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Subject[PATCH 06/10] module: refactor symbol tables and try to reduce code size of each_symbol()
Date
find_symbol() will use bsearch() instead of each_symbol(). each_symbol()
is still desired by Ksplice (although it is not in-tree yet). Let's try
to minimize the code which will be duplicated between these two
functions, by changing how the symbol tables are declared.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
---
include/linux/module.h | 102 ++++++++++++-------
kernel/module.c | 251 ++++++++++++++++++++++++------------------------
2 files changed, 191 insertions(+), 162 deletions(-)
diff --git a/include/linux/module.h b/include/linux/module.h
index b9e860a..0bb0f74 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -168,6 +168,62 @@ void *__symbol_get(const char *symbol);
void *__symbol_get_gpl(const char *symbol);
#define symbol_get(x) ((typeof(&x))(__symbol_get(MODULE_SYMBOL_PREFIX #x)))

+#ifdef CONFIG_UNUSED_SYMBOLS
+enum export_type {
+ /* GPL-only exported symbols. */
+ __EXPORT_FLAG_GPL_ONLY = 0x1,
+
+ /* unused exported symbols. */
+ __EXPORT_FLAG_UNUSED = 0x2,
+
+ /* exports that will be GPL-only in the near future. */
+ __EXPORT_FLAG_GPL_FUTURE = 0x4,
+
+ EXPORT_TYPE_PLAIN = 0x0,
+ EXPORT_TYPE_GPL = 0x1,
+ EXPORT_TYPE_UNUSED = 0x2,
+ EXPORT_TYPE_UNUSED_GPL = 0x3,
+ EXPORT_TYPE_GPL_FUTURE = 0x4,
+
+ EXPORT_TYPE_MAX
+};
+
+#else /* !CONFIG_UNUSED_EXPORTS */
+enum export_type {
+ __EXPORT_FLAG_UNUSED = 0x0,
+ __EXPORT_FLAG_GPL_ONLY = 0x1,
+ __EXPORT_FLAG_GPL_FUTURE = 0x2,
+
+ EXPORT_TYPE_PLAIN = 0x0,
+ EXPORT_TYPE_GPL = 0x1,
+ EXPORT_TYPE_GPL_FUTURE = 0x2,
+ EXPORT_TYPE_MAX
+};
+#endif
+
+static inline bool export_is_gpl_only(enum export_type type)
+{
+ return (type & __EXPORT_FLAG_GPL_ONLY);
+}
+
+static inline bool export_is_unused(enum export_type type)
+{
+ return (type & __EXPORT_FLAG_UNUSED);
+}
+
+static inline bool export_is_gpl_future(enum export_type type)
+{
+ return (type & __EXPORT_FLAG_GPL_FUTURE);
+}
+
+struct ksymtab {
+ const struct kernel_symbol *syms;
+#ifdef CONFIG_MODVERSIONS
+ const unsigned long *crcs;
+#endif
+ unsigned int num_syms;
+};
+
enum module_state
{
MODULE_STATE_LIVE,
@@ -193,36 +249,12 @@ struct module
struct kobject *holders_dir;

/* Exported symbols */
- const struct kernel_symbol *syms;
- const unsigned long *crcs;
- unsigned int num_syms;
+ struct ksymtab syms[EXPORT_TYPE_MAX];

/* Kernel parameters. */
struct kernel_param *kp;
unsigned int num_kp;

- /* GPL-only exported symbols. */
- unsigned int num_gpl_syms;
- const struct kernel_symbol *gpl_syms;
- const unsigned long *gpl_crcs;
-
-#ifdef CONFIG_UNUSED_SYMBOLS
- /* unused exported symbols. */
- const struct kernel_symbol *unused_syms;
- const unsigned long *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;
-#endif
-
- /* symbols that will be GPL-only in the near future. */
- const struct kernel_symbol *gpl_future_syms;
- const unsigned long *gpl_future_crcs;
- unsigned int num_gpl_future_syms;
-
/* Exception table */
unsigned int num_exentries;
struct exception_table_entry *extable;
@@ -352,17 +384,6 @@ static inline int within_module_init(unsigned long addr, struct module *mod)
/* Search for module by name: must hold module_mutex. */
struct module *find_module(const char *name);

-struct symsearch {
- const struct kernel_symbol *start, *stop;
- const unsigned long *crcs;
- enum {
- NOT_GPL_ONLY,
- GPL_ONLY,
- WILL_BE_GPL_ONLY,
- } licence;
- bool unused;
-};
-
/* Search for an exported symbol by name. */
const struct kernel_symbol *find_symbol(const char *name,
struct module **owner,
@@ -370,9 +391,14 @@ const struct kernel_symbol *find_symbol(const char *name,
bool gplok,
bool warn);

