@@ -18,6 +18,7 @@
#endif
#ifndef __ASSEMBLY__
+#include <kunit/bug.h>
#include <linux/panic.h>
#include <linux/printk.h>
@@ -39,8 +40,14 @@ struct bug_entry {
#ifdef CONFIG_DEBUG_BUGVERBOSE
#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
const char *file;
+#ifdef HAVE_BUG_FUNCTION
+ const char *function;
+#endif
#else
signed int file_disp;
+#ifdef HAVE_BUG_FUNCTION
+ signed int function_disp;
+#endif
#endif
unsigned short line;
#endif
@@ -96,15 +103,18 @@ extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
#define __WARN() __WARN_printf(TAINT_WARN, NULL)
#define __WARN_printf(taint, arg...) do { \
instrumentation_begin(); \
- warn_slowpath_fmt(__FILE__, __LINE__, taint, arg); \
+ if (!IS_SUPPRESSED_WARNING(__func__)) \
+ warn_slowpath_fmt(__FILE__, __LINE__, taint, arg);\
instrumentation_end(); \
} while (0)
#else
#define __WARN() __WARN_FLAGS(BUGFLAG_TAINT(TAINT_WARN))
#define __WARN_printf(taint, arg...) do { \
instrumentation_begin(); \
- __warn_printk(arg); \
- __WARN_FLAGS(BUGFLAG_NO_CUT_HERE | BUGFLAG_TAINT(taint));\
+ if (!IS_SUPPRESSED_WARNING(__func__)) { \
+ __warn_printk(arg); \
+ __WARN_FLAGS(BUGFLAG_NO_CUT_HERE | BUGFLAG_TAINT(taint));\
+ } \
instrumentation_end(); \
} while (0)
#define WARN_ON_ONCE(condition) ({ \
new file mode 100644
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * KUnit helpers for backtrace suppression
+ *
+ * Copyright (c) 2024 Guenter Roeck <linux@roeck-us.net>
+ */
+
+#ifndef _KUNIT_BUG_H
+#define _KUNIT_BUG_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/kconfig.h>
+
+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE
+
+#include <linux/stringify.h>
+#include <linux/types.h>
+
+struct __suppressed_warning {
+ struct list_head node;
+ const char *function;
+};
+
+void __start_suppress_warning(struct __suppressed_warning *warning);
+void __end_suppress_warning(struct __suppressed_warning *warning);
+bool __is_suppressed_warning(const char *function);
+
+#define DEFINE_SUPPRESSED_WARNING(func) \
+ struct __suppressed_warning __kunit_suppress_##func = \
+ { .function = __stringify(func) }
+
+#define START_SUPPRESSED_WARNING(func) \
+ __start_suppress_warning(&__kunit_suppress_##func)
+
+#define END_SUPPRESSED_WARNING(func) \
+ __end_suppress_warning(&__kunit_suppress_##func)
+
+#define IS_SUPPRESSED_WARNING(func) \
+ __is_suppressed_warning(func)
+
+#else /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */
+
+#define DEFINE_SUPPRESSED_WARNING(func)
+#define START_SUPPRESSED_WARNING(func)
+#define END_SUPPRESSED_WARNING(func)
+#define IS_SUPPRESSED_WARNING(func) (false)
+
+#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */
+#endif /* __ASSEMBLY__ */
+#endif /* _KUNIT_BUG_H */
@@ -10,6 +10,7 @@
#define _KUNIT_TEST_H
#include <kunit/assert.h>
+#include <kunit/bug.h>
#include <kunit/try-catch.h>
#include <linux/args.h>
@@ -36,6 +36,9 @@ static inline int is_warning_bug(const struct bug_entry *bug)
return bug->flags & BUGFLAG_WARNING;
}
+void bug_get_file_function_line(struct bug_entry *bug, const char **file,
+ const char **function, unsigned int *line);
+
void bug_get_file_line(struct bug_entry *bug, const char **file,
unsigned int *line);
@@ -62,6 +65,16 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr,
}
struct bug_entry;
+static inline void bug_get_file_function_line(struct bug_entry *bug,
+ const char **file,
+ const char **function,
+ unsigned int *line)
+{
+ *file = NULL;
+ *function = NULL;
+ *line = 0;
+}
+
static inline void bug_get_file_line(struct bug_entry *bug, const char **file,
unsigned int *line)
{
@@ -26,6 +26,14 @@
when CONFIG_DEBUG_BUGVERBOSE is not enabled, so you must generate
the values accordingly.
+ 2a.Optionally implement support for the "function" entry in struct
+ bug_entry. This entry must point to the name of the function triggering
+ the warning or bug trap (normally __func__). This is only needed if
+ both CONFIG_DEBUG_BUGVERBOSE and CONFIG_KUNIT_SUPPRESS_BACKTRACE are
+ enabled and if the architecture wants to implement support for suppressing
+ warning backtraces. The architecture must define HAVE_BUG_FUNCTION if it
+ adds pointers to function names to struct bug_entry.
