Merge branch 'modversions' (modversions fixes for powerpc from Ard)

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

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a8ee573..db8a1ef 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -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

diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index cc12c61..5388551 100644 (file)
--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -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 */

diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index bb18071..0b0f896 100644 (file)
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -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
                }
 }
 

diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 63554e9..719db19 100644 (file)
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -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
@@ -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

diff --git a/include/linux/export.h b/include/linux/export.h
index 2a0f61f..1a1dfdb 100644 (file)
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -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

diff --git a/include/linux/module.h b/include/linux/module.h
index 7c84273..cc7cba2 100644 (file)
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -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. */
@@ -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
@@ -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 */
@@ -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,
@@ -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);
 

diff --git a/init/Kconfig b/init/Kconfig
index e1a9373..4dd8bd2 100644 (file)
--- 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/kernel/module.c b/kernel/module.c
index 38d4270..3d8f126 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -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
@@ -497,7 +497,7 @@ struct find_symbol_arg {
 
        /* Output */
        struct module *owner;
-       const unsigned long *crc;
+       const s32 *crc;
        const struct kernel_symbol *sym;
 };
 
@@ -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)
 {
@@ -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;
@@ -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;
        }
 
@@ -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
@@ -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. */
@@ -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;
 }
@@ -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;
 
        /*
@@ -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;
        }

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index eadcd4d..d883116 100644 (file)
--- 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 06121ce..c9235d8 100644 (file)
--- 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 299b92c..5d55441 100644 (file)
--- 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 29c89a6..4dedd0d 100644 (file)
--- 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);
        }