perf: Add perf probe subcommand, a kprobe-event setup helper

Add perf probe subcommand that implements a kprobe-event setup helper
to the perf command.
This allows user to define kprobe events using C expressions (C line
numbers, C function names, and C local variables).

Usage
-----
 perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

    -k, --vmlinux <file>  vmlinux/module pathname
    -P, --probe <p|r:[GRP/]NAME FUNC[+OFFS][@SRC]|@SRC:LINE [ARG ...]>
                          probe point definition, where
		p:	kprobe probe
		r:	kretprobe probe
		GRP:	Group name (optional)
		NAME:	Event name
		FUNC:	Function name
		OFFS:	Offset from function entry (in byte)
		SRC:	Source code path
		LINE:	Line number
		ARG:	Probe argument (local variable name or
			kprobe-tracer argument format is supported.)

Changes in v4:
 - Add _GNU_SOURCE macro for strndup().

Changes in v3:
 - Remove -r option because perf always be used for online kernel.
 - Check malloc/calloc results.

Changes in v2:
 - Check synthesized string length.
 - Rename perf kprobe to perf probe.
 - Use spaces for separator and update usage comment.
 - Check error paths in parse_probepoint().
 - Check optimized-out variables.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
LKML-Reference: <20091008211737.29299.14784.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
new file mode 100644
index 000000000000..af920de64866
--- /dev/null
+++ b/tools/perf/util/probe-finder.h
@@ -0,0 +1,68 @@
+#ifndef _PROBE_FINDER_H
+#define _PROBE_FINDER_H
+
+#define _stringify(n)   #n
+#define stringify(n)    _stringify(n)
+
+#ifdef DEBUG
+#define debug(fmt ...)  \
+        fprintf(stderr, "DBG(" __FILE__ ":" stringify(__LINE__) "): " fmt)
+#else
+#define debug(fmt ...)  do {} while (0)
+#endif
+
+#define ERR_IF(cnd)     \
+        do { if (cnd) { \
+                fprintf(stderr, "Error (" __FILE__ ":" stringify(__LINE__) \
+                        "): " stringify(cnd) "\n");                     \
+                exit(1);                                                \
+        } } while (0)
+
+#define MAX_PATH_LEN 256
+#define MAX_PROBE_BUFFER 1024
+#define MAX_PROBES 128
+
+static inline int is_c_varname(const char *name)
+{
+        /* TODO */
+        return isalpha(name[0]) || name[0] == '_';
+}
+
+struct probe_point {
+        /* Inputs */
+        char    *file;          /* File name */
+        int     line;           /* Line number */
+
+        char    *function;      /* Function name */
+        int     offset;         /* Offset bytes */
+
+        int     nr_args;        /* Number of arguments */
+        char    **args;         /* Arguments */
+
+        /* Output */
+        int     found;          /* Number of found probe points */
+        char    *probes[MAX_PROBES];    /* Output buffers (will be allocated)*/
+};
+
+extern int find_probepoint(int fd, struct probe_point *pp);
+
+#include <libdwarf/dwarf.h>
+#include <libdwarf/libdwarf.h>
+
+struct probe_finder {
+        struct probe_point      *pp;    /* Target probe point */
+
+        /* For function searching */
+        Dwarf_Addr      addr;           /* Address */
+        Dwarf_Unsigned  fno;            /* File number */
+        Dwarf_Off       inl_offs;       /* Inline offset */
+
+        /* For variable searching */
+        Dwarf_Addr      cu_base;        /* Current CU base address */
+        Dwarf_Locdesc   fbloc;          /* Location of Current Frame Base */
+        const char      *var;           /* Current variable name */
+        char            *buf;           /* Current output buffer */
+        int             len;            /* Length of output buffer */
+};
+
+#endif /*_PROBE_FINDER_H */