linux-kernel - [PATCH] lib: Add test module for CONFIG_DEBUG

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Date:   Tue,  8 Aug 2017 09:40:26 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     ard.biesheuvel@...aro.org, labbott@...hat.com,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Kees Cook <keescook@...omium.org>,
        Ingo Molnar <mingo@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Olof Johansson <olof@...om.net>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        "Theodore Ts'o" <tytso@....edu>,
        Thomas Gleixner <tglx@...utronix.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Bart Van Assche <bart.vanassche@...disk.com>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Jiri Pirko <jiri@...lanox.com>,
        Jeff Layton <jlayton@...hat.com>
Subject: [PATCH] lib: Add test module for CONFIG_DEBUG_VIRTUAL

Add a test module that allows testing that CONFIG_DEBUG_VIRTUAL works
correctly, at least that it can catch invalid calls to virt_to_phys()
against the non-linear kernel virtual address map.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 lib/Kconfig.debug        | 11 +++++++++++
 lib/Makefile             |  1 +
 lib/test_debug_virtual.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 lib/test_debug_virtual.c

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 98fe715522e8..d16bbc12429f 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1902,6 +1902,17 @@ config TEST_KMOD
 
 	  If unsure, say N.
 
+config TEST_DEBUG_VIRTUAL
+	tristate "Test CONFIG_DEBUG_VIRTUAL feature"
+	depends on DEBUG_VIRTUAL
+	help
+	  Test the kernel's ability to detect incorrect calls to
+	  virt_to_phys() done against the non-linear part of the
+	  kernel's virtual address map.
+
+	  If unsure, say N.
+
+
 source "samples/Kconfig"
 
 source "lib/Kconfig.kgdb"
diff --git a/lib/Makefile b/lib/Makefile
index 40c18372b301..469ce5e24e4f 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
 obj-$(CONFIG_TEST_UUID) += test_uuid.o
 obj-$(CONFIG_TEST_PARMAN) += test_parman.o
 obj-$(CONFIG_TEST_KMOD) += test_kmod.o
+obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o
 
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG
diff --git a/lib/test_debug_virtual.c b/lib/test_debug_virtual.c
new file mode 100644
index 000000000000..b9cdeecc19dc
--- /dev/null
+++ b/lib/test_debug_virtual.c
@@ -0,0 +1,49 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+#include <linux/sizes.h>
+
+#include <asm/page.h>
+#ifdef CONFIG_MIPS
+#include <asm/bootinfo.h>
+#endif
+
+struct foo {
+	unsigned int bar;
+};
+
+struct foo *foo;
+
+static int __init test_debug_virtual_init(void)
+{
+	phys_addr_t pa;
+	void *va;
+
+	va = (void *)VMALLOC_START;
+	pa = virt_to_phys(va);
+
+	pr_info("PA: %pa for VA: 0x%lx\n", &pa, (unsigned long)va);
+
+	foo = kzalloc(sizeof(*foo), GFP_KERNEL);
+	if (!foo)
+		return -ENOMEM;
+
+	pa = virt_to_phys(foo);
+	va = foo;
+	pr_info("PA: %pa for VA: 0x%lx\n", &pa, (unsigned long)va);
+
+	return 0;
+}
+module_init(test_debug_virtual_init);
+
+static void __exit test_debug_virtual_exit(void)
+{
+	kfree(foo);
+}
+module_exit(test_debug_virtual_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Test module for CONFIG_DEBUG_VIRTUAL");
-- 
2.9.3