From: Guenter Roeck linux@roeck-us.net

Some unit tests intentionally trigger warning backtraces by passing bad parameters to API functions. Such unit tests typically check the return value from those calls, not the existence of the warning backtrace.

Such intentionally generated warning backtraces are neither desirable nor useful for a number of reasons. - They can result in overlooked real problems. - A warning that suddenly starts to show up in unit tests needs to be investigated and has to be marked to be ignored, for example by adjusting filter scripts. Such filters are ad-hoc because there is no real standard format for warnings. On top of that, such filter scripts would require constant maintenance.

One option to address problem would be to add messages such as "expected warning backtraces start / end here" to the kernel log. However, that would again require filter scripts, it might result in missing real problematic warning backtraces triggered while the test is running, and the irrelevant backtrace(s) would still clog the kernel log.

Solve the problem by providing a means to identify and suppress specific warning backtraces while executing test code. Since the new functionality results in an image size increase of about 1% if CONFIG_KUNIT is enabled, provide configuration option KUNIT_SUPPRESS_BACKTRACE to be able to disable the new functionality. This option is by default enabled since almost all systems with CONFIG_KUNIT enabled will want to benefit from it.

Cc: Dan Carpenter dan.carpenter@linaro.org Cc: Daniel Diaz daniel.diaz@linaro.org Cc: Naresh Kamboju naresh.kamboju@linaro.org Cc: Kees Cook keescook@chromium.org Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Alessandro Carminati acarmina@redhat.com --- include/asm-generic/bug.h | 16 +++++++++--- include/kunit/bug.h | 51 +++++++++++++++++++++++++++++++++++++++ include/kunit/test.h | 1 + include/linux/bug.h | 13 ++++++++++ lib/bug.c | 51 ++++++++++++++++++++++++++++++++++++--- lib/kunit/Kconfig | 9 +++++++ lib/kunit/Makefile | 6 +++-- lib/kunit/bug.c | 40 ++++++++++++++++++++++++++++++ 8 files changed, 178 insertions(+), 9 deletions(-) create mode 100644 include/kunit/bug.h create mode 100644 lib/kunit/bug.c

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index 387720933973..9194cf743ec3 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -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 (!KUNIT_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 (!KUNIT_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) ({ \ diff --git a/include/kunit/bug.h b/include/kunit/bug.h new file mode 100644 index 000000000000..0a8e62c1fcaf --- /dev/null +++ b/include/kunit/bug.h @@ -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 __kunit_start_suppress_warning(struct __suppressed_warning *warning); +void __kunit_end_suppress_warning(struct __suppressed_warning *warning); +bool __kunit_is_suppressed_warning(const char *function); + +#define DEFINE_SUPPRESSED_WARNING(func) \ + struct __suppressed_warning __kunit_suppress_##func = \ + { .function = __stringify(func) } + +#define KUNIT_START_SUPPRESSED_WARNING(func) \ + __kunit_start_suppress_warning(&__kunit_suppress_##func) + +#define KUNIT_END_SUPPRESSED_WARNING(func) \ + __kunit_end_suppress_warning(&__kunit_suppress_##func) + +#define KUNIT_IS_SUPPRESSED_WARNING(func) \ + __kunit_is_suppressed_warning(func) + +#else /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ + +#define DEFINE_SUPPRESSED_WARNING(func) +#define KUNIT_START_SUPPRESSED_WARNING(func) +#define KUNIT_END_SUPPRESSED_WARNING(func) +#define KUNIT_IS_SUPPRESSED_WARNING(func) (false) + +#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ +#endif /* __ASSEMBLY__ */ +#endif /* _KUNIT_BUG_H */ diff --git a/include/kunit/test.h b/include/kunit/test.h index 58dbab60f853..cad32d174872 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.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> diff --git a/include/linux/bug.h b/include/linux/bug.h index a9948a9f1093..e42f20cf8830 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.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) { diff --git a/lib/bug.c b/lib/bug.c index e0ff21989990..5eb2ee66916f 100644 --- a/lib/bug.c +++ b/lib/bug.c @@ -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 && KUNIT_IS_SUPPRESSED_WARNING(function)) + return BUG_TRAP_TYPE_WARN; + if (warning && once) { if (done) return BUG_TRAP_TYPE_WARN; diff --git a/lib/kunit/Kconfig b/lib/kunit/Kconfig index a97897edd964..201402f0ab49 100644 --- a/lib/kunit/Kconfig +++ b/lib/kunit/Kconfig @@ -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 diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index 5aa51978e456..3195e861d63c 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -16,8 +16,10 @@ 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-$(CONFIG_KUNIT_TEST) += kunit-test.o obj-$(CONFIG_KUNIT_TEST) += platform-test.o diff --git a/lib/kunit/bug.c b/lib/kunit/bug.c new file mode 100644 index 000000000000..351f9a595a71 --- /dev/null +++ b/lib/kunit/bug.c @@ -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 __kunit_start_suppress_warning(struct __suppressed_warning *warning) +{ + list_add(&warning->node, &suppressed_warnings); +} +EXPORT_SYMBOL_GPL(__kunit_start_suppress_warning); + +void __kunit_end_suppress_warning(struct __suppressed_warning *warning) +{ + list_del(&warning->node); +} +EXPORT_SYMBOL_GPL(__kunit_end_suppress_warning); + +bool __kunit_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(__kunit_is_suppressed_warning);

