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From:   Jia Zhang <zhang.jia@linux.alibaba.com>
To:     tglx@linutronix.de, jolsa@redhat.com, mingo@redhat.com,
        hpa@zytor.com
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/2] x86/mm/64: Add vsyscall page to /proc/kcore conditionally
Date:   Mon, 12 Feb 2018 22:44:54 +0800
Message-Id: <1518446694-21124-3-git-send-email-zhang.jia@linux.alibaba.com>
In-Reply-To: <1518446694-21124-1-git-send-email-zhang.jia@linux.alibaba.com>
References: <1518446694-21124-1-git-send-email-zhang.jia@linux.alibaba.com>
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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>
---
 arch/x86/mm/init_64.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 14cd7f8..cbd6ea4 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1193,8 +1193,10 @@ 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);
 }
-- 
1.8.3.1