gdb/doc/ChangeLog:

2012-04-27  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Tom Tromey  <tromey@redhat.com>

	* gdb.texinfo (Static Probe Points): New entry, explaining SystemTap
	and generic static probe support on GDB.

gdb/testsuite/ChangeLog:
2012-04-27  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Tom Tromey  <tromey@redhat.com>

	* gdb.base/default.exp: Add `$_probe_arg*' convenience
	variables.
	* gdb.base/stap-probe.c: New file.
	* gdb.base/stap-probe.exp: New file.
	* gdb.trace/stap-trace.c: New file.
	* gdb.trace/stap-trace.exp: New file.
	* gdb.cp/nextoverthrow.exp: Add check for SystemTap probe in
	libgcc's unwinder.
This commit is contained in:
Sergio Durigan Junior 2012-04-27 20:52:06 +00:00
parent 28106bc2fe
commit 62e5f89c34
9 changed files with 623 additions and 0 deletions

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@ -1,3 +1,9 @@
2012-04-27 Sergio Durigan Junior <sergiodj@redhat.com>
Tom Tromey <tromey@redhat.com>
* gdb.texinfo (Static Probe Points): New entry, explaining SystemTap
and generic static probe support on GDB.
2012-04-25 Doug Evans <dje@google.com>
* gdb.texinfo (Go): Fix thinko.

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@ -3342,6 +3342,7 @@ all breakpoints in that range are operated on.
* Conditions:: Break conditions
* Break Commands:: Breakpoint command lists
* Save Breakpoints:: How to save breakpoints in a file
* Static Probe Points:: Listing static probe points
* Error in Breakpoints:: ``Cannot insert breakpoints''
* Breakpoint-related Warnings:: ``Breakpoint address adjusted...''
@end menu
@ -4652,6 +4653,69 @@ and remove the breakpoint definitions you're not interested in, or
that can no longer be recreated.
@end table
@node Static Probe Points
@subsection Static Probe Points
@cindex static probe point, SystemTap
@value{GDBN} supports @dfn{SDT} probes in the code. @acronym{SDT} stands
for Statically Defined Tracing, and the probes are designed to have a tiny
runtime code and data footprint, and no dynamic relocations. They are
usable from assembly, C and C@t{++} languages. See
@uref{http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation}
for a good reference on how the @acronym{SDT} probes are implemented.
Currently, @code{SystemTap} (@uref{http://sourceware.org/systemtap/})
@acronym{SDT} probes are supported on ELF-compatible systems. See
@uref{http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps}
for more information on how to add @code{SystemTap} @acronym{SDT} probes
in your applications.
@cindex semaphores on static probe points
Some probes have an associated semaphore variable; for instance, this
happens automatically if you defined your probe using a DTrace-style
@file{.d} file. If your probe has a semaphore, @value{GDBN} will
automatically enable it when you specify a breakpoint using the
@samp{-probe-stap} notation. But, if you put a breakpoint at a probe's
location by some other method (e.g., @code{break file:line}), then
@value{GDBN} will not automatically set the semaphore.
You can examine the available static static probes using @code{info
probes}, with optional arguments:
@table @code
@kindex info probes
@item info probes stap @r{[}@var{provider} @r{[}@var{name} @r{[}@var{objfile}@r{]}@r{]}@r{]}
If given, @var{provider} is a regular expression used to match against provider
names when selecting which probes to list. If omitted, probes by all
probes from all providers are listed.
If given, @var{name} is a regular expression to match against probe names
when selecting which probes to list. If omitted, probe names are not
considered when deciding whether to display them.
If given, @var{objfile} is a regular expression used to select which
object files (executable or shared libraries) to examine. If not
given, all object files are considered.
@item info probes all
List the available static probes, from all types.
@end table
@vindex $_probe_arg@r{, convenience variable}
A probe may specify up to twelve arguments. These are available at the
point at which the probe is defined---that is, when the current PC is
at the probe's location. The arguments are available using the
convenience variables (@pxref{Convenience Vars})
@code{$_probe_arg0}@dots{}@code{$_probe_arg11}. Each probe argument is
an integer of the appropriate size; types are not preserved. The
convenience variable @code{$_probe_argc} holds the number of arguments
at the current probe point.
These variables are always available, but attempts to access them at
any location other than a probe point will cause @value{GDBN} to give
an error message.
@c @ifclear BARETARGET
@node Error in Breakpoints
@subsection ``Cannot insert breakpoints''
@ -6667,6 +6731,19 @@ specify the function unambiguously, e.g., if there are several
functions with identical names in different source files.
@end table
@cindex breakpoint at static probe point
@item -pstap|-probe-stap @r{[}@var{objfile}:@r{[}@var{provider}:@r{]}@r{]}@var{name}
The @sc{gnu}/Linux tool @code{SystemTap} provides a way for
applications to embed static probes. @xref{Static Probe Points}, for more
information on finding and using static probes. This form of linespec
specifies the location of such a static probe.
If @var{objfile} is given, only probes coming from that shared library
or executable matching @var{objfile} as a regular expression are considered.
If @var{provider} is given, then only probes from that provider are considered.
If several probes match the spec, @value{GDBN} will insert a breakpoint at
each one of those probes.
@end table
@ -9071,6 +9148,10 @@ to match the format in which the data was printed.
The variable @code{$_exitcode} is automatically set to the exit code when
the program being debugged terminates.
@item $_probe_argc
@itemx $_probe_arg0@dots{}$_probe_arg11
Arguments to a static probe. @xref{Static Probe Points}.
@item $_sdata
@vindex $_sdata@r{, inspect, convenience variable}
The variable @code{$_sdata} contains extra collected static tracepoint
@ -11015,6 +11096,16 @@ Collect all local variables.
Collect the return address. This is helpful if you want to see more
of a backtrace.
@item $_probe_argc
Collects the number of arguments from the static probe at which the
tracepoint is located.
@xref{Static Probe Points}.
@item $_probe_arg@var{n}
@var{n} is an integer between 0 and 11. Collects the @var{n}th argument
from the static probe at which the tracepoint is located.
@xref{Static Probe Points}.
@item $_sdata
@vindex $_sdata@r{, collect}
Collect static tracepoint marker specific data. Only available for

