![Matt Fleming](/assets/img/avatar_default.png)
Dan Carpenter reports that passing the address of the pointer to the kmalloc()'d memory for 'capsule' is dangerous: "drivers/firmware/efi/capsule.c:109 efi_capsule_supported() warn: did you mean to pass the address of 'capsule' 108 109 status = efi.query_capsule_caps(&capsule, 1, &max_size, reset); ^^^^^^^^ If we modify capsule inside this function call then at the end of the function we aren't freeing the original pointer that we allocated." Ard Biesheuvel noted that we don't even need to call kmalloc() since the object we allocate isn't very big and doesn't need to persist after the function returns. Place 'capsule' on the stack instead. Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Bryan O'Donoghue <pure.logic@nexus-software.ie> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kweh Hock Leong <hock.leong.kweh@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: joeyli <jlee@suse.com> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1462570771-13324-4-git-send-email-matt@codeblueprint.co.uk Signed-off-by: Ingo Molnar <mingo@kernel.org>
309 lines
8.7 KiB
C
309 lines
8.7 KiB
C
/*
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* EFI capsule support.
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*
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* Copyright 2013 Intel Corporation; author Matt Fleming
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*
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* This file is part of the Linux kernel, and is made available under
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* the terms of the GNU General Public License version 2.
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*/
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#define pr_fmt(fmt) "efi: " fmt
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/highmem.h>
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#include <linux/efi.h>
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#include <linux/vmalloc.h>
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#include <asm/io.h>
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typedef struct {
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u64 length;
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u64 data;
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} efi_capsule_block_desc_t;
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static bool capsule_pending;
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static bool stop_capsules;
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static int efi_reset_type = -1;
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/*
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* capsule_mutex serialises access to both capsule_pending and
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* efi_reset_type and stop_capsules.
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*/
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static DEFINE_MUTEX(capsule_mutex);
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/**
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* efi_capsule_pending - has a capsule been passed to the firmware?
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* @reset_type: store the type of EFI reset if capsule is pending
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*
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* To ensure that the registered capsule is processed correctly by the
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* firmware we need to perform a specific type of reset. If a capsule is
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* pending return the reset type in @reset_type.
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*
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* This function will race with callers of efi_capsule_update(), for
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* example, calling this function while somebody else is in
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* efi_capsule_update() but hasn't reached efi_capsue_update_locked()
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* will miss the updates to capsule_pending and efi_reset_type after
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* efi_capsule_update_locked() completes.
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*
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* A non-racy use is from platform reboot code because we use
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* system_state to ensure no capsules can be sent to the firmware once
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* we're at SYSTEM_RESTART. See efi_capsule_update_locked().
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*/
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bool efi_capsule_pending(int *reset_type)
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{
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if (!capsule_pending)
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return false;
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if (reset_type)
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*reset_type = efi_reset_type;
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return true;
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}
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/*
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* Whitelist of EFI capsule flags that we support.
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*
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* We do not handle EFI_CAPSULE_INITIATE_RESET because that would
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* require us to prepare the kernel for reboot. Refuse to load any
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* capsules with that flag and any other flags that we do not know how
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* to handle.
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*/
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#define EFI_CAPSULE_SUPPORTED_FLAG_MASK \
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(EFI_CAPSULE_PERSIST_ACROSS_RESET | EFI_CAPSULE_POPULATE_SYSTEM_TABLE)
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/**
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* efi_capsule_supported - does the firmware support the capsule?
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* @guid: vendor guid of capsule
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* @flags: capsule flags
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* @size: size of capsule data
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* @reset: the reset type required for this capsule
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*
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* Check whether a capsule with @flags is supported by the firmware
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* and that @size doesn't exceed the maximum size for a capsule.
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*
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* No attempt is made to check @reset against the reset type required
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* by any pending capsules because of the races involved.
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*/
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int efi_capsule_supported(efi_guid_t guid, u32 flags, size_t size, int *reset)
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{
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efi_capsule_header_t capsule;
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efi_capsule_header_t *cap_list[] = { &capsule };
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efi_status_t status;
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u64 max_size;
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if (flags & ~EFI_CAPSULE_SUPPORTED_FLAG_MASK)
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return -EINVAL;
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capsule.headersize = capsule.imagesize = sizeof(capsule);
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memcpy(&capsule.guid, &guid, sizeof(efi_guid_t));
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capsule.flags = flags;
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status = efi.query_capsule_caps(cap_list, 1, &max_size, reset);
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if (status != EFI_SUCCESS)
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return efi_status_to_err(status);
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if (size > max_size)
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return -ENOSPC;
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return 0;
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}
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EXPORT_SYMBOL_GPL(efi_capsule_supported);
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/*
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* Every scatter gather list (block descriptor) page must end with a
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* continuation pointer. The last continuation pointer of the last
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* page must be zero to mark the end of the chain.
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*/
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#define SGLIST_PER_PAGE ((PAGE_SIZE / sizeof(efi_capsule_block_desc_t)) - 1)
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/*
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* How many scatter gather list (block descriptor) pages do we need
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* to map @count pages?
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*/
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static inline unsigned int sg_pages_num(unsigned int count)
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{
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return DIV_ROUND_UP(count, SGLIST_PER_PAGE);
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}
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/**
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* efi_capsule_update_locked - pass a single capsule to the firmware
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* @capsule: capsule to send to the firmware
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* @sg_pages: array of scatter gather (block descriptor) pages
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* @reset: the reset type required for @capsule
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*
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* Since this function must be called under capsule_mutex check
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* whether efi_reset_type will conflict with @reset, and atomically
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* set it and capsule_pending if a capsule was successfully sent to
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* the firmware.
