[PATCH 5/7] Pmalloc selftest

[Igor Stoppa]

Add basic self-test functionality for pmalloc.

The testing is introduced as early as possible, right after the main
dependency, genalloc, has passed successfully, so that it can help
diagnosing failures in pmalloc users.

Signed-off-by: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
---
 include/linux/test_pmalloc.h | 24 ++++++++++++++
 init/main.c                  |  2 ++
 mm/Kconfig                   |  9 +++++
 mm/Makefile                  |  1 +
 mm/test_pmalloc.c            | 79 ++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 115 insertions(+)
 create mode 100644 include/linux/test_pmalloc.h
 create mode 100644 mm/test_pmalloc.c

diff --git a/include/linux/test_pmalloc.h b/include/linux/test_pmalloc.h
new file mode 100644
index 000000000000..c7e2e451c17c
--- /dev/null
+++ b/include/linux/test_pmalloc.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * test_pmalloc.h
+ *
+ * (C) Copyright 2018 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
+ */
+
+
+#ifndef __LINUX_TEST_PMALLOC_H
+#define __LINUX_TEST_PMALLOC_H
+
+
+#ifdef CONFIG_TEST_PROTECTABLE_MEMORY
+
+void test_pmalloc(void);
+
+#else
+
+static inline void test_pmalloc(void){};
+
+#endif
+
+#endif
diff --git a/init/main.c b/init/main.c
index bfccf1fd463c..a61e3a5fd321 100644
--- a/init/main.c
+++ b/init/main.c
@@ -90,6 +90,7 @@
 #include <linux/cache.h>
 #include <linux/rodata_test.h>
 #include <linux/test_genalloc.h>
+#include <linux/test_pmalloc.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
@@ -662,6 +663,7 @@ asmlinkage __visible void __init start_kernel(void)
 	mem_encrypt_init();
 
 	test_genalloc();
+	test_pmalloc();
 #ifdef CONFIG_BLK_DEV_INITRD
 	if (initrd_start && !initrd_below_start_ok &&
 	    page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
diff --git a/mm/Kconfig b/mm/Kconfig
index be578fbdce6d..81dcc5345631 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -766,3 +766,12 @@ config PROTECTABLE_MEMORY
     depends on ARCH_HAS_SET_MEMORY
     select GENERIC_ALLOCATOR
     default y
+
+config TEST_PROTECTABLE_MEMORY
+	bool "Run self test for pmalloc memory allocator"
+	depends on ARCH_HAS_SET_MEMORY
+	select PROTECTABLE_MEMORY
+	default n
+	help
+	  Tries to verify that pmalloc works correctly and that the memory
+	  is effectively protected.
diff --git a/mm/Makefile b/mm/Makefile
index 959fdbdac118..1de4be5fd0bc 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -66,6 +66,7 @@ obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
 obj-$(CONFIG_SLOB) += slob.o
 obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
 obj-$(CONFIG_PROTECTABLE_MEMORY) += pmalloc.o
+obj-$(CONFIG_TEST_PROTECTABLE_MEMORY) += test_pmalloc.o
 obj-$(CONFIG_KSM) += ksm.o
 obj-$(CONFIG_PAGE_POISONING) += page_poison.o
 obj-$(CONFIG_SLAB) += slab.o
diff --git a/mm/test_pmalloc.c b/mm/test_pmalloc.c
new file mode 100644
index 000000000000..5de21c462d3d
--- /dev/null
+++ b/mm/test_pmalloc.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * test_pmalloc.c
+ *
+ * (C) Copyright 2018 Huawei Technologies Co. Ltd.
+ * Author: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
+ */
+
+#include <linux/pmalloc.h>
+#include <linux/mm.h>
+#include <linux/test_pmalloc.h>
+
+#define SIZE_1 (PAGE_SIZE * 3)
+#define SIZE_2 1000
+
+#define validate_alloc(expected, variable, size)	\
+	pr_notice("must be " expected ": %s",		\
+		  is_pmalloc_object(variable, size) > 0 ? "ok" : "no")
+
+#define is_alloc_ok(variable, size)	\
+	validate_alloc("ok", variable, size)
+
+#define is_alloc_no(variable, size)	\
+	validate_alloc("no", variable, size)
+
+void test_pmalloc(void)
+{
+	struct gen_pool *pool_unprot;
+	struct gen_pool *pool_prot;
+	void *var_prot, *var_unprot, *var_vmall;
+
+	pr_notice("pmalloc-selftest");
+	pool_unprot = pmalloc_create_pool("unprotected", 0);
+	if (unlikely(!pool_unprot))
+		goto error;
+	pool_prot = pmalloc_create_pool("protected", 0);
+	if (unlikely(!(pool_prot)))
+		goto error_release;
+
+	var_unprot = pmalloc(pool_unprot,  SIZE_1 - 1, GFP_KERNEL);
+	var_prot = pmalloc(pool_prot,  SIZE_1, GFP_KERNEL);
+	*(int *)var_prot = 0;
+	var_vmall = vmalloc(SIZE_2);
+	is_alloc_ok(var_unprot, 10);
+	is_alloc_ok(var_unprot, SIZE_1);
+	is_alloc_ok(var_unprot, PAGE_SIZE);
+	is_alloc_no(var_unprot, SIZE_1 + 1);
+	is_alloc_no(var_vmall, 10);
+
+
+	pfree(pool_unprot, var_unprot);
+	vfree(var_vmall);
+
+	pmalloc_protect_pool(pool_prot);
+
+	/*
+	 * This will intentionally trigger a WARN because the pool being
+	 * destroyed is not protected, which is unusual and should happen
+	 * on error paths only, where probably other warnings are already
+	 * displayed.
+	 */
+	pr_notice("pmalloc-selftest:"
+		  " Expect WARN in pmalloc_pool_set_protection below.");
+	pmalloc_destroy_pool(pool_unprot);
+	pr_notice("pmalloc-selftest:"
+		  "Critical point for expected WARN passed.");
+
+	/* This must not cause WARNings */
+	pr_notice("pmalloc-selftest:"
+		  "Expect no WARN below.");
+	pmalloc_destroy_pool(pool_prot);
+	pr_notice("pmalloc-selftest:"
+		  "Critical point for unexpected WARN passed.");
+	return;
+error_release:
+	pmalloc_destroy_pool(pool_unprot);
+error:
+	WARN(true, "Unable to allocate memory for pmalloc selftest.");
+}
-- 
2.14.1