elf coredump: replace ELF_CORE_EXTRA_* macros by functions

elf_core_dump() and elf_fdpic_core_dump() use #ifdef and the corresponding
macro for hiding _multiline_ logics in functions.  This patch removes
#ifdef and replaces ELF_CORE_EXTRA_* by corresponding functions.  For
architectures not implemeonting ELF_CORE_EXTRA_*, we use weak functions in
order to reduce a range of modification.

This cleanup is for my next patches, but I think this cleanup itself is
worth doing regardless of my firnal purpose.

Signed-off-by: Daisuke HATAYAMA <d.hatayama@jp.fujitsu.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 18 insertions, 0 deletions

diff --git a/include/linux/elf.h b/include/linux/elf.h
index ad990c5f63f6..ccde3fd45f36 100644
--- a/include/linux/elf.h
+++ b/include/linux/elf.h
@@ -396,6 +396,7 @@ extern Elf32_Dyn _DYNAMIC [];
 #define elf_phdr        elf32_phdr
 #define elf_note        elf32_note
 #define elf_addr_t      Elf32_Off
+#define Elf_Half        Elf32_Half
 
 #else
 
@@ -404,6 +405,7 @@ extern Elf64_Dyn _DYNAMIC [];
 #define elf_phdr        elf64_phdr
 #define elf_note        elf64_note
 #define elf_addr_t      Elf64_Off
+#define Elf_Half        Elf64_Half
 
 #endif
 
diff --git a/include/linux/elfcore.h b/include/linux/elfcore.h
index 00d6a68d0421..cfda74f521b5 100644
--- a/include/linux/elfcore.h
+++ b/include/linux/elfcore.h
@@ -8,6 +8,8 @@
 #include <linux/user.h>
 #endif
 #include <linux/ptrace.h>
+#include <linux/elf.h>
+#include <linux/fs.h>
 
 struct elf_siginfo
 {
@@ -150,5 +152,19 @@ static inline int elf_core_copy_task_xfpregs(struct task_struct *t, elf_fpxregse
 
 #endif /* __KERNEL__ */
 
+/*
+ * These functions parameterize elf_core_dump in fs/binfmt_elf.c to write out
+ * extra segments containing the gate DSO contents.  Dumping its
+ * contents makes post-mortem fully interpretable later without matching up
+ * the same kernel and hardware config to see what PC values meant.
+ * Dumping its extra ELF program headers includes all the other information
+ * a debugger needs to easily find how the gate DSO was being used.
+ */
+extern Elf_Half elf_core_extra_phdrs(void);
+extern int
+elf_core_write_extra_phdrs(struct file *file, loff_t offset, size_t *size,
+                           unsigned long limit);
+extern int
+elf_core_write_extra_data(struct file *file, size_t *size, unsigned long limit);
 
 #endif /* _LINUX_ELFCORE_H */