livepatch: Cleanup module page permission changes
Calling set_memory_rw() and set_memory_ro() for every iteration of the
loop in klp_write_object_relocations() is messy, inefficient, and
error-prone.
Change all the read-only pages to read-write before the loop and convert
them back to read-only again afterwards.
Suggested-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 94893e8..bc2c85c 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -28,6 +28,7 @@
#include <linux/list.h>
#include <linux/kallsyms.h>
#include <linux/livepatch.h>
+#include <asm/cacheflush.h>
/**
* struct klp_ops - structure for tracking registered ftrace ops structs
@@ -232,7 +233,7 @@
static int klp_write_object_relocations(struct module *pmod,
struct klp_object *obj)
{
- int ret;
+ int ret = 0;
unsigned long val;
struct klp_reloc *reloc;
@@ -242,13 +243,16 @@
if (WARN_ON(!obj->relocs))
return -EINVAL;
+ module_disable_ro(pmod);
+
for (reloc = obj->relocs; reloc->name; reloc++) {
/* discover the address of the referenced symbol */
if (reloc->external) {
if (reloc->sympos > 0) {
pr_err("non-zero sympos for external reloc symbol '%s' is not supported\n",
reloc->name);
- return -EINVAL;
+ ret = -EINVAL;
+ goto out;
}
ret = klp_find_external_symbol(pmod, reloc->name, &val);
} else
@@ -257,18 +261,20 @@
reloc->sympos,
&val);
if (ret)
- return ret;
+ goto out;
ret = klp_write_module_reloc(pmod, reloc->type, reloc->loc,
val + reloc->addend);
if (ret) {
pr_err("relocation failed for symbol '%s' at 0x%016lx (%d)\n",
reloc->name, val, ret);
- return ret;
+ goto out;
}
}
- return 0;
+out:
+ module_enable_ro(pmod);
+ return ret;
}
static void notrace klp_ftrace_handler(unsigned long ip,