make "descriptor" a special static local variable

The "descriptor" static local variables and their containing __verbose
section are used for dynamic debug printks.  They should be considered
as special static local variable symbols because they have the same
requirements: they should never be correlated and they should only be
included if referenced by an included function.

kpatch-build/create-diff-object.c

@@ -534,11 +534,19 @@ char *special_static_prefix(struct symbol *sym)
 
 		if (!strncmp(sym->name, "__warned.", 9))
 			return "__warned.";
+
+		if (!strncmp(sym->name, "descriptor.", 11))
+			return "descriptor.";
 	}
 
-	if (sym->type == STT_SECTION &&
-	    !strncmp(sym->name, ".bss.__key.", 11))
-		return ".bss.__key.";
+	if (sym->type == STT_SECTION) {
+		if (!strncmp(sym->name, ".bss.__key.", 11))
+			return ".bss.__key.";
+
+		/* __verbose section contains the descriptor variables */
+		if (!strcmp(sym->name, "__verbose"))
+			return sym->name;
+	}
 
 	return NULL;
 }
@@ -941,14 +949,6 @@ void kpatch_correlate_static_local_variables(struct kpatch_elf *base,
 		if (special_static_prefix(sym))
 			continue;
 
-		/*
-		 * The static variables in the __verbose section contain
-		 * debugging information specific to the patched object and
-		 * shouldn't be correlated.
-		 */
-		if (!strcmp(sym->sec->name, "__verbose"))
-			continue;
-
 		if (!strchr(sym->name, '.'))
 			continue;
 

test/integration/gcc-static-local-var-4.patch

@@ -0,0 +1,21 @@
+Index: src/fs/aio.c
+===================================================================
+--- src.orig/fs/aio.c
++++ src/fs/aio.c
+@@ -229,9 +229,16 @@ static int __init aio_setup(void)
+ }
+ __initcall(aio_setup);
+ 
++void kpatch_aio_foo(void)
++{
++	if (!jiffies)
++		printk("kpatch aio foo\n");
++}
++
+ static void put_aio_ring_file(struct kioctx *ctx)
+ {
+ 	struct file *aio_ring_file = ctx->aio_ring_file;
++	kpatch_aio_foo();
+ 	if (aio_ring_file) {
+ 		truncate_setsize(aio_ring_file->f_inode, 0);
+ 

test/integration/gcc-static-local-var-4.test

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+if $(nm kpatch-gcc-static-local-var-4.ko | grep -q free_ioctx); then
+	exit 1
+else
+	exit 0
+fi