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PJ4 is a v7 core that incorporates a iWMMXt coprocessor. However, GCC
does not support this combination (its iWMMXt configuration always
implies v5te), and so there is no v6/v7 user space that actually makes
use of this, beyond generic support for things like setjmp() that
preserve/restore the iWMMXt register file using generic LDC/STC
instructions emitted in assembler. As [0] appears to imply, this logic
is triggered for the init process at boot, and so most user threads will
have a iWMMXt register context associated with it, even though it is
never used.
At this point, it is highly unlikely that such GCC support will ever
materialize (and Clang does not implement support for iWMMXt to begin
with).
This means that advertising iWMMXt support on these cores results in
context switch overhead without any associated benefit, and so it is
better to simply ignore the iWMMXt unit on these systems. So rip out the
support. Doing so also fixes the issue reported in [0] related to UNDEF
handling of co-processor #0/#1 instructions issued from user space
running in Thumb2 mode.
The PJ4 cores are used in four platforms: Armada 370/xp, Dove (Cubox,
d2plug), MMP2 (xo-1.75) and Berlin (Google TV). Out of these, only the
first is still widely used, but that one actually doesn't have iWMMXt
but instead has only VFPV3-D16, and so it is not impacted by this
change.
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218427 [0]
Fixes: 8bcba70cb5c22 ("ARM: entry: Disregard Thumb undef exception ...")
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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Define a undef hook to deal with undef exceptions triggered by iwmmxt
instructions that were issued with the coprocessor disabled. This
removes the dependency on the coprocessor dispatch code in entry-armv.S,
which will be made NWFPE-only in a subsequent patch.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The PJ4 inline asm sequence to write to cp15 cannot be built in Thumb-2
mode, due to the way it performs arithmetic on the program counter, so it
is built in ARM mode instead. However, building C files in ARM mode under
CONFIG_THUMB2_KERNEL is problematic, since the instrumentation performed
by subsystems like ftrace does not expect having to deal with interworking
branches.
Since the sequence in question is simply a poor man's ISB instruction,
let's use a straight 'isb' instead when building in Thumb2 mode. Thumb2
implies V7, so 'isb' should always be supported in that case.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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commit fdb487f5c961b94486a78fa61fa28b8eff1954ab
("ARM: 8015/1: Add cpu_is_pj4 to distinguish PJ4 because it
has some differences with V7")
introduced a fix for checking PJ4 cpuid to not use PJ4 specific
coprocessor access on non-PJ4 platforms.
Unfortunately, this in turn broke Marvell Armada 370/XP, both
comprising Marvell PJ4B CPUs without iWMMXt extension. Instead
of only checking for cpuid, which may not be sufficient to
determine iWMMXt support, the presence of iWMMXt coprocessors
can be checked by enabling and reading the Coprocessor ID
register (wCID, register 0 of CP1).
Therefore this adds an explicit check for the presence and correct
wCID value, before enabling iWMMXt capabilities. As a bonus, also
print the iWMMXt version of a detected coprocessor.
This has been tested to properly detect iWMMXt presence/absence on:
- PJ4, CPUID 0x560f5815, wCID 0x56052001: Marvell Dove, iWMMXt v2
- PJ4B, CPUID 0x561f5811: Marvell Armada 370, no iWMMXt
- PJ4B, CPUID 0x562f5841, wCID 0x56052001: Marvell Armada 1500, iWMMXt v2
- PJ4B, CPUID 0x562f5842: Marvell Armada XP, no iWMMXt
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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This fixes PJ4 coprocessor init to only expose iWMMXt capabilities,
if the corresponding kernel support for iWMMXt is enabled.
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Check cpu id in pj4_cp0_init. So for no-PJ4 V7 cpus,
pj4_cpu0_init just return.
This fix will help to make the all the V7 cpus(PJ4 and no-PJ4)
can use code.
Signed-off-by: Chao Xie <chao.xie@marvell.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Building these files does not reveal a hidden need for
any of these. Since module.h brings in the whole kitchen
sink, it just needlessly adds 30k+ lines to the cpp burden.
There are probably lots more, but ARM files of mach-* and plat-*
don't get coverage via a simple yesconfig build. They will have
to be cleaned up and tested via using their respective configs.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
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iwmmxt is used in XScale, XScale3, Mohawk and PJ4 core. But the instructions
of accessing CP0 and CP1 is changed in PJ4. Append more files to support
iwmmxt in PJ4 core.
Signed-off-by: Zhou Zhu <zzhu3@marvell.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
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