+typedef bool each_symbol_fn_t (enum export_type type,
+ const struct kernel_symbol *sym,
+ const unsigned long *crc,
+ struct module *owner,
+ void *data);
+
/* Walk the exported symbol table */
-bool each_symbol(bool (*fn)(const struct symsearch *arr, struct module *owner,
- unsigned int symnum, void *data), void *data);
+bool each_symbol(each_symbol_fn_t *fn, void *data);

/* Returns 0 and fills in value, defined and namebuf, or -ERANGE if
symnum out of range. */
diff --git a/kernel/module.c b/kernel/module.c
index fe748a8..38a2859 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -192,25 +192,64 @@ extern const unsigned long __start___kcrctab_unused[];
extern const unsigned long __start___kcrctab_unused_gpl[];
#endif

+static struct ksymtab ksymtab[EXPORT_TYPE_MAX];
+
+static int __init init_ksymtab(void)
+{
+ struct ksymtab tmp[EXPORT_TYPE_MAX] = {
+ [EXPORT_TYPE_PLAIN] = {
+ __start___ksymtab, __start___kcrctab,
+ __stop___ksymtab - __start___ksymtab,
+ },
+ [EXPORT_TYPE_GPL] = {
+ __start___ksymtab_gpl, __start___kcrctab_gpl,
+ __stop___ksymtab_gpl - __start___ksymtab_gpl,
+ },
+#ifdef CONFIG_UNUSED_EXPORTS
+ [EXPORT_TYPE_UNUSED] = {
+ __start___ksymtab_unused, __start___kcrctab_unused,
+ __stop___ksymtab_unused - __start___ksymtab_unused,
+ },
+ [EXPORT_TYPE_UNUSED_GPL] = {
+ __start___ksymtab_unused_gpl,
+ __start___kcrctab_unused_gpl,
+ __stop___ksymtab_unused_gpl -
+ __start___ksymtab_unused_gpl,
+ },
+#endif
+ [EXPORT_TYPE_GPL_FUTURE] = {
+ __start___ksymtab_gpl_future,
+ __start___kcrctab_gpl_future,
+ __stop___ksymtab_gpl_future -
+ __start___ksymtab_gpl_future,
+ },
+ };
+
+ memcpy(ksymtab, tmp, sizeof(ksymtab));
+
+ return 0;
+}
+pure_initcall(init_ksymtab);
+
#ifndef CONFIG_MODVERSIONS
#define symversion(base, idx) NULL
#else
#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)
#endif

-static bool each_symbol_in_section(const struct symsearch *arr,
- unsigned int arrsize,
+static bool each_symbol_in_section(const struct ksymtab syms[EXPORT_TYPE_MAX],
struct module *owner,
- bool (*fn)(const struct symsearch *syms,
- struct module *owner,
- unsigned int symnum, void *data),
+ each_symbol_fn_t *fn,
void *data)
{
- unsigned int i, j;
+ enum export_type type;
+ unsigned int i;

- for (j = 0; j < arrsize; j++) {
- for (i = 0; i < arr[j].stop - arr[j].start; i++)
- if (fn(&arr[j], owner, i, data))
+ for (type = 0; type < EXPORT_TYPE_MAX; type++) {
+ for (i = 0; i < syms[type].num_syms; i++)
+ if (fn(type, &syms[type].syms[i],
+ symversion(syms[type].crcs, i),
+ owner, data))
return true;
}

@@ -218,56 +257,15 @@ static bool each_symbol_in_section(const struct symsearch *arr,
}

/* Returns true as soon as fn returns true, otherwise false. */
-bool each_symbol(bool (*fn)(const struct symsearch *arr, struct module *owner,
- unsigned int symnum, void *data), void *data)
+bool each_symbol(each_symbol_fn_t *fn, void *data)
{
struct module *mod;
- const struct symsearch arr[] = {
- { __start___ksymtab, __stop___ksymtab, __start___kcrctab,
- NOT_GPL_ONLY, false },
- { __start___ksymtab_gpl, __stop___ksymtab_gpl,
- __start___kcrctab_gpl,
- GPL_ONLY, false },
- { __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,
- __start___kcrctab_gpl_future,
- WILL_BE_GPL_ONLY, false },
-#ifdef CONFIG_UNUSED_SYMBOLS
- { __start___ksymtab_unused, __stop___ksymtab_unused,
- __start___kcrctab_unused,
- NOT_GPL_ONLY, true },
- { __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,
- __start___kcrctab_unused_gpl,
- GPL_ONLY, true },
-#endif
- };

