[kernel-hardening][PATCH v5 2/3] arm: mm: dump: make the page table dumping seq_file optional

[Jinbum Park]

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"))

Tested-by: Laura Abbott <labb...@redhat.com>
Reviewed-by: Laura Abbott <labb...@redhat.com>
Acked-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: Jinbum Park <jinb.pa...@gmail.com>
---
v5: No changes
        (Just add Tested-by, Reviewed-by from Laura Abbott)
---
 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