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arm64: Make Aarch32 compatibility enablement optional at boot

Andrea della Porta linux-arm-kernel lkml 2 versions – In review

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  1. v2 Latest4 patches 4 repliesIn review
  2. v14 patches 16 repliesSuperseded

Patches in v2 No applies recorded yet

#Subject and filesSizeRepliesApplied
1/4arm64: Introduce aarch32_enabled()arch/arm64/include/asm/cpufeature.h arch/arm64/kernel/entry-common.c+17 -02 replies
2/4arm64/process: Make loading of 32bit processes depend on aarch32_enabled()arch/arm64/include/asm/cpufeature.h+3 -20 replies
3/4arm64/entry-common: Make Aarch32 exceptions' availability depend on aarch32_enabled()arch/arm64/include/asm/exception.h arch/arm64/kernel/entry-common.c+29 -32 replies
4/4arm64: Make Aarch32 support boot time configurableDocumentation/admin-guide/kernel-parameters.txt arch/arm64/Kconfig arch/arm64/kernel/entry-common.c+23 -10 replies

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Cover letter [PATCH v2 0/4] arm64: Make Aarch32 compatibility enablement optional at boot

This is the second attempt of the patch, reviewed as follows:

* Reworked subject and description to avoid the term 'emulation' and to address generically 'exceptions' instead of 'syscalls' (mark.rutland)

* Moved aarch32_enabled() check inside system_supports_32bit_el0() (mark.rutland)

* Renamed AARCH32_EMULATION_DEFAULT_DISABLED to AARCH32_SUPPORT_DEFAULT_DISABLED (mark.rutland)

* Fixed a compilation Warning about missing function prototype

Closes https://lore.kernel.org/oe-kbuild-all/[email protected]/ open here

This is just for completeness since other possible solutions have been proposed that could be better suited, see for example:
https://lkml.kernel.org/linux-fsdevel/[email protected]/
and followups. So, this patchset is just for reference, may be useful in the future if some kind of exploit is found to bypass the 32bit process enablement check (letting a process call 32bit syscalls) and nothing better has been proposed meanwhile.

Andrea della Porta (4):
arm64: Introduce aarch32_enabled() arm64/process: Make loading of 32bit processes depend on

    aarch32_enabled()
  arm64/entry-common: Make Aarch32 exceptions' availability depend on
    aarch32_enabled()

arm64: Make Aarch32 support boot time configurable

 .../admin-guide/kernel-parameters.txt         |  7 ++++
 arch/arm64/Kconfig                            |  9 +++++
 arch/arm64/include/asm/cpufeature.h           | 20 +++++++++--
 arch/arm64/include/asm/exception.h            |  7 ++++
 arch/arm64/kernel/entry-common.c              | 33 +++++++++++++++++--
 5 files changed, 71 insertions(+), 5 deletions(-)
Signature · 7 lines
2.35.3


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