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-rw-r--r--Documentation/trace/uprobetracer.txt25
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
index 8f1a8b8956fc..6e5cff263e2b 100644
--- a/Documentation/trace/uprobetracer.txt
+++ b/Documentation/trace/uprobetracer.txt
@@ -31,6 +31,31 @@ Synopsis of uprobe_tracer
FETCHARGS : Arguments. Each probe can have up to 128 args.
%REG : Fetch register REG
+ @ADDR : Fetch memory at ADDR (ADDR should be in userspace)
+ $stackN : Fetch Nth entry of stack (N >= 0)
+ $stack : Fetch stack address.
+ $retval : Fetch return value.(*)
+ +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**)
+ NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
+ FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
+ (u8/u16/u32/u64/s8/s16/s32/s64), "string" and bitfield
+ are supported.
+
+ (*) only for return probe.
+ (**) this is useful for fetching a field of data structures.
+
+Types
+-----
+Several types are supported for fetch-args. Uprobe tracer will access memory
+by given type. Prefix 's' and 'u' means those types are signed and unsigned
+respectively. Traced arguments are shown in decimal (signed) or hex (unsigned).
+String type is a special type, which fetches a "null-terminated" string from
+user space.
+Bitfield is another special type, which takes 3 parameters, bit-width, bit-
+offset, and container-size (usually 32). The syntax is;
+
+ b<bit-width>@<bit-offset>/<container-size>
+
Event Profiling
---------------