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Christophe Leroy f2719b26ae video: fbdev: chipsfb: use memset_io() instead of memset()
While investigating a lockup at startup on Powerbook 3400C, it was
identified that the fbdev driver generates alignment exception at
startup:

  --- interrupt: 600 at memset+0x60/0xc0
  NIP:  c0021414 LR: c03fc49c CTR: 00007fff
  REGS: ca021c10 TRAP: 0600   Tainted: G        W          (5.14.2-pmac-00727-g12a41fa69492)
  MSR:  00009032 <EE,ME,IR,DR,RI>  CR: 44008442  XER: 20000100
  DAR: cab80020 DSISR: 00017c07
  GPR00: 00000007 ca021cd0 c14412e0 cab80000 00000000 00100000 cab8001c 00000004
  GPR08: 00100000 00007fff 00000000 00000000 84008442 00000000 c0006fb4 00000000
  GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00100000
  GPR24: 00000000 81800000 00000320 c15fa400 c14d1878 00000000 c14d1800 c094e19c
  NIP [c0021414] memset+0x60/0xc0
  LR [c03fc49c] chipsfb_pci_init+0x160/0x580
  --- interrupt: 600
  [ca021cd0] [c03fc46c] chipsfb_pci_init+0x130/0x580 (unreliable)
  [ca021d20] [c03a3a70] pci_device_probe+0xf8/0x1b8
  [ca021d50] [c043d584] really_probe.part.0+0xac/0x388
  [ca021d70] [c043d914] __driver_probe_device+0xb4/0x170
  [ca021d90] [c043da18] driver_probe_device+0x48/0x144
  [ca021dc0] [c043e318] __driver_attach+0x11c/0x1c4
  [ca021de0] [c043ad30] bus_for_each_dev+0x88/0xf0
  [ca021e10] [c043c724] bus_add_driver+0x190/0x22c
  [ca021e40] [c043ee94] driver_register+0x9c/0x170
  [ca021e60] [c0006c28] do_one_initcall+0x54/0x1ec
  [ca021ed0] [c08246e4] kernel_init_freeable+0x1c0/0x270
  [ca021f10] [c0006fdc] kernel_init+0x28/0x11c
  [ca021f30] [c0017148] ret_from_kernel_thread+0x14/0x1c
  Instruction dump:
  7d4601a4 39490777 7d4701a4 39490888 7d4801a4 39490999 7d4901a4 39290aaa
  7d2a01a4 4c00012c 4bfffe88 0fe00000 <4bfffe80> 9421fff0 38210010 48001970

This is due to 'dcbz' instruction being used on non-cached memory.
'dcbz' instruction is used by memset() to zeroize a complete
cacheline at once, and memset() is not expected to be used on non
cached memory.

When performing a 'sparse' check on fbdev driver, it also appears
that the use of memset() is unexpected:

  drivers/video/fbdev/chipsfb.c:334:17: warning: incorrect type in argument 1 (different address spaces)
  drivers/video/fbdev/chipsfb.c:334:17:    expected void *
  drivers/video/fbdev/chipsfb.c:334:17:    got char [noderef] __iomem *screen_base
  drivers/video/fbdev/chipsfb.c:334:15: warning: memset with byte count of 1048576

Use fb_memset() instead of memset(). fb_memset() is defined as
memset_io() for powerpc.

Fixes: 8c8709334c ("[PATCH] ppc32: Remove CONFIG_PMAC_PBOOK")
Reported-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/884a54f1e5cb774c1d9b4db780209bee5d4f6718.1631712563.git.christophe.leroy@csgroup.eu
2021-10-09 00:15:59 +11:00
Documentation Devicetree fixes for v5.15, take 2: 2021-09-18 12:40:55 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch powerpc/powernv/dump: Fix typo in comment 2021-10-09 00:15:59 +11:00
block blk-cgroup: fix UAF by grabbing blkcg lock before destroying blkg pd 2021-09-15 12:03:18 -06:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
drivers video: fbdev: chipsfb: use memset_io() instead of memset() 2021-10-09 00:15:59 +11:00
fs iov_iter.3-5.15-2021-09-17 2021-09-17 09:23:44 -07:00
include pci_iounmap'2: Electric Boogaloo: try to make sense of it all 2021-09-19 17:13:35 -07:00
init memblock: introduce saner 'memblock_free_ptr()' interface 2021-09-14 13:23:22 -07:00
ipc ipc: remove memcg accounting for sops objects in do_semtimedop() 2021-09-14 10:22:11 -07:00
kernel A single fix for the perf core where a value read with READ_ONCE() was 2021-09-19 13:22:40 -07:00
lib pci_iounmap'2: Electric Boogaloo: try to make sense of it all 2021-09-19 17:13:35 -07:00
mm memblock: introduce saner 'memblock_free_ptr()' interface 2021-09-14 13:23:22 -07:00
net Networking fixes for 5.15-rc2, including fixes from bpf. 2021-09-16 13:05:42 -07:00
samples kgdb patches for 5.15 2021-09-07 12:08:04 -07:00
scripts Kbuild fixes for v5.15 2021-09-19 12:55:12 -07:00
security Kbuild updates for v5.15 2021-09-03 15:33:47 -07:00
sound sound fixes for 5.15-rc1 2021-09-09 16:05:10 -07:00
tools powerpc fixes for 5.15 #2 2021-09-19 13:00:23 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Drop unused kvm_dirty_gfn_invalid() 2021-09-06 08:23:46 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update email address of Matthias Fuchs and Thomas Körper 2021-08-19 09:39:44 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: Add Nirmal Patel as VMD maintainer 2021-09-15 16:44:03 -05:00
Makefile Linux 5.15-rc2 2021-09-19 17:28:22 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.