overlay: parse tracepoints from sysfs to figure out fields' location

With changes going to drm-tip, the tracepoints field locations are
going to change. This change introduces a tracepoint parser (using a
peg parser) which lets us figure out field positions on the fly.

v2: Fix automake build (Lionel)

v3: Make overlay build conditional on peg (Petri)
    Make wait_end callback more readable (Chris)
    Drop tracepoint_id(), instead parsing from format file (Lionel)

v4: Fix existing configure.ac issue with overlay build (Petri)

v5: Silence unused function (Lionel)

v6: Fix missing double quote in v4 (Lionel)

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
For the build system changes:
Acked-by: Petri Latvala <petri.latvala@intel.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/overlay/tracepoint_format.leg b/overlay/tracepoint_format.leg
new file mode 100644
index 00000000..7a09149d
--- /dev/null
+++ b/overlay/tracepoint_format.leg
@@ -0,0 +1,35 @@
+TracepointFmt =
+    'name' ':' Space n:PropertyName EndLine
+        { free(v.string); }
+    'ID:' Space v:Number EndLine
+        { yy->ctx.tp->event_id = v.integer; }
+    'format:' EndLine
+    Field+
+    'print fmt:' [^.]* !.
+
+Field         = Space (Property ';' Space)+ EndLine
+        { yy->ctx.tp->n_fields++; }
+              | EndLine
+
+Property      = 'offset' ':' v:Number
+        { yy->ctx.tp->fields[yy->ctx.tp->n_fields].offset = v.integer; }
+              | 'size' ':' v:Number
+        { yy->ctx.tp->fields[yy->ctx.tp->n_fields].size = v.integer; }
+              | 'signed' ':' v:Number
+        { yy->ctx.tp->fields[yy->ctx.tp->n_fields].is_signed = v.integer != 0; }
+              | 'field' ':' v:PropertyValue
+        { snprintf(yy->ctx.tp->fields[yy->ctx.tp->n_fields].name,
+                   sizeof(yy->ctx.tp->fields[yy->ctx.tp->n_fields].name),
+                   "%s", strrchr(v.string, ' ') + 1); free(v.string); }
+              | n:PropertyName ':' v:PropertyValue
+        { free(n.string); free(v.string); }
+
+PropertyName  = < [A-Za-z0-9_]+ >
+        { $$.string = strdup(yytext); }
+PropertyValue = < [^;]+ >
+        { $$.string = strdup(yytext); }
+Number        = < [0-9]+ >
+        { $$.integer = atoi(yytext); }
+
+EndLine       = [\n]
+Space         = [ \t]*