[PATCH] x86_64 ia32 vDSO: use VM_ALWAYSDUMP

This patch fixes ia32 core dumps on x86_64 to include just one phdr for the
vDSO vma.  Currently it writes a confused format with two phdrs for the
address, one without contents and one with.  This patch removes the
special-case core writing macros for the ia32 vDSO.  Instead, it uses
VM_ALWAYSDUMP in the vma.  This changes core dumps so they no longer include
the non-PT_LOAD phdrs from the vDSO, consistent with fixed native i386 core
dumps.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/x86_64/ia32/syscall32.c b/arch/x86_64/ia32/syscall32.c
index 3e5ed20cba45..3ac935535e20 100644
--- a/arch/x86_64/ia32/syscall32.c
+++ b/arch/x86_64/ia32/syscall32.c
@@ -59,6 +59,13 @@ int syscall32_setup_pages(struct linux_binprm *bprm, int exstack)
 	vma->vm_end = VSYSCALL32_END;
 	/* MAYWRITE to allow gdb to COW and set breakpoints */
 	vma->vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC|VM_MAYWRITE;
+	/*
+	 * Make sure the vDSO gets into every core dump.
+	 * Dumping its contents makes post-mortem fully interpretable later
+	 * without matching up the same kernel and hardware config to see
+	 * what PC values meant.
+	 */
+	vma->vm_flags |= VM_ALWAYSDUMP;
 	vma->vm_flags |= mm->def_flags;
 	vma->vm_page_prot = protection_map[vma->vm_flags & 7];
 	vma->vm_ops = &syscall32_vm_ops;