forked from Minki/linux
module: simplify load_module.
Linus' recent catch of stack overflow in load_module lead me to look at the code. A couple of helpers to get a section address and get objects from a section can help clean things up a little. (And in case you're wondering, the stack size also dropped from 328 to 284 bytes). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
parent
2515ddc6db
commit
5e458cc0f4
@ -277,7 +277,7 @@ struct module
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/* Exception table */
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unsigned int num_exentries;
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const struct exception_table_entry *extable;
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struct exception_table_entry *extable;
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/* Startup function. */
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int (*init)(void);
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235
kernel/module.c
235
kernel/module.c
@ -132,6 +132,29 @@ static unsigned int find_sec(Elf_Ehdr *hdr,
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return 0;
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}
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/* Find a module section, or NULL. */
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static void *section_addr(Elf_Ehdr *hdr, Elf_Shdr *shdrs,
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const char *secstrings, const char *name)
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{
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/* Section 0 has sh_addr 0. */
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return (void *)shdrs[find_sec(hdr, shdrs, secstrings, name)].sh_addr;
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}
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/* Find a module section, or NULL. Fill in number of "objects" in section. */
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static void *section_objs(Elf_Ehdr *hdr,
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Elf_Shdr *sechdrs,
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const char *secstrings,
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const char *name,
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size_t object_size,
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unsigned int *num)
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{
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unsigned int sec = find_sec(hdr, sechdrs, secstrings, name);
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/* Section 0 has sh_addr 0 and sh_size 0. */
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*num = sechdrs[sec].sh_size / object_size;
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return (void *)sechdrs[sec].sh_addr;
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}
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/* Provided by the linker */
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extern const struct kernel_symbol __start___ksymtab[];
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extern const struct kernel_symbol __stop___ksymtab[];
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@ -1789,32 +1812,20 @@ static inline void add_kallsyms(struct module *mod,
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}
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#endif /* CONFIG_KALLSYMS */
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static void dynamic_printk_setup(struct mod_debug *debug, unsigned int num)
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{
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#ifdef CONFIG_DYNAMIC_PRINTK_DEBUG
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static void dynamic_printk_setup(Elf_Shdr *sechdrs, unsigned int verboseindex)
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{
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struct mod_debug *debug_info;
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unsigned long pos, end;
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unsigned int num_verbose;
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unsigned int i;
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pos = sechdrs[verboseindex].sh_addr;
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num_verbose = sechdrs[verboseindex].sh_size /
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sizeof(struct mod_debug);
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end = pos + (num_verbose * sizeof(struct mod_debug));
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for (; pos < end; pos += sizeof(struct mod_debug)) {
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debug_info = (struct mod_debug *)pos;
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register_dynamic_debug_module(debug_info->modname,
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debug_info->type, debug_info->logical_modname,
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debug_info->flag_names, debug_info->hash,
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debug_info->hash2);
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for (i = 0; i < num; i++) {
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register_dynamic_debug_module(debug[i].modname,
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debug[i].type,
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debug[i].logical_modname,
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debug[i].flag_names,
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debug[i].hash, debug[i].hash2);
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}
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}
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#else
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static inline void dynamic_printk_setup(Elf_Shdr *sechdrs,
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unsigned int verboseindex)
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{
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}
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#endif /* CONFIG_DYNAMIC_PRINTK_DEBUG */
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}
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static void *module_alloc_update_bounds(unsigned long size)
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{
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@ -1843,37 +1854,14 @@ static noinline struct module *load_module(void __user *umod,
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unsigned int i;
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unsigned int symindex = 0;
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unsigned int strindex = 0;
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unsigned int setupindex;
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unsigned int exindex;
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unsigned int exportindex;
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unsigned int modindex;
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unsigned int obsparmindex;
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unsigned int infoindex;
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unsigned int gplindex;
