Run system tap with a user defined function

Run system tap with a user defined function

[Yeshpal Jain]

I want to run a user defined function inside one of the function probes.
for ex :
#! /usr/bin/env stap


function __read_phase:long(phase:long) %{ /* pure */
        struct phase *phase_s = (struct phase *)((long)STAP_ARG_phase);
        int phase_st = phase->p_state;
        STAP_RETURN(phase_st);
%} /* <-- function body */

function trace_phase(entry_p, extra) {
  %( $# > 1 %? if (tid() in trace) %)
                  printf("%s%s%s %s phase = %d\n",
                                  thread_indent (entry_p),
                                  (entry_p>0?"->":"<-"),
                                  ppfunc (),
                                  extra, __read_phase($fom))

}

probe process("/root/test/.libs/mylib.so").function("*_test_func").call   {
trace_phase(1, $$parms) }

i am running stap with -g option,
when i compile i am getting error,
error: dereferencing pointer to incomplete type ‘struct phase’
struct phase is a structure defined in mylibrary,
Is there a way to include custom directory/headers while generating system
tap.

-- 
Thanks and Regards,
Yeshpal Jain.

Re: Run system tap with a user defined function

[Bryn M. Reeves]

On Sun, Aug 07, 2022 at 09:39:23PM +0530, Yeshpal Jain via Systemtap wrote:
> I want to run a user defined function inside one of the function probes.
> for ex :
> #! /usr/bin/env stap
> 
> 
> function __read_phase:long(phase:long) %{ /* pure */
>         struct phase *phase_s = (struct phase *)((long)STAP_ARG_phase);
>         int phase_st = phase->p_state;
>         STAP_RETURN(phase_st);
> %} /* <-- function body */
> 
> function trace_phase(entry_p, extra) {
>   %( $# > 1 %? if (tid() in trace) %)
>                   printf("%s%s%s %s phase = %d\n",
>                                   thread_indent (entry_p),
>                                   (entry_p>0?"->":"<-"),
>                                   ppfunc (),
>                                   extra, __read_phase($fom))
> 
> }
> 
> probe process("/root/test/.libs/mylib.so").function("*_test_func").call   {
> trace_phase(1, $$parms) }
> 
> i am running stap with -g option,
> when i compile i am getting error,
> error: dereferencing pointer to incomplete type ‘struct phase’
> struct phase is a structure defined in mylibrary,
> Is there a way to include custom directory/headers while generating system
> tap.

Just put the include directives inside %{..%} at file level, e.g.:

  %{
  #include <myheader.h>
  %}

  ... rest of script

Regards,
Bryn.

Re: Run system tap with a user defined function

[Yeshpal Jain]

Thanks for your reply,
Is there a way i can add my header path in stap common so that it looks in
my header path, when i try to add a header it is erroring out because other
files in myheader.h are not accessible, if somehow i can include the header
path in compilation command then that should resolve this problem.
Below is the command which stap will execute.

 gcc -Wp,-MD,/tmp/stap0qTelA/.stap_symbols.o.d  -nostdinc -isystem
/usr/lib/gcc/x86_64-redhat-linux/8/include -I./arch/x86/include
-I./arch/x86/include/generated   -I./include/drm-backport -I./include
-I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi
-I./include/uapi -I./include/generated/uapi -include
./include/linux/kconfig.h -include ./include/linux/compiler_types.h
-D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs
-fno-strict-aliasing -fno-common -fshort-wchar
-Werror-implicit-function-declaration -Wno-format-security -std=gnu89
-fno-PIE -DCC_HAVE_ASM_GOTO -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
-m64 -falign-jumps=1 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387
-mpreferred-stack-boundary=3 -mskip-rax-setup -mtune=generic -mno-red-zone
-mcmodel=kernel -funit-at-a-time -DCONFIG_AS_CFI=1
-DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1
-DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_SSSE3=1 -DCONFIG_AS_CRC32=1
-DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 -DCONFIG_AS_AVX512=1
-DCONFIG_AS_SHA1_NI=1 -DCONFIG_AS_SHA256_NI=1 -DCONFIG_TPAUSE=1 -pipe
-Wno-sign-compare -fno-asynchronous-unwind-tables
-mindirect-branch=thunk-extern -mindirect-branch-register -fno-jump-tables
-fno-delete-null-pointer-checks -Wno-frame-address -Wno-format-truncation
-Wno-format-overflow -Wno-int-in-bool-context -O2
--param=allow-store-data-races=0 -Wframe-larger-than=2048
-fstack-protector-strong -Wno-unused-but-set-variable
-Wno-unused-const-variable -gdwarf-4 -pg -mrecord-mcount -mfentry
-DCC_USING_FENTRY -fno-inline-functions-called-once
-Wdeclaration-after-statement -Wno-pointer-sign -Wno-stringop-truncation
-fno-strict-overflow -fno-merge-all-constants -fmerge-constants
-fno-stack-check -fconserve-stack -Werror=implicit-int
-Werror=strict-prototypes -Werror=date-time
-Werror=incompatible-pointer-types -Werror=designated-init
-fmacro-prefix-map=./= -Wno-packed-not-aligned -Iinclude2/asm/mach-default
-I/lib/modules/4.18.0-305.3.1.el8_4.x86_64/build -include
/tmp/stap0qTelA/stapconf_ee8a8c12ef5d50607466e03c8831c981_784.h
-freorder-blocks -fasynchronous-unwind-tables -fno-ipa-icf -Wno-unused
-Werror -Wno-pragmas -Wno-pointer-to-int-cast -Wno-int-to-pointer-cast
-I/usr/share/systemtap/runtime  -DMODULE
 -DKBUILD_BASENAME='"stap_symbols"' -DKBUILD_MODNAME='"stap_3268232"' -c -o
/tmp/stap0qTelA/stap_symbols.o /tmp/stap0qTelA/stap_symbols.c

