From patchwork Fri May 20 19:50:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Guilherme G. Piccoli" X-Patchwork-Id: 574677 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22B1AC433EF for ; Fri, 20 May 2022 19:52:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353316AbiETTwf (ORCPT ); Fri, 20 May 2022 15:52:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353342AbiETTwd (ORCPT ); Fri, 20 May 2022 15:52:33 -0400 Received: from fanzine2.igalia.com (fanzine.igalia.com [178.60.130.6]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A841519C38A; Fri, 20 May 2022 12:52:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=sN/LpPLdT2mbsP7DF3PDcCREB6oSMVQAq5zqlYlmSbg=; b=jkPDL8A4W/pvGUu0xaZAVxejzh rwNPL/9VrA1vhD5VyCfsIbOG+DQhTNF8A90elI7Qkp0XkK9VmorpU7gxvAnHbQKjcGIfrklkj5zEl ID7zK9z4VhTn/P+dbjGNQZaSrsE2l1M2cZG7iaCCc/cGjWpmdEdN2Gkr8hroisd1vaIpuMRPH+blg QJfkh6mQu71Il4vr7Ydq8HgS6gs0qQ1YNUMgnMXWZ1IPbg/YVlz5yB5a5Yhnhl9G2cDWaDr18kE7q KSQ9vE5/5BQO2DUbeIQ1uUKfD+1nrSUWYL9cq1Ujyb80oOCd7IdS6ipvqEjT0yLqWOiDGd8doERdy Hcf8QoQg==; Received: from 200-161-159-120.dsl.telesp.net.br ([200.161.159.120] helo=localhost) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_SECP256R1__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1ns8fm-00D3rs-3e; Fri, 20 May 2022 21:52:30 +0200 From: "Guilherme G. Piccoli" To: ardb@kernel.org, linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-dev@igalia.com, kernel@gpiccoli.net, anton@enomsg.org, ccross@android.com, keescook@chromium.org, matt@codeblueprint.co.uk, matthew.garrett@nebula.com, tony.luck@intel.com, "Guilherme G. Piccoli" Subject: [PATCH 2/2] efi-panic: Introduce the UEFI panic notification module Date: Fri, 20 May 2022 16:50:28 -0300 Message-Id: <20220520195028.1347426-3-gpiccoli@igalia.com> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220520195028.1347426-1-gpiccoli@igalia.com> References: <20220520195028.1347426-1-gpiccoli@igalia.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org Despite we have pstore, kdump and other panic-time mechanisms, there's no generic way to let the firmware know a panic event happened. Some hypervisors might have special code for that, but that's not generic. The UEFI panic notification module hereby proposed aims to fill this need: once we face a panic, through the panic notifier infrastructure we set a UEFI variable named PanicWarn with a value - default is 0xFF, but it's adjustable via module parameter. The firmware is then enabled to take a proper action. The module also let the users know that last execution likely panicked if the UEFI variable is present on module load - then it clears that to avoid confusing users, only the last panic event is recorded. Signed-off-by: Guilherme G. Piccoli --- drivers/firmware/efi/Kconfig | 10 ++++ drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/efi-panic.c | 97 ++++++++++++++++++++++++++++++++ include/linux/efi.h | 1 + 4 files changed, 109 insertions(+) create mode 100644 drivers/firmware/efi/efi-panic.c diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index 2c3dac5ecb36..12f2d963333e 100644 --- a/drivers/firmware/efi/Kconfig +++ b/drivers/firmware/efi/Kconfig @@ -145,6 +145,16 @@ config EFI_BOOTLOADER_CONTROL bootloader reads this reboot reason and takes particular action according to its policy. +config EFI_PANIC_NOTIFIER + tristate "UEFI Panic Notifier" + depends on EFI + default n + help + With this module, kernel creates the UEFI variable "PanicWarn" if + the system faces a panic event. With that, the firmware is entitled + to take an action if the last kernel panicked; it also shows a + message during boot time if last run faced a panic event. + config EFI_CAPSULE_LOADER tristate "EFI capsule loader" depends on EFI && !IA64 diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index c02ff25dd477..abbc7d9af2da 100644 --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile @@ -26,6 +26,7 @@ obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o