// SPDX-License-Identifier: GPL-2.0 /* * EFI capsule support. * * Copyright 2013 Intel Corporation; author Matt Fleming */ #define pr_fmt(fmt) … #include <linux/slab.h> #include <linux/mutex.h> #include <linux/highmem.h> #include <linux/efi.h> #include <linux/vmalloc.h> #include <asm/efi.h> #include <asm/io.h> efi_capsule_block_desc_t; static bool capsule_pending; static bool stop_capsules; static int efi_reset_type = …; /* * capsule_mutex serialises access to both capsule_pending and * efi_reset_type and stop_capsules. */ static DEFINE_MUTEX(capsule_mutex); /** * efi_capsule_pending - has a capsule been passed to the firmware? * @reset_type: store the type of EFI reset if capsule is pending * * To ensure that the registered capsule is processed correctly by the * firmware we need to perform a specific type of reset. If a capsule is * pending return the reset type in @reset_type. * * This function will race with callers of efi_capsule_update(), for * example, calling this function while somebody else is in * efi_capsule_update() but hasn't reached efi_capsue_update_locked() * will miss the updates to capsule_pending and efi_reset_type after * efi_capsule_update_locked() completes. * * A non-racy use is from platform reboot code because we use * system_state to ensure no capsules can be sent to the firmware once * we're at SYSTEM_RESTART. See efi_capsule_update_locked(). */ bool efi_capsule_pending(int *reset_type) { … } /* * Whitelist of EFI capsule flags that we support. * * We do not handle EFI_CAPSULE_INITIATE_RESET because that would * require us to prepare the kernel for reboot. Refuse to load any * capsules with that flag and any other flags that we do not know how * to handle. */ #define EFI_CAPSULE_SUPPORTED_FLAG_MASK … /** * efi_capsule_supported - does the firmware support the capsule? * @guid: vendor guid of capsule * @flags: capsule flags * @size: size of capsule data * @reset: the reset type required for this capsule * * Check whether a capsule with @flags is supported by the firmware * and that @size doesn't exceed the maximum size for a capsule. * * No attempt is made to check @reset against the reset type required * by any pending capsules because of the races involved. */ int efi_capsule_supported(efi_guid_t guid, u32 flags, size_t size, int *reset) { … } EXPORT_SYMBOL_GPL(…); /* * Every scatter gather list (block descriptor) page must end with a * continuation pointer. The last continuation pointer of the last * page must be zero to mark the end of the chain. */ #define SGLIST_PER_PAGE … /* * How many scatter gather list (block descriptor) pages do we need * to map @count pages? */ static inline unsigned int sg_pages_num(unsigned int count) { … } /** * efi_capsule_update_locked - pass a single capsule to the firmware * @capsule: capsule to send to the firmware * @sg_pages: array of scatter gather (block descriptor) pages * @reset: the reset type required for @capsule * * Since this function must be called under capsule_mutex check * whether efi_reset_type will conflict with @reset, and atomically * set it and capsule_pending if a capsule was successfully sent to * the firmware. * * We also check to see if the system is about to restart, and if so, * abort. This avoids races between efi_capsule_update() and * efi_capsule_pending(). */ static int efi_capsule_update_locked(efi_capsule_header_t *capsule, struct page **sg_pages, int reset) { … } /** * efi_capsule_update - send a capsule to the firmware * @capsule: capsule to send to firmware * @pages: an array of capsule data pages * * Build a scatter gather list with EFI capsule block descriptors to * map the capsule described by @capsule with its data in @pages and * send it to the firmware via the UpdateCapsule() runtime service. * * @capsule must be a virtual mapping of the complete capsule update in the * kernel address space, as the capsule can be consumed immediately. * A capsule_header_t that describes the entire contents of the capsule * must be at the start of the first data page. * * Even though this function will validate that the firmware supports * the capsule guid, users will likely want to check that * efi_capsule_supported() returns true before calling this function * because it makes it easier to print helpful error messages. * * If the capsule is successfully submitted to the firmware, any * subsequent calls to efi_capsule_pending() will return true. @pages * must not be released or modified if this function returns * successfully. * * Callers must be prepared for this function to fail, which can * happen if we raced with system reboot or if there is already a * pending capsule that has a reset type that conflicts with the one * required by @capsule. Do NOT use efi_capsule_pending() to detect * this conflict since that would be racy. Instead, submit the capsule * to efi_capsule_update() and check the return value. * * Return 0 on success, a converted EFI status code on failure. */ int efi_capsule_update(efi_capsule_header_t *capsule, phys_addr_t *pages) { … } EXPORT_SYMBOL_GPL(…); static int capsule_reboot_notify(struct notifier_block *nb, unsigned long event, void *cmd) { … } static struct notifier_block capsule_reboot_nb = …; static int __init capsule_reboot_register(void) { … } core_initcall(capsule_reboot_register);
Codebase Browser
linux