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/*
* CDDL HEADER START
*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2012 by Delphix. All rights reserved.
*/
/*
* This file implements an audit library that can be used to force the loading
* of helper providers. The default disposition for a helper provider -- USDT
* and ustack helpers -- is to load itself from it's containing object's .init
* section. In cases where startup time is deemed critical, USDT authors can
* use the -xlazyload option to dtrace(8) to disable automatic loading (it's
* difficult to make the case for the utility of this feature for anything
* other than libc which, indeed, was the sole motivation). If a binary has
* been compiled with automatic loading disabled, this audit library may be
* used to force automatic loading:
*
* LD_AUDIT_32=/usr/lib/dtrace/libdaudit.so
* LD_AUDIT_64=/usr/lib/dtrace/64/libdaudit.so
*/
#include <link.h>
#include <stdio.h>
#include <libproc.h>
#include <strings.h>
#include <dlink.h>
typedef struct obj_list {
struct obj_list *ol_next;
char *ol_name;
uintptr_t ol_addr;
Lmid_t ol_lmid;
} obj_list_t;
static obj_list_t *list;
#pragma init(dtrace_daudit_init)
static void
dtrace_daudit_init(void)
{
dtrace_link_init();
}
/*ARGSUSED*/
uint_t
la_version(uint_t version)
{
return (LAV_CURRENT);
}
/*
* Record objects into our linked list as they're loaded.
*/
/*ARGSUSED*/
uint_t
la_objopen(Link_map *lmp, Lmid_t lmid, uintptr_t *cookie)
{
obj_list_t *node;
/*
* If we can't allocate the next node in our list, we'll try to emit a
* message, but it's possible that might fail as well.
*/
if ((node = malloc(sizeof (obj_list_t))) == NULL) {
dprintf(0, "libdaudit: failed to allocate");
return (0);
}
node->ol_next = list;
node->ol_name = strdup(lmp->l_name);
node->ol_addr = lmp->l_addr;
node->ol_lmid = lmid;
list = node;
return (0);
}
/*
* Once the link maps have reached a consistent state, process the list of
* objects that were loaded. We need to use libproc to search for the
* ___SUNW_dof symbol rather than dlsym(3C) since the symbol is not in the
* dynamic (run-time) symbol table (though it is, of course, in the symtab).
* Once we find it, we ioctl(2) it to the kernel just as we would have from
* the .init section if automatic loading were enabled.
*/
/*ARGSUSED*/
void
la_activity(uintptr_t *cookie, uint_t flags)
{
struct ps_prochandle *P;
int err, ret;
GElf_Sym sym;
if (flags != LA_ACT_CONSISTENT)
return;
while (list != NULL) {
obj_list_t *node = list;
char *name = node->ol_name;
list = node->ol_next;
P = Pgrab(getpid(), PGRAB_RDONLY, &err);
ret = Plookup_by_name(P, name, "___SUNW_dof", &sym);
Prelease(P, 0);
if (ret == 0) {
dtrace_link_dof((void *)(uintptr_t)sym.st_value,
node->ol_lmid, node->ol_name, node->ol_addr);
}
free(node->ol_name);
free(node);
}
}
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