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@ -1,3 +1,15 @@
2012-04-27 Sergio Durigan Junior <sergiodj@redhat.com>
Tom Tromey <tromey@redhat.com>
* gdb.base/default.exp: Add `$_probe_arg*' convenience
variables.
* gdb.base/stap-probe.c: New file.
* gdb.base/stap-probe.exp: New file.
* gdb.trace/stap-trace.c: New file.
* gdb.trace/stap-trace.exp: New file.
* gdb.cp/nextoverthrow.exp: Add check for SystemTap probe in
libgcc's unwinder.
2012-04-26 Maciej W. Rozycki <macro@codesourcery.com>
* gdb.arch/mips16-thunks-inmain.c: New file.

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@ -604,6 +604,19 @@ gdb_test_list_exact "show convenience" "show convenience" \
{$_sdata = void} \
{$_siginfo = void} \
{$_thread = 0} \
{$_probe_argc = <error: No frame selected>} \
{$_probe_arg0 = <error: No frame selected>} \
{$_probe_arg1 = <error: No frame selected>} \
{$_probe_arg2 = <error: No frame selected>} \
{$_probe_arg3 = <error: No frame selected>} \
{$_probe_arg4 = <error: No frame selected>} \
{$_probe_arg5 = <error: No frame selected>} \
{$_probe_arg6 = <error: No frame selected>} \
{$_probe_arg7 = <error: No frame selected>} \
{$_probe_arg8 = <error: No frame selected>} \
{$_probe_arg9 = <error: No frame selected>} \
{$_probe_arg10 = <error: No frame selected>} \
{$_probe_arg11 = <error: No frame selected>} \
}
#test show directories

