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libelf: Use a red-black tree to manage the section list.

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The tree is indexed by section number.  This speeds up elf_getscn()
and its callers, which previously had to traverse a linked list. In
particular, since .shstrtab is often the last section in a file,
elf_strptr() would have to traverse the entire list.

PR:		234949
Reviewed by:	emaste
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D20443
This commit is contained in:
Mark Johnston 2019-06-04 18:26:29 +00:00
parent 9ccaf2215a
commit 8c953901bf
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=348652
7 changed files with 41 additions and 19 deletions
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8
contrib/elftoolchain/libelf/_libelf.h
View File

@ -30,6 +30,7 @@
#define __LIBELF_H_
#include <sys/queue.h>
#include <sys/tree.h>
#include "_libelf_config.h"
@ -80,6 +81,9 @@ extern struct _libelf_globals _libelf;
#define LIBELF_F_SHDRS_LOADED 0x200000U /* whether all shdrs were read in */
#define LIBELF_F_SPECIAL_FILE 0x400000U /* non-regular file */
RB_HEAD(scntree, _Elf_Scn);
RB_PROTOTYPE(scntree, _Elf_Scn, e_scn, elfscn_cmp);
struct _Elf {
int e_activations; /* activation count */
unsigned int e_byteorder; /* ELFDATA* */
@ -122,7 +126,7 @@ struct _Elf {
Elf32_Phdr *e_phdr32;
Elf64_Phdr *e_phdr64;
} e_phdr;
STAILQ_HEAD(, _Elf_Scn) e_scn; /* section list */
struct scntree e_scn; /* sections */
size_t e_nphdr; /* number of Phdr entries */
size_t e_nscn; /* number of sections */
size_t e_strndx; /* string table section index */
@ -147,7 +151,7 @@ struct _Elf_Scn {
} s_shdr;
STAILQ_HEAD(, _Libelf_Data) s_data; /* translated data */
STAILQ_HEAD(, _Libelf_Data) s_rawdata; /* raw data */
STAILQ_ENTRY(_Elf_Scn) s_next;
RB_ENTRY(_Elf_Scn) s_tree;
struct _Elf *s_elf; /* parent ELF descriptor */
unsigned int s_flags; /* flags for the section as a whole */
size_t s_ndx; /* index# for this section */

3
contrib/elftoolchain/libelf/elf_end.c
View File

@ -66,8 +66,7 @@ elf_end(Elf *e)
/*
* Reclaim all section descriptors.
*/
STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next,
tscn)
RB_FOREACH_SAFE(scn, scntree, &e->e_u.e_elf.e_scn, tscn)
scn = _libelf_release_scn(scn);
break;
case ELF_K_NUM:

31
contrib/elftoolchain/libelf/elf_scn.c
View File

@ -38,6 +38,19 @@
ELFTC_VCSID("$Id: elf_scn.c 3632 2018-10-10 21:12:43Z jkoshy $");
static int
elfscn_cmp(struct _Elf_Scn *s1, struct _Elf_Scn *s2)
{
if (s1->s_ndx < s2->s_ndx)
return (-1);
if (s1->s_ndx > s2->s_ndx)
return (1);
return (0);
}
RB_GENERATE(scntree, _Elf_Scn, s_tree, elfscn_cmp);
/*
* Load an ELF section table and create a list of Elf_Scn structures.
*/
@ -95,9 +108,9 @@ _libelf_load_section_headers(Elf *e, void *ehdr)
*/
i = 0;
if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) ==
STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next));
if (!RB_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(RB_MIN(scntree, &e->e_u.e_elf.e_scn) ==
RB_MAX(scntree, &e->e_u.e_elf.e_scn));
i = 1;
src += fsz;
@ -148,10 +161,16 @@ elf_getscn(Elf *e, size_t index)
_libelf_load_section_headers(e, ehdr) == 0)
return (NULL);
STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
for (s = RB_ROOT(&e->e_u.e_elf.e_scn); s != NULL;) {
if (s->s_ndx == index)
return (s);
if (s->s_ndx < index)
s = RB_RIGHT(s, s_tree);
else
s = RB_LEFT(s, s_tree);
}
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
@ -201,7 +220,7 @@ elf_newscn(Elf *e)
_libelf_load_section_headers(e, ehdr) == 0)
return (NULL);
if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
if (RB_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(e->e_u.e_elf.e_nscn == 0);
if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) ==
NULL)
@ -231,5 +250,5 @@ elf_nextscn(Elf *e, Elf_Scn *s)
}
return (s == NULL ? elf_getscn(e, (size_t) 1) :
STAILQ_NEXT(s, s_next));
RB_NEXT(scntree, &e->e_u.e_elf.e_scn, s));
}

