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When writing EFI variables, one might get errors with no other message
on why it fails. Being able to see how much is used by EFI variables
helps analyzing such issues.
Since this is not a conventional filesystem, block size is intentionally
set to 1 instead of PAGE_SIZE.
x86 quirks of reserved size are taken into account; so that available
and free size can be different, further helping debugging space issues.
With this patch, one can see the remaining space in EFI variable storage
via efivarfs, like this:
$ df -h /sys/firmware/efi/efivars/
Filesystem Size Used Avail Use% Mounted on
efivarfs 176K 106K 66K 62% /sys/firmware/efi/efivars
Signed-off-by: Anisse Astier <an.astier@criteo.com>
[ardb: - rename efi_reserved_space() to efivar_reserved_space()
- whitespace/coding style tweaks]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Fundamentally semaphores are a counted primitive, but
DEFINE_SEMAPHORE() does not expose this and explicitly creates a
binary semaphore.
Change DEFINE_SEMAPHORE() to take a number argument and use that in the
few places that open-coded it using __SEMAPHORE_INITIALIZER().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[mcgrof: add some tribal knowledge about why some folks prefer
binary sempahores over mutexes]
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Add the missing sanity check to efivars_register() so that it is no
longer possible to override an already registered set of efivar ops
(without first deregistering them).
This can help debug initialisation ordering issues where drivers have so
far unknowingly been relying on overriding the generic ops.
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Add an 'efivars: ' printk prefix to make the log entries stand out more,
for example:
efivars: Registered efivars operations
While at it, change the sole remaining direct printk() call to pr_err().
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
For consistency with the new efivar_is_available() function, change the
return type of efivar_supports_writes() to bool.
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Since commit 0f5b2c69a4 ("efi: vars: Remove deprecated 'efivars' sysfs
interface") and the removal of the sysfs interface there are no users of
the efivars kobject.
Drop the kobject argument from efivars_register() and add a new
efivar_is_available() helper in favour of the old efivars_kobject().
Note that the new helper uses the prefix 'efivar' (i.e. without an 's')
for consistency with efivar_supports_writes() and the rest of the
interface (except the registration functions).
For the benefit of drivers with optional EFI support, also provide a
dummy implementation of efivar_is_available().
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Commit 8a254d90a7 ("efi: efivars: Fix variable writes without
query_variable_store()") addressed an issue that was introduced during
the EFI variable store refactor, where alternative implementations of
the efivars layer that lacked query_variable_store() would no longer
work.
Unfortunately, there is another case to consider here, which was missed:
if the efivars layer is backed by the EFI runtime services as usual, but
the EFI implementation predates the introduction of QueryVariableInfo(),
we will return EFI_UNSUPPORTED, and this is no longer being dealt with
correctly.
So let's fix this, and while at it, clean up the code a bit, by merging
the check_var_size() routines as well as their callers.
Cc: <stable@vger.kernel.org> # v6.0
Fixes: bbc6d2c6ef ("efi: vars: Switch to new wrapper layer")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Aditya Garg <gargaditya08@live.com>
Commit bbc6d2c6ef ("efi: vars: Switch to new wrapper layer")
refactored the efivars layer so that the 'business logic' related to
which UEFI variables affect the boot flow in which way could be moved
out of it, and into the efivarfs driver.
This inadvertently broke setting variables on firmware implementations
that lack the QueryVariableInfo() boot service, because we no longer
tolerate a EFI_UNSUPPORTED result from check_var_size() when calling
efivar_entry_set_get_size(), which now ends up calling check_var_size()
a second time inadvertently.
If QueryVariableInfo() is missing, we support writes of up to 64k -
let's move that logic into check_var_size(), and drop the redundant
call.
Cc: <stable@vger.kernel.org> # v6.0
Fixes: bbc6d2c6ef ("efi: vars: Switch to new wrapper layer")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Move the fiddly bits of the efivar layer into its only remaining user,
efivarfs, and confine its use to that particular module. All other uses
of the EFI variable store have no need for this additional layer of
complexity, given that they either only read variables, or read and
write variables into a separate GUIDed namespace, and cannot be used to
manipulate EFI variables that are covered by the EFI spec and/or affect
the boot flow.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Switch the caching linked-list efivars layer implementation to the newly
introduced efivar get/set variable wrappers, instead of accessing the
lock and the ops pointer directly. This will permit us to move this code
out of the public efivars API, and into efivarfs once the obsolete sysfs
access method is finally removed.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Commit 5d9db88376 ("efi: Add support for a UEFI variable filesystem")
dated Oct 5, 2012, introduced a new efivarfs pseudo-filesystem to
replace the efivars sysfs interface that was used up to that point to
expose EFI variables to user space.
