From cd026ca2861e7f384d677626a483da797c76b9da Mon Sep 17 00:00:00 2001
From: Jia Zhang <zhang.jia@linux.alibaba.com>
Date: Mon, 12 Feb 2018 22:44:54 +0800
Subject: [PATCH] x86/mm/kcore: Add vsyscall page to /proc/kcore conditionally

The vsyscall page should be visible only if vsyscall=emulate/native when dumping /proc/kcore.

Signed-off-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jolsa@redhat.com
Link: http://lkml.kernel.org/r/1518446694-21124-3-git-send-email-zhang.jia@linux.alibaba.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/mm/init_64.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 6aa33d1e198f..8ba9c3128947 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1193,7 +1193,8 @@ void __init mem_init(void)
 	register_page_bootmem_info();
 
 	/* Register memory areas for /proc/kcore */
-	kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE, KCORE_USER);
+	if (get_gate_vma(&init_mm))
+		kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE, KCORE_USER);
 
 	mem_init_print_info(NULL);
 }
-- 
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