linux-kernel - [PATCH] lib/hexdump: introduce DUMP_PREFIX

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Message-Id: <20210106213547.1077789-1-timur@tabi.org>
Date:   Wed,  6 Jan 2021 15:35:47 -0600
From:   Timur Tabi <timur@...i.org>
To:     torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:     Timur Tabi <timur@...i.org>, Roman Fietze <roman.fietze@...na.com>
Subject: [PATCH] lib/hexdump: introduce DUMP_PREFIX_UNHASHED for unhashed addresses

Hashed addresses are useless in hexdumps unless you're comparing
with other hashed addresses, which is unlikely.  However, there's
no need to break existing code, so introduce a new prefix type
that prints unhashed addresses.

Signed-off-by: Timur Tabi <timur@...i.org>
Cc: Roman Fietze <roman.fietze@...na.com>
---
 include/linux/printk.h | 3 ++-
 lib/hexdump.c          | 9 +++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index fe7eb2351610..5d833bad785c 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -567,7 +567,8 @@ extern const struct file_operations kmsg_fops;
 enum {
 	DUMP_PREFIX_NONE,
 	DUMP_PREFIX_ADDRESS,
-	DUMP_PREFIX_OFFSET
+	DUMP_PREFIX_OFFSET,
+	DUMP_PREFIX_UNHASHED,
 };
 extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
 			      int groupsize, char *linebuf, size_t linebuflen,
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 9301578f98e8..b5acfc4168a8 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -211,8 +211,9 @@ EXPORT_SYMBOL(hex_dump_to_buffer);
  * @level: kernel log level (e.g. KERN_DEBUG)
  * @prefix_str: string to prefix each line with;
  *  caller supplies trailing spaces for alignment if desired
- * @prefix_type: controls whether prefix of an offset, address, or none
- *  is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
+ * @prefix_type: controls whether prefix of an offset, hashed address,
+ *  unhashed address, or none is printed (%DUMP_PREFIX_OFFSET,
+ *  %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_UNHASHED, %DUMP_PREFIX_NONE)
  * @rowsize: number of bytes to print per line; must be 16 or 32
  * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
  * @buf: data blob to dump
@@ -256,6 +257,10 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
 				   linebuf, sizeof(linebuf), ascii);
 
 		switch (prefix_type) {
+		case DUMP_PREFIX_UNHASHED:
+			printk("%s%s%px: %s\n",
+			       level, prefix_str, ptr + i, linebuf);
+			break;
 		case DUMP_PREFIX_ADDRESS:
 			printk("%s%s%p: %s\n",
 			       level, prefix_str, ptr + i, linebuf);
-- 
2.25.1