The main problem with the sysfs interface was that it only supported up
to 1024 bytes of payload per file, whereas the underlying variables
themselves are only bounded by a platform specific per-variable and
global limit that is typically much higher than 1024 bytes.
The deprecated sysfs interface is only enabled on x86 and Itanium, other
EFI enabled architectures only support the efivarfs pseudo-filesystem.
So let's finally rip off the band aid, and drop the old interface
entirely. This will make it easier to refactor and clean up the
underlying infrastructure that is shared between efivars, efivarfs and
efi-pstore, and is long overdue for a makeover.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
__efivar_entry_iter() uses a list iterator in a dubious way, i.e., it
assumes that the iteration variable always points to an object of the
appropriate type, even if the list traversal exhausts the list
completely, in which case it will point somewhere in the vicinity of the
list's anchor instead.
Fortunately, we no longer use this function so we can just get rid of it
entirely.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Both efivars and efivarfs uses __efivar_entry_iter() to go over the
linked list that shadows the list of EFI variables held by the firmware,
but fail to call the begin/end helpers that are documented as a
prerequisite.
So switch to the proper version, which is efivar_entry_iter(). Given
that in both cases, efivar_entry_remove() is invoked with the lock held
already, don't take the lock there anymore.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Avoid the efivars layer and simply call the newly introduced EFI
varstore helpers instead. This simplifies the code substantially, and
also allows us to remove some hacks in the shared efivars layer that
were added for efi-pstore specifically.
In order to be able to delete the EFI variable associated with a record,
store the UTF-16 name of the variable in the pstore record's priv field.
That way, we don't have to make guesses regarding which variable the
record may have been loaded from.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
The current efivars layer is a jumble of list iterators, shadow data
structures and safe variable manipulation helpers that really belong in
the efivarfs pseudo file system once the obsolete sysfs access method to
EFI variables is removed.
So split off a minimal efivar get/set variable API that reuses the
existing efivars_lock semaphore to mediate access to the various runtime
services, primarily to ensure that performing a SetVariable() on one CPU
while another is calling GetNextVariable() in a loop to enumerate the
contents of the EFI variable store does not result in surprises.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Even though the efivars_lock lock is documented as protecting the
efivars->ops pointer (among other things), efivar_init() happily
releases and reacquires the lock for every EFI variable that it
enumerates. This used to be needed because the lock was originally a
spinlock, which prevented the callback that is invoked for every
variable from being able to sleep. However, releasing the lock could
potentially invalidate the ops pointer, but more importantly, it might
allow a SetVariable() runtime service call to take place concurrently,
and the UEFI spec does not define how this affects an enumeration that
is running in parallel using the GetNextVariable() runtime service,
which is what efivar_init() uses.
In the meantime, the lock has been converted into a semaphore, and the
only reason we need to drop the lock is because the efivarfs pseudo
filesystem driver will otherwise deadlock when it invokes the efivars
API from the callback to create the efivar_entry items and insert them
into the linked list. (EFI pstore is affected in a similar way)
So let's switch to helpers that can be used while the lock is already
taken. This way, we can hold on to the lock throughout the enumeration.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
When the "block" flag is false, the old code would sometimes still call
check_var_size(), which wrongly tells ->query_variable_store() that it can
block.
As far as I can tell, this can't really materialize as a bug at the moment,
because ->query_variable_store only does something on X86 with generic EFI,
and in that configuration we always take the efivar_entry_set_nonblocking()
path.
Fixes: ca0e30dcaa ("efi: Add nonblocking option to efi_query_variable_store()")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220218180559.1432559-1-jannh@google.com
As per UEFI spec 2.8B section 8.2, EFI_UNSUPPORTED may be returned by
EFI variable runtime services if no variable storage is supported by
firmware. In this case, there is no point for kernel to continue
efivars initialization. That said, efivar_init() should fail by
returning an error code, so that efivarfs will not be mounted on
/sys/firmware/efi/efivars at all. Otherwise, user space like efibootmgr
will be confused by the EFIVARFS_MAGIC seen there, while EFI variable
calls cannot be made successfully.
