linux-kernel - [PATCH] arm64: dump: hide kernel pointers

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Message-ID: <1488265536-20441-1-git-send-email-miles.chen@mediatek.com>
Date:   Tue, 28 Feb 2017 15:05:36 +0800
From:   Miles Chen <miles.chen@...iatek.com>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>
CC:     <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <wsd_upstream@...iatek.com>,
        Miles Chen <miles.chen@...iatek.com>
Subject: [PATCH] arm64: dump: hide kernel pointers

Mask kernel pointers of /sys/kernel/debug/kernel_page_tables entry like
/proc/vmallocinfo does.

With sysctl kernel.kptr_restrict=0 or 1:
cat /sys/kernel/debug/kernel_page_tables
---[ Modules start ]---
---[ Modules end ]---
---[ vmalloc() Area ]---
ffffff8008000000-ffffff8008010000          64K PTE       RW NX SHD AF...
ffffff8008015000-ffffff8008016000           4K PTE       RW NX SHD AF...
ffffff8008020000-ffffff8008030000          64K PTE       RW NX SHD AF...
ffffff8008031000-ffffff8008071000         256K PTE       RW NX SHD AF...
ffffff8008080000-ffffff8008200000        1536K PTE       ro x  SHD AF...
ffffff8008200000-ffffff8008400000           2M PMD       ro x  SHD AF...
ffffff8008400000-ffffff8008540000        1280K PTE       ro x  SHD AF...
ffffff8008540000-ffffff8008690000        1344K PTE       ro NX SHD AF...
ffffff8008940000-ffffff8008a10000         832K PTE       RW NX SHD AF...
ffffff8008aca000-ffffff8008acd000          12K PTE       RW NX SHD AF...
ffffffbebffd8000-ffffffbebffdb000          12K PTE       RW NX SHD AF...
---[ vmalloc() End ]---
---[ Fixmap start ]---
ffffffbefe800000-ffffffbefea00000           2M PMD       ro NX SHD AF...
---[ Fixmap end ]---
---[ PCI I/O start ]---
---[ PCI I/O end ]---
---[ Linear Mapping ]---
ffffffc000000000-ffffffc000080000         512K PTE       RW NX SHD AF...
ffffffc000080000-ffffffc000200000        1536K PTE       ro NX SHD AF...
ffffffc000200000-ffffffc000600000           4M PMD       ro NX SHD AF...
ffffffc000600000-ffffffc000690000         576K PTE       ro NX SHD AF...
ffffffc000690000-ffffffc000800000        1472K PTE       RW NX SHD AF...
ffffffc000800000-ffffffc002000000          24M PMD       RW NX SHD AF...
ffffffc002000000-ffffffc040000000         992M PMD       RW NX SHD AF...
ffffffc040000000-ffffffc080000000           1G PGD       RW NX SHD AF...

With sysctl kernel.kptr_restrict=2:
cat /sys/kernel/debug/kernel_page_tables
---[ Modules start ]---
---[ Modules end ]---
---[ vmalloc() Area ]---
0000000000000000-0000000000000000          64K PTE       RW NX SHD AF...
0000000000000000-0000000000000000           4K PTE       RW NX SHD AF...
0000000000000000-0000000000000000          64K PTE       RW NX SHD AF...
0000000000000000-0000000000000000         256K PTE       RW NX SHD AF...
0000000000000000-0000000000000000        1536K PTE       ro x  SHD AF...
0000000000000000-0000000000000000           2M PMD       ro x  SHD AF...
0000000000000000-0000000000000000        1280K PTE       ro x  SHD AF...
0000000000000000-0000000000000000        1344K PTE       ro NX SHD AF...
0000000000000000-0000000000000000         832K PTE       RW NX SHD AF...
0000000000000000-0000000000000000          12K PTE       RW NX SHD AF...
0000000000000000-0000000000000000          12K PTE       RW NX SHD AF...
---[ vmalloc() End ]---
---[ Fixmap start ]---
0000000000000000-0000000000000000           2M PMD       ro NX SHD AF...
---[ Fixmap end ]---
---[ PCI I/O start ]---
---[ PCI I/O end ]---
---[ Linear Mapping ]---
0000000000000000-0000000000000000         512K PTE       RW NX SHD AF...
0000000000000000-0000000000000000        1536K PTE       ro NX SHD AF...
0000000000000000-0000000000000000           4M PMD       ro NX SHD AF...
0000000000000000-0000000000000000         576K PTE       ro NX SHD AF...
0000000000000000-0000000000000000        1472K PTE       RW NX SHD AF...
0000000000000000-0000000000000000          24M PMD       RW NX SHD AF...
0000000000000000-0000000000000000         992M PMD       RW NX SHD AF...
0000000000000000-0000000000000000           1G PGD       RW NX SHD AF...

Signed-off-by: Miles Chen <miles.chen@...iatek.com>
---
 arch/arm64/mm/dump.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index ca74a2a..e055ecf 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -253,8 +253,8 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 		if (st->current_prot) {
 			note_prot_uxn(st, addr);
 			note_prot_wx(st, addr);
-			pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
-				   st->start_address, addr);
+			pt_dump_seq_printf(st->seq, "%pK-%pK   ",
+				   (void *)st->start_address, (void *)addr);
 
 			delta = (addr - st->start_address) >> 10;
 			while (!(delta & 1023) && unit[1]) {
-- 
1.9.1