提交 f0133f3c 编写于 作者: M Matt Fleming 提交者: Ingo Molnar

efi: Add 'capsule' update support

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: NMatt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Cc: Kweh Hock Leong <hock.leong.kweh@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Peter Jones <pjones@redhat.com>
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/1461614832-17633-28-git-send-email-matt@codeblueprint.co.ukSigned-off-by: NIngo Molnar <mingo@kernel.org>
上级 806b0351
......@@ -10,6 +10,7 @@
KASAN_SANITIZE_runtime-wrappers.o := n
obj-$(CONFIG_EFI) += efi.o vars.o reboot.o memattr.o
obj-$(CONFIG_EFI) += capsule.o
obj-$(CONFIG_EFI_VARS) += efivars.o
obj-$(CONFIG_EFI_ESRT) += esrt.o
obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o
......
/*
* 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);
......@@ -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);
}
......
......@@ -124,6 +124,13 @@ typedef struct {
u32 imagesize;
} 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.
*/
......@@ -1370,6 +1377,13 @@ 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 *);
......
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