linux/arch/arm/vfp
Ard Biesheuvel c79f816311 ARM: 9283/1: permit non-nested kernel mode NEON in softirq context
We currently only permit kernel mode NEON in process context, to avoid
the need to preserve/restore the NEON register file when taking an
exception while running in the kernel.

Like we did on arm64, we can relax this restriction substantially, by
permitting kernel mode NEON from softirq context, while ensuring that
softirq processing is disabled when the NEON is being used in task
context. This guarantees that only NEON context belonging to user space
needs to be preserved and restored, which is already taken care of.

This is especially relevant for network encryption, where incoming
frames are typically handled in softirq context, and deferring software
decryption to a kernel thread or falling back to C code are both
undesirable from a performance PoV.

Tested-by: Martin Willi <martin@strongswan.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
2023-01-11 16:21:21 +00:00
..
entry.S ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled 2023-01-11 16:21:20 +00:00
Makefile ARM: 8989/1: use .fpu assembler directives instead of assembler arguments 2020-07-21 16:33:37 +01:00
vfp.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
vfpdouble.c
vfphw.S ARM: 9282/1: vfp: Manipulate task VFP state with softirqs disabled 2023-01-11 16:21:20 +00:00
vfpinstr.h ARM: 8991/1: use VFP assembler mnemonics if available 2020-07-21 16:33:39 +01:00
vfpmodule.c ARM: 9283/1: permit non-nested kernel mode NEON in softirq context 2023-01-11 16:21:21 +00:00
vfpsingle.c