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-rw-r--r--Documentation/printk-formats.txt12
1 files changed, 11 insertions, 1 deletions
diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 71b62db7eca2..b4e668ac4fe3 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -5,7 +5,6 @@ How to get printk format specifiers right
:Author: Randy Dunlap <rdunlap@infradead.org>
:Author: Andrew Murray <amurray@mpc-data.co.uk>
-
Integer types
=============
@@ -45,6 +44,17 @@ return from vsnprintf.
Raw pointer value SHOULD be printed with %p. The kernel supports
the following extended format specifiers for pointer types:
+Pointer Types
+=============
+
+Pointers printed without a specifier extension (i.e unadorned %p) are
+hashed to give a unique identifier without leaking kernel addresses to user
+space. On 64 bit machines the first 32 bits are zeroed.
+
+::
+
+ %p abcdef12 or 00000000abcdef12
+
Symbols/Function Pointers
=========================