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Merge branch 'modversions' (modversions fixes for powerpc from Ard)
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Merge kcrctab entry fixes from Ard Biesheuvel:
 "This is a followup to [0] 'modversions: redefine kcrctab entries as
  relative CRC pointers', but since relative CRC pointers do not work in
  modules, and are actually only needed by powerpc with
  CONFIG_RELOCATABLE=y, I have made it a Kconfig selectable feature
  instead.

  First it introduces the MODULE_REL_CRCS Kconfig symbol, and adds the
  kbuild handling of it, i.e., modpost, genksyms and kallsyms.

  Then it switches all architectures to 32-bit CRC entries in kcrctab,
  where all architectures except powerpc with CONFIG_RELOCATABLE=y use
  absolute ELF symbol references as before"

[0] http://marc.info/?l=linux-arch&m=148493613415294&w=2

* emailed patches from Ard Biesheuvel:
  module: unify absolute krctab definitions for 32-bit and 64-bit
  modversions: treat symbol CRCs as 32 bit quantities
  kbuild: modversions: add infrastructure for emitting relative CRCs
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@torvalds
torvalds committed Feb 3, 2017
2 parents 29905b5 + 4b9eee9 commit 2cb54ce
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Showing 12 changed files with 93 additions and 62 deletions.
1 change: 1 addition & 0 deletions arch/powerpc/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -484,6 +484,7 @@ config RELOCATABLE
bool "Build a relocatable kernel"
depends on (PPC64 && !COMPILE_TEST) || (FLATMEM && (44x || FSL_BOOKE))
select NONSTATIC_KERNEL
select MODULE_REL_CRCS if MODVERSIONS
help
This builds a kernel image that is capable of running at the
location the kernel is loaded at. For ppc32, there is no any
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4 changes: 0 additions & 4 deletions arch/powerpc/include/asm/module.h
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Original file line number Diff line number Diff line change
Expand Up @@ -90,9 +90,5 @@ static inline int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sec
}
#endif

#if defined(CONFIG_MODVERSIONS) && defined(CONFIG_PPC64)
#define ARCH_RELOCATES_KCRCTAB
#define reloc_start PHYSICAL_START
#endif
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_MODULE_H */
8 changes: 0 additions & 8 deletions arch/powerpc/kernel/module_64.c
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Original file line number Diff line number Diff line change
Expand Up @@ -286,14 +286,6 @@ static void dedotify_versions(struct modversion_info *vers,
for (end = (void *)vers + size; vers < end; vers++)
if (vers->name[0] == '.') {
memmove(vers->name, vers->name+1, strlen(vers->name));
#ifdef ARCH_RELOCATES_KCRCTAB
/* The TOC symbol has no CRC computed. To avoid CRC
* check failing, we must force it to the expected
* value (see CRC check in module.c).
*/
if (!strcmp(vers->name, "TOC."))
vers->crc = -(unsigned long)reloc_start;
#endif
}
}

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11 changes: 6 additions & 5 deletions include/asm-generic/export.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,18 +9,15 @@
#ifndef KSYM_ALIGN
#define KSYM_ALIGN 8
#endif
#ifndef KCRC_ALIGN
#define KCRC_ALIGN 8
#endif
#else
#define __put .long
#ifndef KSYM_ALIGN
#define KSYM_ALIGN 4
#endif
#endif
#ifndef KCRC_ALIGN
#define KCRC_ALIGN 4
#endif
#endif

