linux-stable.git/drivers/firmware/efi, branch v3.18

Merge branch 'next' into efi-next-merge

2014-10-03T21:15:56+00:00

Conflicts:
	arch/x86/boot/compressed/eboot.c

efi: Delete the in_nmi() conditional runtime locking

2014-10-03T17:41:03+00:00

commit 5dc3826d9f08 ("efi: Implement mandatory locking for UEFI Runtime
Services") implemented some conditional locking when accessing variable
runtime services that Ingo described as "pretty disgusting".

The intention with the !efi_in_nmi() checks was to avoid live-locks when
trying to write pstore crash data into an EFI variable. Such lockless
accesses are allowed according to the UEFI specification when we're in a
"non-recoverable" state, but whether or not things are implemented
correctly in actual firmware implementations remains an unanswered
question, and so it would seem sensible to avoid doing any kind of
unsynchronized variable accesses.

Furthermore, the efi_in_nmi() tests are inadequate because they don't
account for the case where we call EFI variable services from panic or
oops callbacks and aren't executing in NMI context. In other words,
live-locking is still possible.

Let's just remove the conditional locking altogether. Now we've got the
->set_variable_nonblocking() EFI variable operation we can abort if the
runtime lock is already held. Aborting is by far the safest option.

Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Ard Biesheuvel 
Cc: Matthew Garrett 
Signed-off-by: Matt Fleming

efi: Provide a non-blocking SetVariable() operation

2014-10-03T17:41:03+00:00

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 
Cc: Ingo Molnar 
Cc: Ard Biesheuvel 
Cc: Matthew Garrett 
Signed-off-by: Matt Fleming

efi: Resolve some shadow warnings

2014-10-03T17:41:01+00:00

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 
Signed-off-by: Jeff Kirsher 
Signed-off-by: Matt Fleming

efi: Introduce efi_md_typeattr_format()

2014-10-03T17:41:00+00:00

At the moment, there are three architectures debug-printing the EFI memory
map at initialization: x86, ia64, and arm64. They all use different format
strings, plus the EFI memory type and the EFI memory attributes are
similarly hard to decode for a human reader.

Introduce a helper __init function that formats the memory type and the
memory attributes in a unified way, to a user-provided character buffer.

The array "memory_type_name" is copied from the arm64 code, temporarily
duplicating it. The (otherwise optional) braces around each string literal
in the initializer list are dropped in order to match the kernel coding
style more closely. The element size is tightened from 32 to 20 bytes
(maximum actual string length + 1) so that we can derive the field width
from the element size.

Signed-off-by: Laszlo Ersek 
Tested-by: Ard Biesheuvel 
Acked-by: Ard Biesheuvel 
[ Dropped useless 'register' keyword, which compiler will ignore ]
Signed-off-by: Matt Fleming

efi: Add kernel param efi=noruntime

2014-10-03T17:40:59+00:00

noefi kernel param means actually disabling efi runtime, Per suggestion
from Leif Lindholm efi=noruntime should be better. But since noefi is
already used in X86 thus just adding another param efi=noruntime for
same purpose.

Signed-off-by: Dave Young 
Signed-off-by: Matt Fleming

efi: Move noefi early param code out of x86 arch code

2014-10-03T17:40:58+00:00

noefi param can be used for arches other than X86 later, thus move it
out of x86 platform code.

Signed-off-by: Dave Young 
Signed-off-by: Matt Fleming

efi: Add efi= parameter parsing to the EFI boot stub

2014-10-03T17:40:57+00:00

We need a way to customize the behaviour of the EFI boot stub, in
particular, we need a way to disable the "chunking" workaround, used
when reading files from the EFI System Partition.

One of my machines doesn't cope well when reading files in 1MB chunks to
a buffer above the 4GB mark - it appears that the "chunking" bug
workaround triggers another firmware bug. This was only discovered with
commit 4bf7111f5016 ("x86/efi: Support initrd loaded above 4G"), and
that commit is perfectly valid. The symptom I observed was a corrupt
initrd rather than any kind of crash.

efi= is now used to specify EFI parameters in two very different
execution environments, the EFI boot stub and during kernel boot.

There is also a slight performance optimization by enabling efi=nochunk,
but that's offset by the fact that you're more likely to run into
firmware issues, at least on x86. This is the rationale behind leaving
the workaround enabled by default.

Also provide some documentation for EFI_READ_CHUNK_SIZE and why we're
using the current value of 1MB.

Tested-by: Ard Biesheuvel 
Cc: Roy Franz 
Cc: Maarten Lankhorst 
Cc: Leif Lindholm 
Cc: Borislav Petkov 
Signed-off-by: Matt Fleming

efi: Implement mandatory locking for UEFI Runtime Services

2014-10-03T17:40:57+00:00

According to section 7.1 of the UEFI spec, Runtime Services are not fully
reentrant, and there are particular combinations of calls that need to be
serialized. Use a spinlock to serialize all Runtime Services with respect
to all others, even if this is more than strictly needed.

We've managed to get away without requiring a runtime services lock
until now because most of the interactions with EFI involve EFI
variables, and those operations are already serialised with
__efivars->lock.

Some of the assumptions underlying the decision whether locks are
needed or not (e.g., SetVariable() against ResetSystem()) may not
apply universally to all [new] architectures that implement UEFI.
Rather than try to reason our way out of this, let's just implement at
least what the spec requires in terms of locking.

Signed-off-by: Ard Biesheuvel 
Signed-off-by: Matt Fleming

Revert "efi/x86: efistub: Move shared dependencies to "

2014-09-23T21:01:55+00:00

This reverts commit f23cf8bd5c1f ("efi/x86: efistub: Move shared
dependencies to ") as well as the x86 parts of commit
f4f75ad5741f ("efi: efistub: Convert into static library").

The road leading to these two reverts is long and winding.

The above two commits were merged during the v3.17 merge window and
turned the common EFI boot stub code into a static library. This
necessitated making some symbols global in the x86 boot stub which
introduced new entries into the early boot GOT.

The problem was that we weren't fixing up the newly created GOT entries
before invoking the EFI boot stub, which sometimes resulted in hangs or
resets. This failure was reported by Maarten on his Macbook pro.

The proposed fix was commit 9cb0e394234d ("x86/efi: Fixup GOT in all
boot code paths"). However, that caused issues for Linus when booting
his Sony Vaio Pro 11. It was subsequently reverted in commit
f3670394c29f.

So that leaves us back with Maarten's Macbook pro not booting.

At this stage in the release cycle the least risky option is to revert
the x86 EFI boot stub to the pre-merge window code structure where we
explicitly #include efi-stub-helper.c instead of linking with the static
library. The arm64 code remains unaffected.

We can take another swing at the x86 parts for v3.18.

Conflicts:
	arch/x86/include/asm/efi.h

Tested-by: Josh Boyer 
Tested-by: Maarten Lankhorst 
Tested-by: Leif Lindholm  [arm64]
Tested-by: Linus Torvalds 
Cc: H. Peter Anvin 
Cc: Ard Biesheuvel ,
Cc: Ingo Molnar 
Signed-off-by: Matt Fleming