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433 lines (387 loc) · 10.5 KB
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/*
* "Optimize" a list of dependencies as spit out by gcc -MD
* for the kernel build
* ===========================================================================
*
* Author Kai Germaschewski
* Copyright 2002 by Kai Germaschewski <kai.germaschewski@gmx.de>
*
* This software may be used and distributed according to the terms
* of the GNU General Public License, incorporated herein by reference.
*
*
* Introduction:
*
* gcc produces a very nice and correct list of dependencies which
* tells make when to remake a file.
*
* To use this list as-is however has the drawback that virtually
* every file in the kernel includes autoconf.h.
*
* If the user re-runs make *config, autoconf.h will be
* regenerated. make notices that and will rebuild every file which
* includes autoconf.h, i.e. basically all files. This is extremely
* annoying if the user just changed CONFIG_HIS_DRIVER from n to m.
*
* So we play the same trick that "mkdep" played before. We replace
* the dependency on autoconf.h by a dependency on every config
* option which is mentioned in any of the listed prequisites.
*
* kconfig populates a tree in include/config/ with an empty file
* for each config symbol and when the configuration is updated
* the files representing changed config options are touched
* which then let make pick up the changes and the files that use
* the config symbols are rebuilt.
*
* So if the user changes his CONFIG_HIS_DRIVER option, only the objects
* which depend on "include/linux/config/his/driver.h" will be rebuilt,
* so most likely only his driver ;-)
*
* The idea above dates, by the way, back to Michael E Chastain, AFAIK.
*
* So to get dependencies right, there are two issues:
* o if any of the files the compiler read changed, we need to rebuild
* o if the command line given to the compile the file changed, we
* better rebuild as well.
*
* The former is handled by using the -MD output, the later by saving
* the command line used to compile the old object and comparing it
* to the one we would now use.
*
* Again, also this idea is pretty old and has been discussed on
* kbuild-devel a long time ago. I don't have a sensibly working
* internet connection right now, so I rather don't mention names
* without double checking.
*
* This code here has been based partially based on mkdep.c, which
* says the following about its history:
*
* Copyright abandoned, Michael Chastain, <mailto:mec@shout.net>.
* This is a C version of syncdep.pl by Werner Almesberger.
*
*
* It is invoked as
*
* fixdep <depfile> <target> <cmdline>
*
* and will read the dependency file <depfile>
*
* The transformed dependency snipped is written to stdout.
*
* It first generates a line
*
* cmd_<target> = <cmdline>
*
* and then basically copies the .<target>.d file to stdout, in the
* process filtering out the dependency on autoconf.h and adding
* dependencies on include/config/my/option.h for every
* CONFIG_MY_OPTION encountered in any of the prequisites.
*
* It will also filter out all the dependencies on *.ver. We need
* to make sure that the generated version checksum are globally up
* to date before even starting the recursive build, so it's too late
* at this point anyway.
*
* The algorithm to grep for "CONFIG_..." is bit unusual, but should
* be fast ;-) We don't even try to really parse the header files, but
* merely grep, i.e. if CONFIG_FOO is mentioned in a comment, it will
* be picked up as well. It's not a problem with respect to
* correctness, since that can only give too many dependencies, thus
* we cannot miss a rebuild. Since people tend to not mention totally
* unrelated CONFIG_ options all over the place, it's not an
* efficiency problem either.
*
* (Note: it'd be easy to port over the complete mkdep state machine,
* but I don't think the added complexity is worth it)
*/
/*
* Note 2: if somebody writes HELLO_CONFIG_BOOM in a file, it will depend onto
* CONFIG_BOOM. This could seem a bug (not too hard to fix), but please do not
* fix it! Some UserModeLinux files (look at arch/um/) call CONFIG_BOOM as
* UML_CONFIG_BOOM, to avoid conflicts with /usr/include/linux/autoconf.h,
* through arch/um/include/uml-config.h; this fixdep "bug" makes sure that
* those files will have correct dependencies.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include <ctype.h>
#include <arpa/inet.h>
#define INT_CONF ntohl(0x434f4e46)
#define INT_ONFI ntohl(0x4f4e4649)
#define INT_NFIG ntohl(0x4e464947)
#define INT_FIG_ ntohl(0x4649475f)
char *target;
char *depfile;
char *cmdline;
static void usage(void)
{
fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
exit(1);
}
/*
* Print out the commandline prefixed with cmd_<target filename> :=
*/
static void print_cmdline(void)
{
printf("cmd_%s := %s\n\n", target, cmdline);
}
struct item {
struct item *next;
unsigned int len;
unsigned int hash;
char name[0];
};
#define HASHSZ 256
static struct item *hashtab[HASHSZ];
static unsigned int strhash(const char *str, unsigned int sz)
{
/* fnv32 hash */
unsigned int i, hash = 2166136261U;
for (i = 0; i < sz; i++)
hash = (hash ^ str[i]) * 0x01000193;
return hash;
}
/*
* Lookup a value in the configuration string.
*/
static int is_defined_config(const char *name, int len, unsigned int hash)
{
struct item *aux;
for (aux = hashtab[hash % HASHSZ]; aux; aux = aux->next) {
if (aux->hash == hash && aux->len == len &&
memcmp(aux->name, name, len) == 0)
return 1;
}
return 0;
}
/*
* Add a new value to the configuration string.