Regards,
Yeshpal.

On Mon, Aug 8, 2022 at 3:00 PM Bryn M. Reeves <breeves@redhat.com> wrote:

> On Sun, Aug 07, 2022 at 09:39:23PM +0530, Yeshpal Jain via Systemtap wrote:
> > I want to run a user defined function inside one of the function probes.
> > for ex :
> > #! /usr/bin/env stap
> >
> >
> > function __read_phase:long(phase:long) %{ /* pure */
> >         struct phase *phase_s = (struct phase *)((long)STAP_ARG_phase);
> >         int phase_st = phase->p_state;
> >         STAP_RETURN(phase_st);
> > %} /* <-- function body */
> >
> > function trace_phase(entry_p, extra) {
> >   %( $# > 1 %? if (tid() in trace) %)
> >                   printf("%s%s%s %s phase = %d\n",
> >                                   thread_indent (entry_p),
> >                                   (entry_p>0?"->":"<-"),
> >                                   ppfunc (),
> >                                   extra, __read_phase($fom))
> >
> > }
> >
> > probe process("/root/test/.libs/mylib.so").function("*_test_func").call
>  {
> > trace_phase(1, $$parms) }
> >
> > i am running stap with -g option,
> > when i compile i am getting error,
> > error: dereferencing pointer to incomplete type ‘struct phase’
> > struct phase is a structure defined in mylibrary,
> > Is there a way to include custom directory/headers while generating
> system
> > tap.
>
> Just put the include directives inside %{..%} at file level, e.g.:
>
>   %{
>   #include <myheader.h>
>   %}
>
>   ... rest of script
>
> Regards,
> Bryn.
>
>

-- 
Thanks and Regards,
Yeshpal Jain.

Re: Run system tap with a user defined function

[Yeshpal Jain]

I mean,is there a way i can include my project header path while running
stap to avoid compilation error related to header inclusion.

Regards,
Yeshpal.

On Tue, Aug 9, 2022 at 10:47 AM Yeshpal Jain <jainyeshpal@gmail.com> wrote:

