Workarounds for CVE-2017-5715 on A9/A15 and A17 + serial console reporting #1228
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January 18, 2018 10:36
As we are using the errata framework to handle workarounds in a more general sense, change the default string to reflect that. Change-Id: I2e266af2392c9d95e18fe4e965f9a1d46fd0e95e Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
Even though the workaround for CVE-2017-5715 is not a CPU erratum, the code is piggybacking on the errata framework to print whether the workaround was applied, missing or not needed. Change-Id: I821197a4b8560c73fd894cd7cd9ecf9503c72fa3 Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
This patch introduces two workarounds for ARMv7 systems. The workarounds need to be applied prior to any `branch` instruction in secure world. This is achieved using a custom vector table where each entry is an `add sp, sp, #1` instruction. On entry to monitor mode, once the sequence of `ADD` instructions is executed, the branch target buffer (BTB) is invalidated. The bottom bits of `SP` are then used to decode the exception entry type. A side effect of this change is that the exception vectors are installed before the CPU specific reset function. This is now consistent with how it is done on AArch64. Note, on AArch32 systems, the exception vectors are typically tightly integrated with the secure payload (e.g. the Trusted OS). This workaround will need porting to each secure payload that requires it. The patch to modify the AArch32 per-cpu vbar to the corresponding workaround vector table according to the CPU type will be done in a later patch. Change-Id: I5786872497d359e496ebe0757e8017fa98f753fa Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
A per-cpu vbar is installed that implements the workaround by invalidating the branch target buffer (BTB) directly in the case of A9 and A17 and indirectly by invalidating the icache in the case of A15. For Cortex A57 and A72 there is currently no workaround implemented when EL3 is in AArch32 mode so report it as missing. For other vulnerable CPUs (e.g. Cortex A73 and Cortex A75), there are no changes since there is currently no upstream AArch32 EL3 support for these CPUs. Change-Id: Ib42c6ef0b3c9ff2878a9e53839de497ff736258f Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
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jenkins: test this please |
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jenkins: test this please |
sivadur
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Apr 10, 2018
Workarounds for CVE-2017-5715 on A9/A15 and A17 + serial console reporting (cherry picked from commit d95eb47)
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This PR includes the workarounds for A9, A15 and A17. The workarounds target sp_min but can easily be adapted to work on other implementations.
Two patches are included to enable workaround reporting on the affected AArch64 and AArch32 CPUs.