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*
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* We also check to see if the system is about to restart, and if so,
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* abort. This avoids races between efi_capsule_update() and
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* efi_capsule_pending().
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*/
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static int
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efi_capsule_update_locked(efi_capsule_header_t *capsule,
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struct page **sg_pages, int reset)
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{
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efi_physical_addr_t sglist_phys;
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efi_status_t status;
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lockdep_assert_held(&capsule_mutex);
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/*
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* If someone has already registered a capsule that requires a
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* different reset type, we're out of luck and must abort.
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*/
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if (efi_reset_type >= 0 && efi_reset_type != reset) {
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pr_err("Conflicting capsule reset type %d (%d).\n",
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reset, efi_reset_type);
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return -EINVAL;
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}
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/*
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* If the system is getting ready to restart it may have
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* called efi_capsule_pending() to make decisions (such as
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* whether to force an EFI reboot), and we're racing against
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* that call. Abort in that case.
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*/
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if (unlikely(stop_capsules)) {
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pr_warn("Capsule update raced with reboot, aborting.\n");
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return -EINVAL;
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}
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sglist_phys = page_to_phys(sg_pages[0]);
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status = efi.update_capsule(&capsule, 1, sglist_phys);
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if (status == EFI_SUCCESS) {
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capsule_pending = true;
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efi_reset_type = reset;
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}
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return efi_status_to_err(status);
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}
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/**
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* efi_capsule_update - send a capsule to the firmware
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* @capsule: capsule to send to firmware
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* @pages: an array of capsule data pages
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*
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* Build a scatter gather list with EFI capsule block descriptors to
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* map the capsule described by @capsule with its data in @pages and
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* send it to the firmware via the UpdateCapsule() runtime service.
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*
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* @capsule must be a virtual mapping of the first page in @pages
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* (@pages[0]) in the kernel address space. That is, a
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* capsule_header_t that describes the entire contents of the capsule
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* must be at the start of the first data page.
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*
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* Even though this function will validate that the firmware supports
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* the capsule guid, users will likely want to check that
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* efi_capsule_supported() returns true before calling this function
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* because it makes it easier to print helpful error messages.
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*
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* If the capsule is successfully submitted to the firmware, any
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* subsequent calls to efi_capsule_pending() will return true. @pages
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* must not be released or modified if this function returns
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* successfully.
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*
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* Callers must be prepared for this function to fail, which can
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* happen if we raced with system reboot or if there is already a
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* pending capsule that has a reset type that conflicts with the one
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* required by @capsule. Do NOT use efi_capsule_pending() to detect
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* this conflict since that would be racy. Instead, submit the capsule
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* to efi_capsule_update() and check the return value.
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*
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* Return 0 on success, a converted EFI status code on failure.
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*/
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int efi_capsule_update(efi_capsule_header_t *capsule, struct page **pages)
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{
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u32 imagesize = capsule->imagesize;
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efi_guid_t guid = capsule->guid;
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unsigned int count, sg_count;
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u32 flags = capsule->flags;
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struct page **sg_pages;
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int rv, reset_type;
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int i, j;
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rv = efi_capsule_supported(guid, flags, imagesize, &reset_type);
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if (rv)
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return rv;
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count = DIV_ROUND_UP(imagesize, PAGE_SIZE);
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sg_count = sg_pages_num(count);
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sg_pages = kzalloc(sg_count * sizeof(*sg_pages), GFP_KERNEL);
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if (!sg_pages)
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return -ENOMEM;
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for (i = 0; i < sg_count; i++) {
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sg_pages[i] = alloc_page(GFP_KERNEL);
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if (!sg_pages[i]) {
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rv = -ENOMEM;
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goto out;
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}
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}
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for (i = 0; i < sg_count; i++) {
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efi_capsule_block_desc_t *sglist;
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sglist = kmap(sg_pages[i]);
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if (!sglist) {
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rv = -ENOMEM;
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goto out;
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}
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for (j = 0; j < SGLIST_PER_PAGE && count > 0; j++) {
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u64 sz = min_t(u64, imagesize, PAGE_SIZE);
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sglist[j].length = sz;
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sglist[j].data = page_to_phys(*pages++);
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imagesize -= sz;
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count--;
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}
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/* Continuation pointer */
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sglist[j].length = 0;
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if (i + 1 == sg_count)
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sglist[j].data = 0;
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else
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sglist[j].data = page_to_phys(sg_pages[i + 1]);
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kunmap(sg_pages[i]);
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}
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mutex_lock(&capsule_mutex);
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rv = efi_capsule_update_locked(capsule, sg_pages, reset_type);
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mutex_unlock(&capsule_mutex);
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out:
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for (i = 0; rv && i < sg_count; i++) {
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if (sg_pages[i])
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__free_page(sg_pages[i]);
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}
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kfree(sg_pages);
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return rv;
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}
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EXPORT_SYMBOL_GPL(efi_capsule_update);
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static int capsule_reboot_notify(struct notifier_block *nb, unsigned long event, void *cmd)
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{
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mutex_lock(&capsule_mutex);
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stop_capsules = true;
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mutex_unlock(&capsule_mutex);
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return NOTIFY_DONE;
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}
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static struct notifier_block capsule_reboot_nb = {
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.notifier_call = capsule_reboot_notify,
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};
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static int __init capsule_reboot_register(void)
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{
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return register_reboot_notifier(&capsule_reboot_nb);
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}
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core_initcall(capsule_reboot_register);
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