#ifdef CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
#define KSYM(name) _##name
Expand Down Expand Up @@ -52,7 +49,11 @@ KSYM(__kstrtab_\name):
.section ___kcrctab\sec+\name,"a"
.balign KCRC_ALIGN
KSYM(__kcrctab_\name):
__put KSYM(__crc_\name)
#if defined(CONFIG_MODULE_REL_CRCS)
.long KSYM(__crc_\name) - .
#else
.long KSYM(__crc_\name)
#endif
.weak KSYM(__crc_\name)
.previous
#endif
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17 changes: 12 additions & 5 deletions include/linux/export.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,12 +43,19 @@ extern struct module __this_module;
#ifdef CONFIG_MODVERSIONS
/* Mark the CRC weak since genksyms apparently decides not to
* generate a checksums for some symbols */
#if defined(CONFIG_MODULE_REL_CRCS)
#define __CRC_SYMBOL(sym, sec) \
extern __visible void *__crc_##sym __attribute__((weak)); \
static const unsigned long __kcrctab_##sym \
__used \
__attribute__((section("___kcrctab" sec "+" #sym), used)) \
= (unsigned long) &__crc_##sym;
asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
" .weak " VMLINUX_SYMBOL_STR(__crc_##sym) " \n" \
" .long " VMLINUX_SYMBOL_STR(__crc_##sym) " - . \n" \
" .previous \n");
#else
#define __CRC_SYMBOL(sym, sec) \
asm(" .section \"___kcrctab" sec "+" #sym "\", \"a\" \n" \
" .weak " VMLINUX_SYMBOL_STR(__crc_##sym) " \n" \
" .long " VMLINUX_SYMBOL_STR(__crc_##sym) " \n" \
" .previous \n");
#endif
#else
#define __CRC_SYMBOL(sym, sec)
#endif
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14 changes: 7 additions & 7 deletions include/linux/module.h
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Original file line number Diff line number Diff line change
Expand Up @@ -346,7 +346,7 @@ struct module {

/* Exported symbols */
const struct kernel_symbol *syms;
const unsigned long *crcs;
const s32 *crcs;
unsigned int num_syms;

/* Kernel parameters. */
Expand All @@ -359,18 +359,18 @@ struct module {
/* GPL-only exported symbols. */
unsigned int num_gpl_syms;
const struct kernel_symbol *gpl_syms;
const unsigned long *gpl_crcs;
const s32 *gpl_crcs;

#ifdef CONFIG_UNUSED_SYMBOLS
/* unused exported symbols. */
const struct kernel_symbol *unused_syms;
const unsigned long *unused_crcs;
const s32 *unused_crcs;
unsigned int num_unused_syms;

/* GPL-only, unused exported symbols. */
unsigned int num_unused_gpl_syms;
const struct kernel_symbol *unused_gpl_syms;
const unsigned long *unused_gpl_crcs;
const s32 *unused_gpl_crcs;
#endif

#ifdef CONFIG_MODULE_SIG
Expand All @@ -382,7 +382,7 @@ struct module {

/* symbols that will be GPL-only in the near future. */
const struct kernel_symbol *gpl_future_syms;
const unsigned long *gpl_future_crcs;
const s32 *gpl_future_crcs;
unsigned int num_gpl_future_syms;

/* Exception table */
Expand Down Expand Up @@ -523,7 +523,7 @@ struct module *find_module(const char *name);

struct symsearch {
const struct kernel_symbol *start, *stop;
const unsigned long *crcs;
const s32 *crcs;
enum {
NOT_GPL_ONLY,
GPL_ONLY,
Expand All @@ -539,7 +539,7 @@ struct symsearch {
*/
const struct kernel_symbol *find_symbol(const char *name,
struct module **owner,
const unsigned long **crc,
const s32 **crc,
bool gplok,
bool warn);

Expand Down
4 changes: 4 additions & 0 deletions init/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -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
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53 changes: 25 additions & 28 deletions kernel/module.c
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Original file line number Diff line number Diff line change
Expand Up @@ -389,16 +389,16 @@ extern const struct kernel_symbol __start___ksymtab_gpl[];
extern const struct kernel_symbol __stop___ksymtab_gpl[];
extern const struct kernel_symbol __start___ksymtab_gpl_future[];
extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
extern const unsigned long __start___kcrctab[];
extern const unsigned long __start___kcrctab_gpl[];
extern const unsigned long __start___kcrctab_gpl_future[];
extern const s32 __start___kcrctab[];
extern const s32 __start___kcrctab_gpl[];
extern const s32 __start___kcrctab_gpl_future[];
#ifdef CONFIG_UNUSED_SYMBOLS
extern const struct kernel_symbol __start___ksymtab_unused[];
extern const struct kernel_symbol __stop___ksymtab_unused[];
extern const struct kernel_symbol __start___ksymtab_unused_gpl[];
extern const struct kernel_symbol __stop___ksymtab_unused_gpl[];
extern const unsigned long __start___kcrctab_unused[];
extern const unsigned long __start___kcrctab_unused_gpl[];
extern const s32 __start___kcrctab_unused[];
extern const s32 __start___kcrctab_unused_gpl[];
#endif