Cc: <stable@vger.kernel.org> # v5.10+
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
The worker thread that gets kicked off to sync the state of the
EFI variable list is only used by the EFI pstore implementation,
and is defined in its source file. So let's move its scheduling
there as well. Since our efivar_init() scan will bail on duplicate
entries, there is no need to disable the workqueue like we did
before, so we can run it unconditionally.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Delete deprecated parameter comments to fix warnings reported by make
W=1.
drivers/firmware/efi/vars.c:428: warning: Excess function parameter
'atomic' description in 'efivar_init'
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Link: https://lore.kernel.org/r/1600914018-12697-1-git-send-email-tiantao6@hisilicon.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Commit
bf67fad19e ("efi: Use more granular check for availability for variable services")
introduced a check into the efivarfs, efi-pstore and other drivers that
aborts loading of the module if not all three variable runtime services
(GetVariable, SetVariable and GetNextVariable) are supported. However, this
results in efivarfs being unavailable entirely if only SetVariable support
is missing, which is only needed if you want to make any modifications.
Also, efi-pstore and the sysfs EFI variable interface could be backed by
another implementation of the 'efivars' abstraction, in which case it is
completely irrelevant which services are supported by the EFI firmware.
So make the generic 'efivars' abstraction dependent on the availibility of
the GetVariable and GetNextVariable EFI runtime services, and add a helper
'efivar_supports_writes()' to find out whether the currently active efivars
abstraction supports writes (and wire it up to the availability of
SetVariable for the generic one).
Then, use the efivar_supports_writes() helper to decide whether to permit
efivarfs to be mounted read-write, and whether to enable efi-pstore or the
sysfs EFI variable interface altogether.
Fixes: bf67fad19e ("efi: Use more granular check for availability for variable services")
Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Tested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Replace all GPL license blurbs with an equivalent SPDX header (most
files are GPLv2, some are GPLv2+). While at it, drop some outdated
header changelogs as well.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190202094119.13230-7-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Since commit:
ce2e6db554 ("brcmfmac: Add support for getting nvram contents from EFI variables")
we have a device driver accessing the efivars API. Several functions in
the efivars API assume __efivars is set, i.e., that they will be accessed
only after efivars_register() has been called. However, the following NULL
pointer access was reported calling efivar_entry_size() from the brcmfmac
device driver:
Unable to handle kernel NULL pointer dereference at virtual address 00000008
pgd = 60bfa5f1
[00000008] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
...
Hardware name: NVIDIA Tegra SoC (Flattened Device Tree)
Workqueue: events request_firmware_work_func
PC is at efivar_entry_size+0x28/0x90
LR is at brcmf_fw_complete_request+0x3f8/0x8d4 [brcmfmac]
pc : [<c0c40718>] lr : [<bf2a3ef4>] psr: a00d0113
sp : ede7fe28 ip : ee983410 fp : c1787f30
r10: 00000000 r9 : 00000000 r8 : bf2b2258
r7 : ee983000 r6 : c1604c48 r5 : ede7fe88 r4 : edf337c0
r3 : 00000000 r2 : 00000000 r1 : ede7fe88 r0 : c17712c8
Flags: NzCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none
Control: 10c5387d Table: ad16804a DAC: 00000051
Disassembly showed that the local static variable __efivars is NULL,
which is not entirely unexpected given that it is a non-EFI platform.
So add a NULL pointer check to efivar_entry_size(), and to related
functions while at it. In efivars_register() a couple of sanity checks
are added as well.
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Eric Snowberg <eric.snowberg@oracle.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Joe Perches <joe@perches.com>
Cc: Julien Thierry <julien.thierry@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: YiFei Zhu <zhuyifei1999@gmail.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20181129171230.18699-9-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All efivars operations are protected by a spinlock which prevents
interruptions and preemption. This is too restricted, we just need a
lock preventing concurrency.
The idea is to use a semaphore of count 1 and to have two ways of
locking, depending on the context:
- In interrupt context, we call down_trylock(), if it fails we return
an error
- In normal context, we call down_interruptible()
We don't use a mutex here because the mutex_trylock() function must not
be called from interrupt context, whereas the down_trylock() can.
Signed-off-by: Sylvain Chouleur <sylvain.chouleur@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sylvain Chouleur <sylvain.chouleur@gmail.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
This patch replaces the spinlock in the efivars struct with a single lock
for the whole vars.c file. The goal of this lock is to protect concurrent
calls to efi variable services, registering and unregistering. This allows
us to register new efivars operations without having in-progress call.
