[kernel-hardening][PATCH v6 2/3] arm: mm: dump: make the page table dumping seq_file optional

From: Jinbum Park
Date: Fri Dec 08 2017 - 06:01:42 EST


This patch makes the page table dumping seq_file optional.
It makes the page table dumping code usable for other cases.

This patch refers below commit of arm64.
(ae5d1cf358a5
("arm64: dump: Make the page table dumping seq_file optional"))

Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Tested-by: Laura Abbott <labbott@xxxxxxxxxx>
Reviewed-by: Laura Abbott <labbott@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Jinbum Park <jinb.park7@xxxxxxxxx>
---
v6: No changes
(Just add Reviewed-by from Kees Cook)
---
arch/arm/mm/dump.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/arch/arm/mm/dump.c b/arch/arm/mm/dump.c
index 8dfe7c3..43a2bee 100644
--- a/arch/arm/mm/dump.c
+++ b/arch/arm/mm/dump.c
@@ -34,6 +34,18 @@
{ -1, NULL },
};

+#define pt_dump_seq_printf(m, fmt, args...) \
+({ \
+ if (m) \
+ seq_printf(m, fmt, ##args); \
+})
+
+#define pt_dump_seq_puts(m, fmt) \
+({ \
+ if (m) \
+ seq_printf(m, fmt); \
+})
+
struct pg_state {
struct seq_file *seq;
const struct addr_marker *marker;
@@ -210,7 +222,7 @@ static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t
s = bits->clear;

if (s)
- seq_printf(st->seq, " %s", s);
+ pt_dump_seq_printf(st->seq, " %s", s);
}
}

@@ -224,7 +236,7 @@ static void note_page(struct pg_state *st, unsigned long addr,
st->level = level;
st->current_prot = prot;
st->current_domain = domain;
- seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+ pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
} else if (prot != st->current_prot || level != st->level ||
domain != st->current_domain ||
addr >= st->marker[1].start_address) {
@@ -232,7 +244,7 @@ static void note_page(struct pg_state *st, unsigned long addr,
unsigned long delta;

if (st->current_prot) {
- seq_printf(st->seq, "0x%08lx-0x%08lx ",
+ pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ",
st->start_address, addr);

delta = (addr - st->start_address) >> 10;
@@ -240,17 +252,19 @@ static void note_page(struct pg_state *st, unsigned long addr,
delta >>= 10;
unit++;
}
- seq_printf(st->seq, "%9lu%c", delta, *unit);
+ pt_dump_seq_printf(st->seq, "%9lu%c", delta, *unit);
if (st->current_domain)
- seq_printf(st->seq, " %s", st->current_domain);
+ pt_dump_seq_printf(st->seq, " %s",
+ st->current_domain);
if (pg_level[st->level].bits)
dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num);
- seq_printf(st->seq, "\n");
+ pt_dump_seq_printf(st->seq, "\n");
}

if (addr >= st->marker[1].start_address) {
st->marker++;
- seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
+ pt_dump_seq_printf(st->seq, "---[ %s ]---\n",
+ st->marker->name);
}
st->start_address = addr;
st->current_prot = prot;
--
1.9.1