[PATCH v2 0/9] arm64: rework UNDEFINED instruction traps

Mark Rutland
2022-10-19T15:01:16Z

This series reworks the way UNDEFINED instruction traps are handled,
removing some dynamic data structure manipulation and related locking.
This makes the code a bit simpler and removes some unnecessary
bottlenecks when traps are handled.

My original aim for this series was to get rid of the RCU_NONIDLE() call
in cpu_suspend(), requiring the removal of the undef_hook list
manipulation. In the process of looking at that I figured we had a set
of related problems with UNDEF handling and deprecated instruction
handling, which this series addresses. This series does not remove the
RCU_NONIDLE() call from cpu_suspend() as removing that will require
further rework of the suspend code (e.g. for noinstr safety).

I've tested this series in VMs on ThunderX2 (for the ID reg emulation
changes) and a Raspberry Pi 4 (for the armv8_deprecated changes), as
described in the relevant commits.

Since v1 [1]:
* Rebase atop v6.1-rc1
* Fix typos

[1] https://lore.kernel.org/linux-arm-kernel/20220928102659.247510-1-mark.rutland@arm.com/

Thanks,
Mark.

Mark Rutland (9):
arm64: allow kprobes on EL0 handlers
arm64: split EL0/EL1 UNDEF handlers
arm64: factor out EL1 SSBS emulation hook
arm64: factor insn read out of call_undef_hook()
arm64: rework EL0 MRS emulation
arm64: armv8_deprecated: fold ops into insn_emulation
arm64: armv8_deprecated move emulation functions
arm64: armv8_deprecated: move aarch32 helper earlier
arm64: armv8_deprecated: rework deprected instruction handling

arch/arm64/include/asm/cpufeature.h | 3 +-
arch/arm64/include/asm/exception.h | 7 +-
arch/arm64/include/asm/spectre.h | 2 +
arch/arm64/include/asm/traps.h | 19 +-
arch/arm64/kernel/armv8_deprecated.c | 567 +++++++++++++--------------
arch/arm64/kernel/cpufeature.c | 23 +-
arch/arm64/kernel/entry-common.c | 8 +-
arch/arm64/kernel/proton-pack.c | 26 +-
arch/arm64/kernel/traps.c | 93 ++---
9 files changed, 345 insertions(+), 403 deletions(-)