Author: trasz
Date: Sun Oct 22 10:32:40 2017
New Revision: 324856
URL: https://svnweb.freebsd.org/changeset/base/324856
Log:
Don't call realpath(3) from libmap rtld code. This gets rid of a few calls
to fstatat(2) at binary startup; the difference looks like this:
--- przed 2017-10-14 13:55:49.983528000 +0100
+++ po 2017-10-14 14:10:39.134343000 +0100
@@ -1,15 +1,10 @@
mmap(0x0,32768,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) =
34366173184 (0x800623000)
issetugid() = 0 (0x0)
-fstatat(AT_FDCWD,"/etc",{ mode=drwxr-xr-x
,inode=1364352,size=2560,blksize=32768 },AT_SYMLINK_NOFOLLOW) = 0 (0x0)
-fstatat(AT_FDCWD,"/etc/libmap.conf",{ mode=-rw-r--r--
,inode=1373288,size=102,blksize=32768 },AT_SYMLINK_NOFOLLOW) = 0 (0x0)
openat(AT_FDCWD,"/etc/libmap.conf",O_RDONLY|O_CLOEXEC,00) = 3 (0x3)
fstat(3,{ mode=-rw-r--r-- ,inode=1373288,size=102,blksize=32768 }) = 0 (0x0)
mmap(0x0,102,PROT_READ,MAP_PRIVATE,3,0x0) = 34366205952 (0x80062b000)
close(3) = 0 (0x0)
-fstatat(AT_FDCWD,"/usr",{ mode=drwxr-xr-x
,inode=561792,size=512,blksize=32768 },AT_SYMLINK_NOFOLLOW) = 0 (0x0)
-fstatat(AT_FDCWD,"/usr/local",{ mode=drwxr-xr-x
,inode=561800,size=512,blksize=32768 },AT_SYMLINK_NOFOLLOW) = 0 (0x0)
-fstatat(AT_FDCWD,"/usr/local/etc",{ mode=drwxr-xr-x
,inode=653279,size=1536,blksize=32768 },AT_SYMLINK_NOFOLLOW) = 0 (0x0)
-fstatat(AT_FDCWD,"/usr/local/etc/libmap.d",0x7fffffffcf50,AT_SYMLINK_NOFOLLOW)
ERR#2 'No such file or directory'
+open("/usr/local/etc/libmap.d",O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC,0165)
ERR#2 'No such file or directory'
munmap(0x80062b000,102) = 0 (0x0)
openat(AT_FDCWD,"/var/run/ld-elf.so.hints",O_RDONLY|O_CLOEXEC,00) = 3 (0x3)
read(3,"Ehnt\^A\0\0\0\M^@\0\0\0\M-2\0\0"...,128) = 128 (0x80)
Reviewed by: kib
MFC after: 2 weeks
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D12741
Modified:
head/libexec/rtld-elf/libmap.c
Modified: head/libexec/rtld-elf/libmap.c
==============================================================================
--- head/libexec/rtld-elf/libmap.c Sun Oct 22 08:47:13 2017
(r324855)
+++ head/libexec/rtld-elf/libmap.c Sun Oct 22 10:32:40 2017
(r324856)
@@ -36,6 +36,8 @@ struct lmp {
static TAILQ_HEAD(lmc_list, lmc) lmc_head = TAILQ_HEAD_INITIALIZER(lmc_head);
struct lmc {
char *path;
+ dev_t dev;
+ ino_t ino;
TAILQ_ENTRY(lmc) next;
};
@@ -99,45 +101,45 @@ lmc_parse_file(char *path)
struct lmc *p;
struct stat st;
int fd;
- char *rpath;
char *lm_map;
- rpath = realpath(path, NULL);
- if (rpath == NULL)
- return;
-
TAILQ_FOREACH(p, &lmc_head, next) {
- if (strcmp(p->path, rpath) == 0) {
- free(rpath);
+ if (strcmp(p->path, path) == 0)
return;
- }
}
- fd = open(rpath, O_RDONLY | O_CLOEXEC);
+ fd = open(path, O_RDONLY | O_CLOEXEC);
if (fd == -1) {
- dbg("lm_parse_file: open(\"%s\") failed, %s", rpath,
+ dbg("lm_parse_file: open(\"%s\") failed, %s", path,
rtld_strerror(errno));
- free(rpath);
return;
}
if (fstat(fd, &st) == -1) {
close(fd);
- dbg("lm_parse_file: fstat(\"%s\") failed, %s", rpath,
+ dbg("lm_parse_file: fstat(\"%s\") failed, %s", path,
rtld_strerror(errno));
- free(rpath);
return;
}
+
+ TAILQ_FOREACH(p, &lmc_head, next) {
+ if (p->dev == st.st_dev && p->ino == st.st_ino) {
+ close(fd);
+ return;
+ }
+ }
+
lm_map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (lm_map == (const char *)MAP_FAILED) {
close(fd);
- dbg("lm_parse_file: mmap(\"%s\") failed, %s", rpath,
+ dbg("lm_parse_file: mmap(\"%s\") failed, %s", path,
rtld_strerror(errno));
- free(rpath);
return;
}
close(fd);
p = xmalloc(sizeof(struct lmc));
- p->path = rpath;
+ p->path = xstrdup(path);
+ p->dev = st.st_dev;
+ p->ino = st.st_ino;
TAILQ_INSERT_HEAD(&lmc_head, p, next);
lmc_parse(lm_map, st.st_size);
munmap(lm_map, st.st_size);
@@ -151,26 +153,19 @@ lmc_parse_dir(char *idir)
struct lmc *p;
char conffile[MAXPATHLEN];
char *ext;
- char *rpath;
- rpath = realpath(idir, NULL);
- if (rpath == NULL)
- return;
-
TAILQ_FOREACH(p, &lmc_head, next) {
- if (strcmp(p->path, rpath) == 0) {
- free(rpath);
+ if (strcmp(p->path, idir) == 0)
return;
- }
}
d = opendir(idir);
- if (d == NULL) {
- free(rpath);
+ if (d == NULL)
return;
- }
p = xmalloc(sizeof(struct lmc));
- p->path = rpath;
+ p->path = xstrdup(idir);
+ p->dev = NODEV;
+ p->ino = 0;
TAILQ_INSERT_HEAD(&lmc_head, p, next);
while ((dp = readdir(d)) != NULL) {
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