[PATCH] flush icache early when loading module

Change 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 <thomas@koeller.dyndns.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 19 insertions, 14 deletions

diff --git a/kernel/module.c b/kernel/module.c
index c32995fbd8fd..4b39d3793c72 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1509,6 +1509,7 @@ static struct module *load_module(void __user *umod,
         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);
@@ -1779,6 +1780,24 @@ static struct module *load_module(void __user *umod,
         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,
@@ -1860,7 +1879,6 @@ 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 */
@@ -1878,19 +1896,6 @@ 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);