[PATCH] Add EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL
Temporarily add EXPORT_UNUSED_SYMBOL and EXPORT_UNUSED_SYMBOL_GPL. These
will be used as a transition measure for symbols that aren't used in the
kernel and are on the way out. When a module uses such a symbol, a warning
is printk'd at modprobe time.
The main reason for removing unused exports is size: eacho export takes
roughly between 100 and 150 bytes of kernel space in the binary. This
patch gives users the option to immediately get this size gain via a config
option.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/module.c b/kernel/module.c
index 10e5b87..03b7381 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1,4 +1,4 @@
-/* Rewritten by Rusty Russell, on the backs of many others...
+/*
Copyright (C) 2002 Richard Henderson
Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
@@ -122,9 +122,17 @@
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 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 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 unsigned long __start___kcrctab_unused[];
+extern const unsigned long __start___kcrctab_unused_gpl[];
#ifndef CONFIG_MODVERSIONS
#define symversion(base, idx) NULL
@@ -144,6 +152,17 @@
return NULL;
}
+static void printk_unused_warning(const char *name)
+{
+ printk(KERN_WARNING "Symbol %s is marked as UNUSED, "
+ "however this module is using it.\n", name);
+ printk(KERN_WARNING "This symbol will go away in the future.\n");
+ printk(KERN_WARNING "Please evalute if this is the right api to use, "
+ "and if it really is, submit a report the linux kernel "
+ "mailinglist together with submitting your code for "
+ "inclusion.\n");
+}
+
/* Find a symbol, return value, crc and module which owns it */
static unsigned long __find_symbol(const char *name,
struct module **owner,
@@ -186,6 +205,25 @@
return ks->value;
}
+ ks = lookup_symbol(name, __start___ksymtab_unused,
+ __stop___ksymtab_unused);
+ if (ks) {
+ printk_unused_warning(name);
+ *crc = symversion(__start___kcrctab_unused,
+ (ks - __start___ksymtab_unused));
+ return ks->value;
+ }
+
+ if (gplok)
+ ks = lookup_symbol(name, __start___ksymtab_unused_gpl,
+ __stop___ksymtab_unused_gpl);
+ if (ks) {
+ printk_unused_warning(name);
+ *crc = symversion(__start___kcrctab_unused_gpl,
+ (ks - __start___ksymtab_unused_gpl));
+ return ks->value;
+ }
+
/* Now try modules. */
list_for_each_entry(mod, &modules, list) {
*owner = mod;
@@ -204,6 +242,23 @@
return ks->value;
}
}
+ ks = lookup_symbol(name, mod->unused_syms, mod->unused_syms + mod->num_unused_syms);
+ if (ks) {
+ printk_unused_warning(name);
+ *crc = symversion(mod->unused_crcs, (ks - mod->unused_syms));
+ return ks->value;
+ }
+
+ if (gplok) {
+ ks = lookup_symbol(name, mod->unused_gpl_syms,
+ mod->unused_gpl_syms + mod->num_unused_gpl_syms);
+ if (ks) {
+ printk_unused_warning(name);
+ *crc = symversion(mod->unused_gpl_crcs,
+ (ks - mod->unused_gpl_syms));
+ return ks->value;
+ }
+ }
ks = lookup_symbol(name, mod->gpl_future_syms,
(mod->gpl_future_syms +
mod->num_gpl_future_syms));
@@ -1407,6 +1462,8 @@
exportindex, modindex, obsparmindex, infoindex, gplindex,
crcindex, gplcrcindex, versindex, pcpuindex, gplfutureindex,
gplfuturecrcindex, unwindex = 0;
+ unsigned int unusedindex, unusedcrcindex, unusedgplindex,
+ unusedgplcrcindex;
struct module *mod;
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
@@ -1487,9 +1544,13 @@
exportindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab");
gplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl");
gplfutureindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_gpl_future");
+ unusedindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused");
+ unusedgplindex = find_sec(hdr, sechdrs, secstrings, "__ksymtab_unused_gpl");
crcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab");
gplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl");
gplfuturecrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_gpl_future");
+ unusedcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused");
+ unusedgplcrcindex = find_sec(hdr, sechdrs, secstrings, "__kcrctab_unused_gpl");
setupindex = find_sec(hdr, sechdrs, secstrings, "__param");
exindex = find_sec(hdr, sechdrs, secstrings, "__ex_table");
obsparmindex = find_sec(hdr, sechdrs, secstrings, "__obsparm");
@@ -1638,14 +1699,27 @@
mod->gpl_crcs = (void *)sechdrs[gplcrcindex].sh_addr;
mod->num_gpl_future_syms = sechdrs[gplfutureindex].sh_size /
sizeof(*mod->gpl_future_syms);
+ 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->gpl_future_syms = (void *)sechdrs[gplfutureindex].sh_addr;
if (gplfuturecrcindex)
mod->gpl_future_crcs = (void *)sechdrs[gplfuturecrcindex].sh_addr;
+ 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_crcs = (void *)sechdrs[unusedgplcrcindex].sh_addr;
+
#ifdef CONFIG_MODVERSIONS
if ((mod->num_syms && !crcindex) ||
(mod->num_gpl_syms && !gplcrcindex) ||
- (mod->num_gpl_future_syms && !gplfuturecrcindex)) {
+ (mod->num_gpl_future_syms && !gplfuturecrcindex) ||
+ (mod->num_unused_syms && !unusedcrcindex) ||
+ (mod->num_unused_gpl_syms && !unusedgplcrcindex)) {
printk(KERN_WARNING "%s: No versions for exported symbols."
" Tainting kernel.\n", mod->name);
add_taint(TAINT_FORCED_MODULE);