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[PATCH 1/3] utrace-probe: add $argN variable support on utrace-syscall probe
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: systemtap-ml <systemtap at sources dot redhat dot com>, David Smith <dsmith at redhat dot com>
- Date: Fri, 05 Sep 2008 12:53:48 -0400
- Subject: [PATCH 1/3] utrace-probe: add $argN variable support on utrace-syscall probe
Hi
This patch allows you to get syscall arguments from
process.syscall probes. This just uses _stp_user_syscall_arg()
function declared in syscall.h.
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
---
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
tapset/utrace.stp | 5 ++-
tapsets.cxx | 80 +++++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 74 insertions(+), 11 deletions(-)
Index: systemtap/tapsets.cxx
===================================================================
--- systemtap.orig/tapsets.cxx 2008-09-03 15:14:37.000000000 -0400
+++ systemtap/tapsets.cxx 2008-09-03 16:00:27.000000000 -0400
@@ -5842,6 +5842,8 @@
enum utrace_derived_probe_flags flags;
bool target_symbol_seen;
+ void visit_target_symbol_arg (target_symbol* e);
+ void visit_target_symbol_syscall (target_symbol* e);
void visit_target_symbol (target_symbol* e);
};
@@ -5916,18 +5918,58 @@
void
-utrace_var_expanding_copy_visitor::visit_target_symbol (target_symbol* e)
+utrace_var_expanding_copy_visitor::visit_target_symbol_arg (target_symbol* e)
{
- assert(e->base_name.size() > 0 && e->base_name[0] == '$');
+ string argnum_s = e->base_name.substr(4,e->base_name.length()-4);
+ int argnum = atoi (argnum_s.c_str());
- if (flags != UDPF_SYSCALL && flags != UDPF_SYSCALL_RETURN)
- throw semantic_error ("only \"process(PATH_OR_PID).syscall\" and \"process(PATH_OR_PID).syscall.return\" probes support target symbols",
- e->tok);
+ if (e->components.size() > 0)
+ {
+ switch (e->components[0].first)
+ {
+ case target_symbol::comp_literal_array_index:
+ throw semantic_error("utrace target variable '$argN' may not be used as array",
+ e->tok);
+ break;
+ case target_symbol::comp_struct_member:
+ throw semantic_error("utrace target variable '$argN' may not be used as a structure",
+ e->tok);
+ break;
+ default:
+ throw semantic_error ("invalid use of utrace target variable '$argN'",
+ e->tok);
+ break;
+ }
+ }
- if (e->base_name != "$syscall")
- throw semantic_error ("invalid target symbol for utrace probe, $syscall expected",
- e->tok);
+ // FIXME: max argnument number should not be hardcoded.
+ if (argnum < 1 || argnum > 6)
+ throw semantic_error ("invalid syscall argument number (1-6)", e->tok);
+
+ bool lvalue = is_active_lvalue(e);
+ if (lvalue)
+ throw semantic_error("utrace '$argN' variable is read-only", e->tok);
+ // Remember that we've seen a target variable.
+ target_symbol_seen = true;
+
+ // We're going to substitute a synthesized '_utrace_syscall_arg'
+ // function call for the '$argN' reference.
+ functioncall* n = new functioncall;
+ n->tok = e->tok;
+ n->function = "_utrace_syscall_arg";
+ n->referent = 0; // NB: must not resolve yet, to ensure inclusion in session
+
+ literal_number *num = new literal_number(argnum - 1);
+ num->tok = e->tok;
+ n->args.push_back(num);
+
+ provide <functioncall*> (this, n);
+}
+
+void
+utrace_var_expanding_copy_visitor::visit_target_symbol_syscall (target_symbol* e)
+{
if (e->components.size() > 0)
{
switch (e->components[0].first)
@@ -5949,12 +5991,12 @@
bool lvalue = is_active_lvalue(e);
if (lvalue)
- throw semantic_error("utrace $syscall variable is read-only", e->tok);
+ throw semantic_error("utrace '$syscall' variable is read-only", e->tok);
// Remember that we've seen a target variable.
target_symbol_seen = true;
- // We're going to substitute a synthesized '_syscall_nr_get'
+ // We're going to substitute a synthesized '_utrace_syscall_nr'
// function call for the '$syscall' reference.
functioncall* n = new functioncall;
n->tok = e->tok;
@@ -5964,6 +6006,24 @@
provide <functioncall*> (this, n);
}
+void
+utrace_var_expanding_copy_visitor::visit_target_symbol (target_symbol* e)
+{
+ assert(e->base_name.size() > 0 && e->base_name[0] == '$');
+
+ if (flags != UDPF_SYSCALL && flags != UDPF_SYSCALL_RETURN)
+ throw semantic_error ("only \"process(PATH_OR_PID).syscall\" and \"process(PATH_OR_PID).syscall.return\" probes support target symbols",
+ e->tok);
+
+ if (e->base_name.substr(0,4) == "$arg")
+ visit_target_symbol_arg(e);
+ else if (e->base_name == "$syscall")
+ visit_target_symbol_syscall(e);
+ else
+ throw semantic_error ("invalid target symbol for utrace probe, $syscall or $argN expected",
+ e->tok);
+}
+
struct utrace_builder: public derived_probe_builder
{
Index: systemtap/tapset/utrace.stp
===================================================================
--- systemtap.orig/tapset/utrace.stp 2008-09-03 15:14:34.000000000 -0400
+++ systemtap/tapset/utrace.stp 2008-09-03 15:59:44.000000000 -0400
@@ -5,7 +5,10 @@
#include "syscall.h"
%}
-
function _utrace_syscall_nr:long () %{
THIS->__retvalue = __stp_user_syscall_nr(CONTEXT->regs); /* pure */
%}
+
+function _utrace_syscall_arg:long (n:long) %{
+ THIS->__retvalue = *__stp_user_syscall_arg(current, CONTEXT->regs, (int)THIS->n); /* pure */
+%}