linux-kernel - [PATCH 1/2] seq_buf: Add printing formatted hex dumps

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Message-Id: <1573021660-30540-1-git-send-email-piotrx.maziarz@linux.intel.com>
Date:   Wed,  6 Nov 2019 07:27:39 +0100
From:   Piotr Maziarz <piotrx.maziarz@...ux.intel.com>
To:     linux-kernel@...r.kernel.org
Cc:     rostedt@...dmis.org, mingo@...hat.com, andriy.shevchenko@...el.com,
        cezary.rojewski@...el.com, gustaw.lewandowski@...el.com,
        Piotr Maziarz <piotrx.maziarz@...ux.intel.com>
Subject: [PATCH 1/2] seq_buf: Add printing formatted hex dumps

Provided function is an analogue of print_hex_dump().

Implementing this function in seq_buf allows using for multiple
purposes (e.g. for tracing) and therefore prevents from code duplication
in every layer that uses seq_buf.

print_hex_dump() is an essential part of logging data to dmesg. Adding
similar capability for other purposes is beneficial to all users.

Signed-off-by: Piotr Maziarz <piotrx.maziarz@...ux.intel.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@...el.com>
---
 include/linux/seq_buf.h |  3 +++
 lib/seq_buf.c           | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index aa5deb0..fb0205d 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -125,6 +125,9 @@ extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
 extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
 			      unsigned int len);
 extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
+extern int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str,
+			    int prefix_type, int rowsize, int groupsize,
+			    const void *buf, size_t len, bool ascii);
 
 #ifdef CONFIG_BINARY_PRINTF
 extern int
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index bd807f5..0509706 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -328,3 +328,41 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
 	s->readpos += cnt;
 	return cnt;
 }
+
+int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type,
+		     int rowsize, int groupsize,
+		     const void *buf, size_t len, bool ascii)
+{
+	const u8 *ptr = buf;
+	int i, linelen, remaining = len;
+	unsigned char linebuf[32 * 3 + 2 + 32 + 1];
+	int ret;
+
+	if (rowsize != 16 && rowsize != 32)
+		rowsize = 16;
+
+	for (i = 0; i < len; i += rowsize) {
+		linelen = min(remaining, rowsize);
+		remaining -= rowsize;
+
+		hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
+				   linebuf, sizeof(linebuf), ascii);
+
+		switch (prefix_type) {
+		case DUMP_PREFIX_ADDRESS:
+			ret = seq_buf_printf(s, "%s%p: %s\n",
+			       prefix_str, ptr + i, linebuf);
+			break;
+		case DUMP_PREFIX_OFFSET:
+			ret = seq_buf_printf(s, "%s%.8x: %s\n",
+					     prefix_str, i, linebuf);
+			break;
+		default:
+			ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
+			break;
+		}
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
-- 
2.7.4