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unsigned int crcindex;
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unsigned int gplcrcindex;
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unsigned int versindex;
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unsigned int pcpuindex;
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unsigned int gplfutureindex;
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unsigned int gplfuturecrcindex;
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unsigned int modindex, versindex, infoindex, pcpuindex;
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unsigned int unwindex = 0;
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#ifdef CONFIG_UNUSED_SYMBOLS
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unsigned int unusedindex;
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unsigned int unusedcrcindex;
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unsigned int unusedgplindex;
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unsigned int unusedgplcrcindex;
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#endif
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unsigned int markersindex;
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unsigned int markersstringsindex;
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unsigned int verboseindex;
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unsigned int tracepointsindex;
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unsigned int tracepointsstringsindex;
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unsigned int mcountindex;
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unsigned int num_kp, num_mcount;
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struct kernel_param *kp;
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struct module *mod;
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long err = 0;
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void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
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void *mseg;
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struct exception_table_entry *extable;
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unsigned long *mseg;
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mm_segment_t old_fs;
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DEBUGP("load_module: umod=%p, len=%lu, uargs=%p\n",
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@ -1937,6 +1925,7 @@ static noinline struct module *load_module(void __user *umod,
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err = -ENOEXEC;
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goto free_hdr;
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}
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/* This is temporary: point mod into copy of data. */
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mod = (void *)sechdrs[modindex].sh_addr;
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if (symindex == 0) {
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@ -1946,22 +1935,6 @@ static noinline struct module *load_module(void __user *umod,
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goto free_hdr;
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}
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/* Optional sections */
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exportindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab");
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gplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl");
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gplfutureindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl_future");
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crcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab");
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gplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl");
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gplfuturecrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl_future");
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#ifdef CONFIG_UNUSED_SYMBOLS
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unusedindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused");
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unusedgplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused_gpl");
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unusedcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused");
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unusedgplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused_gpl");
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#endif
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setupindex = find_sec(hdr, sechdrs, secstrings, "__param");
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exindex = find_sec(hdr, sechdrs, secstrings, "__ex_table");
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obsparmindex = find_sec(hdr, sechdrs, secstrings, "__obsparm");
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versindex = find_sec(hdr, sechdrs, secstrings, "__versions");
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infoindex = find_sec(hdr, sechdrs, secstrings, ".modinfo");
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pcpuindex = find_pcpusec(hdr, sechdrs, secstrings);
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@ -2117,42 +2090,57 @@ static noinline struct module *load_module(void __user *umod,
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if (err < 0)
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goto cleanup;
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/* Set up EXPORTed & EXPORT_GPLed symbols (section 0 is 0 length) */
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mod->num_syms = sechdrs[exportindex].sh_size / sizeof(*mod->syms);
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mod->syms = (void *)sechdrs[exportindex].sh_addr;
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if (crcindex)
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mod->crcs = (void *)sechdrs[crcindex].sh_addr;
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mod->num_gpl_syms = sechdrs[gplindex].sh_size / sizeof(*mod->gpl_syms);
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mod->gpl_syms = (void *)sechdrs[gplindex].sh_addr;
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if (gplcrcindex)
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mod->gpl_crcs = (void *)sechdrs[gplcrcindex].sh_addr;
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mod->num_gpl_future_syms = sechdrs[gplfutureindex].sh_size /
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sizeof(*mod->gpl_future_syms);
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mod->gpl_future_syms = (void *)sechdrs[gplfutureindex].sh_addr;
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if (gplfuturecrcindex)
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mod->gpl_future_crcs = (void *)sechdrs[gplfuturecrcindex].sh_addr;
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/* Now we've got everything in the final locations, we can
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* find optional sections. */