From: Guenter Roeck linux@roeck-us.net

Count suppressed warning backtraces to enable code which suppresses warning backtraces to check if the expected backtrace(s) have been observed.

Using atomics for the backtrace count resulted in build errors on some architectures due to include file recursion, so use a plain integer for now.

Acked-by: Dan Carpenter dan.carpenter@linaro.org Reviewed-by: Kees Cook keescook@chromium.org Tested-by: Linux Kernel Functional Testing lkft@linaro.org Signed-off-by: Guenter Roeck linux@roeck-us.net Reviewed-by: David Gow davidgow@google.com Signed-off-by: Alessandro Carminati acarmina@redhat.com --- include/kunit/bug.h | 7 ++++++- lib/kunit/bug.c | 4 +++- 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/kunit/bug.h b/include/kunit/bug.h index 0a8e62c1fcaf..44efa7d5c902 100644 --- a/include/kunit/bug.h +++ b/include/kunit/bug.h @@ -20,6 +20,7 @@ struct __suppressed_warning { struct list_head node; const char *function; + int counter; };

void __kunit_start_suppress_warning(struct __suppressed_warning *warning); @@ -28,7 +29,7 @@ bool __kunit_is_suppressed_warning(const char *function);

#define DEFINE_SUPPRESSED_WARNING(func) \ struct __suppressed_warning __kunit_suppress_##func = \ - { .function = __stringify(func) } + { .function = __stringify(func), .counter = 0 }

#define KUNIT_START_SUPPRESSED_WARNING(func) \ __kunit_start_suppress_warning(&__kunit_suppress_##func) @@ -39,12 +40,16 @@ bool __kunit_is_suppressed_warning(const char *function); #define KUNIT_IS_SUPPRESSED_WARNING(func) \ __kunit_is_suppressed_warning(func)

+#define SUPPRESSED_WARNING_COUNT(func) \ + (__kunit_suppress_##func.counter) + #else /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */

#define DEFINE_SUPPRESSED_WARNING(func) #define KUNIT_START_SUPPRESSED_WARNING(func) #define KUNIT_END_SUPPRESSED_WARNING(func) #define KUNIT_IS_SUPPRESSED_WARNING(func) (false) +#define SUPPRESSED_WARNING_COUNT(func) (0)

#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ #endif /* __ASSEMBLY__ */ diff --git a/lib/kunit/bug.c b/lib/kunit/bug.c index 351f9a595a71..84c05b1a9e8b 100644 --- a/lib/kunit/bug.c +++ b/lib/kunit/bug.c @@ -32,8 +32,10 @@ bool __kunit_is_suppressed_warning(const char *function) return false;

list_for_each_entry(warning, &suppressed_warnings, node) { - if (!strcmp(function, warning->function)) + if (!strcmp(function, warning->function)) { + warning->counter++; return true; + } } return false; }

From: Guenter Roeck linux@roeck-us.net

Add unit tests to verify that warning backtrace suppression works.

If backtrace suppression does _not_ work, the unit tests will likely trigger unsuppressed backtraces, which should actually help to get the affected architectures / platforms fixed.

Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Alessandro Carminati acarmina@redhat.com --- lib/kunit/Makefile | 7 +- lib/kunit/backtrace-suppression-test.c | 104 +++++++++++++++++++++++++ 2 files changed, 109 insertions(+), 2 deletions(-) create mode 100644 lib/kunit/backtrace-suppression-test.c

diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index 3195e861d63c..539a044a9f12 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -18,11 +18,14 @@ endif

# KUnit 'hooks' and bug handling are built-in even when KUnit is built # as a module. -obj-y += hooks.o \ - bug.o +obj-y += hooks.o +obj-$(CONFIG_KUNIT_SUPPRESS_BACKTRACE) += bug.o

obj-$(CONFIG_KUNIT_TEST) += kunit-test.o obj-$(CONFIG_KUNIT_TEST) += platform-test.o +ifeq ($(CONFIG_KUNIT_SUPPRESS_BACKTRACE),y) +obj-$(CONFIG_KUNIT_TEST) += backtrace-suppression-test.o +endif

# string-stream-test compiles built-in only. ifeq ($(CONFIG_KUNIT_TEST),y) diff --git a/lib/kunit/backtrace-suppression-test.c b/lib/kunit/backtrace-suppression-test.c new file mode 100644 index 000000000000..8b4125af2481 --- /dev/null +++ b/lib/kunit/backtrace-suppression-test.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit test for suppressing warning tracebacks + * + * Copyright (C) 2024, Guenter Roeck + * Author: Guenter Roeck linux@roeck-us.net + */ + +#include <kunit/test.h> +#include <linux/bug.h> + +static void backtrace_suppression_test_warn_direct(struct kunit *test) +{ + DEFINE_SUPPRESSED_WARNING(backtrace_suppression_test_warn_direct); + + KUNIT_START_SUPPRESSED_WARNING(backtrace_suppression_test_warn_direct); + WARN(1, "This backtrace should be suppressed"); + KUNIT_END_SUPPRESSED_WARNING(backtrace_suppression_test_warn_direct); + + KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(backtrace_suppression_test_warn_direct), 1); +} + +static void trigger_backtrace_warn(void) +{ + WARN(1, "This backtrace should be suppressed"); +} + +static void backtrace_suppression_test_warn_indirect(struct kunit *test) +{ + DEFINE_SUPPRESSED_WARNING(trigger_backtrace_warn); + + KUNIT_START_SUPPRESSED_WARNING(trigger_backtrace_warn); + trigger_backtrace_warn(); + KUNIT_END_SUPPRESSED_WARNING(trigger_backtrace_warn); + + KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(trigger_backtrace_warn), 1); +} + +static void backtrace_suppression_test_warn_multi(struct kunit *test) +{ + DEFINE_SUPPRESSED_WARNING(trigger_backtrace_warn); + DEFINE_SUPPRESSED_WARNING(backtrace_suppression_test_warn_multi); + + KUNIT_START_SUPPRESSED_WARNING(backtrace_suppression_test_warn_multi); + KUNIT_START_SUPPRESSED_WARNING(trigger_backtrace_warn); + WARN(1, "This backtrace should be suppressed"); + trigger_backtrace_warn(); + KUNIT_END_SUPPRESSED_WARNING(trigger_backtrace_warn); + KUNIT_END_SUPPRESSED_WARNING(backtrace_suppression_test_warn_multi); + + KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(backtrace_suppression_test_warn_multi), 1); + KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(trigger_backtrace_warn), 1); +} + +static void backtrace_suppression_test_warn_on_direct(struct kunit *test) +{ + DEFINE_SUPPRESSED_WARNING(backtrace_suppression_test_warn_on_direct); + + if (!IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE) && !IS_ENABLED(CONFIG_KALLSYMS)) + kunit_skip(test, "requires CONFIG_DEBUG_BUGVERBOSE or CONFIG_KALLSYMS"); + + KUNIT_START_SUPPRESSED_WARNING(backtrace_suppression_test_warn_on_direct); + WARN_ON(1); + KUNIT_END_SUPPRESSED_WARNING(backtrace_suppression_test_warn_on_direct); + + KUNIT_EXPECT_EQ(test, + SUPPRESSED_WARNING_COUNT(backtrace_suppression_test_warn_on_direct), 1); +} + +static void trigger_backtrace_warn_on(void) +{ + WARN_ON(1); +} + +static void backtrace_suppression_test_warn_on_indirect(struct kunit *test) +{ + DEFINE_SUPPRESSED_WARNING(trigger_backtrace_warn_on); + + if (!IS_ENABLED(CONFIG_DEBUG_BUGVERBOSE)) + kunit_skip(test, "requires CONFIG_DEBUG_BUGVERBOSE"); + + KUNIT_START_SUPPRESSED_WARNING(trigger_backtrace_warn_on); + trigger_backtrace_warn_on(); + KUNIT_END_SUPPRESSED_WARNING(trigger_backtrace_warn_on); + + KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(trigger_backtrace_warn_on), 1); +} + +static struct kunit_case backtrace_suppression_test_cases[] = { + KUNIT_CASE(backtrace_suppression_test_warn_direct), + KUNIT_CASE(backtrace_suppression_test_warn_indirect), + KUNIT_CASE(backtrace_suppression_test_warn_multi), + KUNIT_CASE(backtrace_suppression_test_warn_on_direct), + KUNIT_CASE(backtrace_suppression_test_warn_on_indirect), + {} +}; + +static struct kunit_suite backtrace_suppression_test_suite = { + .name = "backtrace-suppression-test", + .test_cases = backtrace_suppression_test_cases, +}; +kunit_test_suites(&backtrace_suppression_test_suite); + +MODULE_LICENSE("GPL");

