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path: root/arch/s390/kernel/nospec-branch.c (follow)
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2018-07-18s390: detect etoken facilityMartin Schwidefsky1-1/+11
Detect and report the etoken facility. With spectre_v2=auto or CONFIG_EXPOLINE_AUTO=y automatically disable expolines and use the full branch prediction mode for the kernel. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-05-09s390: remove closung punctuation from spectre messagesMartin Schwidefsky1-2/+2
There should not be a '.' at the end of the spectre syslog messages. Remove them. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-05-07s390: extend expoline to BC instructionsMartin Schwidefsky1-5/+20
The BPF JIT uses a 'b <disp>(%r<x>)' instruction in the definition of the sk_load_word and sk_load_half functions. Add support for branch-on-condition instructions contained in the thunk code of an expoline. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-05-07s390: move spectre sysfs attribute codeMartin Schwidefsky1-19/+0
The nospec-branch.c file is compiled without the gcc options to generate expoline thunks. The return branch of the sysfs show functions cpu_show_spectre_v1 and cpu_show_spectre_v2 is an indirect branch as well. These need to be compiled with expolines. Move the sysfs functions for spectre reporting to a separate file and loose an '.' for one of the messages. Cc: stable@vger.kernel.org # 4.16 Fixes: d424986f1d ("s390: add sysfs attributes for spectre") Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-04-16s390/nospec: include cpu.hSebastian Ott1-0/+1
Fix the following sparse warnings: symbol 'cpu_show_spectre_v1' was not declared. Should it be static? symbol 'cpu_show_spectre_v2' was not declared. Should it be static? Signed-off-by: Sebastian Ott <sebott@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-04-11s390: correct nospec auto detection init orderMartin Schwidefsky1-6/+2
With CONFIG_EXPOLINE_AUTO=y the call of spectre_v2_auto_early() via early_initcall is done *after* the early_param functions. This overwrites any settings done with the nobp/no_spectre_v2/spectre_v2 parameters. The code patching for the kernel is done after the evaluation of the early parameters but before the early_initcall is done. The end result is a kernel image that is patched correctly but the kernel modules are not. Make sure that the nospec auto detection function is called before the early parameters are evaluated and before the code patching is done. Fixes: 6e179d64126b ("s390: add automatic detection of the spectre defense") Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-03-28s390: add sysfs attributes for spectreMartin Schwidefsky1-0/+19
Set CONFIG_GENERIC_CPU_VULNERABILITIES and provide the two functions cpu_show_spectre_v1 and cpu_show_spectre_v2 to report the spectre mitigations. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-03-28s390: report spectre mitigation via syslogMartin Schwidefsky1-0/+10
Add a boot message if either of the spectre defenses is active. The message is "Spectre V2 mitigation: execute trampolines." or "Spectre V2 mitigation: limited branch prediction." Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-03-28s390: add automatic detection of the spectre defenseMartin Schwidefsky1-26/+42
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>
2018-03-28s390: move nobp parameter functions to nospec-branch.cMartin Schwidefsky1-0/+27
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>
2018-02-19s390: Replace IS_ENABLED(EXPOLINE_*) with IS_ENABLED(CONFIG_EXPOLINE_*)Eugeniu Rosca1-2/+2
I've accidentally stumbled upon the IS_ENABLED(EXPOLINE_*) lines, which obviously always evaluate to false. Fix this. Fixes: f19fbd5ed642 ("s390: introduce execute-trampolines for branches") Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2018-02-07s390: introduce execute-trampolines for branchesMartin Schwidefsky1-0/+100
Add CONFIG_EXPOLINE to enable the use of the new -mindirect-branch= and -mfunction_return= compiler options to create a kernel fortified against the specte v2 attack. With CONFIG_EXPOLINE=y all indirect branches will be issued with an execute type instruction. For z10 or newer the EXRL instruction will be used, for older machines the EX instruction. The typical indirect call basr %r14,%r1 is replaced with a PC relative call to a new thunk brasl %r14,__s390x_indirect_jump_r1 The thunk contains the EXRL/EX instruction to the indirect branch __s390x_indirect_jump_r1: exrl 0,0f j . 0: br %r1 The detour via the execute type instruction has a performance impact. To get rid of the detour the new kernel parameter "nospectre_v2" and "spectre_v2=[on,off,auto]" can be used. If the parameter is specified the kernel and module code will be patched at runtime. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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