Signed-off-by: Sylvain Chouleur <sylvain.chouleur@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Sylvain Chouleur <sylvain.chouleur@gmail.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
The parameters atomic and duplicates of efivar_init always have opposite
values. Drop the parameter atomic, replace the uses of !atomic with
duplicates, and update the call sites accordingly.
The code using duplicates is slightly reorganized with an 'else', to avoid
duplicating the lock code.
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Saurabh Sengar <saurabh.truth@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vaishali Thakkar <vaishali.thakkar@oracle.com>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1462570771-13324-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Move efi_status_to_err() to the architecture independent code as it's
generally useful in all bits of EFI code where there is a need to
convert an efi_status_t to a kernel error value.
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Kweh Hock Leong <hock.leong.kweh@intel.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/1461614832-17633-27-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The variable_matches() function can currently read "var_name[len]", for
example when:
- var_name[0] == 'a',
- len == 1
- match_name points to the NUL-terminated string "ab".
This function is supposed to accept "var_name" inputs that are not
NUL-terminated (hence the "len" parameter"). Document the function, and
access "var_name[*match]" only if "*match" is smaller than "len".
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Cc: Peter Jones <pjones@redhat.com>
Cc: Matthew Garrett <mjg59@coreos.com>
Cc: Jason Andryuk <jandryuk@gmail.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: <stable@vger.kernel.org> # v3.10+
Link: http://thread.gmane.org/gmane.comp.freedesktop.xorg.drivers.intel/86906
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Laszlo explains why this is a good idea,
'This is because the pstore filesystem can be backed by UEFI variables,
and (for example) a crash might dump the last kilobytes of the dmesg
into a number of pstore entries, each entry backed by a separate UEFI
variable in the above GUID namespace, and with a variable name
according to the above pattern.
Please see "drivers/firmware/efi/efi-pstore.c".
While this patch series will not prevent the user from deleting those
UEFI variables via the pstore filesystem (i.e., deleting a pstore fs
entry will continue to delete the backing UEFI variable), I think it
would be nice to preserve the possibility for the sysadmin to delete
Linux-created UEFI variables that carry portions of the crash log,
*without* having to mount the pstore filesystem.'
There's also no chance of causing machines to become bricked by
deleting these variables, which is the whole purpose of excluding
things from the whitelist.
Use the LINUX_EFI_CRASH_GUID guid and a wildcard '*' for the match so
that we don't have to update the string in the future if new variable
name formats are created for crash dump variables.
Reported-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Peter Jones <pjones@redhat.com>
Tested-by: Peter Jones <pjones@redhat.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: "Lee, Chun-Yi" <jlee@suse.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
"rm -rf" is bricking some peoples' laptops because of variables being
used to store non-reinitializable firmware driver data that's required
to POST the hardware.
These are 100% bugs, and they need to be fixed, but in the mean time it
shouldn't be easy to *accidentally* brick machines.
We have to have delete working, and picking which variables do and don't
work for deletion is quite intractable, so instead make everything
immutable by default (except for a whitelist), and make tools that
aren't quite so broad-spectrum unset the immutable flag.
Signed-off-by: Peter Jones <pjones@redhat.com>
Tested-by: Lee, Chun-Yi <jlee@suse.com>
Acked-by: Matthew Garrett <mjg59@coreos.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
All the variables in this list so far are defined to be in the global
namespace in the UEFI spec, so this just further ensures we're
validating the variables we think we are.
Including the guid for entries will become more important in future
patches when we decide whether or not to allow deletion of variables
based on presence in this list.
Signed-off-by: Peter Jones <pjones@redhat.com>
Tested-by: Lee, Chun-Yi <jlee@suse.com>
Acked-by: Matthew Garrett <mjg59@coreos.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Actually translate from ucs2 to utf8 before doing the test, and then
test against our other utf8 data, instead of fudging it.
Signed-off-by: Peter Jones <pjones@redhat.com>
Acked-by: Matthew Garrett <mjg59@coreos.com>
Tested-by: Lee, Chun-Yi <jlee@suse.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
The function efi_query_variable_store() may be invoked by
efivar_entry_set_nonblocking(), which itself takes care to only
call a non-blocking version of the SetVariable() runtime
wrapper. However, efi_query_variable_store() may call the
SetVariable() wrapper directly, as well as the wrapper for
QueryVariableInfo(), both of which could deadlock in the same
way we are trying to prevent by calling
efivar_entry_set_nonblocking() in the first place.