From: Guenter Roeck linux@roeck-us.net

Document API functions for suppressing warning backtraces.

Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Reviewed-by: Kees Cook keescook@chromium.org Signed-off-by: Guenter Roeck linux@roeck-us.net Reviewed-by: David Gow davidgow@google.com Signed-off-by: Alessandro Carminati acarmina@redhat.com --- Documentation/dev-tools/kunit/usage.rst | 30 ++++++++++++++++++++++++- 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/Documentation/dev-tools/kunit/usage.rst b/Documentation/dev-tools/kunit/usage.rst index 22955d56b379..b2f1e56d53b4 100644 --- a/Documentation/dev-tools/kunit/usage.rst +++ b/Documentation/dev-tools/kunit/usage.rst @@ -157,6 +157,34 @@ Alternatively, one can take full control over the error message by using if (some_setup_function()) KUNIT_FAIL(test, "Failed to setup thing for testing");

+Suppressing warning backtraces +------------------------------ + +Some unit tests trigger warning backtraces either intentionally or as side +effect. Such backtraces are normally undesirable since they distract from +the actual test and may result in the impression that there is a problem. + +Such backtraces can be suppressed. To suppress a backtrace in some_function(), +use the following code. + +.. code-block:: c + + static void some_test(struct kunit *test) + { + DEFINE_SUPPRESSED_WARNING(some_function); + + KUNIT_START_SUPPRESSED_WARNING(some_function); + trigger_backtrace(); + KUNIT_END_SUPPRESSED_WARNING(some_function); + } + +SUPPRESSED_WARNING_COUNT() returns the number of suppressed backtraces. If the +suppressed backtrace was triggered on purpose, this can be used to check if +the backtrace was actually triggered. + +.. code-block:: c + + KUNIT_EXPECT_EQ(test, SUPPRESSED_WARNING_COUNT(some_function), 1);

Test Suites ~~~~~~~~~~~ @@ -857,4 +885,4 @@ For example: dev_managed_string = devm_kstrdup(fake_device, "Hello, World!");

// Everything is cleaned up automatically when the test ends. - } \ No newline at end of file + }

From: Guenter Roeck linux@roeck-us.net

Add name of functions triggering warning backtraces to the __bug_table object section to enable support for suppressing WARNING backtraces.

To limit image size impact, the pointer to the function name is only added to the __bug_table section if both CONFIG_KUNIT_SUPPRESS_BACKTRACE and CONFIG_DEBUG_BUGVERBOSE are enabled. Otherwise, the __func__ assembly parameter is replaced with a (dummy) NULL parameter to avoid an image size increase due to unused __func__ entries (this is necessary because __func__ is not a define but a virtual variable).

Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Dave Hansen dave.hansen@linux.intel.com Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Alessandro Carminati acarmina@redhat.com --- arch/x86/include/asm/bug.h | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h index e85ac0c7c039..f6e13fc675ab 100644 --- a/arch/x86/include/asm/bug.h +++ b/arch/x86/include/asm/bug.h @@ -35,18 +35,28 @@

#ifdef CONFIG_DEBUG_BUGVERBOSE

+#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE +# define HAVE_BUG_FUNCTION +# define __BUG_FUNC_PTR __BUG_REL(%c1) +# define __BUG_FUNC __func__ +#else +# define __BUG_FUNC_PTR +# define __BUG_FUNC NULL +#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ + #define _BUG_FLAGS(ins, flags, extra) \ do { \ asm_inline volatile("1:\t" ins "\n" \ ".pushsection __bug_table,"aw"\n" \ "2:\t" __BUG_REL(1b) "\t# bug_entry::bug_addr\n" \ "\t" __BUG_REL(%c0) "\t# bug_entry::file\n" \ - "\t.word %c1" "\t# bug_entry::line\n" \ - "\t.word %c2" "\t# bug_entry::flags\n" \ - "\t.org 2b+%c3\n" \ + "\t" __BUG_FUNC_PTR "\t# bug_entry::function\n" \ + "\t.word %c2" "\t# bug_entry::line\n" \ + "\t.word %c3" "\t# bug_entry::flags\n" \ + "\t.org 2b+%c4\n" \ ".popsection\n" \ extra \ - : : "i" (__FILE__), "i" (__LINE__), \ + : : "i" (__FILE__), "i" (__BUG_FUNC), "i" (__LINE__),\ "i" (flags), \ "i" (sizeof(struct bug_entry))); \ } while (0) @@ -92,7 +102,8 @@ do { \ do { \ __auto_type __flags = BUGFLAG_WARNING|(flags); \ instrumentation_begin(); \ - _BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE(1b)); \ + if (!KUNIT_IS_SUPPRESSED_WARNING(__func__)) \ + _BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE(1b)); \ instrumentation_end(); \ } while (0)

From: Guenter Roeck linux@roeck-us.net

Add name of functions triggering warning backtraces to the __bug_table object section to enable support for suppressing WARNING backtraces.

To limit image size impact, the pointer to the function name is only added to the __bug_table section if both CONFIG_KUNIT_SUPPRESS_BACKTRACE and CONFIG_DEBUG_BUGVERBOSE are enabled. Otherwise, the __func__ assembly parameter is replaced with a (dummy) NULL parameter to avoid an image size increase due to unused __func__ entries (this is necessary because __func__ is not a define but a virtual variable).

While at it, declare assembler parameters as constants where possible. Refine .blockz instructions to calculate the necessary padding instead of using fixed values.

Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Acked-by: Helge Deller deller@gmx.de Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Alessandro Carminati acarmina@redhat.com --- arch/parisc/include/asm/bug.h | 29 +++++++++++++++++++++-------- 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/parisc/include/asm/bug.h b/arch/parisc/include/asm/bug.h index 833555f74ffa..b59c3f7380bf 100644 --- a/arch/parisc/include/asm/bug.h +++ b/arch/parisc/include/asm/bug.h @@ -23,8 +23,17 @@ # define __BUG_REL(val) ".word " __stringify(val) #endif

