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e6ed91fd |
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11-May-2022 |
Heiko Carstens <hca@linux.ibm.com> |
s390/alternatives: remove padding generation code clang fails to handle ".if" statements in inline assembly which are heavily used in the alternatives code. To work around this remove this code, and enforce that users of alternatives must specify original and alternative instruction sequences which have identical sizes. Add a compile time check with two ".org" statements similar to arm64. In result not only clang can handle this, but also quite a lot of code can be removed. Acked-by: Vasily Gorbik <gor@linux.ibm.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://github.com/ClangBuiltLinux/linux/issues/1356 Link: https://lore.kernel.org/r/20220511120532.2228616-3-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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e16d02ee |
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30-Sep-2021 |
Heiko Carstens <hca@linux.ibm.com> |
s390: introduce text_poke_sync() Introduce a text_poke_sync() similar to what x86 has. This can be used to execute a serializing instruction on all CPUs (including the current one). Note: according to the Principles of Operation an IPI (= interrupt) will already serialize a CPU, however it is better to be explicit. In addition on_each_cpu() makes sure that also the current CPU get serialized - just to make sure that possible preemption can prevent some theoretical case where a CPU will not be serialized. Therefore text_poke_sync() has to be used whenever code got modified, just to avoid to rely on implicit serialization. Also introduce text_poke_sync_lock() which will also disable CPU hotplug, to prevent that any CPU is just going online with a prefetched old version of a modified instruction. Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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17e89e13 |
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05-May-2021 |
Sven Schnelle <svens@linux.ibm.com> |
s390/facilities: move stfl information from lowcore to global data With gcc-11, there are a lot of warnings because the facility functions are accessing lowcore through a null pointer. Fix this by moving the facility arrays away from lowcore. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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6e179d64 |
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23-Mar-2018 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390: add automatic detection of the spectre defense Automatically decide between nobp vs. expolines if the spectre_v2=auto kernel parameter is specified or CONFIG_EXPOLINE_AUTO=y is set. The decision made at boot time due to CONFIG_EXPOLINE_AUTO=y being set can be overruled with the nobp, nospec and spectre_v2 kernel parameters. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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b2e2f43a |
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23-Mar-2018 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390: move nobp parameter functions to nospec-branch.c Keep the code for the nobp parameter handling with the code for expolines. Both are related to the spectre v2 mitigation. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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d768bd89 |
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15-Jan-2018 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390: add options to change branch prediction behaviour for the kernel Add the PPA instruction to the system entry and exit path to switch the kernel to a different branch prediction behaviour. The instructions are added via CPU alternatives and can be disabled with the "nospec" or the "nobp=0" kernel parameter. If the default behaviour selected with CONFIG_KERNEL_NOBP is set to "n" then the "nobp=1" parameter can be used to enable the changed kernel branch prediction. Acked-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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cf148998 |
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15-Jan-2018 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390/alternative: use a copy of the facility bit mask To be able to switch off specific CPU alternatives with kernel parameters make a copy of the facility bit mask provided by STFLE and use the copy for the decision to apply an alternative. Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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9fa1db4c |
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04-Dec-2017 |
Martin Schwidefsky <schwidefsky@de.ibm.com> |
s390: add a few more SPDX identifiers Add the correct SPDX license to a few more files under arch/s390 and drivers/s390 which have been missed to far. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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686140a1 |
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12-Oct-2017 |
Vasily Gorbik <gor@linux.vnet.ibm.com> |
s390: introduce CPU alternatives Implement CPU alternatives, which allows to optionally patch newer instructions at runtime, based on CPU facilities availability. A new kernel boot parameter "noaltinstr" disables patching. Current implementation is derived from x86 alternatives. Although ideal instructions padding (when altinstr is longer then oldinstr) is added at compile time, and no oldinstr nops optimization has to be done at runtime. Also couple of compile time sanity checks are done: 1. oldinstr and altinstr must be <= 254 bytes long, 2. oldinstr and altinstr must not have an odd length. alternative(oldinstr, altinstr, facility); alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2); Both compile time and runtime padding consists of either 6/4/2 bytes nop or a jump (brcl) + 2 bytes nop filler if padding is longer then 6 bytes. .altinstructions and .altinstr_replacement sections are part of __init_begin : __init_end region and are freed after initialization. Signed-off-by: Vasily Gorbik <gor@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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