- if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
+ if (each_symbol_in_section(ksymtab, NULL, fn, data))
return true;

list_for_each_entry_rcu(mod, &modules, list) {
- struct symsearch arr[] = {
- { mod->syms, mod->syms + mod->num_syms, mod->crcs,
- NOT_GPL_ONLY, false },
- { mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,
- mod->gpl_crcs,
- GPL_ONLY, false },
- { mod->gpl_future_syms,
- mod->gpl_future_syms + mod->num_gpl_future_syms,
- mod->gpl_future_crcs,
- WILL_BE_GPL_ONLY, false },
-#ifdef CONFIG_UNUSED_SYMBOLS
- { mod->unused_syms,
- mod->unused_syms + mod->num_unused_syms,
- mod->unused_crcs,
- NOT_GPL_ONLY, true },
- { mod->unused_gpl_syms,
- mod->unused_gpl_syms + mod->num_unused_gpl_syms,
- mod->unused_gpl_crcs,
- GPL_ONLY, true },
-#endif
- };
-
- if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data))
+ if (each_symbol_in_section(mod->syms, mod, fn, data))
return true;
}
return false;
@@ -281,24 +279,26 @@ struct find_symbol_arg {
bool warn;

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

-static bool find_symbol_in_section(const struct symsearch *syms,
+static bool find_symbol_in_section(enum export_type type,
+ const struct kernel_symbol *sym,
+ const unsigned long *crc,
struct module *owner,
- unsigned int symnum, void *data)
+ void *data)
{
struct find_symbol_arg *fsa = data;

- if (strcmp(syms->start[symnum].name, fsa->name) != 0)
+ if (strcmp(sym->name, fsa->name) != 0)
return false;

if (!fsa->gplok) {
- if (syms->licence == GPL_ONLY)
+ if (export_is_gpl_only(type))
return false;
- if (syms->licence == WILL_BE_GPL_ONLY && fsa->warn) {
+ if (export_is_gpl_future(type) && fsa->warn) {
printk(KERN_WARNING "Symbol %s is being used "
"by a non-GPL module, which will not "
"be allowed in the future\n", fsa->name);
@@ -309,7 +309,7 @@ static bool find_symbol_in_section(const struct symsearch *syms,
}

#ifdef CONFIG_UNUSED_SYMBOLS
- if (syms->unused && fsa->warn) {
+ if (export_is_unused(type) && fsa->warn) {
printk(KERN_WARNING "Symbol %s is marked as UNUSED, "
"however this module is using it.\n", fsa->name);
printk(KERN_WARNING
@@ -322,9 +322,9 @@ static bool find_symbol_in_section(const struct symsearch *syms,
}
#endif

+ fsa->sym = sym;
+ fsa->crc = crc;
fsa->owner = owner;
- fsa->crc = symversion(syms->crcs, symnum);
- fsa->sym = &syms->start[symnum];
return true;
}

@@ -1564,23 +1564,13 @@ EXPORT_SYMBOL_GPL(__symbol_get);
static int verify_export_symbols(struct module *mod)
{
unsigned int i;
- struct module *owner;
+ enum export_type type;
const struct kernel_symbol *s;
- struct {
- const struct kernel_symbol *sym;
- unsigned int num;
- } arr[] = {
- { mod->syms, mod->num_syms },
- { mod->gpl_syms, mod->num_gpl_syms },
- { mod->gpl_future_syms, mod->num_gpl_future_syms },
-#ifdef CONFIG_UNUSED_SYMBOLS
- { mod->unused_syms, mod->num_unused_syms },
- { mod->unused_gpl_syms, mod->num_unused_gpl_syms },
-#endif
- };
+ struct module *owner;

- for (i = 0; i < ARRAY_SIZE(arr); i++) {
- for (s = arr[i].sym; s < arr[i].sym + arr[i].num; s++) {
+ for (type = 0; type < EXPORT_TYPE_MAX; type++) {
+ for (i = 0; i < mod->syms[type].num_syms; i++) {
+ s = &mod->syms[type].syms[i];
if (find_symbol(s->name, &owner, NULL, true, false)) {
printk(KERN_ERR
"%s: exports duplicate symbol %s"
@@ -1812,24 +1802,30 @@ static void free_modinfo(struct module *mod)

