[DTrace-devel] [PATCH 7/8] Add support for strstr() subroutine

[Kris Van Hees]

On Wed, Sep 29, 2021 at 11:13:40AM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>

Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>

... and added to my staging dev branch.  I did add the .type and .size
markers to the strchr.S file.

> ---
>  libdtrace/dt_cg.c                | 91 +++++++++++++++++++++++++++++++-
>  test/unittest/dif/strstr.d       |  1 -
>  test/unittest/funcs/tst.strstr.d |  5 +-
>  3 files changed, 93 insertions(+), 4 deletions(-)
> 
> diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
> index 5b6ec4a9..6aac64ae 100644
> --- a/libdtrace/dt_cg.c
> +++ b/libdtrace/dt_cg.c
> @@ -3492,6 +3492,95 @@ dt_cg_subr_strjoin(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>  	TRACE_REGSET("    subr-strjoin:End  ");
>  }
>  
> +static void
> +dt_cg_subr_strstr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
> +{
> +	dt_node_t	*s = dnp->dn_args;
> +	dt_node_t	*t = s->dn_list;
> +	dt_ident_t	*idp;
> +	uint64_t	off1, off2;
> +	uint_t		Ldone = dt_irlist_label(dlp);
> +
> +	TRACE_REGSET("    subr-strstr:Begin");
> +
> +	/* get args */
> +	dt_cg_node(s, dlp, drp);
> +	dt_cg_check_notnull(dlp, drp, s->dn_reg);
> +	dt_cg_node(t, dlp, drp);
> +	dt_cg_check_notnull(dlp, drp, t->dn_reg);
> +
> +	/* call dt_index() call */
> +	if (dt_regset_xalloc_args(drp) == -1)
> +		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
> +
> +	emit(dlp,  BPF_MOV_REG(BPF_REG_1, s->dn_reg));
> +	emit(dlp,  BPF_MOV_REG(BPF_REG_2, t->dn_reg));
> +	dt_regset_free(drp, t->dn_reg);
> +	if (t->dn_tstring)
> +		dt_cg_tstring_free(yypcb, t);
> +	emit(dlp,  BPF_MOV_IMM(BPF_REG_3, 0));
> +
> +	off1 = dt_cg_tstring_xalloc(yypcb);
> +	off2 = dt_cg_tstring_xalloc(yypcb);
> +
> +	emit(dlp,  BPF_LOAD(BPF_DW, BPF_REG_4, BPF_REG_FP, DT_STK_DCTX));
> +	emit(dlp,  BPF_LOAD(BPF_DW, BPF_REG_4, BPF_REG_4, DCTX_MEM));
> +	emit(dlp,  BPF_MOV_REG(BPF_REG_5, BPF_REG_4));
> +	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, off1));
> +	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, BPF_REG_5, off2));
> +
> +	dt_regset_xalloc(drp, BPF_REG_0);
> +	idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_index");
> +	assert(idp != NULL);
> +	emite(dlp, BPF_CALL_FUNC(idp->di_id), idp);
> +	dt_regset_free_args(drp);
> +
> +	dt_cg_tstring_xfree(yypcb, off1);
> +	dt_cg_tstring_xfree(yypcb, off2);
> +
> +	/*
> +	 * Allocate the result register and associate it with a temporary
> +	 * string slot.
> +	 */
> +	dnp->dn_reg = dt_regset_alloc(drp);
> +	if (dnp->dn_reg == -1)
> +		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
> +	dt_cg_tstring_alloc(yypcb, dnp);
> +
> +	/* account for not finding the substring */
> +
> +	emit(dlp,  BPF_MOV_IMM(dnp->dn_reg, 0));
> +	emit(dlp,  BPF_BRANCH_IMM(BPF_JSLT, BPF_REG_0, 0, Ldone));
> +
> +	emit(dlp,  BPF_LOAD(BPF_DW, dnp->dn_reg, BPF_REG_FP, DT_STK_DCTX));
> +	emit(dlp,  BPF_LOAD(BPF_DW, dnp->dn_reg, dnp->dn_reg, DCTX_MEM));
> +	emit(dlp,  BPF_ALU64_IMM(BPF_ADD, dnp->dn_reg, dnp->dn_tstring->dn_value));
> +
> +	/* call dt_substr() using the index we already found */
> +
> +	if (dt_regset_xalloc_args(drp) == -1)
> +		longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
> +
> +	emit(dlp, BPF_MOV_REG(BPF_REG_1, dnp->dn_reg));
> +	emit(dlp, BPF_MOV_REG(BPF_REG_2, s->dn_reg));
> +	dt_regset_free(drp, s->dn_reg);
> +	if (s->dn_tstring)
> +		dt_cg_tstring_free(yypcb, s);
> +	emit(dlp, BPF_MOV_REG(BPF_REG_3, BPF_REG_0));
> +	emit(dlp, BPF_MOV_IMM(BPF_REG_5, 2));
> +	idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_substr");
> +	assert(idp != NULL);
> +	emite(dlp,  BPF_CALL_FUNC(idp->di_id), idp);
> +	dt_regset_free_args(drp);
> +
> +	emitl(dlp, Ldone,
> +		   BPF_NOP());
> +
> +	dt_regset_free(drp, BPF_REG_0);
> +
> +	TRACE_REGSET("    subr-strstr:End  ");
> +}
> +
>  static void
>  dt_cg_subr_substr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
>  {
> @@ -3606,7 +3695,7 @@ static dt_cg_subr_f *_dt_cg_subr[DIF_SUBR_MAX + 1] = {
>  	[DIF_SUBR_CLEANPATH]		= NULL,
>  	[DIF_SUBR_STRCHR]		= &dt_cg_subr_strchr,
>  	[DIF_SUBR_STRRCHR]		= &dt_cg_subr_strrchr,
> -	[DIF_SUBR_STRSTR]		= NULL,
> +	[DIF_SUBR_STRSTR]		= &dt_cg_subr_strstr,
>  	[DIF_SUBR_STRTOK]		= NULL,
>  	[DIF_SUBR_SUBSTR]		= &dt_cg_subr_substr,
>  	[DIF_SUBR_INDEX]		= &dt_cg_subr_index,
> diff --git a/test/unittest/dif/strstr.d b/test/unittest/dif/strstr.d
> index 8d1349e4..d5be34aa 100644
> --- a/test/unittest/dif/strstr.d
> +++ b/test/unittest/dif/strstr.d
> @@ -1,4 +1,3 @@
> -/* @@xfail: dtv2 */
>  BEGIN
>  {
>  	trace(strstr(probename, "GIN"));
> diff --git a/test/unittest/funcs/tst.strstr.d b/test/unittest/funcs/tst.strstr.d
> index 279e3ae6..de96cd28 100644
> --- a/test/unittest/funcs/tst.strstr.d
> +++ b/test/unittest/funcs/tst.strstr.d
> @@ -1,12 +1,13 @@
>  /*
>   * Oracle Linux DTrace.
> - * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
> + * Copyright (c) 2006, 2021, 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 */
>  
> +/* limit the string size to relieve pressure on the BPF verifier */
>  #pragma D option quiet
> +#pragma D option strsize=184
>  
>  BEGIN
>  {
> -- 
> 2.18.4
> 
> 
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