So instead, modify efi_query_variable_store() to use the
non-blocking variants of QueryVariableInfo() (and give up rather
than free up space if the available space is below
EFI_MIN_RESERVE) if invoked with the 'nonblocking' argument set
to true.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/1454364428-494-5-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
There are some circumstances that call for trying to write an EFI
variable in a non-blocking way. One such scenario is when writing pstore
data in efi_pstore_write() via the pstore_dump() kdump callback.
Now that we have an EFI runtime spinlock we need a way of aborting if
there is contention instead of spinning, since when writing pstore data
from the kdump callback, the runtime lock may already be held by the CPU
that's running the callback if we crashed in the middle of an EFI
variable operation.
The situation is sufficiently special that a new EFI variable operation
is warranted.
Introduce ->set_variable_nonblocking() for this use case. It is an
optional EFI backend operation, and need only be implemented by those
backends that usually acquire locks to serialize access to EFI
variables, as is the case for virt_efi_set_variable() where we now grab
the EFI runtime spinlock.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
It is a really bad idea to declare variables or parameters that
have the same name as common types. It is valid C, but it gets
surprising if a macro expansion attempts to declare an inner
local with that type. Change the local names to eliminate the
hazard.
Change s16 => str16, s8 => str8.
This resolves warnings seen when using W=2 during make, for instance:
drivers/firmware/efi/vars.c: In function ‘dup_variable_bug’:
drivers/firmware/efi/vars.c:324:44: warning: declaration of ‘s16’ shadows a global declaration [-Wshadow]
static void dup_variable_bug(efi_char16_t *s16, efi_guid_t *vendor_guid,
drivers/firmware/efi/vars.c:328:8: warning: declaration of ‘s8’ shadows a global declaration [-Wshadow]
char *s8;
Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
spin_is_locked() always returns false for uniprocessor configurations
in several architectures, so do not use WARN_ON with it.
Use lockdep_assert_held() instead to also reduce overhead in
non-debug kernels.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
In preparation for compat support, we can't assume that user variable
object is represented by a 'struct efi_variable'. Convert the validation
functions to take the variable name as an argument, which is the only
piece of the struct that was ever used anyway.
Cc: Mike Waychison <mikew@google.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Currently, when mounting pstore file system, a read callback of
efi_pstore driver runs mutiple times as below.
- In the first read callback, scan efivar_sysfs_list from head and pass
a kmsg buffer of a entry to an upper pstore layer.
- In the second read callback, rescan efivar_sysfs_list from the entry
and pass another kmsg buffer to it.
- Repeat the scan and pass until the end of efivar_sysfs_list.
In this process, an entry is read across the multiple read function
calls. To avoid race between the read and erasion, the whole process
above is protected by a spinlock, holding in open() and releasing in
close().
At the same time, kmemdup() is called to pass the buffer to pstore
filesystem during it. And then, it causes a following lockdep warning.
To make the dynamic memory allocation runnable without taking spinlock,
holding off a deletion of sysfs entry if it happens while scanning it
via efi_pstore, and deleting it after the scan is completed.
To implement it, this patch introduces two flags, scanning and deleting,
to efivar_entry.
On the code basis, it seems that all the scanning and deleting logic is
not needed because __efivars->lock are not dropped when reading from the
EFI variable store.
But, the scanning and deleting logic is still needed because an
efi-pstore and a pstore filesystem works as follows.
In case an entry(A) is found, the pointer is saved to psi->data. And
efi_pstore_read() passes the entry(A) to a pstore filesystem by
releasing __efivars->lock.
And then, the pstore filesystem calls efi_pstore_read() again and the
same entry(A), which is saved to psi->data, is used for resuming to scan
a sysfs-list.
So, to protect the entry(A), the logic is needed.
