Refactor VFP support code and reimplement in C

The VFP related changes to permit kernel mode NEON in softirq context
 resulted in some issues regarding en/disabling of sofirqs from asm code,
 and this made it clear that it would be better to handle more of it from
 C code.
 
 Given that we already have infrastructure that associates undefined
 instruction exceptions with handler code based on value/mask pairs, we
 can easily move the dispatch of VFP and NEON instructions to C code once
 we reimplement the actual VFP support routine (which reasons about how
 to deal with the exception and whether any emulation is needed) in C
 code first.
 
 With those out of the way, we can drop the partial decoding logic in asm
 that reasons about which ISA is being used by user space, as the
 remaining cases are all 32-bit ARM only. This leaves a FPE specific
 routine with some iWMMXT logic that is easily duplicated in C as well,
 allowing us to move the FPE asm code into the FPE asm source file, and
 out of the shared entry code.
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Merge tag 'arm-vfp-refactor-for-rmk' of git://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux into devel-stable

Refactor VFP support code and reimplement in C

The VFP related changes to permit kernel mode NEON in softirq context
resulted in some issues regarding en/disabling of sofirqs from asm code,
and this made it clear that it would be better to handle more of it from
C code.

Given that we already have infrastructure that associates undefined
instruction exceptions with handler code based on value/mask pairs, we
can easily move the dispatch of VFP and NEON instructions to C code once
we reimplement the actual VFP support routine (which reasons about how
to deal with the exception and whether any emulation is needed) in C
code first.

With those out of the way, we can drop the partial decoding logic in asm
that reasons about which ISA is being used by user space, as the
remaining cases are all 32-bit ARM only. This leaves a FPE specific
routine with some iWMMXT logic that is easily duplicated in C as well,
allowing us to move the FPE asm code into the FPE asm source file, and
out of the shared entry code.
This commit is contained in:
Russell King (Oracle) 2023-06-27 14:17:19 +01:00
commit 53ae158f6d
205 changed files with 3178 additions and 2555 deletions

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