[DTrace-devel] [PATCH 6/7] cg: allow input to translator to be NULL

[Kris Van Hees]

On Thu, Jul 27, 2023 at 08:06:00PM -0400, Eugene Loh via DTrace-devel wrote:
> Reviewed-by: Eugene Loh <eugene.loh at oracle.com>
> 
> nodemis?
> 
> trask_struct?

Thanks.  Having more trouble typing on my backup keyboard.

> On 7/27/23 11:30, Kris Van Hees via DTrace-devel wrote:
> > Some translators support NULL as input pointer value.  The code generator
> > was performing a NULL-check on a the LHS of a PTR or DOT node before
> > considering the possibility that the nodemis subject to translator
> > handling.  The check should happen after translator handling.
> > 
> > With this patch, tst.ProcModelTrans.d works but only for the case of
> > NULL input.  The test is changed to actually use a real trask_struct as
> > input.  New test tst.NullInput.d exercises the case this patch fixes.
> > 
> > Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> > ---
> >   libdtrace/dt_cg.c                             |  4 +--
> >   test/unittest/translators/tst.NullInput.d     | 31 +++++++++++++++++++
> >   .../unittest/translators/tst.ProcModelTrans.d | 16 ++++------
> >   3 files changed, 39 insertions(+), 12 deletions(-)
> >   create mode 100644 test/unittest/translators/tst.NullInput.d
> > 
> > diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
> > index e05a1f64..ebe2e043 100644
> > --- a/libdtrace/dt_cg.c
> > +++ b/libdtrace/dt_cg.c
> > @@ -6305,8 +6305,6 @@ dt_cg_node(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
> >   		assert(dnp->dn_right->dn_kind == DT_NODE_IDENT);
> >   		dt_cg_node(dnp->dn_left, dlp, drp);
> > -		dt_cg_check_notnull(dlp, drp, dnp->dn_left->dn_reg);
> > -
> >   		/*
> >   		 * If the left-hand side of PTR or DOT is a dynamic variable,
> >   		 * we expect it to be the output of a D translator.   In this
> > @@ -6340,6 +6338,8 @@ dt_cg_node(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
> >   			break;
> >   		}
> > +		dt_cg_check_notnull(dlp, drp, dnp->dn_left->dn_reg);
> > +
> >   		ctfp = dnp->dn_left->dn_ctfp;
> >   		type = ctf_type_resolve(ctfp, dnp->dn_left->dn_type);
> > diff --git a/test/unittest/translators/tst.NullInput.d b/test/unittest/translators/tst.NullInput.d
> > new file mode 100644
> > index 00000000..6d5f085b
> > --- /dev/null
> > +++ b/test/unittest/translators/tst.NullInput.d
> > @@ -0,0 +1,31 @@
> > +/*
> > + * Oracle Linux DTrace.
> > + * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
> > + * Licensed under the Universal Permissive License v 1.0 as shown at
> > + * http://oss.oracle.com/licenses/upl.
> > + */
> > +
> > +/*
> > + * ASSERTION: Translators can receive NULL as input.
> > + *
> > + * SECTION: Translators/Translator Declarations
> > + * SECTION: Translators/Translate Operator
> > + *
> > + */
> > +
> > +#pragma D option quiet
> > +
> > +struct task_struct *T;
> > +
> > +BEGIN
> > +{
> > +	T = 0;
> > +	mypr_addr = xlate < psinfo_t > (T).pr_addr;
> > +	printf("pr_addr: %p", mypr_addr);
> > +	exit(0);
> > +}
> > +
> > +ERROR
> > +{
> > +	exit(1);
> > +}
> > diff --git a/test/unittest/translators/tst.ProcModelTrans.d b/test/unittest/translators/tst.ProcModelTrans.d
> > index cf445658..7d5fff78 100644
> > --- a/test/unittest/translators/tst.ProcModelTrans.d
> > +++ b/test/unittest/translators/tst.ProcModelTrans.d
> > @@ -1,29 +1,25 @@
> >   /*
> >    * Oracle Linux DTrace.
> > - * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
> > + * Copyright (c) 2006, 2023, Oracle and/or its affiliates. All rights reserved.
> >    * Licensed under the Universal Permissive License v 1.0 as shown at
> >    * http://oss.oracle.com/licenses/upl.
> >    */
> > -/* @@xfail: dtv2 */
> >   /*
> > - * ASSERTION:
> > - * Use the translators in /usr/lib/dtrace/procfs.d
> > + * ASSERTION: Basic test for translators in /usr/lib/dtrace/procfs.d
> >    *
> > - * SECTION: Translators/ Translator Declarations
> > - * SECTION: Translators/ Translate Operator
> > + * SECTION: Translators/Translator Declarations
> > + * SECTION: Translators/Translate Operator
> >    * SECTION: Translators/Process Model Translators
> >    *
> >    */
> >   #pragma D option quiet
> > -struct task_struct *T;
> > -
> >   BEGIN
> >   {
> > -	mypr_addr = xlate < psinfo_t > (T).pr_addr;
> > -	printf("pr_addr: %d", mypr_addr);
> > +	mypr_addr = xlate < psinfo_t > (curthread).pr_addr;
> > +	printf("pr_addr: %p", mypr_addr);
> >   	exit(0);
> >   }
> 
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