[ 1.143710] ------------[ cut here ]------------
[ 1.144058] WARNING: CPU: 1 PID: 1 at kernel/lockdep.c:2740 lockdep_trace_alloc+0x104/0x110()
[ 1.144058] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags))
[ 1.144058] Modules linked in:
[ 1.144058] CPU: 1 PID: 1 Comm: systemd Not tainted 3.11.0-rc5 #2
[ 1.144058] 0000000000000009 ffff8800797e9ae0 ffffffff816614a5 ffff8800797e9b28
[ 1.144058] ffff8800797e9b18 ffffffff8105510d 0000000000000080 0000000000000046
[ 1.144058] 00000000000000d0 00000000000003af ffffffff81ccd0c0 ffff8800797e9b78
[ 1.144058] Call Trace:
[ 1.144058] [<ffffffff816614a5>] dump_stack+0x54/0x74
[ 1.144058] [<ffffffff8105510d>] warn_slowpath_common+0x7d/0xa0
[ 1.144058] [<ffffffff8105517c>] warn_slowpath_fmt+0x4c/0x50
[ 1.144058] [<ffffffff8131290f>] ? vsscanf+0x57f/0x7b0
[ 1.144058] [<ffffffff810bbd74>] lockdep_trace_alloc+0x104/0x110
[ 1.144058] [<ffffffff81192da0>] __kmalloc_track_caller+0x50/0x280
[ 1.144058] [<ffffffff815147bb>] ? efi_pstore_read_func.part.1+0x12b/0x170
[ 1.144058] [<ffffffff8115b260>] kmemdup+0x20/0x50
[ 1.144058] [<ffffffff815147bb>] efi_pstore_read_func.part.1+0x12b/0x170
[ 1.144058] [<ffffffff81514800>] ? efi_pstore_read_func.part.1+0x170/0x170
[ 1.144058] [<ffffffff815148b4>] efi_pstore_read_func+0xb4/0xe0
[ 1.144058] [<ffffffff81512b7b>] __efivar_entry_iter+0xfb/0x120
[ 1.144058] [<ffffffff8151428f>] efi_pstore_read+0x3f/0x50
[ 1.144058] [<ffffffff8128d7ba>] pstore_get_records+0x9a/0x150
[ 1.158207] [<ffffffff812af25c>] ? selinux_d_instantiate+0x1c/0x20
[ 1.158207] [<ffffffff8128ce30>] ? parse_options+0x80/0x80
[ 1.158207] [<ffffffff8128ced5>] pstore_fill_super+0xa5/0xc0
[ 1.158207] [<ffffffff811ae7d2>] mount_single+0xa2/0xd0
[ 1.158207] [<ffffffff8128ccf8>] pstore_mount+0x18/0x20
[ 1.158207] [<ffffffff811ae8b9>] mount_fs+0x39/0x1b0
[ 1.158207] [<ffffffff81160550>] ? __alloc_percpu+0x10/0x20
[ 1.158207] [<ffffffff811c9493>] vfs_kern_mount+0x63/0xf0
[ 1.158207] [<ffffffff811cbb0e>] do_mount+0x23e/0xa20
[ 1.158207] [<ffffffff8115b51b>] ? strndup_user+0x4b/0xf0
[ 1.158207] [<ffffffff811cc373>] SyS_mount+0x83/0xc0
[ 1.158207] [<ffffffff81673cc2>] system_call_fastpath+0x16/0x1b
[ 1.158207] ---[ end trace 61981bc62de9f6f4 ]---
Signed-off-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Madper Xie <cxie@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
The intent is that if we aren't allowed to block because we're in an
NMI or an emergency then we only take the lock if it is uncontended.
Part of the problem is the test is reversed so we return -EBUSY if we
acquire the lock.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Seiji reported getting empty dmesg-* files, because the data was never
actually read in efi_pstore_read_func(), and so the memcpy() was copying
garbage data.
This patch necessitated adding __efivar_entry_get() which is callable
between efivar_entry_iter_{begin,end}(). We can also delete
__efivar_entry_size() because efi_pstore_read_func() was the only
caller.
Reported-by: Seiji Aguchi <seiji.aguchi@hds.com>
Tested-by: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
This registers /sys/firmware/efi/{,systab,efivars/} whenever EFI is enabled
and the system is booted with EFI.
This allows
*) userspace to check for the existence of /sys/firmware/efi as a way
to determine whether or it is running on an EFI system.
*) 'mount -t efivarfs none /sys/firmware/efi/efivars' without manually
loading any modules.
[ Also, move the efivar API into vars.c and unconditionally compile it.
This allows us to move efivars.c, which now only contains the sysfs
variable code, into the firmware/efi directory. Note that the efivars.c
filename is kept to maintain backwards compatability with the old
efivars.ko module. With this patch it is now possible for efivarfs
to be built without CONFIG_EFI_VARS - Matt ]
Cc: Seiji Aguchi <seiji.aguchi@hds.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Mike Waychison <mikew@google.com>
Cc: Kay Sievers <kay@vrfy.org>
Cc: Jeremy Kerr <jk@ozlabs.org>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Chun-Yi Lee <jlee@suse.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Tobias Powalowski <tpowa@archlinux.org>
Signed-off-by: Tom Gundersen <teg@jklm.no>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