- #ifdef CONFIG_DEBUG_BUGVERBOSE + +#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE +# define HAVE_BUG_FUNCTION +# define __BUG_FUNC_PTR __BUG_REL(%c1) +# define __BUG_FUNC __func__ +#else +# define __BUG_FUNC_PTR +# define __BUG_FUNC NULL +#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ + #define BUG() \ do { \ asm volatile("\n" \ @@ -33,10 +42,12 @@ "\t.align 4\n" \ "2:\t" __BUG_REL(1b) "\n" \ "\t" __BUG_REL(%c0) "\n" \ - "\t.short %1, %2\n" \ - "\t.blockz %3-2*4-2*2\n" \ + "\t" __BUG_FUNC_PTR "\n" \ + "\t.short %c2, %c3\n" \ + "\t.blockz %c4-(.-2b)\n" \ "\t.popsection" \ - : : "i" (__FILE__), "i" (__LINE__), \ + : : "i" (__FILE__), "i" (__BUG_FUNC), \ + "i" (__LINE__), \ "i" (0), "i" (sizeof(struct bug_entry)) ); \ unreachable(); \ } while(0) @@ -58,10 +69,12 @@ "\t.align 4\n" \ "2:\t" __BUG_REL(1b) "\n" \ "\t" __BUG_REL(%c0) "\n" \ - "\t.short %1, %2\n" \ - "\t.blockz %3-2*4-2*2\n" \ + "\t" __BUG_FUNC_PTR "\n" \ + "\t.short %c2, %3\n" \ + "\t.blockz %c4-(.-2b)\n" \ "\t.popsection" \ - : : "i" (__FILE__), "i" (__LINE__), \ + : : "i" (__FILE__), "i" (__BUG_FUNC), \ + "i" (__LINE__), \ "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry)) ); \ } while(0) @@ -74,7 +87,7 @@ "\t.align 4\n" \ "2:\t" __BUG_REL(1b) "\n" \ "\t.short %0\n" \ - "\t.blockz %1-4-2\n" \ + "\t.blockz %c1-(.-2b)\n" \ "\t.popsection" \ : : "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry)) ); \

From: Guenter Roeck linux@roeck-us.net

Add name of functions triggering warning backtraces to the __bug_table object section to enable support for suppressing WARNING backtraces.

To limit image size impact, the pointer to the function name is only added to the __bug_table section if both CONFIG_KUNIT_SUPPRESS_BACKTRACE and CONFIG_DEBUG_BUGVERBOSE are enabled. Otherwise, the __func__ assembly parameter is replaced with a (dummy) NULL parameter to avoid an image size increase due to unused __func__ entries (this is necessary because __func__ is not a define but a virtual variable).

Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Cc: Yoshinori Sato ysato@users.sourceforge.jp Cc: Rich Felker dalias@libc.org Cc: John Paul Adrian Glaubitz glaubitz@physik.fu-berlin.de Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Alessandro Carminati acarmina@redhat.com --- arch/sh/include/asm/bug.h | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/sh/include/asm/bug.h b/arch/sh/include/asm/bug.h index 05a485c4fabc..470ce6567d20 100644 --- a/arch/sh/include/asm/bug.h +++ b/arch/sh/include/asm/bug.h @@ -24,21 +24,36 @@ * The offending file and line are encoded in the __bug_table section. */ #ifdef CONFIG_DEBUG_BUGVERBOSE + +#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE +# define HAVE_BUG_FUNCTION +# define __BUG_FUNC_PTR "\t.long %O2\n" +#else +# define __BUG_FUNC_PTR +#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ + #define _EMIT_BUG_ENTRY \ "\t.pushsection __bug_table,"aw"\n" \ "2:\t.long 1b, %O1\n" \ - "\t.short %O2, %O3\n" \ - "\t.org 2b+%O4\n" \ + __BUG_FUNC_PTR \ + "\t.short %O3, %O4\n" \ + "\t.org 2b+%O5\n" \ "\t.popsection\n" #else #define _EMIT_BUG_ENTRY \ "\t.pushsection __bug_table,"aw"\n" \ "2:\t.long 1b\n" \ - "\t.short %O3\n" \ - "\t.org 2b+%O4\n" \ + "\t.short %O4\n" \ + "\t.org 2b+%O5\n" \ "\t.popsection\n" #endif

+#ifdef HAVE_BUG_FUNCTION +# define __BUG_FUNC __func__ +#else +# define __BUG_FUNC NULL +#endif + #define BUG() \ do { \ __asm__ __volatile__ ( \ @@ -47,6 +62,7 @@ do { \ : \ : "n" (TRAPA_BUG_OPCODE), \ "i" (__FILE__), \ + "i" (__BUG_FUNC), \ "i" (__LINE__), "i" (0), \ "i" (sizeof(struct bug_entry))); \ unreachable(); \ @@ -60,6 +76,7 @@ do { \ : \ : "n" (TRAPA_BUG_OPCODE), \ "i" (__FILE__), \ + "i" (__BUG_FUNC), \ "i" (__LINE__), \ "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry))); \ @@ -85,6 +102,7 @@ do { \ : \ : "n" (TRAPA_BUG_OPCODE), \ "i" (__FILE__), \ + "i" (__BUG_FUNC), \ "i" (__LINE__), \ "i" (BUGFLAG_UNWINDER), \ "i" (sizeof(struct bug_entry))); \

From: Guenter Roeck linux@roeck-us.net

Add name of functions triggering warning backtraces to the __bug_table object section to enable support for suppressing WARNING backtraces.