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kp = section_objs(hdr, sechdrs, secstrings, "__param", sizeof(*kp),
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&num_kp);
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mod->syms = section_objs(hdr, sechdrs, secstrings, "__ksymtab",
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sizeof(*mod->syms), &mod->num_syms);
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mod->crcs = section_addr(hdr, sechdrs, secstrings, "__kcrctab");
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mod->gpl_syms = section_objs(hdr, sechdrs, secstrings, "__ksymtab_gpl",
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sizeof(*mod->gpl_syms),
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&mod->num_gpl_syms);
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mod->gpl_crcs = section_addr(hdr, sechdrs, secstrings, "__kcrctab_gpl");
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mod->gpl_future_syms = section_objs(hdr, sechdrs, secstrings,
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"__ksymtab_gpl_future",
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sizeof(*mod->gpl_future_syms),
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&mod->num_gpl_future_syms);
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mod->gpl_future_crcs = section_addr(hdr, sechdrs, secstrings,
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"__kcrctab_gpl_future");
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#ifdef CONFIG_UNUSED_SYMBOLS
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mod->num_unused_syms = sechdrs[unusedindex].sh_size /
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sizeof(*mod->unused_syms);
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mod->num_unused_gpl_syms = sechdrs[unusedgplindex].sh_size /
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sizeof(*mod->unused_gpl_syms);
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mod->unused_syms = (void *)sechdrs[unusedindex].sh_addr;
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if (unusedcrcindex)
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mod->unused_crcs = (void *)sechdrs[unusedcrcindex].sh_addr;
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mod->unused_gpl_syms = (void *)sechdrs[unusedgplindex].sh_addr;
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if (unusedgplcrcindex)
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mod->unused_gpl_crcs
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= (void *)sechdrs[unusedgplcrcindex].sh_addr;
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mod->unused_syms = section_objs(hdr, sechdrs, secstrings,
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"__ksymtab_unused",
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sizeof(*mod->unused_syms),
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&mod->num_unused_syms);
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mod->unused_crcs = section_addr(hdr, sechdrs, secstrings,
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"__kcrctab_unused");
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mod->unused_gpl_syms = section_objs(hdr, sechdrs, secstrings,
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"__ksymtab_unused_gpl",
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sizeof(*mod->unused_gpl_syms),
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&mod->num_unused_gpl_syms);
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mod->unused_gpl_crcs = section_addr(hdr, sechdrs, secstrings,
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"__kcrctab_unused_gpl");
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#endif
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#ifdef CONFIG_MARKERS
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mod->markers = section_objs(hdr, sechdrs, secstrings, "__markers",
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sizeof(*mod->markers), &mod->num_markers);
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#endif
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#ifdef CONFIG_TRACEPOINTS
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mod->tracepoints = section_objs(hdr, sechdrs, secstrings,
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"__tracepoints",
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sizeof(*mod->tracepoints),
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&mod->num_tracepoints);
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#endif
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#ifdef CONFIG_MODVERSIONS
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if ((mod->num_syms && !crcindex)
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|| (mod->num_gpl_syms && !gplcrcindex)
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|| (mod->num_gpl_future_syms && !gplfuturecrcindex)
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if ((mod->num_syms && !mod->crcs)
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|| (mod->num_gpl_syms && !mod->gpl_crcs)
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|| (mod->num_gpl_future_syms && !mod->gpl_future_crcs)
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#ifdef CONFIG_UNUSED_SYMBOLS
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|| (mod->num_unused_syms && !unusedcrcindex)
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|| (mod->num_unused_gpl_syms && !unusedgplcrcindex)
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|| (mod->num_unused_syms && !mod->unused_crcs)
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|| (mod->num_unused_gpl_syms && !mod->unused_gpl_crcs)
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#endif
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) {
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printk(KERN_WARNING "%s: No versions for exported symbols.\n", mod->name);
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@ -2161,16 +2149,6 @@ static noinline struct module *load_module(void __user *umod,
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goto cleanup;
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}
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#endif
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markersindex = find_sec(hdr, sechdrs, secstrings, "__markers");
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markersstringsindex = find_sec(hdr, sechdrs, secstrings,
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"__markers_strings");
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verboseindex = find_sec(hdr, sechdrs, secstrings, "__verbose");
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tracepointsindex = find_sec(hdr, sechdrs, secstrings, "__tracepoints");
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tracepointsstringsindex = find_sec(hdr, sechdrs, secstrings,
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"__tracepoints_strings");
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mcountindex = find_sec(hdr, sechdrs, secstrings,
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"__mcount_loc");
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/* Now do relocations. */
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for (i = 1; i < hdr->e_shnum; i++) {
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@ -2193,28 +2171,16 @@ static noinline struct module *load_module(void __user *umod,
