kfence: add test suite

Add KFENCE test suite, testing various error detection scenarios. Makes
use of KUnit for test organization. Since KFENCE's interface to obtain
error reports is via the console, the test verifies that KFENCE outputs
expected reports to the console.

[elver@google.com: fix typo in test]
  Link: https://lkml.kernel.org/r/X9lHQExmHGvETxY4@elver.google.com
[elver@google.com: show access type in report]
  Link: https://lkml.kernel.org/r/20210111091544.3287013-2-elver@google.com

Link: https://lkml.kernel.org/r/20201103175841.3495947-9-elver@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Co-developed-by: Alexander Potapenko <glider@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joern Engel <joern@purestorage.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: SeongJae Park <sjpark@amazon.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/include/linux/kfence.h b/include/linux/kfence.h
index 5a56bcf5606c..a70d1ea03532 100644
--- a/include/linux/kfence.h
+++ b/include/linux/kfence.h
@@ -186,6 +186,7 @@ static __always_inline __must_check bool kfence_free(void *addr)
 /**
  * kfence_handle_page_fault() - perform page fault handling for KFENCE pages
  * @addr: faulting address
+ * @is_write: is access a write
  * @regs: current struct pt_regs (can be NULL, but shows full stack trace)
  *
  * Return:
@@ -197,7 +198,7 @@ static __always_inline __must_check bool kfence_free(void *addr)
  * cases KFENCE prints an error message and marks the offending page as
  * present, so that the kernel can proceed.
  */
-bool __must_check kfence_handle_page_fault(unsigned long addr, struct pt_regs *regs);
+bool __must_check kfence_handle_page_fault(unsigned long addr, bool is_write, struct pt_regs *regs);
 
 #else /* CONFIG_KFENCE */
 
@@ -210,7 +211,11 @@ static inline size_t kfence_ksize(const void *addr) { return 0; }
 static inline void *kfence_object_start(const void *addr) { return NULL; }
 static inline void __kfence_free(void *addr) { }
 static inline bool __must_check kfence_free(void *addr) { return false; }
-static inline bool __must_check kfence_handle_page_fault(unsigned long addr, struct pt_regs *regs) { return false; }
+static inline bool __must_check kfence_handle_page_fault(unsigned long addr, bool is_write,
+							 struct pt_regs *regs)
+{
+	return false;
+}
 
 #endif