Re: [PATCH v2 4/6] panic: Consolidate open-coded panic_on_warn checks

Marco Elver
2022-11-14T09:57:54Z

On Wed, 9 Nov 2022 at 21:00, Kees Cook <keescook@chromium.org> wrote:
>
> Several run-time checkers (KASAN, UBSAN, KFENCE, KCSAN, sched) roll
> their own warnings, and each check "panic_on_warn". Consolidate this
> into a single function so that future instrumentation can be added in
> a single location.
>
> Cc: Marco Elver <elver@google.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Juri Lelli <juri.lelli@redhat.com>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Ben Segall <bsegall@google.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
> Cc: Valentin Schneider <vschneid@redhat.com>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Luis Chamberlain <mcgrof@kernel.org>
> Cc: David Gow <davidgow@google.com>
> Cc: tangmeng <tangmeng@uniontech.com>
> Cc: Jann Horn <jannh@google.com>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: "Paul E. McKenney" <paulmck@kernel.org>
> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
> Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
> Cc: kasan-dev@googlegroups.com
> Cc: linux-mm@kvack.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> include/linux/panic.h | 1 +
> kernel/kcsan/report.c | 3 +--
> kernel/panic.c | 9 +++++++--
> kernel/sched/core.c | 3 +--
> lib/ubsan.c | 3 +--
> mm/kasan/report.c | 4 ++--
> mm/kfence/report.c | 3 +--
> 7 files changed, 14 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/panic.h b/include/linux/panic.h
> index c7759b3f2045..1702aeb74927 100644
> --- a/include/linux/panic.h
> +++ b/include/linux/panic.h
> @@ -11,6 +11,7 @@ extern long (*panic_blink)(int state);
> __printf(1, 2)
> void panic(const char *fmt, ...) __noreturn __cold;
> void nmi_panic(struct pt_regs *regs, const char *msg);
> +void check_panic_on_warn(const char *reason);
> extern void oops_enter(void);
> extern void oops_exit(void);
> extern bool oops_may_print(void);
> diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c
> index 67794404042a..e95ce7d7a76e 100644
> --- a/kernel/kcsan/report.c
> +++ b/kernel/kcsan/report.c
> @@ -492,8 +492,7 @@ static void print_report(enum kcsan_value_change value_change,
> dump_stack_print_info(KERN_DEFAULT);
> pr_err("==================================================================\n");
>
> - if (panic_on_warn)
> - panic("panic_on_warn set ...\n");
> + check_panic_on_warn("KCSAN");
> }
>
> static void release_report(unsigned long *flags, struct other_info *other_info)
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 129936511380..3afd234767bc 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -201,6 +201,12 @@ static void panic_print_sys_info(bool console_flush)
> ftrace_dump(DUMP_ALL);
> }
>
> +void check_panic_on_warn(const char *reason)
> +{
> + if (panic_on_warn)
> + panic("%s: panic_on_warn set ...\n", reason);
> +}
> +
> /**
> * panic - halt the system
> * @fmt: The text string to print
> @@ -619,8 +625,7 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
> if (regs)
> show_regs(regs);
>
> - if (panic_on_warn)
> - panic("panic_on_warn set ...\n");
> + check_panic_on_warn("kernel");

What is the reason "kernel" in this context? The real reason is a WARN
- so would the reason "WARNING" be more intuitive?