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Maciej W. Rozycki 326f02f172 MIPS: Fix CP0 counter erratum detection for R4k CPUs
commit f0a6c68f69981214cb7858738dd2bc81475111f7 upstream.

Fix the discrepancy between the two places we check for the CP0 counter
erratum in along with the incorrect comparison of the R4400 revision
number against 0x30 which matches none and consistently consider all
R4000 and R4400 processors affected, as documented in processor errata
publications[1][2][3], following the mapping between CP0 PRId register
values and processor models:

  PRId   |  Processor Model
---------+--------------------
00000422 | R4000 Revision 2.2
00000430 | R4000 Revision 3.0
00000440 | R4400 Revision 1.0
00000450 | R4400 Revision 2.0
00000460 | R4400 Revision 3.0

No other revision of either processor has ever been spotted.

Contrary to what has been stated in commit ce202cbb9e ("[MIPS] Assume
R4000/R4400 newer than 3.0 don't have the mfc0 count bug") marking the
CP0 counter as buggy does not preclude it from being used as either a
clock event or a clock source device.  It just cannot be used as both at
a time, because in that case clock event interrupts will be occasionally
lost, and the use as a clock event device takes precedence.

Compare against 0x4ff in `can_use_mips_counter' so that a single machine
instruction is produced.

References:

[1] "MIPS R4000PC/SC Errata, Processor Revision 2.2 and 3.0", MIPS
    Technologies Inc., May 10, 1994, Erratum 53, p.13

[2] "MIPS R4400PC/SC Errata, Processor Revision 1.0", MIPS Technologies
    Inc., February 9, 1994, Erratum 21, p.4

[3] "MIPS R4400PC/SC Errata, Processor Revision 2.0 & 3.0", MIPS
    Technologies Inc., January 24, 1995, Erratum 14, p.3

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: ce202cbb9e ("[MIPS] Assume R4000/R4400 newer than 3.0 don't have the mfc0 count bug")
Cc: stable@vger.kernel.org # v2.6.24+
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-12 12:25:29 +02:00
arch MIPS: Fix CP0 counter erratum detection for R4k CPUs 2022-05-12 12:25:29 +02:00
block iocost: don't reset the inuse weight of under-weighted debtors 2022-05-09 09:05:00 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: authenc - Fix sleep in atomic context in decrypt_tail 2022-04-08 14:39:59 +02:00
Documentation ext4, doc: fix incorrect h_reserved size 2022-04-27 13:53:57 +02:00
drivers tty: n_gsm: fix software flow control handling 2022-05-09 09:05:08 +02:00
fs zonefs: Clear inode information flags on inode creation 2022-05-09 09:05:06 +02:00
include tcp: make sure treq->af_specific is initialized 2022-05-09 09:05:04 +02:00
init init/main.c: return 1 from handled __setup() functions 2022-04-13 21:01:01 +02:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:19:10 +01:00
kernel perf/core: Fix perf_mmap fail when CONFIG_PERF_USE_VMALLOC enabled 2022-04-27 13:53:56 +02:00
lib hex2bin: fix access beyond string end 2022-05-09 09:04:59 +02:00
LICENSES
mm kasan: prevent cpu_quarantine corruption when CPU offline and cache shrink occur at same time 2022-05-09 09:05:07 +02:00
net netfilter: nft_socket: only do sk lookups when indev is available 2022-05-09 09:05:08 +02:00
samples samples/bpf, xdpsock: Fix race when running for fix duration of time 2022-04-08 14:40:21 +02:00
scripts gcc-plugins: latent_entropy: use /dev/urandom 2022-04-20 09:23:26 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-08 14:40:31 +02:00
sound ASoC: wm8731: Disable the regulator when probing fails 2022-05-09 09:05:06 +02:00
tools perf symbol: Remove arch__symbols__fixup_end() 2022-05-09 09:05:09 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Prevent module exit until all VMs are freed 2022-04-08 14:40:38 +02:00
.clang-format
.cocciconfig
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MAINTAINERS MAINTAINERS: adjust GCC PLUGINS after gcc-plugin.sh removal 2021-12-14 11:32:46 +01:00
Makefile Linux 5.10.114 2022-05-09 09:05:09 +02:00
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