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Ard Biesheuvel f8585539df fbdev/efifb: Ignore framebuffer memmap entries that lack any memory types 
The following commit:

  38ac0287b7 ("fbdev/efifb: Honour UEFI memory map attributes when mapping the FB")

updated the EFI framebuffer code to use memory mappings for the linear
framebuffer that are permitted by the memory attributes described by the
EFI memory map for the particular region, if the framebuffer happens to
be covered by the EFI memory map (which is typically only the case for
framebuffers in shared memory). This is required since non-x86 systems
may require cacheable attributes for memory mappings that are shared
with other masters (such as GPUs), and this information cannot be
described by the Graphics Output Protocol (GOP) EFI protocol itself,
and so we rely on the EFI memory map for this.

As reported by James, this breaks some x86 systems:

  [ 1.173368] efifb: probing for efifb
  [ 1.173386] efifb: abort, cannot remap video memory 0x1d5000 @ 0xcf800000
  [ 1.173395] Trying to free nonexistent resource <00000000cf800000-00000000cf9d4bff>
  [ 1.173413] efi-framebuffer: probe of efi-framebuffer.0 failed with error -5

The problem turns out to be that the memory map entry that describes the
framebuffer has no memory attributes listed at all, and so we end up with
a mem_flags value of 0x0.

So work around this by ensuring that the memory map entry's attribute field
has a sane value before using it to mask the set of usable attributes.

Reported-by: James Hilliard <james.hilliard1@gmail.com>
Tested-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: <stable@vger.kernel.org> # v4.19+
Cc: Borislav Petkov <bp@alien8.de>
Cc: James Morse <james.morse@arm.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 38ac0287b7 ("fbdev/efifb: Honour UEFI memory map attributes when ...")
Link: http://lkml.kernel.org/r/20190516213159.3530-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
 		2019-05-17 11:07:42 +02:00
..
backlight lib/math: move int_pow() from pwm_bl.c for wider use 2019-05-14 19:52:49 -07:00
console vgacon: unconfuse vc_origin when using soft scrollback 2019-01-18 13:45:22 +01:00
fbdev fbdev/efifb: Ignore framebuffer memmap entries that lack any memory types 2019-05-17 11:07:42 +02:00
logo fbdev: fbmem: convert CONFIG_FB_LOGO_CENTER into a cmd line option 2019-01-16 17:42:35 +01:00
Kconfig fbdev changes for v4.17: 2018-04-10 10:20:00 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
display_timing.c
…
hdmi.c drm-misc-next for v4.21, part 1: 2018-11-19 10:40:33 +10:00
of_display_timing.c fbdev: Convert to using %pOFn instead of device_node.name 2018-10-08 12:57:36 +02:00
of_videomode.c video: fbdev: Convert to using %pOF instead of full_name 2017-08-07 17:22:13 +02:00
vgastate.c Video: vgastate: fixed a spacing coding style 2018-10-08 12:57:35 +02:00
videomode.c
…