[PATCH 1/4] proc/vmcore: allow archs to override vmcore_elf_check_arch()

[Mika Westerberg <mika.westerberg@iki.fi>]

From: Mika Westerberg <ext-mika.1.westerberg@nokia.com>

Allow architectures to redefine this macro if needed. This is useful for
example in architectures where 64-bit ELF vmcores are not supported.
Specifying zero vmcore_elf64_check_arch() allows compiler to optimize
away unnecessary parts of parse_crash_elf64_headers().

We also rename the macro to vmcore_elf64_check_arch() to reflect that it
is used for 64-bit vmcores only.

Signed-off-by: Mika Westerberg <ext-mika.1.westerberg@nokia.com>
---
 fs/proc/vmcore.c           |    2 +-
 include/linux/crash_dump.h |    9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 2367fb3..74802bc5 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -499,7 +499,7 @@ static int __init parse_crash_elf64_headers(void)
 	/* Do some basic Verification. */
 	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
 		(ehdr.e_type != ET_CORE) ||
-		!vmcore_elf_check_arch(&ehdr) ||
+		!vmcore_elf64_check_arch(&ehdr) ||
 		ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
 		ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
 		ehdr.e_version != EV_CURRENT ||
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 0026f26..088cd4a 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -20,7 +20,14 @@ extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
 #define vmcore_elf_check_arch_cross(x) 0
 #endif
 
-#define vmcore_elf_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
+/*
+ * Architecture code can redefine this if there are any special checks
+ * needed for 64-bit ELF vmcores. In case of 32-bit only architecture,
+ * this can be set to zero.
+ */
+#ifndef vmcore_elf64_check_arch
+#define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
+#endif
 
 /*
  * is_kdump_kernel() checks whether this kernel is booting after a panic of
-- 
1.7.2.3