The patch below, created against linux-2.6.12.3, changes the sequence of
operations performed during module loading to flush the instruction cache
before module parameters are processed. If a module has parameters of an
unusual type that cannot be handled using the standard accessor functions
param_set_xxx and param_get_xxx, it has to to provide a set of accessor
functions for this type. This requires module code to be executed during
parameter processing, which is of course only possible after the icache
has been flushed.
Signed-off-by: Thomas Koeller <[email protected]>
--- linux-2.6.12.3-orig/kernel/module.c 2005-08-04 01:11:32.000000000 +0200
+++ linux-2.6.12.3/kernel/module.c 2005-08-04 02:00:16.000000000 +0200
@@ -1413,6 +1413,7 @@ static struct module *load_module(void _
long err = 0;
void *percpu = NULL, *ptr = NULL; /* Stops spurious gcc warning */
struct exception_table_entry *extable;
+ mm_segment_t old_fs;
DEBUGP("load_module: umod=%p, len=%lu, uargs=%p\n",
umod, len, uargs);
@@ -1677,6 +1678,24 @@ static struct module *load_module(void _
if (err < 0)
goto cleanup;
+ /* flush the icache in correct context */
+ old_fs = get_fs();
+ set_fs(KERNEL_DS);
+
+ /*
+ * Flush the instruction cache, since we've played with text.
+ * Do it before processing of module parameters, so the module
+ * can provide parameter accessor functions of its own.
+ */
+ if (mod->module_init)
+ flush_icache_range((unsigned long)mod->module_init,
+ (unsigned long)mod->module_init
+ + mod->init_size);
+ flush_icache_range((unsigned long)mod->module_core,
+ (unsigned long)mod->module_core + mod->core_size);
+
+ set_fs(old_fs);
+
mod->args = args;
if (obsparmindex) {
err = obsolete_params(mod->name, mod->args,
@@ -1758,7 +1777,6 @@ sys_init_module(void __user *umod,
const char __user *uargs)
{
struct module *mod;
- mm_segment_t old_fs = get_fs();
int ret = 0;
/* Must have permission */
@@ -1776,19 +1794,6 @@ sys_init_module(void __user *umod,
return PTR_ERR(mod);
}
- /* flush the icache in correct context */
- set_fs(KERNEL_DS);
-
- /* Flush the instruction cache, since we've played with text */
- if (mod->module_init)
- flush_icache_range((unsigned long)mod->module_init,
- (unsigned long)mod->module_init
- + mod->init_size);
- flush_icache_range((unsigned long)mod->module_core,
- (unsigned long)mod->module_core + mod->core_size);
-
- set_fs(old_fs);
-
/* Now sew it into the lists. They won't access us, since
strong_try_module_get() will fail. */
stop_machine_run(__link_module, mod, NR_CPUS);
--
Thomas Koeller
[email protected]
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