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if (err < 0)
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goto cleanup;
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}
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#ifdef CONFIG_MARKERS
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mod->markers = (void *)sechdrs[markersindex].sh_addr;
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mod->num_markers =
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sechdrs[markersindex].sh_size / sizeof(*mod->markers);
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#endif
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#ifdef CONFIG_TRACEPOINTS
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mod->tracepoints = (void *)sechdrs[tracepointsindex].sh_addr;
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mod->num_tracepoints =
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sechdrs[tracepointsindex].sh_size / sizeof(*mod->tracepoints);
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#endif
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/* Find duplicate symbols */
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err = verify_export_symbols(mod);
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if (err < 0)
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goto cleanup;
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/* Set up and sort exception table */
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mod->num_exentries = sechdrs[exindex].sh_size / sizeof(*mod->extable);
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mod->extable = extable = (void *)sechdrs[exindex].sh_addr;
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sort_extable(extable, extable + mod->num_exentries);
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mod->extable = section_objs(hdr, sechdrs, secstrings, "__ex_table",
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sizeof(*mod->extable), &mod->num_exentries);
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sort_extable(mod->extable, mod->extable + mod->num_exentries);
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/* Finally, copy percpu area over. */
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percpu_modcopy(mod->percpu, (void *)sechdrs[pcpuindex].sh_addr,
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@ -2223,11 +2189,17 @@ static noinline struct module *load_module(void __user *umod,
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add_kallsyms(mod, sechdrs, symindex, strindex, secstrings);
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if (!mod->taints) {
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struct mod_debug *debug;
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unsigned int num_debug;
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#ifdef CONFIG_MARKERS
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marker_update_probe_range(mod->markers,
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mod->markers + mod->num_markers);
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#endif
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dynamic_printk_setup(sechdrs, verboseindex);
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debug = section_objs(hdr, sechdrs, secstrings, "__verbose",
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sizeof(*debug), &num_debug);
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dynamic_printk_setup(debug, num_debug);
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#ifdef CONFIG_TRACEPOINTS
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tracepoint_update_probe_range(mod->tracepoints,
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mod->tracepoints + mod->num_tracepoints);
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@ -2235,8 +2207,9 @@ static noinline struct module *load_module(void __user *umod,
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}
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/* sechdrs[0].sh_size is always zero */
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mseg = (void *)sechdrs[mcountindex].sh_addr;
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ftrace_init_module(mseg, mseg + sechdrs[mcountindex].sh_size);
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mseg = section_objs(hdr, sechdrs, secstrings, "__mcount_loc",
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sizeof(*mseg), &num_mcount);
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ftrace_init_module(mseg, mseg + num_mcount);
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err = module_finalize(hdr, sechdrs, mod);
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if (err < 0)
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@ -2261,7 +2234,7 @@ static noinline struct module *load_module(void __user *umod,
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set_fs(old_fs);
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mod->args = args;
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if (obsparmindex)
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if (section_addr(hdr, sechdrs, secstrings, "__obsparm"))
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printk(KERN_WARNING "%s: Ignoring obsolete parameters\n",
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mod->name);
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@ -2270,21 +2243,11 @@ static noinline struct module *load_module(void __user *umod,
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* strong_try_module_get() will fail. */
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stop_machine(__link_module, mod, NULL);
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/* Size of section 0 is 0, so this works well if no params */
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err = parse_args(mod->name, mod->args,
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(struct kernel_param *)
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sechdrs[setupindex].sh_addr,
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sechdrs[setupindex].sh_size
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/ sizeof(struct kernel_param),
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NULL);
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err = parse_args(mod->name, mod->args, kp, num_kp, NULL);
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if (err < 0)
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goto unlink;
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err = mod_sysfs_setup(mod,
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(struct kernel_param *)
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sechdrs[setupindex].sh_addr,
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sechdrs[setupindex].sh_size
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/ sizeof(struct kernel_param));
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err = mod_sysfs_setup(mod, kp, num_kp);
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if (err < 0)
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goto unlink;
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add_sect_attrs(mod, hdr->e_shnum, secstrings, sechdrs);
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