linux-kernel - [PATCH 1/3] lib/hexdump: Add a raw pointer printing format for slub debugging

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Date:   Wed, 19 May 2021 18:35:37 -0700
From:   Stephen Boyd <swboyd@...omium.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org
Subject: [PATCH 1/3] lib/hexdump: Add a raw pointer printing format for slub debugging

We want to get actual pointer addresses when we're looking at slub
debugging reports. Add another prefix format specifier that says we want
raw pointer addresses, i.e. %px, in the printk format.

Signed-off-by: Stephen Boyd <swboyd@...omium.org>
---
 include/linux/printk.h |  1 +
 lib/hexdump.c          | 12 ++++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/include/linux/printk.h b/include/linux/printk.h
index fe7eb2351610..a7b0b620982d 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -567,6 +567,7 @@ extern const struct file_operations kmsg_fops;
 enum {
 	DUMP_PREFIX_NONE,
 	DUMP_PREFIX_ADDRESS,
+	DUMP_PREFIX_RAW_ADDRESS,
 	DUMP_PREFIX_OFFSET
 };
 extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 9301578f98e8..87af5755563f 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -211,8 +211,12 @@ 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 how prefix is printed
+ *   %DUMP_PREFIX_OFFSET - offset prefix
+ *   %DUMP_PREFIX_ADDRESS - hashed address prefix
+ *   %DUMP_PREFIX_RAW_ADDRESS - non-hashed address prefix
+ *   %DUMP_PREFIX_NONE - no prefix
+ *
  * @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
@@ -260,6 +264,10 @@ void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
 			printk("%s%s%p: %s\n",
 			       level, prefix_str, ptr + i, linebuf);
 			break;
+		case DUMP_PREFIX_RAW_ADDRESS:
+			printk("%s%s%px: %s\n",
+			       level, prefix_str, ptr + i, linebuf);
+			break;
 		case DUMP_PREFIX_OFFSET:
 			printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
 			break;
-- 
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