> Thanks for your reply,
> Is there a way i can add my header path in stap common so that it looks in
> my header path, when i try to add a header it is erroring out because other
> files in myheader.h are not accessible, if somehow i can include the header
> path in compilation command then that should resolve this problem.
> Below is the command which stap will execute.
>
>  gcc -Wp,-MD,/tmp/stap0qTelA/.stap_symbols.o.d  -nostdinc -isystem
> /usr/lib/gcc/x86_64-redhat-linux/8/include -I./arch/x86/include
> -I./arch/x86/include/generated   -I./include/drm-backport -I./include
> -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi
> -I./include/uapi -I./include/generated/uapi -include
> ./include/linux/kconfig.h -include ./include/linux/compiler_types.h
> -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs
> -fno-strict-aliasing -fno-common -fshort-wchar
> -Werror-implicit-function-declaration -Wno-format-security -std=gnu89
> -fno-PIE -DCC_HAVE_ASM_GOTO -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
> -m64 -falign-jumps=1 -falign-loops=1 -mno-80387 -mno-fp-ret-in-387
> -mpreferred-stack-boundary=3 -mskip-rax-setup -mtune=generic -mno-red-zone
> -mcmodel=kernel -funit-at-a-time -DCONFIG_AS_CFI=1
> -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1
> -DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_SSSE3=1 -DCONFIG_AS_CRC32=1
> -DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 -DCONFIG_AS_AVX512=1
> -DCONFIG_AS_SHA1_NI=1 -DCONFIG_AS_SHA256_NI=1 -DCONFIG_TPAUSE=1 -pipe
> -Wno-sign-compare -fno-asynchronous-unwind-tables
> -mindirect-branch=thunk-extern -mindirect-branch-register -fno-jump-tables
> -fno-delete-null-pointer-checks -Wno-frame-address -Wno-format-truncation
> -Wno-format-overflow -Wno-int-in-bool-context -O2
> --param=allow-store-data-races=0 -Wframe-larger-than=2048
> -fstack-protector-strong -Wno-unused-but-set-variable
> -Wno-unused-const-variable -gdwarf-4 -pg -mrecord-mcount -mfentry
> -DCC_USING_FENTRY -fno-inline-functions-called-once
> -Wdeclaration-after-statement -Wno-pointer-sign -Wno-stringop-truncation
> -fno-strict-overflow -fno-merge-all-constants -fmerge-constants
> -fno-stack-check -fconserve-stack -Werror=implicit-int
> -Werror=strict-prototypes -Werror=date-time
> -Werror=incompatible-pointer-types -Werror=designated-init
> -fmacro-prefix-map=./= -Wno-packed-not-aligned -Iinclude2/asm/mach-default
> -I/lib/modules/4.18.0-305.3.1.el8_4.x86_64/build -include
> /tmp/stap0qTelA/stapconf_ee8a8c12ef5d50607466e03c8831c981_784.h
> -freorder-blocks -fasynchronous-unwind-tables -fno-ipa-icf -Wno-unused
> -Werror -Wno-pragmas -Wno-pointer-to-int-cast -Wno-int-to-pointer-cast
> -I/usr/share/systemtap/runtime  -DMODULE
>  -DKBUILD_BASENAME='"stap_symbols"' -DKBUILD_MODNAME='"stap_3268232"' -c -o
> /tmp/stap0qTelA/stap_symbols.o /tmp/stap0qTelA/stap_symbols.c
>
> Regards,
> Yeshpal.
>
> On Mon, Aug 8, 2022 at 3:00 PM Bryn M. Reeves <breeves@redhat.com> wrote:
>
>> On Sun, Aug 07, 2022 at 09:39:23PM +0530, Yeshpal Jain via Systemtap
>> wrote:
>> > I want to run a user defined function inside one of the function probes.
>> > for ex :
>> > #! /usr/bin/env stap
>> >
>> >
>> > function __read_phase:long(phase:long) %{ /* pure */
>> >         struct phase *phase_s = (struct phase *)((long)STAP_ARG_phase);
>> >         int phase_st = phase->p_state;
>> >         STAP_RETURN(phase_st);
>> > %} /* <-- function body */
>> >
>> > function trace_phase(entry_p, extra) {
>> >   %( $# > 1 %? if (tid() in trace) %)
>> >                   printf("%s%s%s %s phase = %d\n",
>> >                                   thread_indent (entry_p),
>> >                                   (entry_p>0?"->":"<-"),
>> >                                   ppfunc (),
>> >                                   extra, __read_phase($fom))
>> >
>> > }
>> >
>> > probe
>> process("/root/test/.libs/mylib.so").function("*_test_func").call   {
>> > trace_phase(1, $$parms) }
>> >
>> > i am running stap with -g option,
>> > when i compile i am getting error,
>> > error: dereferencing pointer to incomplete type ‘struct phase’
>> > struct phase is a structure defined in mylibrary,
>> > Is there a way to include custom directory/headers while generating
>> system
>> > tap.
>>
>> Just put the include directives inside %{..%} at file level, e.g.:
>>
>>   %{
>>   #include <myheader.h>
>>   %}
>>
>>   ... rest of script
>>
>> Regards,
>> Bryn.
>>
>>
>
> --
> Thanks and Regards,
> Yeshpal Jain.
>


-- 
Thanks and Regards,
Yeshpal Jain.

Re: Run system tap with a user defined function

[Frank Ch. Eigler]

Yeshpal Jain via Systemtap <systemtap@sourceware.org> writes:

> function __read_phase:long(phase:long) %{ /* pure */
>         struct phase *phase_s = (struct phase *)((long)STAP_ARG_phase);
>         int phase_st = phase->p_state;
>         STAP_RETURN(phase_st);
> %} /* <-- function body */

Keeping in mind that, by default, you're using the linux kernel runtime,
this means that any declarations your embedded-C code needs need to be
included manually (like Bryn said), but in such a way that a
kernel-oriented module build can use it.  So no #include <stdio.h>,
which is a userspace header.

You might find it simpler to code this up as pure script code:


   { ... 
     print ("%s",  @cast($fom, "phase", "<mylibrary/phase.h>")->p_state;
     ...
   }

In this case, @cast() takes a -userpace- header file name, and should
generate enough debuginfo out of it to let the ->p_state part resolve
naturally.  As a bonus, no -g guru mode required.

- FChE