kasan: use error_report_end tracepoint

Make it possible to trace KASAN error reporting.  A good usecase is
watching for trace events from the userspace to detect and process memory
corruption reports from the kernel.

Link: https://lkml.kernel.org/r/20210121131915.1331302-4-glider@google.comSigned-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/kasan/report.c

@@ -25,6 +25,7 @@
 #include <linux/module.h>
 #include <linux/sched/task_stack.h>
 #include <linux/uaccess.h>
+#include <trace/events/error_report.h>
 
 #include <asm/sections.h>
 
@@ -84,8 +85,9 @@ static void start_report(unsigned long *flags)
 	pr_err("==================================================================\n");
 }
 
-static void end_report(unsigned long *flags)
+static void end_report(unsigned long *flags, unsigned long addr)
 {
+	trace_error_report_end(ERROR_DETECTOR_KASAN, addr);
 	pr_err("==================================================================\n");
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 	spin_unlock_irqrestore(&report_lock, *flags);
@@ -355,7 +357,7 @@ void kasan_report_invalid_free(void *object, unsigned long ip)
 	print_address_description(object, tag);
 	pr_err("\n");
 	print_memory_metadata(object);
-	end_report(&flags);
+	end_report(&flags, (unsigned long)object);
 }
 
 static void __kasan_report(unsigned long addr, size_t size, bool is_write,
@@ -401,7 +403,7 @@ static void __kasan_report(unsigned long addr, size_t size, bool is_write,
 		dump_stack();
 	}
 
-	end_report(&flags);
+	end_report(&flags, addr);
 }
 
 bool kasan_report(unsigned long addr, size_t size, bool is_write,