subdir-$(CONFIG_EFI_STUB) += libstub obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_map.o obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o +obj-$(CONFIG_EFI_PANIC_NOTIFIER) += efi-panic.o obj-$(CONFIG_EFI_TEST) += test/ obj-$(CONFIG_EFI_DEV_PATH_PARSER) += dev-path-parser.o obj-$(CONFIG_APPLE_PROPERTIES) += apple-properties.o diff --git a/drivers/firmware/efi/efi-panic.c b/drivers/firmware/efi/efi-panic.c new file mode 100644 index 000000000000..c59655e22fc7 --- /dev/null +++ b/drivers/firmware/efi/efi-panic.c @@ -0,0 +1,97 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * efi-panic: UEFI panic notification mechanism + */ + +#define pr_fmt(fmt) "efi-panic: " fmt + +#include +#include +#include +#include + +#define EFI_PANIC_ATTR (EFI_VARIABLE_NON_VOLATILE |\ + EFI_VARIABLE_BOOTSERVICE_ACCESS |\ + EFI_VARIABLE_RUNTIME_ACCESS) + +#define EFI_DATA_SIZE (2 * sizeof(efi_char16_t)) + +static struct efivar_entry *entry; + +static u8 panic_warn_val = 0xFF; +module_param(panic_warn_val, byte, 0644); +MODULE_PARM_DESC(panic_warn_val, + "Value written to PanicWarn efivar on panic event [default=0xFF]"); + +static int efi_panic_cb(struct notifier_block *nb, unsigned long ev, + void *unused) +{ + int ret; + + efi_str8_to_str16((efi_char16_t *)entry->var.Data, &panic_warn_val, 1); + ret = efivar_entry_set_safe(entry->var.VariableName, + entry->var.VendorGuid, + EFI_PANIC_ATTR, false, EFI_DATA_SIZE, + entry->var.Data); + if (ret) + pr_err("failed to notify panic to UEFI\n"); + + return NOTIFY_DONE; +} + +static struct notifier_block efi_panic_notifier = { + .notifier_call = efi_panic_cb, +}; + +static int __init efi_panic_init(void) +{ + efi_guid_t guid = LINUX_EFI_PANIC_WARN_GUID; + unsigned long sz = EFI_DATA_SIZE; + const char *name = "PanicWarn"; + u8 data[EFI_DATA_SIZE]; + int err; + + if (!efivars_kobject() || !efivar_supports_writes()) { + pr_err("UEFI vars not available (or not writable)\n"); + return -ENODEV; + } + + entry = kzalloc(sizeof(*entry), GFP_KERNEL); + if (!entry) + return -ENOMEM; + + memcpy(&entry->var.VendorGuid, &guid, sizeof(guid)); + efi_str8_to_str16(entry->var.VariableName, name, strlen(name)); + + err = efivar_entry_get(entry, NULL, &sz, (void *)data); + + if (!err) { + pr_info("previous kernel (likely) had a panic\n"); + + if (__efivar_entry_delete(entry)) + pr_err("cannot delete %s UEFI variable\n", name); + + memset(entry->var.Data, 0, EFI_DATA_SIZE); + } else { + if (err != -ENOENT) + pr_err("can't read the UEFI variables (err=%d)\n", err); + } + + atomic_notifier_chain_register(&panic_notifier_list, + &efi_panic_notifier); + + return 0; +} +module_init(efi_panic_init); + +static void __exit efi_panic_exit(void) +{ + atomic_notifier_chain_unregister(&panic_notifier_list, + &efi_panic_notifier); + kfree(entry); +} +module_exit(efi_panic_exit); + +MODULE_AUTHOR("Guilherme G. Piccoli "); +MODULE_DESCRIPTION("UEFI Panic Notification Mechanism"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/efi.h b/include/linux/efi.h index 066ebc5bcb2a..4219f3d44183 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -365,6 +365,7 @@ void efi_native_runtime_setup(void); #define EFI_GLOBAL_VARIABLE_GUID EFI_GUID(0x8be4df61, 0x93ca, 0x11d2, 0xaa, 0x0d, 0x00, 0xe0, 0x98, 0x03, 0x2b, 0x8c) #define UV_SYSTEM_TABLE_GUID EFI_GUID(0x3b13a7d4, 0x633e, 0x11dd, 0x93, 0xec, 0xda, 0x25, 0x56, 0xd8, 0x95, 0x93) #define LINUX_EFI_CRASH_GUID EFI_GUID(0xcfc8fc79, 0xbe2e, 0x4ddc, 0x97, 0xf0, 0x9f, 0x98, 0xbf, 0xe2, 0x98, 0xa0) +#define LINUX_EFI_PANIC_WARN_GUID EFI_GUID(0x9e85b665, 0x08d4, 0x42c9, 0x83, 0x24, 0x47, 0xed, 0x5f, 0xe5, 0x0b, 0xf3) #define LOADED_IMAGE_PROTOCOL_GUID EFI_GUID(0x5b1b31a1, 0x9562, 0x11d2, 0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b) #define EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID EFI_GUID(0x9042a9de, 0x23dc, 0x4a38, 0x96, 0xfb, 0x7a, 0xde, 0xd0, 0x80, 0x51, 0x6a) #define EFI_UGA_PROTOCOL_GUID EFI_GUID(0x982c298b, 0xf4fa, 0x41cb, 0xb8, 0x38, 0x77, 0xaa, 0x68, 0x8f, 0xb8, 0x39)