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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
parent34e00accf612bc5448ae709245c2b408edf39f46 (diff)
downloadlinux-stericsson-56067812d5b0e737ac2063e94a50f76b810d6ca3.tar.gz
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>
-rw-r--r--init/Kconfig4
-rw-r--r--scripts/Makefile.build2
-rw-r--r--scripts/genksyms/genksyms.c19
-rw-r--r--scripts/kallsyms.c12
-rw-r--r--scripts/mod/modpost.c10
5 files changed, 42 insertions, 5 deletions
diff --git a/init/Kconfig b/init/Kconfig
index e1a937348a3e..4dd8bd232a1d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1987,6 +1987,10 @@ config MODVERSIONS
make them incompatible with the kernel you are running. If
unsure, say N.
+config MODULE_REL_CRCS
+ bool
+ depends on MODVERSIONS
+
config MODULE_SRCVERSION_ALL
bool "Source checksum for all modules"
help
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index eadcd4d359d9..d883116ebaa4 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -164,6 +164,7 @@ cmd_gensymtypes_c = \
$(CPP) -D__GENKSYMS__ $(c_flags) $< | \
$(GENKSYMS) $(if $(1), -T $(2)) \
$(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \
+ $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
$(if $(KBUILD_PRESERVE),-p) \
-r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
@@ -337,6 +338,7 @@ cmd_gensymtypes_S = \
$(CPP) -D__GENKSYMS__ $(c_flags) -xc - | \
$(GENKSYMS) $(if $(1), -T $(2)) \
$(patsubst y,-s _,$(CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX)) \
+ $(patsubst y,-R,$(CONFIG_MODULE_REL_CRCS)) \
$(if $(KBUILD_PRESERVE),-p) \
-r $(firstword $(wildcard $(2:.symtypes=.symref) /dev/null))
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;
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 299b92ca1ae0..5d554419170b 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -219,6 +219,10 @@ static int symbol_valid(struct sym_entry *s)
"_SDA2_BASE_", /* ppc */
NULL };
+ static char *special_prefixes[] = {
+ "__crc_", /* modversions */
+ NULL };
+
static char *special_suffixes[] = {
"_veneer", /* arm */
"_from_arm", /* arm */
@@ -259,6 +263,14 @@ static int symbol_valid(struct sym_entry *s)
if (strcmp(sym_name, special_symbols[i]) == 0)
return 0;
+ for (i = 0; special_prefixes[i]; i++) {
+ int l = strlen(special_prefixes[i]);
+
+ if (l <= strlen(sym_name) &&
+ strncmp(sym_name, special_prefixes[i], l) == 0)
+ return 0;
+ }
+
for (i = 0; special_suffixes[i]; i++) {
int l = strlen(sym_name) - strlen(special_suffixes[i]);
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 29c89a6bad3d..4dedd0d3d3a7 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -621,6 +621,16 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
is_crc = true;
crc = (unsigned int) sym->st_value;
+ if (sym->st_shndx != SHN_UNDEF && sym->st_shndx != SHN_ABS) {
+ unsigned int *crcp;
+
+ /* symbol points to the CRC in the ELF object */
+ crcp = (void *)info->hdr + sym->st_value +
+ info->sechdrs[sym->st_shndx].sh_offset -
+ (info->hdr->e_type != ET_REL ?
+ info->sechdrs[sym->st_shndx].sh_addr : 0);
+ crc = *crcp;
+ }
sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
export);
}