freebsd-dev/lib/libproc/proc_rtld.c
Mark Johnston 07a9c2e65d libproc: Cache ELF handles for loaded objects.
libproc previously created a new handle for each symbol lookup, which
gives rather egregious performance for DTrace's ustack() action. With
this change libproc will cache the libelf descriptor upon access, making
lookups much faster in the common case.
2016-12-06 04:19:08 +00:00

137 lines
3.8 KiB
C

/*-
* Copyright (c) 2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Rui Paulo under sponsorship from the
* FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <rtld_db.h>
#include "_libproc.h"
static void rdl2prmap(const rd_loadobj_t *, prmap_t *);
static int
map_iter(const rd_loadobj_t *lop, void *arg)
{
struct file_info *file;
struct map_info *mapping, *tmp;
struct proc_handle *phdl;
size_t i;
phdl = arg;
if (phdl->nmappings >= phdl->maparrsz) {
phdl->maparrsz *= 2;
tmp = reallocarray(phdl->mappings, phdl->maparrsz,
sizeof(*phdl->mappings));
if (tmp == NULL)
return (-1);
phdl->mappings = tmp;
}
mapping = &phdl->mappings[phdl->nmappings];
rdl2prmap(lop, &mapping->map);
if (strcmp(lop->rdl_path, phdl->execpath) == 0 &&
(lop->rdl_prot & RD_RDL_X) != 0)
phdl->exec_map = &mapping->map;
file = NULL;
if (lop->rdl_path[0] != '\0') {
/* Look for an existing mapping of the same file. */
for (i = 0; i < phdl->nmappings; i++)
if (strcmp(mapping->map.pr_mapname,
phdl->mappings[i].map.pr_mapname) == 0) {
file = phdl->mappings[i].file;
break;
}
if (file == NULL) {
file = malloc(sizeof(*file));
if (file == NULL)
return (-1);
file->elf = NULL;
file->fd = -1;
file->refs = 1;
} else
file->refs++;
}
mapping->file = file;
phdl->nmappings++;
return (0);
}
static void
rdl2prmap(const rd_loadobj_t *rdl, prmap_t *map)
{
map->pr_vaddr = rdl->rdl_saddr;
map->pr_size = rdl->rdl_eaddr - rdl->rdl_saddr;
map->pr_offset = rdl->rdl_offset;
map->pr_mflags = 0;
if (rdl->rdl_prot & RD_RDL_R)
map->pr_mflags |= MA_READ;
if (rdl->rdl_prot & RD_RDL_W)
map->pr_mflags |= MA_WRITE;
if (rdl->rdl_prot & RD_RDL_X)
map->pr_mflags |= MA_EXEC;
(void)strlcpy(map->pr_mapname, rdl->rdl_path,
sizeof(map->pr_mapname));
}
rd_agent_t *
proc_rdagent(struct proc_handle *phdl)
{
if (phdl->rdap == NULL && phdl->status != PS_UNDEAD &&
phdl->status != PS_IDLE) {
if ((phdl->rdap = rd_new(phdl)) == NULL)
return (NULL);
phdl->maparrsz = 64;
phdl->mappings = calloc(phdl->maparrsz,
sizeof(*phdl->mappings));
if (phdl->mappings == NULL)
return (phdl->rdap);
if (rd_loadobj_iter(phdl->rdap, map_iter, phdl) != RD_OK)
return (NULL);
}
return (phdl->rdap);
}
void
proc_updatesyms(struct proc_handle *phdl)
{
memset(phdl->mappings, 0, sizeof(*phdl->mappings) * phdl->maparrsz);
rd_loadobj_iter(phdl->rdap, map_iter, phdl);
}