linux-kernel - [PATCH 2/3] arm64: dump: Make the page table dumping seq

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Message-Id: <20160929213257.30505-3-labbott@redhat.com>
Date:   Thu, 29 Sep 2016 14:32:56 -0700
From:   Laura Abbott <labbott@...hat.com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        David Brown <david.brown@...aro.org>,
        Will Deacon <will.deacon@....com>,
        Catalin Marinas <catalin.marinas@....com>
Cc:     Laura Abbott <labbott@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Kees Cook <keescook@...omium.org>,
        kernel-hardening@...ts.openwall.com
Subject: [PATCH 2/3] arm64: dump: Make the page table dumping seq_file optional

The page table dumping code always assumes it will be dumping to a
seq_file to userspace. The dumping code is useful in other situations.
Let the seq_file be optional.

Signed-off-by: Laura Abbott <labbott@...hat.com>
---
 arch/arm64/mm/dump.c | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index 29e0838..e318f3d 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -50,6 +50,18 @@ static const struct addr_marker address_markers[] = {
 	{ -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);	\
+})
+
 /*
  * The page dumper groups page table entries of the same type into a single
  * description. It uses pg_state to track the range information while
@@ -186,7 +198,7 @@ static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
 			s = bits->clear;
 
 		if (s)
-			seq_printf(st->seq, " %s", s);
+			pt_dump_seq_printf(st->seq, " %s", s);
 	}
 }
 
@@ -200,14 +212,14 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 		st->level = level;
 		st->current_prot = prot;
 		st->start_address = addr;
-		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 ||
 		   addr >= st->marker[1].start_address) {
 		const char *unit = units;
 		unsigned long delta;
 
 		if (st->current_prot) {
-			seq_printf(st->seq, "0x%016lx-0x%016lx   ",
+			pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
 				   st->start_address, addr);
 
 			delta = (addr - st->start_address) >> 10;
@@ -215,17 +227,17 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 				delta >>= 10;
 				unit++;
 			}
-			seq_printf(st->seq, "%9lu%c %s", delta, *unit,
+			pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
 				   pg_level[st->level].name);
 			if (pg_level[st->level].bits)
 				dump_prot(st, pg_level[st->level].bits,
 					  pg_level[st->level].num);
-			seq_puts(st->seq, "\n");
+			pt_dump_seq_puts(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;
@@ -235,7 +247,7 @@ static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 
 	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);
 	}
 
 }
-- 
2.10.0