linux-kernel - [PATCH v3] not adding modules range to kcore if it's equal to vmcore range

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Date:	Tue, 26 Aug 2014 19:38:25 +0800
From:	Baoquan He <bhe@...hat.com>
To:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Cc:	Baoquan He <bhe@...hat.com>
Subject: [PATCH v3] not adding modules range to kcore if it's equal to vmcore range

On some ARCHs modules range is eauql to vmalloc range. E.g on i686
"#define MODULES_VADDR   VMALLOC_START"
"#define MODULES_END     VMALLOC_END"
This will cause 2 duplicate program segments in /proc/kcore, and no
any flag to indicate both of them are different. This is confusing.

And usually people who need check the elf header or read the content
of kcore will check memory ranges. Two program segments which are the
same completely can't give any help on this.

So in this patch a judgment added to check if modules range is equal
to or included in vmalloc range completely. If yes, just skip adding
the modules range. If and only if modules range is not completely
included in vmalloc range just add it since the part out of vmalloc
range need be accessible.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 fs/proc/kcore.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 6df8d07..a4b7ff1 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -610,8 +610,11 @@ static void __init proc_kcore_text_init(void)
 struct kcore_list kcore_modules;
 static void __init add_modules_range(void)
 {
-	kclist_add(&kcore_modules, (void *)MODULES_VADDR,
+	if ( (MODULES_VADDR != VMALLOC_START) &&
+		(MODULES_END <= VMALLOC_END) ) {
+		kclist_add(&kcore_modules, (void *)MODULES_VADDR,
 			MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
+	}
 }
 #else
 static void __init add_modules_range(void)
-- 
1.9.0

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