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 <[email protected]>

---
 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

lib/Kconfig.debug +11 -0

index 98fe715522e8..d16bbc12429f 100644
@@ -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"

lib/Makefile +1 -0

index 40c18372b301..469ce5e24e4f 100644
@@ -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

lib/test_debug_virtual.c new file +26 -0

new file mode 100644
index 000000000000..b9cdeecc19dc
@@ -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);

lib/test_debug_virtual.c new file +13 -0

+
+	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");

Signature · 1 line

2.9.3

Quoted 18 lines · Florian Fainelli

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 <[email protected]>

---

lib/test_debug_virtual.c new file +11 -0

+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);

lib/test_debug_virtual.c line 36

Quoted 6 lines

lib/test_debug_virtual.c new file +6 -0

+	if (!foo)
+		return -ENOMEM;
+
+	pa = virt_to_phys(foo);
+	va = foo;
+	pr_info("PA: %pa for VA: 0x%lx\n", &pa, (unsigned long)va);

Should there be a tests here of some sort? When should this fail, why?

There is no docs on this self test, could one be added?

Quoted 19 lines · Luis R. Rodriguez

Quoted 18 lines · Florian Fainelli

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 <[email protected]>

---

lib/test_debug_virtual.c new file +11 -0

+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);

Quoted 8 lines

lib/test_debug_virtual.c line 36

Quoted 6 lines

lib/test_debug_virtual.c new file +6 -0

+	if (!foo)
+		return -ENOMEM;
+
+	pa = virt_to_phys(foo);
+	va = foo;
+	pr_info("PA: %pa for VA: 0x%lx\n", &pa, (unsigned long)va);

Should there be a tests here of some sort? When should this fail, why?

There is no test per-se, the kernel will produce warning with CONFIG_DEBUG_VIRTUAL telling you that what you are doing is wrong.

Quoted 1 line

There is no docs on this self test, could one be added?

I suppose I could add one even though that just means pointing out the code that produces the warning?

Quoted 34 lines · Florian Fainelli

Quoted 19 lines · Luis R. Rodriguez

Quoted 18 lines · Florian Fainelli

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 <[email protected]>

---

lib/test_debug_virtual.c new file +11 -0

+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);

Quoted 8 lines

lib/test_debug_virtual.c line 36

Quoted 6 lines

lib/test_debug_virtual.c new file +6 -0

+  if (!foo)
+          return -ENOMEM;
+
+  pa = virt_to_phys(foo);
+  va = foo;
+  pr_info("PA: %pa for VA: 0x%lx\n", &pa, (unsigned long)va);

Should there be a tests here of some sort? When should this fail, why?

There is no test per-se, the kernel will produce warning with CONFIG_DEBUG_VIRTUAL telling you that what you are doing is wrong.

Quoted 1 line

There is no docs on this self test, could one be added?

Quoted 2 lines

I suppose I could add one even though that just means pointing out the code that produces the warning?

A /* note */ indicating what you just said above would suffice then but typically tests return back to userspace an error, so another option would be to see if one could get a return value that an error happened and return that back to the module init. Grepping just for warning for an error seems error prone.

Quoted 35 lines · Luis R. Rodriguez

Quoted 34 lines · Florian Fainelli

Quoted 19 lines · Luis R. Rodriguez

Quoted 18 lines · Florian Fainelli

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 <[email protected]>

---

lib/test_debug_virtual.c new file +11 -0

+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);

Quoted 8 lines

lib/test_debug_virtual.c line 36

Quoted 6 lines

lib/test_debug_virtual.c new file +6 -0

+  if (!foo)
+          return -ENOMEM;
+
+  pa = virt_to_phys(foo);
+  va = foo;
+  pr_info("PA: %pa for VA: 0x%lx\n", &pa, (unsigned long)va);

Should there be a tests here of some sort? When should this fail, why?

There is no test per-se, the kernel will produce warning with CONFIG_DEBUG_VIRTUAL telling you that what you are doing is wrong.

Quoted 1 line

There is no docs on this self test, could one be added?

Quoted 8 lines

Quoted 2 lines

I suppose I could add one even though that just means pointing out the code that produces the warning?

A /* note */ indicating what you just said above would suffice then but typically tests return back to userspace an error, so another option would be to see if one could get a return value that an error happened and return that back to the module init. Grepping just for warning for an error seems error prone.

If the test depends on the kernel's response (i.e. WARN, BUG, panic) that cannot be detected in the test itself, it may be better suited for lkdtm (drivers/misc/lkdtm*) which is almost entirely comprised of tests like that.