129 lines
3.2 KiB
C
129 lines
3.2 KiB
C
/*
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* CDDL HEADER START
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*
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* This file and its contents are supplied under the terms of the
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* Common Development and Distribution License ("CDDL"), version 1.0.
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* You may only use this file in accordance with the terms of version
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* 1.0 of the CDDL.
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*
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* A full copy of the text of the CDDL should have accompanied this
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* source. A copy of the CDDL is also available via the Internet at
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* http://www.illumos.org/license/CDDL.
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2012 by Delphix. All rights reserved.
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*/
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/*
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* This file implements an audit library that can be used to force the loading
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* of helper providers. The default disposition for a helper provider -- USDT
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* and ustack helpers -- is to load itself from it's containing object's .init
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* section. In cases where startup time is deemed critical, USDT authors can
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* use the -xlazyload option to dtrace(1M) to disable automatic loading (it's
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* difficult to make the case for the utility of this feature for anything
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* other than libc which, indeed, was the sole motivation). If a binary has
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* been compiled with automatic loading disabled, this audit library may be
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* used to force automatic loading:
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*
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* LD_AUDIT_32=/usr/lib/dtrace/libdaudit.so
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* LD_AUDIT_64=/usr/lib/dtrace/64/libdaudit.so
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*/
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#include <link.h>
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#include <stdio.h>
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#include <libproc.h>
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#include <strings.h>
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#include <dlink.h>
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typedef struct obj_list {
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struct obj_list *ol_next;
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char *ol_name;
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uintptr_t ol_addr;
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Lmid_t ol_lmid;
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} obj_list_t;
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static obj_list_t *list;
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#pragma init(dtrace_daudit_init)
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static void
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dtrace_daudit_init(void)
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{
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dtrace_link_init();
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}
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/*ARGSUSED*/
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uint_t
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la_version(uint_t version)
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{
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return (LAV_CURRENT);
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}
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/*
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* Record objects into our linked list as they're loaded.
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*/
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/*ARGSUSED*/
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uint_t
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la_objopen(Link_map *lmp, Lmid_t lmid, uintptr_t *cookie)
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{
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obj_list_t *node;
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/*
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* If we can't allocate the next node in our list, we'll try to emit a
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* message, but it's possible that might fail as well.
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*/
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if ((node = malloc(sizeof (obj_list_t))) == NULL) {
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dprintf(0, "libdaudit: failed to allocate");
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return (0);
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}
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node->ol_next = list;
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node->ol_name = strdup(lmp->l_name);
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node->ol_addr = lmp->l_addr;
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node->ol_lmid = lmid;
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list = node;
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return (0);
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}
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/*
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* Once the link maps have reached a consistent state, process the list of
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* objects that were loaded. We need to use libproc to search for the
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* ___SUNW_dof symbol rather than dlsym(3C) since the symbol is not in the
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* dynamic (run-time) symbol table (though it is, of course, in the symtab).
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* Once we find it, we ioctl(2) it to the kernel just as we would have from
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* the .init section if automatic loading were enabled.
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*/
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/*ARGSUSED*/
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void
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la_activity(uintptr_t *cookie, uint_t flags)
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{
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struct ps_prochandle *P;
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int err, ret;
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GElf_Sym sym;
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if (flags != LA_ACT_CONSISTENT)
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return;
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while (list != NULL) {
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obj_list_t *node = list;
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char *name = node->ol_name;
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list = node->ol_next;
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P = Pgrab(getpid(), PGRAB_RDONLY, &err);
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ret = Plookup_by_name(P, name, "___SUNW_dof", &sym);
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Prelease(P, 0);
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if (ret == 0) {
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dtrace_link_dof((void *)(uintptr_t)sym.st_value,
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node->ol_lmid, node->ol_name, node->ol_addr);
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}
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free(node->ol_name);
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free(node);
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}
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}
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