/* lookup symbol in given range of kernel_symbols */
static const struct kernel_symbol *lookup_symbol(const char *name,
- const struct kernel_symbol *start,
- const struct kernel_symbol *stop)
+ const struct kernel_symbol *syms,
+ unsigned int count)
{
- const struct kernel_symbol *ks = start;
- for (; ks < stop; ks++)
- if (strcmp(ks->name, name) == 0)
- return ks;
+ unsigned int i;
+
+ for (i = 0; i < count; i++)
+ if (strcmp(syms[i].name, name) == 0)
+ return &syms[i];
return NULL;
}

static int is_exported(const char *name, unsigned long value,
const struct module *mod)
{
+ const struct ksymtab *symtab;
const struct kernel_symbol *ks;
+
if (!mod)
- ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);
+ symtab = &ksymtab[EXPORT_TYPE_PLAIN];
else
- ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
+ symtab = &mod->syms[EXPORT_TYPE_PLAIN];
+
+ ks = lookup_symbol(name, symtab->syms, symtab->num_syms);
+
return ks != NULL && ks->value == value;
}

@@ -2064,6 +2060,26 @@ static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
}
#endif

+static const char *export_section_names[EXPORT_TYPE_MAX] = {
+ [EXPORT_TYPE_PLAIN] = "__ksymtab",
+ [EXPORT_TYPE_GPL] = "__ksymtab_gpl",
+#ifdef CONFIG_UNUSED_SYMBOLS
+ [EXPORT_TYPE_UNUSED] = "__ksymtab_unused",
+ [EXPORT_TYPE_UNUSED_GPL] = "__ksymtab_unused_gpl",
+#endif
+ [EXPORT_TYPE_GPL_FUTURE] = "__ksymtab_gpl_future",
+};
+
+static const char *crc_section_names[EXPORT_TYPE_MAX] = {
+ [EXPORT_TYPE_PLAIN] = "__kcrctab",
+ [EXPORT_TYPE_GPL] = "__kcrctab_gpl",
+#ifdef CONFIG_UNUSED_SYMBOLS
+ [EXPORT_TYPE_UNUSED] = "__kcrctab_unused",
+ [EXPORT_TYPE_UNUSED_GPL] = "__kcrctab_unused_gpl",
+#endif
+ [EXPORT_TYPE_GPL_FUTURE] = "__kcrctab_gpl_future",
+};
+
/* Allocate and load the module: note that size of section 0 is always
zero, and we rely on this for optional sections. */
static noinline struct module *load_module(void __user *umod,
@@ -2078,6 +2094,7 @@ static noinline struct module *load_module(void __user *umod,
unsigned int symindex = 0;
unsigned int strindex = 0;
unsigned int modindex, versindex, infoindex, pcpuindex;
+ enum export_type export_type;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -2338,34 +2355,20 @@ static noinline struct module *load_module(void __user *umod,
* find optional sections. */
mod->kp = section_objs(hdr, sechdrs, secstrings, "__param",
sizeof(*mod->kp), &mod->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->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");
+ for (export_type = 0; export_type < EXPORT_TYPE_MAX; export_type++) {
+ mod->syms[export_type].syms =
+ section_objs(hdr, sechdrs, secstrings,
+ export_section_names[export_type],
+ sizeof(struct kernel_symbol),
+ &mod->syms[export_type].num_syms);
+#ifdef CONFIG_MODVERSIONS
+ mod->syms[export_type].crcs =
+ section_addr(hdr, sechdrs, secstrings,
+ crc_section_names[export_type]);
#endif
+ }
+
#ifdef CONFIG_CONSTRUCTORS
mod->ctors = section_objs(hdr, sechdrs, secstrings, ".ctors",
sizeof(*mod->ctors), &mod->num_ctors);
@@ -2390,19 +2393,19 @@ static noinline struct module *load_module(void __user *umod,
sizeof(*mod->ftrace_callsites),
&mod->num_ftrace_callsites);
#endif
+
#ifdef CONFIG_MODVERSIONS
- 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 && !mod->unused_crcs)
- || (mod->num_unused_gpl_syms && !mod->unused_gpl_crcs)
-#endif
- ) {
- err = try_to_force_load(mod,
- "no versions for exported symbols");
- if (err)
- goto cleanup;
+ for (export_type = 0; export_type < EXPORT_TYPE_MAX; export_type++) {
+ if (mod->syms[export_type].syms &&
+ !mod->syms[export_type].crcs) {
+ err = try_to_force_load(mod,
+ "no versions for exported symbols");
+ if (err)
+ goto cleanup;
+
+ /* force load approved, don't check other sections */
+ break;
+ }
}
#endif

--
1.6.3.2


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