upstream/opnsense-src
1
0
Fork 0
mirror of https://github.com/opnsense/src.git synced 2026-06-11 01:30:30 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

libdtrace: Permit taking the address of an identifier without type info

Browse source 
Symbols defined using assembler directives lack type info, but in this
case one ought to be able to cast a pointer to the symbol and
dereference the pointer to get a value.  Without this change, D
disallows this trick since it requires all identifiers to have a type.

Relax the rules slightly and allow an identifier to have type "void" if
we know we're just taking its address.

As a result, the following dtrace invocation works:

  dtrace -n 'tick-1s {printf("%d", *(int *)&`ticks);}'

In particular, since commit b2b974f7ef ("clock: Simplify subr_ticks
and rename"), "ticks" does not have any type info associated with it, so
its value couldn't be printed.  This trick provides a workaround and is
probably generally useful.

Add a regression test which exercises this functionality.

PR:		287752
Reviewed by:	avg
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D51417
This commit is contained in:
Mark Johnston 2025-07-21 13:34:30 +00:00
parent 654dea5967
commit dabde7d976
4 changed files with 78 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

54
cddl/contrib/opensolaris/cmd/dtrace/test/tst/common/profile-n/tst.ticks.d Normal file
View file

@ -0,0 +1,54 @@
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2025 Mark Johnston <markj@FreeBSD.org>
*/
/*
* For 10s, verify that the value of `ticks goes up by `hz each second.
*/
#pragma D option quiet
BEGIN
{
i = 0;
}
tick-1s
{
if (i == 0) {
t = *(int *)&`ticks;
i++;
} else {
u = *(int *)&`ticks;
if (u - t != `hz) {
printf("ticks: %d, expected %d\n", u - t, `hz);
exit(1);
}
t = u;
i++;
if (i == 10) {
exit(0);
}
}
}

25
cddl/contrib/opensolaris/lib/libdtrace/common/dt_parser.c
View file

@ -1918,6 +1918,14 @@ dt_node_op1(int op, dt_node_t *cp)
return (cp);
}
/*
* When applying the addressof operator to an identifier, it's okay if
* we can't find type information for the identifier, so flag the node
* to ensure that we don't raise an error.
*/
if (op == DT_TOK_ADDROF && cp->dn_kind == DT_NODE_IDENT)
cp->dn_flags |= DT_NF_IDENTADDR;
dnp = dt_node_alloc(DT_NODE_OP1);
assert(op <= USHRT_MAX);
dnp->dn_op = (ushort_t)op;
@ -2786,10 +2794,21 @@ dt_xcook_ident(dt_node_t *dnp, dt_idhash_t *dhp, uint_t idkind, int create)
dt_module_modelname(dtp->dt_ddefs));
}
xyerror(D_SYM_NOTYPES,
/*
* If we're taking the address of an identifier that
* doesn't have type info, try to make it a void *.
* This lets us use identifiers that are defined in
* assembly and don't have type information.
*/
if ((dnp->dn_flags & DT_NF_IDENTADDR) == 0 ||
dtrace_lookup_by_type(dtp, DTRACE_OBJ_CDEFS,
"void", &dtt) != 0) {
xyerror(D_SYM_NOTYPES,
"no symbolic type information is available for "
"%s%s%s: %s\n", dts.dts_object, mark, dts.dts_name,
dtrace_errmsg(dtp, dtrace_errno(dtp)));
"%s%s%s: %s\n", dts.dts_object, mark,
dts.dts_name,
dtrace_errmsg(dtp, dtrace_errno(dtp)));
}
}
idp = dt_ident_create(name, DT_IDENT_SYMBOL, 0, 0,

1
cddl/contrib/opensolaris/lib/libdtrace/common/dt_parser.h
View file

@ -182,6 +182,7 @@ typedef struct dt_node {
#define DT_NF_WRITABLE 0x10 /* node is writable (can be modified) */
#define DT_NF_BITFIELD 0x20 /* node is an integer bitfield */
#define DT_NF_USERLAND 0x40 /* data is a userland address */
#define DT_NF_IDENTADDR 0x80 /* node is an identifier address */
#define DT_TYPE_NAMELEN 128 /* reasonable size for ctf_type_name() */

1
cddl/usr.sbin/dtrace/tests/common/profile-n/Makefile
View file

@ -37,6 +37,7 @@ ${PACKAGE}FILES= \
tst.profileusec.d \
tst.profileusec.d.out \
tst.sym.ksh \
tst.ticks.d \
tst.ufunc.ksh \
tst.ufuncsort.ksh \
tst.ufuncsort.ksh.out \