#ifndef CONFIG_MODVERSIONS
Expand Down Expand Up @@ -497,7 +497,7 @@ struct find_symbol_arg {

/* Output */
struct module *owner;
const unsigned long *crc;
const s32 *crc;
const struct kernel_symbol *sym;
};

Expand Down Expand Up @@ -563,7 +563,7 @@ static bool find_symbol_in_section(const struct symsearch *syms,
* (optional) module which owns it. Needs preempt disabled or module_mutex. */
const struct kernel_symbol *find_symbol(const char *name,
struct module **owner,
const unsigned long **crc,
const s32 **crc,
bool gplok,
bool warn)
{
Expand Down Expand Up @@ -1249,23 +1249,17 @@ static int try_to_force_load(struct module *mod, const char *reason)
}

#ifdef CONFIG_MODVERSIONS
/* If the arch applies (non-zero) relocations to kernel kcrctab, unapply it. */
static unsigned long maybe_relocated(unsigned long crc,
const struct module *crc_owner)

static u32 resolve_rel_crc(const s32 *crc)
{
#ifdef ARCH_RELOCATES_KCRCTAB
if (crc_owner == NULL)
return crc - (unsigned long)reloc_start;
#endif
return crc;
return *(u32 *)((void *)crc + *crc);
}

static int check_version(Elf_Shdr *sechdrs,
unsigned int versindex,
const char *symname,
struct module *mod,
const unsigned long *crc,
const struct module *crc_owner)
const s32 *crc)
{
unsigned int i, num_versions;
struct modversion_info *versions;
Expand All @@ -1283,13 +1277,19 @@ static int check_version(Elf_Shdr *sechdrs,
/ sizeof(struct modversion_info);

for (i = 0; i < num_versions; i++) {
u32 crcval;

if (strcmp(versions[i].name, symname) != 0)
continue;

if (versions[i].crc == maybe_relocated(*crc, crc_owner))
if (IS_ENABLED(CONFIG_MODULE_REL_CRCS))
crcval = resolve_rel_crc(crc);
else
crcval = *crc;
if (versions[i].crc == crcval)
return 1;
pr_debug("Found checksum %lX vs module %lX\n",
maybe_relocated(*crc, crc_owner), versions[i].crc);
pr_debug("Found checksum %X vs module %lX\n",
crcval, versions[i].crc);
goto bad_version;
}

Expand All @@ -1307,7 +1307,7 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
unsigned int versindex,
struct module *mod)
{
const unsigned long *crc;
const s32 *crc;

/*
* Since this should be found in kernel (which can't be removed), no
Expand All @@ -1321,8 +1321,7 @@ static inline int check_modstruct_version(Elf_Shdr *sechdrs,
}
preempt_enable();
return check_version(sechdrs, versindex,
VMLINUX_SYMBOL_STR(module_layout), mod, crc,
NULL);
VMLINUX_SYMBOL_STR(module_layout), mod, crc);
}

/* First part is kernel version, which we ignore if module has crcs. */
Expand All @@ -1340,8 +1339,7 @@ static inline int check_version(Elf_Shdr *sechdrs,
unsigned int versindex,
const char *symname,
struct module *mod,
const unsigned long *crc,
const struct module *crc_owner)
const s32 *crc)
{
return 1;
}
Expand All @@ -1368,7 +1366,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
{
struct module *owner;
const struct kernel_symbol *sym;
const unsigned long *crc;
const s32 *crc;
int err;

/*
Expand All @@ -1383,8 +1381,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
if (!sym)
goto unlock;

if (!check_version(info->sechdrs, info->index.vers, name, mod, crc,
owner)) {
if (!check_version(info->sechdrs, info->index.vers, name, mod, crc)) {
sym = ERR_PTR(-EINVAL);
goto getname;
}
Expand Down
2 changes: 2 additions & 0 deletions scripts/Makefile.build
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Original file line number Diff line number Diff line change
Expand Up @@ -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))

Expand Down Expand Up @@ -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))

Expand Down
19 changes: 14 additions & 5 deletions scripts/genksyms/genksyms.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);
}
}

Expand Down Expand Up @@ -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"
Expand All @@ -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"
Expand All @@ -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);
}
Expand All @@ -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':
Expand Down Expand Up @@ -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;
Expand Down
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