*/
static void define_config(const char *name, int len, unsigned int hash)
{
struct item *aux = malloc(sizeof(*aux) + len);
if (!aux) {
perror("fixdep:malloc");
exit(1);
}
memcpy(aux->name, name, len);
aux->len = len;
aux->hash = hash;
aux->next = hashtab[hash % HASHSZ];
hashtab[hash % HASHSZ] = aux;
}
/*
* Clear the set of configuration strings.
*/
static void clear_config(void)
{
struct item *aux, *next;
unsigned int i;
for (i = 0; i < HASHSZ; i++) {
for (aux = hashtab[i]; aux; aux = next) {
next = aux->next;
free(aux);
}
hashtab[i] = NULL;
}
}
/*
* Record the use of a CONFIG_* word.
*/
static void use_config(const char *m, int slen)
{
unsigned int hash = strhash(m, slen);
int c, i;
if (is_defined_config(m, slen, hash))
return;
define_config(m, slen, hash);
printf(" $(wildcard include/config/");
for (i = 0; i < slen; i++) {
c = m[i];
if (c == '_')
c = '/';
else
c = tolower(c);
putchar(c);
}
printf(".h) \\\n");
}
static void parse_config_file(const char *map, size_t len)
{
const int *end = (const int *) (map + len);
/* start at +1, so that p can never be < map */
const int *m = (const int *) map + 1;
const char *p, *q;
for (; m < end; m++) {
if (*m == INT_CONF) { p = (char *) m ; goto conf; }
if (*m == INT_ONFI) { p = (char *) m-1; goto conf; }
if (*m == INT_NFIG) { p = (char *) m-2; goto conf; }
if (*m == INT_FIG_) { p = (char *) m-3; goto conf; }
continue;
conf:
if (p > map + len - 7)
continue;
if (memcmp(p, "CONFIG_", 7))
continue;
for (q = p + 7; q < map + len; q++) {
if (!(isalnum(*q) || *q == '_'))
goto found;
}
continue;
found:
if (!memcmp(q - 7, "_MODULE", 7))
q -= 7;
if( (q-p-7) < 0 )
continue;
use_config(p+7, q-p-7);
}
}
/* test is s ends in sub */
static int strrcmp(char *s, char *sub)
{
int slen = strlen(s);
int sublen = strlen(sub);
if (sublen > slen)
return 1;
return memcmp(s + slen - sublen, sub, sublen);
}
static void do_config_file(const char *filename)
{
struct stat st;
int fd;
void *map;
fd = open(filename, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "fixdep: error opening config file: ");
perror(filename);
exit(2);
}
fstat(fd, &st);
if (st.st_size == 0) {
close(fd);
return;
}
map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if ((long) map == -1) {
perror("fixdep: mmap");
close(fd);
return;
}
parse_config_file(map, st.st_size);
munmap(map, st.st_size);
close(fd);
}
/*
* Important: The below generated source_foo.o and deps_foo.o variable
* assignments are parsed not only by make, but also by the rather simple
* parser in scripts/mod/sumversion.c.
*/
static void parse_dep_file(void *map, size_t len)
{
char *m = map;
char *end = m + len;
char *p;
char s[PATH_MAX];
int first;
p = strchr(m, ':');
if (!p) {
fprintf(stderr, "fixdep: parse error\n");
exit(1);
}
memcpy(s, m, p-m); s[p-m] = 0;
m = p+1;
clear_config();
first = 1;
while (m < end) {
while (m < end && (*m == ' ' || *m == '\\' || *m == '\n'))
m++;
p = m;
while (p < end && *p != ' ') p++;
if (p == end) {
do p--; while (!isalnum(*p));
p++;
}
memcpy(s, m, p-m); s[p-m] = 0;
if (strrcmp(s, "include/generated/autoconf.h") &&
strrcmp(s, "arch/um/include/uml-config.h") &&
strrcmp(s, "include/linux/kconfig.h") &&
strrcmp(s, ".ver")) {
/*
* Do not list the source file as dependency, so that
* kbuild is not confused if a .c file is rewritten
* into .S or vice versa. Storing it in source_* is
* needed for modpost to compute srcversions.
*/
if (first) {
printf("source_%s := %s\n\n", target, s);
printf("deps_%s := \\\n", target);
} else
printf(" %s \\\n", s);
do_config_file(s);
}
first = 0;
m = p + 1;
}
printf("\n%s: $(deps_%s)\n\n", target, target);
printf("$(deps_%s):\n", target);
}
static void print_deps(void)
{
struct stat st;
int fd;
void *map;
fd = open(depfile, O_RDONLY);
if (fd < 0) {
fprintf(stderr, "fixdep: error opening depfile: ");
perror(depfile);
exit(2);
}
if (fstat(fd, &st) < 0) {
fprintf(stderr, "fixdep: error fstat'ing depfile: ");
perror(depfile);
exit(2);
}
if (st.st_size == 0) {
fprintf(stderr,"fixdep: %s is empty\n",depfile);
close(fd);
return;
}
map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if ((long) map == -1) {
perror("fixdep: mmap");
close(fd);
return;
}
parse_dep_file(map, st.st_size);
munmap(map, st.st_size);
close(fd);
}
static void traps(void)
{
static char test[] __attribute__((aligned(sizeof(int)))) = "CONF";
int *p = (int *)test;
if (*p != INT_CONF) {
fprintf(stderr, "fixdep: sizeof(int) != 4 or wrong endianess? %#x\n",
*p);
exit(2);
}
}
int main(int argc, char *argv[])
{
traps();
if (argc != 4)
usage();
depfile = argv[1];
target = argv[2];
cmdline = argv[3];
print_cmdline();
print_deps();
return 0;
}
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