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kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS

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My main motivation of this commit is to clean up scripts/Kbuild.include
and scripts/Makefile.build.

Currently, CONFIG_TRIM_UNUSED_KSYMS works with a tricky gimmick;
possibly exported symbols are detected by letting $(CPP) replace
EXPORT_SYMBOL* with a special string '=== __KSYM_*===', which is
post-processed by sed, and passed to fixdep. The extra preprocessing
is costly, and hacking cmd_and_fixdep is ugly.

I came up with a new way to find exported symbols; insert a dummy
symbol __ksym_marker_* to each potentially exported symbol. Those
dummy symbols are picked up by $(NM), post-processed by sed, then
appended to .*.cmd files. I collected the post-process part to a
new shell script scripts/gen_ksymdeps.sh for readability. The dummy
symbols are put into the .discard.* section so that the linker
script rips them off the final vmlinux or modules.

A nice side-effect is building with CONFIG_TRIM_UNUSED_KSYMS will
be much faster.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Masahiro Yamada 2018-11-30 10:05:26 +09:00
parent ee3e46b7ef
commit bbda5ec671
6 changed files with 55 additions and 71 deletions
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31
scripts/basic/fixdep.c
View file

@ -105,8 +105,7 @@
static void usage(void)
{
fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
fprintf(stderr, " -e insert extra dependencies given on stdin\n");
fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
exit(1);
}
@ -131,21 +130,6 @@ static void print_dep(const char *m, int slen, const char *dir)
printf(".h) \\\n");
}
static void do_extra_deps(void)
{
char buf[80];
while (fgets(buf, sizeof(buf), stdin)) {
int len = strlen(buf);
if (len < 2 || buf[len - 1] != '\n') {
fprintf(stderr, "fixdep: bad data on stdin\n");
exit(1);
}
print_dep(buf, len - 1, "include/ksym");
}
}
struct item {
struct item *next;
unsigned int len;
@ -293,7 +277,7 @@ static int is_ignored_file(const char *s, int len)
* assignments are parsed not only by make, but also by the rather simple
* parser in scripts/mod/sumversion.c.
*/
static void parse_dep_file(char *m, const char *target, int insert_extra_deps)
static void parse_dep_file(char *m, const char *target)
{
char *p;
int is_last, is_target;
@ -369,9 +353,6 @@ static void parse_dep_file(char *m, const char *target, int insert_extra_deps)
exit(1);
}
if (insert_extra_deps)
do_extra_deps();
printf("\n%s: $(deps_%s)\n\n", target, target);
printf("$(deps_%s):\n", target);
}
@ -379,13 +360,9 @@ static void parse_dep_file(char *m, const char *target, int insert_extra_deps)
int main(int argc, char *argv[])
{
const char *depfile, *target, *cmdline;
int insert_extra_deps = 0;
void *buf;
if (argc == 5 && !strcmp(argv[1], "-e")) {
insert_extra_deps = 1;
argv++;
} else if (argc != 4)
if (argc != 4)
usage();
depfile = argv[1];
@ -395,7 +372,7 @@ int main(int argc, char *argv[])
printf("cmd_%s := %s\n\n", target, cmdline);
buf = read_file(depfile);
parse_dep_file(buf, target, insert_extra_deps);
parse_dep_file(buf, target);
free(buf);
return 0;