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@ -0,0 +1,108 @@
/* This testcase is part of GDB, the GNU debugger.
Copyright 2012 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#if USE_PROBES
#define _SDT_HAS_SEMAPHORES
__extension__ unsigned short test_user_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
#define TEST test_user_semaphore
__extension__ unsigned short test_two_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
#define TEST2 test_two_semaphore
__extension__ unsigned short test_m4_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
__extension__ unsigned short test_pstr_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
__extension__ unsigned short test_ps_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
#else
#define TEST 1
#define TEST2 1
#endif
#include <sys/sdt.h>
/* We only support SystemTap and only the v3 form. */
#if _SDT_NOTE_TYPE != 3
#error "not using SystemTap v3 probes"
#endif
struct funcs
{
int val;
const char *(*ps) (int);
};
static void
m1 (void)
{
if (TEST2)
STAP_PROBE (test, two);
}
static void
m2 (void)
{
if (TEST2)
STAP_PROBE (test, two);
}
static int
f (int x)
{
if (TEST)
STAP_PROBE1 (test, user, x);
return x+5;
}
static const char *
pstr (int val)
{
const char *a = "This is a test message.";
const char *b = "This is another test message.";
STAP_PROBE3 (test, ps, a, b, val);
return val == 0 ? a : b;
}
static void
m4 (const struct funcs *fs, int v)
{
STAP_PROBE3 (test, m4, fs->val, fs->ps (v), v);
}
int
main()
{
struct funcs fs;
fs.val = 42;
fs.ps = pstr;
f (f (23));
m1 ();
m2 ();
m4 (&fs, 0);
m4 (&fs, 1);
return 0; /* last break here */
}