6
contrib/elftoolchain/libelf/elf_update.c
View File

@ -452,7 +452,7 @@ _libelf_resync_sections(Elf *e, off_t rc, struct _Elf_Extent_List *extents)
* Make a pass through sections, computing the extent of each
* section.
*/
STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next) {
RB_FOREACH(s, scntree, &e->e_u.e_elf.e_scn) {
if (ec == ELFCLASS32)
sh_type = s->s_shdr.s_shdr32.sh_type;
else
@ -980,7 +980,7 @@ _libelf_write_shdr(Elf *e, unsigned char *nf, struct _Elf_Extent *ex)
fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
STAILQ_FOREACH(scn, &e->e_u.e_elf.e_scn, s_next) {
RB_FOREACH(scn, scntree, &e->e_u.e_elf.e_scn) {
if (ec == ELFCLASS32)
src.d_buf = &scn->s_shdr.s_shdr32;
else
@ -1142,7 +1142,7 @@ _libelf_write_elf(Elf *e, off_t newsize, struct _Elf_Extent_List *extents)
e->e_flags &= ~ELF_F_DIRTY;
STAILQ_FOREACH_SAFE(scn, &e->e_u.e_elf.e_scn, s_next, tscn)
RB_FOREACH_SAFE(scn, scntree, &e->e_u.e_elf.e_scn, tscn)
_libelf_release_scn(scn);
if (e->e_class == ELFCLASS32) {

8
contrib/elftoolchain/libelf/libelf_allocate.c
View File

@ -76,7 +76,7 @@ _libelf_init_elf(Elf *e, Elf_Kind kind)
switch (kind) {
case ELF_K_ELF:
STAILQ_INIT(&e->e_u.e_elf.e_scn);
RB_INIT(&e->e_u.e_elf.e_scn);
break;
default:
break;
@ -111,7 +111,7 @@ _libelf_release_elf(Elf *e)
break;
}
assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
assert(RB_EMPTY(&e->e_u.e_elf.e_scn));
if (e->e_flags & LIBELF_F_AR_HEADER) {
arh = e->e_hdr.e_arhdr;
@ -174,7 +174,7 @@ _libelf_allocate_scn(Elf *e, size_t ndx)
STAILQ_INIT(&s->s_data);
STAILQ_INIT(&s->s_rawdata);
STAILQ_INSERT_TAIL(&e->e_u.e_elf.e_scn, s, s_next);
RB_INSERT(scntree, &e->e_u.e_elf.e_scn, s);
return (s);
}
@ -202,7 +202,7 @@ _libelf_release_scn(Elf_Scn *s)
assert(e != NULL);
STAILQ_REMOVE(&e->e_u.e_elf.e_scn, s, _Elf_Scn, s_next);
RB_REMOVE(scntree, &e->e_u.e_elf.e_scn, s);
free(s);

2
contrib/elftoolchain/libelf/libelf_ehdr.c
View File

@ -46,7 +46,7 @@ _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
uint32_t shtype;
_libelf_translator_function *xlator;
assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
assert(RB_EMPTY(&e->e_u.e_elf.e_scn));
fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1);
assert(fsz > 0);

2
contrib/elftoolchain/libelf/libelf_extended.c
View File

@ -39,7 +39,7 @@ _libelf_getscn0(Elf *e)
{
Elf_Scn *s;
if ((s = STAILQ_FIRST(&e->e_u.e_elf.e_scn)) != NULL)
if ((s = RB_MIN(scntree, &e->e_u.e_elf.e_scn)) != NULL)
return (s);
return (_libelf_allocate_scn(e, (size_t) SHN_UNDEF));