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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 2008-10-22 10:00:13 -05:00
parent 2515ddc6db
commit 5e458cc0f4
2 changed files with 100 additions and 137 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/module.h
View File

@ -277,7 +277,7 @@ struct module
/* Exception table */
unsigned int num_exentries;
const struct exception_table_entry *extable;
struct exception_table_entry *extable;
/* Startup function. */
int (*init)(void);

235
kernel/module.c
View File

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