From: Matt Fleming <m...@codeblueprint.co.uk> commit f0133f3c5b8bb34ec4dec50c27e7a655aeee8935 upstream.
The EFI capsule mechanism allows data blobs to be passed to the EFI firmware. A common use case is performing firmware updates. This patch just introduces the main infrastructure for interacting with the firmware, and a driver that allows users to upload capsules will come in a later patch. Once a capsule has been passed to the firmware, the next reboot must be performed using the ResetSystem() EFI runtime service, which may involve overriding the reboot type specified by reboot=. This ensures the reset value returned by QueryCapsuleCapabilities() is used to reset the system, which is required for the capsule to be processed. efi_capsule_pending() is provided for this purpose. At the moment we only allow a single capsule blob to be sent to the firmware despite the fact that UpdateCapsule() takes a 'CapsuleCount' parameter. This simplifies the API and shouldn't result in any downside since it is still possible to send multiple capsules by repeatedly calling UpdateCapsule(). Signed-off-by: Matt Fleming <m...@codeblueprint.co.uk> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Borislav Petkov <b...@alien8.de> Cc: Bryan O'Donoghue <pure.lo...@nexus-software.ie> Cc: Kweh Hock Leong <hock.leong.k...@intel.com> Cc: Mark Salter <msal...@redhat.com> Cc: Peter Jones <pjo...@redhat.com> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: joeyli <j...@suse.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1461614832-17633-28-git-send-email-m...@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mi...@kernel.org> --- drivers/firmware/efi/Makefile | 1 + drivers/firmware/efi/capsule.c | 300 +++++++++++++++++++++++++++++++++++++++++ drivers/firmware/efi/reboot.c | 12 +- include/linux/efi.h | 14 ++ 4 files changed, 326 insertions(+), 1 deletion(-) create mode 100644 drivers/firmware/efi/capsule.c diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile index ec379a4164cc..54b19cdbfcf8 100644 --- a/drivers/firmware/efi/Makefile +++ b/drivers/firmware/efi/Makefile @@ -10,6 +10,7 @@ KASAN_SANITIZE_runtime-wrappers.o := n obj-$(CONFIG_EFI) += efi.o vars.o reboot.o +obj-$(CONFIG_EFI) += capsule.o obj-$(CONFIG_EFI_VARS) += efivars.o obj-$(CONFIG_EFI_ESRT) += esrt.o obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o diff --git a/drivers/firmware/efi/capsule.c b/drivers/firmware/efi/capsule.c new file mode 100644 index 000000000000..0de55944ac0b --- /dev/null +++ b/drivers/firmware/efi/capsule.c @@ -0,0 +1,300 @@ +/* + * EFI capsule support. + * + * Copyright 2013 Intel Corporation; author Matt Fleming + * + * This file is part of the Linux kernel, and is made available under + * the terms of the GNU General Public License version 2. + */ + +#define pr_fmt(fmt) "efi: " fmt + +#include <linux/slab.h> +#include <linux/mutex.h> +#include <linux/highmem.h> +#include <linux/efi.h> +#include <linux/vmalloc.h> +#include <asm/io.h> + +typedef struct { + u64 length; + u64 data; +} efi_capsule_block_desc_t; + +static bool capsule_pending; +static int efi_reset_type = -1; + +/* + * capsule_mutex serialises access to both capsule_pending and + * efi_reset_type. + */ +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) +{ + bool rv = false; + + mutex_lock(&capsule_mutex); + if (!capsule_pending) + goto out; + + if (reset_type) + *reset_type = efi_reset_type; + rv = true; +out: + mutex_unlock(&capsule_mutex); + return rv; +} + +/* + * 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_PERSIST_ACROSS_RESET | EFI_CAPSULE_POPULATE_SYSTEM_TABLE) + +/** + * 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) +{ + efi_capsule_header_t *capsule; + efi_status_t status; + u64 max_size; + int rv = 0; + + if (flags & ~EFI_CAPSULE_SUPPORTED_FLAG_MASK) + return -EINVAL; + + capsule = kmalloc(sizeof(*capsule), GFP_KERNEL); + if (!capsule) + return -ENOMEM; + + capsule->headersize = capsule->imagesize = sizeof(*capsule); + memcpy(&capsule->guid, &guid, sizeof(efi_guid_t)); + capsule->flags = flags; + + status = efi.query_capsule_caps(&capsule, 1, &max_size, reset); + if (status != EFI_SUCCESS) { + rv = efi_status_to_err(status); + goto out; + } + + if (size > max_size) + rv = -ENOSPC; +out: + kfree(capsule); + return rv; +} +EXPORT_SYMBOL_GPL(efi_capsule_supported); + +/* + * 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 ((PAGE_SIZE / sizeof(efi_capsule_block_desc_t)) - 1) + +/* + * 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) +{ + return DIV_ROUND_UP(count, SGLIST_PER_PAGE); +} + +/** + * 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_physical_addr_t sglist_phys; + efi_status_t status; + + lockdep_assert_held(&capsule_mutex); + + /* + * If someone has already registered a capsule that requires a + * different reset type, we're out of luck and must abort. + */ + if (efi_reset_type >= 0 && efi_reset_type != reset) { + pr_err("Conflicting capsule reset type %d (%d).