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@ -0,0 +1,183 @@
# Copyright (C) 2012 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
set testfile stap-probe
# Run the tests. We run the tests two different ways: once with a
# plain probe, and once with a probe that has an associated semaphore.
# This returns -1 on failure to compile or start, 0 otherwise.
proc stap_test {exec_name {arg ""}} {
global testfile hex
if {[prepare_for_testing ${testfile}.exp ${exec_name} ${testfile}.c \
[concat $arg debug]]} {
return -1
}
if ![runto_main] {
return -1
}
gdb_test "print \$_probe_argc" "No SystemTap probe at PC $hex" \
"check argument not at probe point"
gdb_test "info probes stap" \
"test *user *$hex .*" \
"info probes stap"
if {[runto "-pstap test:user"]} {
pass "run to -pstap test:user"
} else {
fail "run to -pstap test:user"
}
# Test probe arguments.
gdb_test "print \$_probe_argc" " = 1" \
"print \$_probe_argc for probe user"
gdb_test "print \$_probe_arg0 == x" " = 1" \
"check \$_probe_arg0 for probe user"
gdb_test "print \$_probe_arg1" \
"Invalid probe argument 1 -- probe has 1 arguments available" \
"check \$_probe_arg1 for probe user"
# Set a breakpoint with multiple probe locations.
gdb_test "break -pstap test:two" \
"Breakpoint \[0-9\]+ at $hex.*2 locations.*" \
"set multi-location probe breakpoint (probe two)"
# Reinit GDB, set a breakpoint on probe m4.
delete_breakpoints
rerun_to_main
if {[runto "-pstap test:m4"]} {
pass "run to -pstap test:m4"
} else {
fail "run to -pstap test:m4"
}
# Testing probe arguments.
gdb_test "print \$_probe_argc" " = 3" \
"print \$_probe_argc for probe m4"
gdb_test "print \$_probe_arg0" " = 42" \
"check \$_probe_arg0 for probe m4"
gdb_test "print (const char *) \$_probe_arg1" \
" = $hex .This is a test message.*" \
"check \$_probe_arg1 for probe m4"
gdb_test "print \$_probe_arg2 == v" " = 1" \
"check \$_probe_arg2 for probe m4"
# Reinit GDB, set a breakpoint on probe ps.
delete_breakpoints
rerun_to_main
if {[runto "-pstap test:ps"]} {
pass "run to -pstap test:m4"
} else {
fail "run to -pstap test:m4"
}
gdb_test "print \$_probe_argc" " = 3" \
"print \$_probe_argc for probe ps"
gdb_test "print (const char *) \$_probe_arg1" \
" = $hex .This is another test message.*" \
"print \$_probe_arg1 for probe ps"
return 0
}
proc stap_test_no_debuginfo {exec_name {arg ""}} {
global testfile hex
if {[prepare_for_testing ${testfile}.exp ${exec_name} ${testfile}.c \
{$arg nodebug optimize=-O2}]} {
return -1
}
if {[runto "-pstap test:user"]} {
pass "run to -pstap test:user"
} else {
fail "run to -pstap test:user"
}
# Test probe arguments.
gdb_test "print \$_probe_argc" " = 1" \
"print \$_probe_argc for probe user"
gdb_test "print \$_probe_arg0 == 23" " = 1" \
"check \$_probe_arg0 for probe user"
gdb_test "print \$_probe_arg1" \
"Invalid probe argument 1 -- probe has 1 arguments available" \
"check \$_probe_arg1 for probe user"
# Set a breakpoint with multiple probe locations.
# In this scenario, we may expect more than 2 locations because of
# the optimizations (inlining, loop unrolling, etc).
gdb_test "break -pstap test:two" \
"Breakpoint .* at $hex.*\[0-9\]+ locations.*" \
"set multi-location probe breakpoint (probe two)"
# Reinit GDB, set a breakpoint on probe m4.
delete_breakpoints
rerun_to_main
if {[runto "-pstap test:m4"]} {
pass "run to -pstap test:m4"
} else {
fail "run to -pstap test:m4"
}
# Testing probe arguments.
gdb_test "print \$_probe_argc" " = 3" \
"print \$_probe_argc for probe m4"
gdb_test "print \$_probe_arg0" " = 42" \
"check \$_probe_arg0 for probe m4"
gdb_test "print (const char *) \$_probe_arg1" \
" = $hex .This is a test message.*" \
"check \$_probe_arg1 for probe m4"
gdb_test "print \$_probe_arg2 == 0" " = 1" \
"check \$_probe_arg2 for probe m4"
# Reinit GDB, set a breakpoint on probe ps.
delete_breakpoints
rerun_to_main
if {[runto "-pstap test:ps"]} {
pass "run to -pstap test:m4"
} else {
fail "run to -pstap test:m4"
}
gdb_test "print \$_probe_argc" " = 3" \
"print \$_probe_argc for probe ps"
gdb_test "print (const char *) \$_probe_arg1" \
" = $hex .This is another test message.*" \
"print \$_probe_arg1 for probe ps"
return 0
}
with_test_prefix "without semaphore, not optimized" {
if {[stap_test "stap-probe-nosem-noopt"] == -1} {
untested stap-probe.exp
return -1
}
}
with_test_prefix "with semaphore, not optimized" {
stap_test "stap-probe-sem-noopt" "-DUSE_PROBES"
}
with_test_prefix "without semaphore, optimized" {
stap_test_no_debuginfo "stap-probe-nosem-opt"
}
with_test_prefix "with semaphore, optimized" {
stap_test_no_debuginfo "stap-probe-sem-opt" "-DUSE_PROBES"
}

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@ -53,6 +53,17 @@ gdb_test_multiple "print _Unwind_DebugHook" "check for unwinder hook" {
set ok 0
}
}
if {!$ok} {
gdb_test_multiple "info probe" "check for stap probe in unwinder" {
-re ".*libgcc.*unwind.*\r\n$gdb_prompt $" {
pass "check for stap probe in unwinder"
set ok 1
}
-re "\r\n$gdb_prompt $" {
}
}
}
if {!$ok} {
unsupported "nextoverthrow.exp could not find _Unwind_DebugHook"
return -1

