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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2017-02-03 09:54:05 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2017-02-03 08:28:25 -0800
commit56067812d5b0e737ac2063e94a50f76b810d6ca3 (patch)
tree1627e6abc9001f0b519ed65daa86be46d52c4117 /scripts/genksyms
parent34e00accf612bc5448ae709245c2b408edf39f46 (diff)
kbuild: modversions: add infrastructure for emitting relative CRCs
This add the kbuild infrastructure that will allow architectures to emit vmlinux symbol CRCs as 32-bit offsets to another location in the kernel where the actual value is stored. This works around problems with CRCs being mistaken for relocatable symbols on kernels that self relocate at runtime (i.e., powerpc with CONFIG_RELOCATABLE=y) For the kbuild side of things, this comes down to the following: - introducing a Kconfig symbol MODULE_REL_CRCS - adding a -R switch to genksyms to instruct it to emit the CRC symbols as references into the .rodata section - making modpost distinguish such references from absolute CRC symbols by the section index (SHN_ABS) - making kallsyms disregard non-absolute symbols with a __crc_ prefix Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'scripts/genksyms')
-rw-r--r--scripts/genksyms/genksyms.c19
1 files changed, 14 insertions, 5 deletions
diff --git a/scripts/genksyms/genksyms.c b/scripts/genksyms/genksyms.c
index 06121ce524a7..c9235d8340f1 100644
--- a/scripts/genksyms/genksyms.c
+++ b/scripts/genksyms/genksyms.c
@@ -44,7 +44,7 @@ char *cur_filename, *source_file;
int in_source_file;
static int flag_debug, flag_dump_defs, flag_reference, flag_dump_types,
- flag_preserve, flag_warnings;
+ flag_preserve, flag_warnings, flag_rel_crcs;
static const char *mod_prefix = "";
static int errors;
@@ -693,7 +693,10 @@ void export_symbol(const char *name)
fputs(">\n", debugfile);
/* Used as a linker script. */
- printf("%s__crc_%s = 0x%08lx ;\n", mod_prefix, name, crc);
+ printf(!flag_rel_crcs ? "%s__crc_%s = 0x%08lx;\n" :
+ "SECTIONS { .rodata : ALIGN(4) { "
+ "%s__crc_%s = .; LONG(0x%08lx); } }\n",
+ mod_prefix, name, crc);
}
}
@@ -730,7 +733,7 @@ void error_with_pos(const char *fmt, ...)
static void genksyms_usage(void)
{
- fputs("Usage:\n" "genksyms [-adDTwqhV] > /path/to/.tmp_obj.ver\n" "\n"
+ fputs("Usage:\n" "genksyms [-adDTwqhVR] > /path/to/.tmp_obj.ver\n" "\n"
#ifdef __GNU_LIBRARY__
" -s, --symbol-prefix Select symbol prefix\n"
" -d, --debug Increment the debug level (repeatable)\n"
@@ -742,6 +745,7 @@ static void genksyms_usage(void)
" -q, --quiet Disable warnings (default)\n"
" -h, --help Print this message\n"
" -V, --version Print the release version\n"
+ " -R, --relative-crc Emit section relative symbol CRCs\n"
#else /* __GNU_LIBRARY__ */
" -s Select symbol prefix\n"
" -d Increment the debug level (repeatable)\n"
@@ -753,6 +757,7 @@ static void genksyms_usage(void)
" -q Disable warnings (default)\n"
" -h Print this message\n"
" -V Print the release version\n"
+ " -R Emit section relative symbol CRCs\n"
#endif /* __GNU_LIBRARY__ */
, stderr);
}
@@ -774,13 +779,14 @@ int main(int argc, char **argv)
{"preserve", 0, 0, 'p'},
{"version", 0, 0, 'V'},
{"help", 0, 0, 'h'},
+ {"relative-crc", 0, 0, 'R'},
{0, 0, 0, 0}
};
- while ((o = getopt_long(argc, argv, "s:dwqVDr:T:ph",
+ while ((o = getopt_long(argc, argv, "s:dwqVDr:T:phR",
&long_opts[0], NULL)) != EOF)
#else /* __GNU_LIBRARY__ */
- while ((o = getopt(argc, argv, "s:dwqVDr:T:ph")) != EOF)
+ while ((o = getopt(argc, argv, "s:dwqVDr:T:phR")) != EOF)
#endif /* __GNU_LIBRARY__ */
switch (o) {
case 's':
@@ -823,6 +829,9 @@ int main(int argc, char **argv)
case 'h':
genksyms_usage();
return 0;
+ case 'R':
+ flag_rel_crcs = 1;
+ break;
default:
genksyms_usage();
return 1;