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Sam Ravnborg 4bba72b72c drm/drm_fb_helper: fix fbdev with sparc64 
[ Upstream commit 2a1658bf92 ]

Recent kernels have been reported to panic using the bochs_drm
framebuffer under qemu-system-sparc64 which was bisected to
commit 7a0483ac4f ("drm/bochs: switch to generic drm fbdev emulation").

The backtrace indicates that the shadow framebuffer copy in
drm_fb_helper_dirty_blit_real() is trying to access the real
framebuffer using a virtual address rather than use an IO access
typically implemented using a physical (ASI_PHYS) access on SPARC.

The fix is to replace the memcpy with memcpy_toio() from io.h.

memcpy_toio() uses writeb() where the original fbdev code
used sbus_memcpy_toio(). The latter uses sbus_writeb().

The difference between writeb() and sbus_memcpy_toio() is
that writeb() writes bytes in little-endian, where sbus_writeb() writes
bytes in big-endian. As endian does not matter for byte writes they are
the same. So we can safely use memcpy_toio() here.

Note that this only fixes bochs, in general fbdev helpers still have
issues with mixing up system memory and __iomem space. Fixing that will
require a lot more work.

v3:
  - Improved changelog (Daniel)
  - Added FIXME to fbdev_use_iomem (Daniel)

v2:
  - Added missing __iomem cast (kernel test robot)
  - Made changelog readable and fix typos (Mark)
  - Add flag to select iomem - and set it in the bochs driver

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reported-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reported-by: kernel test robot <lkp@intel.com>
Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: sparclinux@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20200709193016.291267-1-sam@ravnborg.org
Link: https://patchwork.freedesktop.org/patch/msgid/20200725191012.GA434957@ravnborg.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2020-08-11 15:33:37 +02:00
Documentation doc: dt: bindings: usb: dwc3: Update entries for disabling SS instances in park mode 2020-07-22 09:32:59 +02:00
LICENSES
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arch arm64: Workaround circular dependency in pointer_auth.h 2020-08-07 09:34:01 +02:00
block block: fix get_max_segment_size() overflow on 32bit arch 2020-07-22 09:33:17 +02:00
certs
…
crypto keys: asymmetric: fix error return code in software_key_query() 2020-07-22 09:33:04 +02:00
drivers drm/drm_fb_helper: fix fbdev with sparc64 2020-08-11 15:33:37 +02:00
fs io_uring: Fix use-after-free in io_sq_wq_submit_work() 2020-08-11 15:33:33 +02:00
include drm/drm_fb_helper: fix fbdev with sparc64 2020-08-11 15:33:37 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel perf/core: Fix endless multiplex timer 2020-08-11 15:33:32 +02:00
lib random32: remove net_rand_state from the latent entropy gcc plugin 2020-08-07 09:34:01 +02:00
mm mm/filemap.c: don't bother dropping mmap_sem for zero size readahead 2020-08-05 09:59:41 +02:00
net net/9p: validate fds in p9_fd_open 2020-08-11 15:33:36 +02:00
samples samples/vfs: avoid warning in statx override 2020-07-09 09:37:54 +02:00
scripts scripts: add dummy report mode to add_namespace.cocci 2020-08-11 15:33:35 +02:00
security Smack: fix use-after-free in smk_write_relabel_self() 2020-08-11 15:33:35 +02:00
sound ALSA: seq: oss: Serialize ioctls 2020-08-11 15:33:33 +02:00
tools selftests: bpf: Fix detach from sockmap tests 2020-08-07 09:34:02 +02:00
usr
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virt KVM: arm64: Don't inherit exec permission across page-table levels 2020-08-05 09:59:51 +02:00
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.gitattributes
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COPYING
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CREDITS
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Kbuild
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Kconfig
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MAINTAINERS
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Makefile Linux 5.4.57 2020-08-07 09:34:02 +02:00
README
…

README 

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.