The patch titled
Subject: lib/hexdump: introduce DUMP_PREFIX_UNHASHED for unhashed addresses
has been added to the -mm tree. Its filename is
lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses.patch
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------------------------------------------------------
From: Timur Tabi <timur@xxxxxxxxxx>
Subject: lib/hexdump: introduce DUMP_PREFIX_UNHASHED for unhashed addresses
Patch series "introduce DUMP_PREFIX_UNHASHED for hex dumps".
First patch updates print_hex_dump() and related functions to
allow callers to print hex dumps with unhashed addresses. It
adds a new prefix type, so existing code is unchanged.
Second patch changes a page poising function to use the new address type.
This is an example of a change.
Hashed addresses make very little sense for hex dumps, which print
addresses in 16- or 32-byte increments. Typical use-case is to correlate
an addresses in between one of these increments with some other address,
but that can't be done if the addresses are hashed. I expect most
developers to want to replace their usage of DUMP_PREFIX_ADDRESS with
DUMP_PREFIX_UNHASHED, now that they have the opportunity.
This patch (of 2):
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.
Link: https://lkml.kernel.org/r/20210116220950.47078-1-timur@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20210116220950.47078-2-timur@xxxxxxxxxx
Signed-off-by: Timur Tabi <timur@xxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Cc: Roman Fietze <roman.fietze@xxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Cc: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/seq_file.c | 3 +++
include/linux/printk.h | 8 +++++---
lib/hexdump.c | 9 +++++++--
lib/seq_buf.c | 9 +++++++--
4 files changed, 22 insertions(+), 7 deletions(-)
--- a/fs/seq_file.c~lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses
+++ a/fs/seq_file.c
@@ -864,6 +864,9 @@ void seq_hex_dump(struct seq_file *m, co
remaining -= rowsize;
switch (prefix_type) {
+ case DUMP_PREFIX_UNHASHED:
+ seq_printf(m, "%s%px: ", prefix_str, ptr + i);
+ break;
case DUMP_PREFIX_ADDRESS:
seq_printf(m, "%s%p: ", prefix_str, ptr + i);
break;
--- a/include/linux/printk.h~lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses
+++ a/include/linux/printk.h
@@ -567,7 +567,8 @@ extern const struct file_operations kmsg
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,
@@ -612,8 +613,9 @@ static inline void print_hex_dump_debug(
* print_hex_dump_bytes - shorthand form of print_hex_dump() with default params
* @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)
* @buf: data blob to dump
* @len: number of bytes in the @buf
*
--- a/lib/hexdump.c~lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses
+++ a/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, c
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);
--- a/lib/seq_buf.c~lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses
+++ a/lib/seq_buf.c
@@ -335,8 +335,9 @@ int seq_buf_to_user(struct seq_buf *s, c
* @s: seq_buf descriptor
* @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
@@ -374,6 +375,10 @@ int seq_buf_hex_dump(struct seq_buf *s,
linebuf, sizeof(linebuf), ascii);
switch (prefix_type) {
+ case DUMP_PREFIX_UNHASHED:
+ ret = seq_buf_printf(s, "%s%px: %s\n",
+ prefix_str, ptr + i, linebuf);
+ break;
case DUMP_PREFIX_ADDRESS:
ret = seq_buf_printf(s, "%s%p: %s\n",
prefix_str, ptr + i, linebuf);
_
Patches currently in -mm which might be from timur@xxxxxxxxxx are
lib-hexdump-introduce-dump_prefix_unhashed-for-unhashed-addresses.patch
mm-page_poison-use-unhashed-address-in-hexdump-for-check_poison_mem.patch
