[PATCH v3 1/3] hexdump: Simplify print_hex_dump()
From: Miquel Raynal
Date: Wed Mar 19 2025 - 12:12:54 EST
print_hex_dump() already has numerous parameters, and could be extended
with a new one. Adding new parameters is super painful due to the number
of users, and it makes the function calls even longer.
Create a print_hex() to replace print_hex_dump(), with 'prefix_type' and
'ascii' being merged into a 'dump_flags' parameter. This way extending
the list of dump flags will be much easier.
For convenience, a print_hex_dump macro is created to fallback on the
print_hex() implementation. A tree-wide change to remove its use could
be done in the future.
No functional change intended.
Suggested-by: Petr Mladek <pmladek@xxxxxxxx>
Suggested-by: David Laight <david.laight.linux@xxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
Documentation/core-api/printk-formats.rst | 2 +-
include/linux/printk.h | 42 +++++++++++++++++++++++-------
lib/hexdump.c | 43 ++++++++++++++-----------------
3 files changed, 53 insertions(+), 34 deletions(-)
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index ecccc0473da9c10f45f2464566f690472c61401e..f80b5e262e9933992d1291f1d78fba97589d5631 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -310,7 +310,7 @@ Raw buffer as a hex string
For printing small buffers (up to 64 bytes long) as a hex string with a
certain separator. For larger buffers consider using
-:c:func:`print_hex_dump`.
+:c:func:`print_hex`.
MAC/FDDI addresses
------------------
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 4217a9f412b265f1dc027be88eff7f5a0e0e4aab..7dca2270c82c0ed788cd706274f1c1b14ed9a7fe 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -747,22 +747,31 @@ do { \
extern const struct file_operations kmsg_fops;
+/*
+ * Dump flags for print_hex().
+ * DUMP_PREFIX_{NONE,ADDRESS,OFFSET} are mutually exclusive.
+ */
enum {
- DUMP_PREFIX_NONE,
- DUMP_PREFIX_ADDRESS,
- DUMP_PREFIX_OFFSET
+ DUMP_HEX_DATA = 0,
+ DUMP_ASCII = BIT(0),
+ DUMP_PREFIX_NONE = 0, /* Legacy definition for print_hex_dump() */
+ DUMP_PREFIX_ADDRESS = BIT(1),
+ DUMP_PREFIX_OFFSET = BIT(2),
};
+
extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
int groupsize, char *linebuf, size_t linebuflen,
bool ascii);
#ifdef CONFIG_PRINTK
-extern void print_hex_dump(const char *level, const char *prefix_str,
- int prefix_type, int rowsize, int groupsize,
- const void *buf, size_t len, bool ascii);
+extern void print_hex(const char *level, const char *prefix_str,
+ int rowsize, int groupsize,
+ const void *buf, size_t len,
+ unsigned int dump_flags);
#else
-static inline void print_hex_dump(const char *level, const char *prefix_str,
- int prefix_type, int rowsize, int groupsize,
- const void *buf, size_t len, bool ascii)
+static inline void print_hex(const char *level, const char *prefix_str,
+ int rowsize, int groupsize,
+ const void *buf, size_t len,
+ unsigned int dump_flags)
{
}
static inline void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
@@ -791,6 +800,21 @@ static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type,
}
#endif
+/*
+ * print_hex_dump - legacy version of print_hex() with a longer parameter list
+ *
+ * Refer to print_hex() for the parameters definition which are identical except:
+ * - prefix_type: controls whether prefix of an offset, address, or none
+ * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE).
+ * This parameter has been removed in favor of a common 'flags' parameter.
+ * - ascii: include ASCII after the hex output.
+ * This parameter has been removed in favor of a common 'flags' parameter.
+ */
+
+#define print_hex_dump(level, prefix_str, prefix_type, rowsize, groupsize, buf, len, ascii) \
+ print_hex(level, prefix_str, rowsize, groupsize, buf, len, \
+ (prefix_type) | ((ascii) ? DUMP_ASCII : DUMP_HEX_DATA))
+
/**
* print_hex_dump_bytes - shorthand form of print_hex_dump() with default params
* @prefix_str: string to prefix each line with;
diff --git a/lib/hexdump.c b/lib/hexdump.c
index c3db7c3a764365b01e78f8ed0b7f782f33a5ce34..74fdcb4566d27f257a0e1288c261d81d231b06bf 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -228,39 +228,39 @@ EXPORT_SYMBOL(hex_dump_to_buffer);
#ifdef CONFIG_PRINTK
/**
- * print_hex_dump - print a text hex dump to syslog for a binary blob of data
+ * print_hex - print a text hex dump to syslog for a binary blob of data
* @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)
* @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
* @len: number of bytes in the @buf
- * @ascii: include ASCII after the hex output
+ * @dump_flags: controls the output format, typically:
+ * - %DUMP_PREFIX_OFFSET shows the offset in front of each line
+ * - %DUMP_PREFIX_ADDRESS shows the address in front of each line
+ * - %DUMP_ASCII prints the ascii equivalent after the hex output
*
- * Given a buffer of u8 data, print_hex_dump() prints a hex + ASCII dump
+ * Given a buffer of u8 data, print_hex() prints a hex + ASCII dump
* to the kernel log at the specified kernel log level, with an optional
* leading prefix.
*
- * print_hex_dump() works on one "line" of output at a time, i.e.,
+ * print_hex() works on one "line" of output at a time, i.e.,
* 16 or 32 bytes of input data converted to hex + ASCII output.
- * print_hex_dump() iterates over the entire input @buf, breaking it into
+ * print_hex() iterates over the entire input @buf, breaking it into
* "line size" chunks to format and print.
*
* E.g.:
- * print_hex_dump(KERN_DEBUG, "raw data: ", DUMP_PREFIX_ADDRESS,
- * 16, 1, frame->data, frame->len, true);
+ * print_hex(KERN_DEBUG, "raw data: ", 16, 1, frame->data, frame->len,
+ * DUMP_PREFIX_ADDRESS | DUMP_ASCII);
*
* Example output using %DUMP_PREFIX_OFFSET and 1-byte mode:
* 0009ab42: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
* Example output using %DUMP_PREFIX_ADDRESS and 4-byte mode:
* ffffffff88089af0: 73727170 77767574 7b7a7978 7f7e7d7c pqrstuvwxyz{|}~.
*/
-void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
- int rowsize, int groupsize,
- const void *buf, size_t len, bool ascii)
+void print_hex(const char *level, const char *prefix_str, int rowsize, int groupsize,
+ const void *buf, size_t len, unsigned int dump_flags)
{
const u8 *ptr = buf;
int i, linelen, remaining = len;
@@ -274,22 +274,17 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
remaining -= rowsize;
hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
- linebuf, sizeof(linebuf), ascii);
+ linebuf, sizeof(linebuf),
+ dump_flags & DUMP_ASCII);
- switch (prefix_type) {
- case DUMP_PREFIX_ADDRESS:
- printk("%s%s%p: %s\n",
- level, prefix_str, ptr + i, linebuf);
- break;
- case DUMP_PREFIX_OFFSET:
+ if (dump_flags & DUMP_PREFIX_ADDRESS)
+ printk("%s%s%p: %s\n", level, prefix_str, ptr + i, linebuf);
+ else if (dump_flags & DUMP_PREFIX_OFFSET)
printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
- break;
- default:
+ else
printk("%s%s%s\n", level, prefix_str, linebuf);
- break;
- }
}
}
-EXPORT_SYMBOL(print_hex_dump);
+EXPORT_SYMBOL(print_hex);
#endif /* defined(CONFIG_PRINTK) */
--
2.48.1