From nobody Sun Feb 8 04:13:26 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 74D11214A8A for ; Mon, 28 Apr 2025 23:45:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745883923; cv=none; b=sr8YFdfjf7SNMU5VdWSmq8WqAL5jwcp1P5JS3cZ6EjZkWCWKZ/IgmrLeC4ZwrCMOPrvoqZCdUnOP2H1hCmfvUma/gQiKmReBVh7kwldCXlFT6iJYK8beZTYwccfJKkAtQW6fR+dRx69dN0fxP5qwZxz3F5RR8XKzvvIOuho6Urs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745883923; c=relaxed/simple; bh=FSacFZ9dJEJb48n63iZ9igxm6yKlAmEtqNgt/zpRG9Y=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Jh156/5g47VxusJYfp7SC9OPZQj6v5v4WRs2yiO6oagqg7uy/PvUzkzZ//xmLF5iMi7aF7AXS2HQx6mscrXJWVFdvjC8ob4lwST1YdOks0AKn/0S/ZxcQ7nwU/6sAp53Dm2OPZFu+YdePb5DZ+Kh714Vhi9bm4PZIsFJjLELABk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aZTTdgst; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aZTTdgst" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DCF4DC4CEE4; Mon, 28 Apr 2025 23:45:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745883922; bh=FSacFZ9dJEJb48n63iZ9igxm6yKlAmEtqNgt/zpRG9Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aZTTdgstcIuA6N29aq6tPoqKxXOJmtG+fEJvSm4My/XkMoneh9Ql8YrAHQQLxsMvO rnN18S8h6FQylxo47nxWwEVlgtZ/SxrNrOGFh0XKWtW7G0Kbe9OwsoDEaW1HAoWmOO w0RByRiByfcfMegHT8px7Khd7e+JrzTC4uO+GLOYNGQ4rR8kDMfUcd6ZEtcApIZZbx 85tN+nIblTKIHz1mv7WybbjUpVz8AOu+XmBZqn6x/SXLiSgIj5ItPGNfOjaaOjL12U T8kYUE5WbA6agtupbriX3HJz1tX1mOCc8huq0l8wfYKlrt5Gk8Hj/Xde5woYT2T/6Y WwawAxceDs6CQ== From: carlos.bilbao@kernel.org To: tglx@linutronix.de, seanjc@google.com, jan.glauber@gmail.com Cc: bilbao@vt.edu, pmladek@suse.com, akpm@linux-foundation.org, jani.nikula@intel.com, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, takakura@valinux.co.jp, john.ogness@linutronix.de, Carlos Bilbao Subject: [PATCH v2 1/2] panic: Allow for dynamic custom behavior after panic Date: Mon, 28 Apr 2025 16:59:51 -0500 Message-ID: <20250428215952.1332985-2-carlos.bilbao@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250428215952.1332985-1-carlos.bilbao@kernel.org> References: <20250428215952.1332985-1-carlos.bilbao@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Carlos Bilbao Introduce panic_set_handling() to allow overriding the default post-panic behavior. Signed-off-by: Carlos Bilbao (DigitalOcean) --- include/linux/panic.h | 2 ++ kernel/panic.c | 27 +++++++++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/include/linux/panic.h b/include/linux/panic.h index 2494d51707ef..cf8d4a944407 100644 --- a/include/linux/panic.h +++ b/include/linux/panic.h @@ -98,4 +98,6 @@ extern void add_taint(unsigned flag, enum lockdep_ok); extern int test_taint(unsigned flag); extern unsigned long get_taint(void); =20 +void panic_set_handling(void (*fn)(void), int priority); + #endif /* _LINUX_PANIC_H */ diff --git a/kernel/panic.c b/kernel/panic.c index a3889f38153d..2cdd83b4afb6 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -276,6 +276,30 @@ static void panic_other_cpus_shutdown(bool crash_kexec) crash_smp_send_stop(); } =20 +/* + * This is the default function called after a kernel panic has been + * handled. Higher priority alternatives can be set with function + * panic_set_handling() + * + */ +static void after_panic_handling(void) +{ + mdelay(PANIC_TIMER_STEP); +} + +static void (*panic_halt)(void) =3D after_panic_handling; +static int panic_hlt_priority; + +void panic_set_handling(void (*fn)(void), int priority) +{ + if (priority <=3D panic_hlt_priority) + return; + + panic_hlt_priority =3D priority; + panic_halt =3D