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@ -0,0 +1,71 @@
/* This testcase is part of GDB, the GNU debugger.
Copyright 2012 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#if USE_PROBES
#define _SDT_HAS_SEMAPHORES
__extension__ unsigned short test_user_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
#define TEST test_user_semaphore
__extension__ unsigned short test_two_semaphore __attribute__ ((unused)) __attribute__ ((section (".probes")));
#define TEST2 test_two_semaphore
#else
#define TEST 1
#define TEST2 1
#endif /* USE_PROBES */
#include <sys/sdt.h>
/* We only support SystemTap and only the v3 form. */
#if _SDT_NOTE_TYPE != 3
#error "not using SystemTap v3 probes"
#endif
void
m1 (int x)
{
if (TEST2)
STAP_PROBE1 (test, two, x);
}
int
f (int x)
{
if (TEST)
STAP_PROBE1(test, user, x);
return x+5;
}
void
nothing (void)
{
int a = 1 + 1;
return;
}
int
main()
{
f (f (23));
m1 (46);
nothing (); /* end-here */
return 0;
}

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@ -0,0 +1,128 @@
# Copyright 2012 Free Software Foundation, Inc.
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
load_lib "trace-support.exp"
set testfile "stap-trace"
set srcfile ${testfile}.c
set executable ""
set binfile_dir $objdir/$subdir
set ws "\[\r\n\t \]+"
set cr "\[\r\n\]+"
# Only x86 and x86_64 targets are supported for now.
if { ![istarget "x86_64-*"] && ![istarget "i?86-*"] } {
continue
}
proc compile_stap_bin {exec_name {arg ""}} {
global srcfile
global binfile_dir
global srcdir
global subdir
global executable
if { $arg != "" } {
set arg "additional_flags=$arg"
}
set executable ${exec_name}
if { [gdb_compile "$srcdir/$subdir/$srcfile" \
"$binfile_dir/$exec_name" \
executable [concat $arg debug nowarnings]] != "" } {
untested "Could not compile ${srcfile}"
return -1
}
}
proc prepare_for_trace_test {} {
global executable
clean_restart $executable
if { ![runto_main] } {
perror "Could not run to `main'."
continue
}
gdb_breakpoint [gdb_get_line_number "end-here"]
}
proc run_trace_experiment { test_probe msg } {
global gdb_prompt
set test "collect $msg: start trace experiment"
gdb_test_multiple "tstart" "$test" {
-re "^tstart\r\n$gdb_prompt $" {
pass "$test"
}
}
gdb_test "continue" \
"Continuing.*Breakpoint \[0-9\]+.*" \
"collect $msg: run trace experiment"
gdb_test "tstop" \
"\[\r\n\]+" \
"collect $msg: stop trace experiment"
gdb_test "tfind start" \
"#0 .*" \
"collect $msg: tfind test frame"
}
proc gdb_collect_probe_arg { msg probe val_arg0 } {
global gdb_prompt
global cr
prepare_for_trace_test
gdb_test "trace $probe" \
"Tracepoint \[0-9\]+ at .*" \
"collect $msg: set tracepoint"
gdb_trace_setactions "collect $msg: define actions" \
"" \
"collect \$_probe_arg0" "^$"
# Begin the test.
run_trace_experiment $msg $probe
gdb_test "print \$_probe_arg0" \
"\\$\[0-9\]+ = $val_arg0$cr" \
"collect $msg: collected probe arg0"
}
compile_stap_bin "stap-probe-nosem"
clean_restart $executable
if { ![runto_main] } {
perror "Could not run to `main'."
continue
}
if { ![gdb_target_supports_trace] } {
# Test cannot run on this target.
return 1;
}
gdb_collect_probe_arg "probe args without semaphore" "-probe-stap user" "23"
gdb_exit
compile_stap_bin "stap-probe-sem" "-DUSE_PROBES"
gdb_collect_probe_arg "probe args with semaphore" "-probe-stap two" "46"
# Finished!
gdb_test "tfind none" ".*" ""