\n", + reset, efi_reset_type); + return -EINVAL; + } + + /* + * If the system is getting ready to restart it may have + * called efi_capsule_pending() to make decisions (such as + * whether to force an EFI reboot), and we're racing against + * that call. Abort in that case. + */ + if (unlikely(system_state == SYSTEM_RESTART)) { + pr_warn("Capsule update raced with reboot, aborting.\n"); + return -EINVAL; + } + + sglist_phys = page_to_phys(sg_pages[0]); + + status = efi.update_capsule(&capsule, 1, sglist_phys); + if (status == EFI_SUCCESS) { + capsule_pending = true; + efi_reset_type = reset; + } + + return efi_status_to_err(status); +} + +/** + * 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 first page in @pages + * (@pages[0]) in the kernel address space. That is, 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, struct page **pages) +{ + u32 imagesize = capsule->imagesize; + efi_guid_t guid = capsule->guid; + unsigned int count, sg_count; + u32 flags = capsule->flags; + struct page **sg_pages; + int rv, reset_type; + int i, j; + + rv = efi_capsule_supported(guid, flags, imagesize, &reset_type); + if (rv) + return rv; + + count = DIV_ROUND_UP(imagesize, PAGE_SIZE); + sg_count = sg_pages_num(count); + + sg_pages = kzalloc(sg_count * sizeof(*sg_pages), GFP_KERNEL); + if (!sg_pages) + return -ENOMEM; + + for (i = 0; i < sg_count; i++) { + sg_pages[i] = alloc_page(GFP_KERNEL); + if (!sg_pages[i]) { + rv = -ENOMEM; + goto out; + } + } + + for (i = 0; i < sg_count; i++) { + efi_capsule_block_desc_t *sglist; + + sglist = kmap(sg_pages[i]); + if (!sglist) { + rv = -ENOMEM; + goto out; + } + + for (j = 0; j < SGLIST_PER_PAGE && count > 0; j++) { + u64 sz = min_t(u64, imagesize, PAGE_SIZE); + + sglist[j].length = sz; + sglist[j].data = page_to_phys(*pages++); + + imagesize -= sz; + count--; + } + + /* Continuation pointer */ + sglist[j].length = 0; + + if (i + 1 == sg_count) + sglist[j].data = 0; + else + sglist[j].data = page_to_phys(sg_pages[i + 1]); + + kunmap(sg_pages[i]); + } + + mutex_lock(&capsule_mutex); + rv = efi_capsule_update_locked(capsule, sg_pages, reset_type); + mutex_unlock(&capsule_mutex); + +out: + for (i = 0; rv && i < sg_count; i++) { + if (sg_pages[i]) + __free_page(sg_pages[i]); + } + + kfree(sg_pages); + return rv; +} +EXPORT_SYMBOL_GPL(efi_capsule_update); diff --git a/drivers/firmware/efi/reboot.c b/drivers/firmware/efi/reboot.c index 9c59d1c795d1..62ead9b9d871 100644 --- a/drivers/firmware/efi/reboot.c +++ b/drivers/firmware/efi/reboot.c @@ -9,7 +9,8 @@ int efi_reboot_quirk_mode = -1; void efi_reboot(enum reboot_mode reboot_mode, const char *__unused) { - int efi_mode; + const char *str[] = { "cold", "warm", "shutdown", "platform" }; + int efi_mode, cap_reset_mode; if (!efi_enabled(EFI_RUNTIME_SERVICES)) return; @@ -30,6 +31,15 @@ void efi_reboot(enum reboot_mode reboot_mode, const char *__unused) if (efi_reboot_quirk_mode != -1) efi_mode = efi_reboot_quirk_mode; + if (efi_capsule_pending(&cap_reset_mode)) { + if (efi_mode != cap_reset_mode) + printk(KERN_CRIT "efi: %s reset requested but pending " + "capsule update requires %s reset... Performing " + "%s reset.\n", str[efi_mode], str[cap_reset_mode], + str[cap_reset_mode]); + efi_mode = cap_reset_mode; + } + efi.reset_system(efi_mode, EFI_SUCCESS, 0, NULL); } diff --git a/include/linux/efi.h b/include/linux/efi.h index 774e9a0d49f1..4899c679622d 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -123,6 +123,13 @@ typedef struct { } efi_capsule_header_t; /* + * EFI capsule flags + */ +#define EFI_CAPSULE_PERSIST_ACROSS_RESET 0x00010000 +#define EFI_CAPSULE_POPULATE_SYSTEM_TABLE 0x00020000 +#define EFI_CAPSULE_INITIATE_RESET 0x00040000 + +/* * Allocation types for calls to boottime->allocate_pages. */ #define EFI_ALLOCATE_ANY_PAGES 0 @@ -1215,6 +1222,13 @@ int efivars_sysfs_init(void); #define EFIVARS_DATA_SIZE_MAX 1024 #endif /* CONFIG_EFI_VARS */ +extern bool efi_capsule_pending(int *reset_type); + +extern int efi_capsule_supported(efi_guid_t guid, u32 flags, + size_t size, int *reset); + +extern int efi_capsule_update(efi_capsule_header_t *capsule, + struct page **pages); #ifdef CONFIG_EFI_RUNTIME_MAP int efi_runtime_map_init(struct kobject *); -- 2.12.3 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