+
3. Implement the trap
- In the illegal instruction trap handler (typically), verify
that the fault was in kernel mode, and call report_bug()
@@ -127,14 +135,21 @@ static inline struct bug_entry *module_find_bug(unsigned long bugaddr)
}
#endif
-void bug_get_file_line(struct bug_entry *bug, const char **file,
- unsigned int *line)
+void bug_get_file_function_line(struct bug_entry *bug, const char **file,
+ const char **function, unsigned int *line)
{
+ *function = NULL;
#ifdef CONFIG_DEBUG_BUGVERBOSE
#ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
*file = (const char *)&bug->file_disp + bug->file_disp;
+#ifdef HAVE_BUG_FUNCTION
+ *function = (const char *)&bug->function_disp + bug->function_disp;
+#endif
#else
*file = bug->file;
+#ifdef HAVE_BUG_FUNCTION
+ *function = bug->function;
+#endif
#endif
*line = bug->line;
#else
@@ -143,6 +158,13 @@ void bug_get_file_line(struct bug_entry *bug, const char **file,
#endif
}
+void bug_get_file_line(struct bug_entry *bug, const char **file, unsigned int *line)
+{
+ const char *function;
+
+ bug_get_file_function_line(bug, file, &function, line);
+}
+
struct bug_entry *find_bug(unsigned long bugaddr)
{
struct bug_entry *bug;
@@ -157,8 +179,9 @@ struct bug_entry *find_bug(unsigned long bugaddr)
static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *regs)
{
struct bug_entry *bug;
- const char *file;
+ const char *file, *function;
unsigned line, warning, once, done;
+ char __maybe_unused sym[KSYM_SYMBOL_LEN];
if (!is_valid_bugaddr(bugaddr))
return BUG_TRAP_TYPE_NONE;
@@ -169,12 +192,32 @@ static enum bug_trap_type __report_bug(unsigned long bugaddr, struct pt_regs *re
disable_trace_on_warning();
- bug_get_file_line(bug, &file, &line);
+ bug_get_file_function_line(bug, &file, &function, &line);
+#if defined(CONFIG_KUNIT_SUPPRESS_BACKTRACE) && defined(CONFIG_KALLSYMS)
+ if (!function) {
+ /*
+ * This will be seen if report_bug is called on an architecture
+ * with no architecture-specific support for suppressing warning
+ * backtraces, if CONFIG_DEBUG_BUGVERBOSE is not enabled, or if
+ * the calling code is from assembler which does not record a
+ * function name. Extracting the function name from the bug
+ * address is less than perfect since compiler optimization may
+ * result in 'bugaddr' pointing to a function which does not
+ * actually trigger the warning, but it is better than no
+ * suppression at all.
+ */
+ sprint_symbol_no_offset(sym, bugaddr);
+ function = sym;
+ }
+#endif /* defined(CONFIG_KUNIT_SUPPRESS_BACKTRACE) && defined(CONFIG_KALLSYMS) */
warning = (bug->flags & BUGFLAG_WARNING) != 0;
once = (bug->flags & BUGFLAG_ONCE) != 0;
done = (bug->flags & BUGFLAG_DONE) != 0;
+ if (warning && IS_SUPPRESSED_WARNING(function))
+ return BUG_TRAP_TYPE_WARN;
+
if (warning && once) {
if (done)
return BUG_TRAP_TYPE_WARN;
@@ -15,6 +15,15 @@ menuconfig KUNIT
if KUNIT
+config KUNIT_SUPPRESS_BACKTRACE
+ bool "KUnit - Enable backtrace suppression"
+ default y
+ help
+ Enable backtrace suppression for KUnit. If enabled, backtraces
+ generated intentionally by KUnit tests are suppressed. Disable
+ to reduce kernel image size if image size is more important than
+ suppression of backtraces generated by KUnit tests.
+
config KUNIT_DEBUGFS
bool "KUnit - Enable /sys/kernel/debug/kunit debugfs representation" if !KUNIT_ALL_TESTS
default KUNIT_ALL_TESTS
@@ -14,8 +14,10 @@ ifeq ($(CONFIG_KUNIT_DEBUGFS),y)
kunit-objs += debugfs.o
endif
-# KUnit 'hooks' are built-in even when KUnit is built as a module.
-obj-y += hooks.o
+# KUnit 'hooks' and bug handling are built-in even when KUnit is built
+# as a module.
+obj-y += hooks.o \
+ bug.o
obj-$(CONFIG_KUNIT_TEST) += kunit-test.o
new file mode 100644
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit helpers for backtrace suppression
+ *
+ * Copyright (c) 2024 Guenter Roeck <linux@roeck-us.net>
+ */
+
+#include <kunit/bug.h>
+#include <linux/export.h>
+#include <linux/list.h>
+#include <linux/string.h>
+
+static LIST_HEAD(suppressed_warnings);
+
+void __start_suppress_warning(struct __suppressed_warning *warning)
+{
+ list_add(&warning->node, &suppressed_warnings);
+}
+EXPORT_SYMBOL_GPL(__start_suppress_warning);
+
+void __end_suppress_warning(struct __suppressed_warning *warning)
+{
+ list_del(&warning->node);
+}
+EXPORT_SYMBOL_GPL(__end_suppress_warning);
+
+bool __is_suppressed_warning(const char *function)
+{
+ struct __suppressed_warning *warning;
+
+ if (!function)
+ return false;
+
+ list_for_each_entry(warning, &suppressed_warnings, node) {
+ if (!strcmp(function, warning->function))
+ return true;
+ }
+ return false;
+}
+EXPORT_SYMBOL_GPL(__is_suppressed_warning);