To limit image size impact, the pointer to the function name is only added to the __bug_table section if both CONFIG_KUNIT_SUPPRESS_BACKTRACE and CONFIG_DEBUG_BUGVERBOSE are enabled. Otherwise, the __func__ assembly parameter is replaced with a (dummy) NULL parameter to avoid an image size increase due to unused __func__ entries (this is necessary because __func__ is not a define but a virtual variable).

To simplify the implementation, unify the __BUG_ENTRY_ADDR and __BUG_ENTRY_FILE macros into a single macro named __BUG_REL() which takes the address, file, or function reference as parameter.

Tested-by: Linux Kernel Functional Testing lkft@linaro.org Acked-by: Dan Carpenter dan.carpenter@linaro.org Cc: Paul Walmsley paul.walmsley@sifive.com Cc: Palmer Dabbelt palmer@dabbelt.com Cc: Albert Ou aou@eecs.berkeley.edu Signed-off-by: Guenter Roeck linux@roeck-us.net Reviewed-by: Charlie Jenkins charlie@rivosinc.com Signed-off-by: Alessandro Carminati acarmina@redhat.com --- arch/riscv/include/asm/bug.h | 38 ++++++++++++++++++++++++------------ 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h index 1aaea81fb141..79f360af4ad8 100644 --- a/arch/riscv/include/asm/bug.h +++ b/arch/riscv/include/asm/bug.h @@ -30,26 +30,39 @@ typedef u32 bug_insn_t;

#ifdef CONFIG_GENERIC_BUG_RELATIVE_POINTERS -#define __BUG_ENTRY_ADDR RISCV_INT " 1b - ." -#define __BUG_ENTRY_FILE RISCV_INT " %0 - ." +#define __BUG_REL(val) RISCV_INT " " __stringify(val) " - ." #else -#define __BUG_ENTRY_ADDR RISCV_PTR " 1b" -#define __BUG_ENTRY_FILE RISCV_PTR " %0" +#define __BUG_REL(val) RISCV_PTR " " __stringify(val) #endif

#ifdef CONFIG_DEBUG_BUGVERBOSE + +#ifdef CONFIG_KUNIT_SUPPRESS_BACKTRACE +# define HAVE_BUG_FUNCTION +# define __BUG_FUNC_PTR __BUG_REL(%1) +#else +# define __BUG_FUNC_PTR +#endif /* CONFIG_KUNIT_SUPPRESS_BACKTRACE */ + #define __BUG_ENTRY \ - __BUG_ENTRY_ADDR "\n\t" \ - __BUG_ENTRY_FILE "\n\t" \ - RISCV_SHORT " %1\n\t" \ - RISCV_SHORT " %2" + __BUG_REL(1b) "\n\t" \ + __BUG_REL(%0) "\n\t" \ + __BUG_FUNC_PTR "\n\t" \ + RISCV_SHORT " %2\n\t" \ + RISCV_SHORT " %3" #else #define __BUG_ENTRY \ - __BUG_ENTRY_ADDR "\n\t" \ - RISCV_SHORT " %2" + __BUG_REL(1b) "\n\t" \ + RISCV_SHORT " %3" #endif

#ifdef CONFIG_GENERIC_BUG +#ifdef HAVE_BUG_FUNCTION +# define __BUG_FUNC __func__ +#else +# define __BUG_FUNC NULL +#endif + #define __BUG_FLAGS(flags) \ do { \ __asm__ __volatile__ ( \ @@ -58,10 +71,11 @@ do { \ ".pushsection __bug_table,"aw"\n\t" \ "2:\n\t" \ __BUG_ENTRY "\n\t" \ - ".org 2b + %3\n\t" \ + ".org 2b + %4\n\t" \ ".popsection" \ : \ - : "i" (__FILE__), "i" (__LINE__), \ + : "i" (__FILE__), "i" (__BUG_FUNC), \ + "i" (__LINE__), \ "i" (flags), \ "i" (sizeof(struct bug_entry))); \ } while (0)