UEFI stands for "Unified Extensible Firmware Interface", where "Firmware"
is an ancient African word meaning "Why do something right when you can
do it so wrong that children will weep and brave adults will cower before
you", and "UEI" is Celtic for "We missed DOS so we burned it into your
ROMs". The UEFI specification provides for runtime services (ie, another
way for the operating system to be forced to depend on the firmware) and
we rely on these for certain trivial tasks such as setting up the
bootloader. But some hardware fails to work if we attempt to use these
runtime services from physical mode, and so we have to switch into virtual
mode. So far so dreadful.
The specification makes it clear that the operating system is free to do
whatever it wants with boot services code after ExitBootServices() has been
called. SetVirtualAddressMap() can't be called until ExitBootServices() has
been. So, obviously, a whole bunch of EFI implementations call into boot
services code when we do that. Since we've been charmingly naive and
trusted that the specification may be somehow relevant to the real world,
we've already stuffed a picture of a penguin or something in that address
space. And just to make things more entertaining, we've also marked it
non-executable.
This patch allocates the boot services regions during EFI init and makes
sure that they're executable. Then, after SetVirtualAddressMap(), it
discards them and everyone lives happily ever after. Except for the ones
who have to work on EFI, who live sad lives haunted by the knowledge that
someone's eventually going to write yet another firmware specification.
[ hpa: adding this to urgent with a stable tag since it fixes currently-broken
hardware. However, I do not know what the dependencies are and so I do
not know which -stable versions this may be a candidate for. ]
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1306331593-28715-1-git-send-email-mjg@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: <stable@kernel.org>
It's possible for init_memory_mapping() to fail to map the entire region
if it crosses a boundary, so ensure that we complete the mapping.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1304623186-18261-5-git-send-email-mjg@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Experimentation with various EFI implementations has shown that functions
outside runtime services will still update their pointers if
SetVirtualAddressMap() is called with memory descriptors outside the
runtime area. This is obviously insane, and therefore is unsurprising.
Evidence from instrumenting another EFI implementation suggests that it
only passes the set of descriptors covering runtime regions, so let's
avoid any problems by doing the same. Runtime descriptors are copied to
a separate memory map, and only that map is passed back to the firmware.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1304623186-18261-4-git-send-email-mjg@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Some firmware implementations assume that physically contiguous regions
will be contiguous in virtual address space. This assumption is, obviously,
entirely unjustifiable. Said firmware implementations lack the good grace
to handle their failings in a measured and reasonable manner, instead
tending to shit all over address space and oopsing the kernel.
In an ideal universe these firmware implementations would simultaneously
catch fire and cease to be a problem, but since some of them are present
in attractively thin and shiny metal devices vanity wins out and some
poor developer spends an extended period of time surrounded by a
growing array of empty bottles until the underlying reason becomes
apparent. Said developer presents this patch, which simply merges
adjacent regions if they happen to be contiguous and have the same EFI
memory type and caching attributes.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1304623186-18261-3-git-send-email-mjg@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
The core EFI code and 64-bit EFI code currently have independent
implementations of code for setting memory regions as executable or not.
Let's consolidate them.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1304623186-18261-2-git-send-email-mjg@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
The spec says that SetVirtualAddressMap doesn't work once you're in
virtual mode, so there's no point in having infrastructure for calling
it from there.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Link: http://lkml.kernel.org/r/1304623186-18261-1-git-send-email-mjg@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
