  otherwise that would have been the best place).

o kexec.c is not the right place as one can Have CRASH_DUMP enabled in
  second kernel without KEXEC being enabled.

o I don't see sh setup code parsing the command line for
  elfcorehdr_addr.  I am wondering how does vmcore interface work on sh.
  Anyway, I am atleast defining elfcoredhr_addr so that compilation is not
  broken on sh.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 13 insertions, 1 deletions

diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c
index 72d0c56c1b48..f7cdb3b457aa 100644
--- a/arch/x86/kernel/crash_dump_32.c
+++ b/arch/x86/kernel/crash_dump_32.c
@@ -13,6 +13,9 @@
 
 static void *kdump_buf_page;
 
+/* 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/crash_dump_64.c b/arch/x86/kernel/crash_dump_64.c
index e90a60ef10c2..045b36cada65 100644
--- a/arch/x86/kernel/crash_dump_64.c
+++ b/arch/x86/kernel/crash_dump_64.c
@@ -10,6 +10,9 @@
 #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/setup.c b/arch/x86/kernel/setup.c
index 2255782e8d4b..b2c97874ec0f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -561,7 +561,13 @@ static void __init reserve_standard_io_resources(void)
 
 }
 
-#ifdef CONFIG_PROC_VMCORE
+/*
+ * 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.