fn; +} +EXPORT_SYMBOL_GPL(panic_set_handling); + /** * panic - halt the system * @fmt: The text string to print @@ -467,6 +491,9 @@ void panic(const char *fmt, ...) console_flush_on_panic(CONSOLE_FLUSH_PENDING); nbcon_atomic_flush_unsafe(); =20 + if (panic_halt) + panic_halt(); + local_irq_enable(); for (i =3D 0; ; i +=3D PANIC_TIMER_STEP) { touch_softlockup_watchdog(); --=20 2.47.1 From nobody Sun Feb 8 04:13:26 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 32CC8215073 for ; Mon, 28 Apr 2025 23:45:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745883925; cv=none; b=EWDFrKp+f7HlhXJGjfvp/WeeHH8prH0Dc44BCB5zgFso2Ualj9eHWLY2FM161PUzatxg3ecR8A/uL8ySg6X73m760uFsf27gdlPVInxv9UNXnvMhK+X7+ISvAHdauRgYbS2TiQl1ic3fJfJuSy54XfIHlG0o9wpikHD6gSYIqFE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745883925; c=relaxed/simple; bh=HGh6UoyV9o1OozQau9FxeVCn04i8eEsHlhqP5cfL5L8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LJfn2/IKpdHvSHI2XtxeAmaO7GysmHlFmt65GoD22gtlXZd3w8F94tU4ExdExPu0q+a5XFRy/g04GDMCVujUOrh50M7f5ISNHSJgosT5mkzzYSgdEOJ4afoDvc/fXMrfHE2N0eSXCHJ/FnyQRspyAdLkWu2g2xJwAbI3aWLutoU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EfKHgSJz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EfKHgSJz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B770C4CEEA; Mon, 28 Apr 2025 23:45:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745883924; bh=HGh6UoyV9o1OozQau9FxeVCn04i8eEsHlhqP5cfL5L8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EfKHgSJzbhlUMH04Y7HbnPoF3Mwr5dDp4Xbaq6hjK9zd0t811PJdO+YPTz6Rt3PQn 1n5Zqi168uPefCmTfg9Ox/SFGNzqy0fZWpN/UBTP/KCn9WLcQF0ntFogQJXLE2rZtX 4Gs5wLkd56dui5jY/5FI3hNscOiHPSUW7Mg8ySU7BSyl9vvYRrExytwhFauTT+KoXP cfP0YUwI9vGP1B5QW1WB5gdnrY0Ag8J+qkoZFCaWLhJvhmJxOs2NwANVMyR7K7QQF4 h7VgssZdNK/6evgn6YjlTFDnoctdyWMe/Or4vXd/9jQJLuNZb5YlNT5qWm76kS5AVD foSDZTw/DeaFQ== From: carlos.bilbao@kernel.org To: tglx@linutronix.de, seanjc@google.com, jan.glauber@gmail.com Cc: bilbao@vt.edu, pmladek@suse.com, akpm@linux-foundation.org, jani.nikula@intel.com, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, takakura@valinux.co.jp, john.ogness@linutronix.de, Carlos Bilbao Subject: [PATCH v2 2/2] x86/panic: Add x86_panic_handler as default post-panic behavior Date: Mon, 28 Apr 2025 16:59:52 -0500 Message-ID: <20250428215952.1332985-3-carlos.bilbao@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250428215952.1332985-1-carlos.bilbao@kernel.org> References: <20250428215952.1332985-1-carlos.bilbao@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Carlos Bilbao Add function x86_panic_handler() as the default behavior for x86 for post-panic stage via panic_set_handling(). Instead of busy-wait loop, it will halt if there's no console to save CPU cycles. Signed-off-by: Carlos Bilbao (DigitalOcean) --- arch/x86/kernel/setup.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 9d2a13b37833..3bfef55e9adb 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -16,6 +16,7 @@ #include #include #include +#include #include #include #include @@ -837,6 +838,15 @@ static void __init x86_report_nx(void) } } =20 + +static void x86_panic_handler(void) +{ + if (console_trylock()) { + console_unlock(); + safe_halt(); + } +} + /* * Determine if we were loaded by an EFI loader. If so, then we have also= been * passed the efi memmap, systab, etc., so we should use these data struct= ures @@ -1252,6 +1262,8 @@ void __init setup_arch(char **cmdline_p) #endif =20 unwind_init(); + + panic_set_handling(x86_panic_handler, 1); } =20 #ifdef CONFIG_X86_32 --=20 2.47.1