module/decompress: generate sysfs string at compile time

ddiss · mcgrof · commit 77d6354bd422 · 2022-09-08T17:00:43.000-07:00
compression_show() before (with noinline):
   0xffffffff810b5ff0 &lt;+0&gt;:     mov    %rdx,%rdi
   0xffffffff810b5ff3 &lt;+3&gt;:     mov    $0xffffffff81b55629,%rsi
   0xffffffff810b5ffa &lt;+10&gt;:    mov    $0xffffffff81b0cde2,%rdx
   0xffffffff810b6001 &lt;+17&gt;:    call   0xffffffff811b8fd0 &lt;sysfs_emit&gt;
   0xffffffff810b6006 &lt;+22&gt;:    cltq
   0xffffffff810b6008 &lt;+24&gt;:    ret

After:
   0xffffffff810b5ff0 &lt;+0&gt;:     mov    $0xffffffff81b0cde2,%rsi
   0xffffffff810b5ff7 &lt;+7&gt;:     mov    %rdx,%rdi
   0xffffffff810b5ffa &lt;+10&gt;:    call   0xffffffff811b8fd0 &lt;sysfs_emit&gt;
   0xffffffff810b5fff &lt;+15&gt;:    cltq
   0xffffffff810b6001 &lt;+17&gt;:    ret

Signed-off-by: David Disseldorp &lt;ddiss@suse.de&gt;
Reviewed-by: Aaron Tomlin &lt;atomlin@redhat.com&gt;
Reviewed-by: Dmitry Torokhov &lt;dmitry.torokhov@gmail.com&gt;
Signed-off-by: Luis Chamberlain &lt;mcgrof@kernel.org&gt;
diff --git a/kernel/module/decompress.c b/kernel/module/decompress.c
@@ -256,7 +256,7 @@ void module_decompress_cleanup(struct load_info *info)
 static ssize_t compression_show(struct kobject *kobj,
 				struct kobj_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "%s\n", __stringify(MODULE_COMPRESSION));
+	return sysfs_emit(buf, __stringify(MODULE_COMPRESSION) "\n");
 }
 
 static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);

Original file line number	Diff line number	Diff line change
`@@ -256,7 +256,7 @@ void module_decompress_cleanup(struct load_info *info)`
`256`	`256`	`static ssize_t compression_show(struct kobject *kobj,`
`257`	`257`	`struct kobj_attribute attr, char buf)`
`258`	`258`	`{`
`259`		`- return sysfs_emit(buf, "%s\n", __stringify(MODULE_COMPRESSION));`
	`259`	`+ return sysfs_emit(buf, __stringify(MODULE_COMPRESSION) "\n");`
`260`	`260`	`}`
`261`	`261`
`262`	`262`	`static struct kobj_attribute module_compression_attr = __ATTR_RO(compression);`