Commit 11cb3bc1 authored by Sasha Goldshtein's avatar Sasha Goldshtein

Allowing more natural syntax for tracepoints with no "tp" struct prefix

parent 3abb8d69
......@@ -92,7 +92,8 @@ You may use the parameters directly, or valid C expressions that involve the
parameters, such as "size % 10".
Tracepoints may access a special structure called "tp" that is formatted according
to the tracepoint format (which you can obtain using tplist). For example, the
block:block_rq_complete tracepoint can access tp.nr_sector.
block:block_rq_complete tracepoint can access tp.nr_sector. You may also use the
members of the "tp" struct directly, e.g. "nr_sector" instead of "tp.nr_sector".
Return probes can use the argument values received by the
function when it was entered, through the $entry(paramname) special variable.
Return probes can also access the function's return value in $retval, and the
......@@ -147,11 +148,11 @@ Count fork() calls in libc across all processes, grouped by pid:
.TP
Print histogram of number of sectors in completing block I/O requests:
#
.B argdist -H 't:block:block_rq_complete():u32:tp.nr_sector'
.B argdist -H 't:block:block_rq_complete():u32:nr_sector'
.TP
Aggregate interrupts by interrupt request (IRQ):
#
.B argdist -C 't:irq:irq_handler_entry():int:tp.irq'
.B argdist -C 't:irq:irq_handler_entry():int:irq'
.TP
Print histograms of sleep() and nanosleep() parameter values:
#
......
......@@ -92,7 +92,9 @@ same special keywords as in the predicate (arg1, arg2, etc.).
In tracepoints, both the predicate and the arguments may refer to the tracepoint
format structure, which is stored in the special "tp" variable. For example, the
block:block_rq_complete tracepoint can print or filter by tp.nr_sector. To
discover the format of your tracepoint, use the tplist tool.
discover the format of your tracepoint, use the tplist tool. Note that you can
also use the members of the "tp" struct directly, e.g "nr_sector" instead of
"tp.nr_sector".
The predicate expression and the format specifier replacements for printing
may also use the following special keywords: $pid, $tgid to refer to the
......@@ -118,7 +120,7 @@ Trace returns from the readline function in bash and print the return value as a
.TP
Trace the block:block_rq_complete tracepoint and print the number of sectors completed:
#
.B trace 't:block:block_rq_complete """%d sectors"", tp.nr_sector'
.B trace 't:block:block_rq_complete """%d sectors"", nr_sector'
.SH SOURCE
This is from bcc.
.IP
......
......@@ -109,11 +109,12 @@ int __trace_entry_update(struct pt_regs *ctx)
self.category = category
self.event = event
self.tp_id = tp_id
self._retrieve_struct_fields()
def _generate_struct_fields(self):
def _retrieve_struct_fields(self):
self.struct_fields = []
format_lines = Tracepoint.get_tpoint_format(self.category,
self.event)
text = ""
for line in format_lines:
match = re.search(r'field:([^;]*);.*size:(\d+);', line)
if match is None:
......@@ -126,6 +127,11 @@ int __trace_entry_update(struct pt_regs *ctx)
continue
if field_name.startswith("common_"):
continue
self.struct_fields.append((field_type, field_name))
def _generate_struct_fields(self):
text = ""
for field_type, field_name in self.struct_fields:
text += " %s %s;\n" % (field_type, field_name)
return text
......@@ -134,10 +140,17 @@ int __trace_entry_update(struct pt_regs *ctx)
return """
struct %s {
u64 __do_not_use__;
%s
%s
};
""" % (self.struct_name, self._generate_struct_fields())
def _generate_struct_locals(self):
text = ""
for field_type, field_name in self.struct_fields:
text += " %s %s = tp.%s;\n" % (
field_type, field_name, field_name)
return text
def generate_get_struct(self):
return """
u64 tid = bpf_get_current_pid_tgid();
......@@ -145,7 +158,8 @@ struct %s {
if (di == 0) { return 0; }
struct %s tp = {};
bpf_probe_read(&tp, sizeof(tp), (void *)*di);
""" % self.struct_name
%s
""" % (self.struct_name, self._generate_struct_locals())
@classmethod
def enable_tracepoint(cls, category, event):
......
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