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Ard Biesheuvel dcf8f5ce31 drivers/fbdev/efifb: Allow BAR to be moved instead of claiming it
On UEFI systems, the firmware may expose a Graphics Output Protocol (GOP)
instance to which the efifb driver attempts to attach in order to provide
a minimal, unaccelerated framebuffer. The GOP protocol itself is not very
sophisticated, and only describes the offset and size of the framebuffer
in memory, and the pixel format.

If the GOP framebuffer is provided by a PCI device, it will have been
configured and enabled by the UEFI firmware, and the GOP protocol will
simply point into a live BAR region. However, the GOP protocol itself does
not describe this relation, and so we have to take care not to reconfigure
the BAR without taking efifb's dependency on it into account.

Commit:

  55d728a40d ("efi/fb: Avoid reconfiguration of BAR that covers the framebuffer")

attempted to do so by claiming the BAR resource early on, which prevents the
PCI resource allocation routines from changing it.  However, it turns out
that this only works if the PCI device is not behind any bridges, since
the bridge resources need to be claimed first.

So instead, allow the BAR to be moved, but make the efifb driver deal
with that gracefully. So record the resource that covers the BAR early
on, and if it turns out to have moved by the time we probe the efifb
driver, update the framebuffer address accordingly.

While this is less likely to occur on x86, given that the firmware's
PCI resource allocation is more likely to be preserved, this is a
worthwhile sanity check to have in place, and so let's remove the
preprocessor conditional that makes it !X86 only.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Peter Jones <pjones@redhat.com>
Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170818194947.19347-8-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-08-21 09:43:50 +02:00
arch efi/libstub/arm64: Use hidden attribute for struct screen_info reference 2017-08-21 09:43:49 +02:00
block blk-mq-pci: add a fallback when pci_irq_get_affinity returns NULL 2017-08-18 08:08:14 -06:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: authencesn - Fix digest_null crash 2017-07-18 17:01:11 +08:00
Documentation printk-formats.txt: Better describe the difference between %pS and %pF 2017-08-16 21:09:45 +02:00
drivers drivers/fbdev/efifb: Allow BAR to be moved instead of claiming it 2017-08-21 09:43:50 +02:00
firmware firmware/Makefile: force recompilation if makefile changes 2017-05-08 17:15:10 -07:00
fs Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:36:52 -07:00
include Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:20:57 -07:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc: add missing container_of()s for randstruct 2017-08-02 17:16:12 -07:00
kernel Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:20:57 -07:00
lib kernel/watchdog: Prevent false positives with turbo modes 2017-08-18 12:35:02 +02:00
mm Sanitize 'move_pages()' permission checks 2017-08-20 13:26:27 -07:00
net net_sched: remove warning from qdisc_hash_add 2017-08-15 17:16:39 -07:00
samples samples/bpf: fix bpf tunnel cleanup 2017-07-31 22:02:47 -07:00
scripts parse-maintainers: Move matching sections from MAINTAINERS 2017-08-08 11:16:14 -07:00
security Now that IPC and other changes have landed, enable manual markings for 2017-07-19 08:55:18 -07:00
sound ALSA: emu10k1: Fix forgotten user-copy conversion in init code 2017-08-18 10:59:02 +02:00
tools test_kmod: fix description for -s -and -c parameters 2017-08-18 15:32:01 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt KVM/ARM Fixes for v4.13-rc4 2017-08-03 17:59:58 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS avr32: remove support for AVR32 architecture 2017-05-01 09:27:15 +02:00
Kbuild kbuild: Consolidate header generation from ASM offset information 2017-04-13 05:43:37 +09:00
Kconfig kbuild: migrate all arch to the kconfig mainmenu upgrade 2010-09-19 22:54:11 -04:00
MAINTAINERS Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:07:56 -07:00
Makefile Linux 4.13-rc6 2017-08-20 14:13:52 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.